ĶĪMIJAS SEKCIJA - LU

LATVIJAS UNIVERSITĀTES 76. STARPTAUTISKĀ KONFERENCE

ĶĪMIJAS SEKCIJA

Tēžu krājums

2018

Redkolēģija:prof. Edgars Sūnaprof. Arturs Vīksna

Tēžu krājums publicēts autoru redakcijā

Maketētāja Andra Liepiņa

© Latvijas Universitāte, 2018

ISBN 978-9934-18-305-8

SATURS

PLENĀRREFERĀTI ĶĪMIJAS NOZARĒ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Aleksej Zarkov, Andrius Stanulis, Matas Grigaliunas, Aivaras KareivaCHEMICAL SOLUTION DEPOSITION OF FUNCTIONAL OXIDE THIN FILMS . . . . . . . . . . . . . . . . . . . . . 6Vilma Brimienė, Ramūnas Skaudžius, Martynas Misevičius, Gintautas Brimas, Edvardas Brimas, Algirdas Selskis and Aivaras Kareiva3D RECONSTRUCTION OF SEM IMAGES OF ADIPOSE TISSUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Guntars VaivarsINNOVATIVE ADVANCED MATERIALS USING MODIFIED SPEEK MEMBRANES . . . . . . . . . . . . . . . . . 8

ANALĪTISKĀS UN FIZIKĀLĀS ĶĪMIJAS SEKCIJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Agris Auce, Indulis Andris Horns, C. Ipbüker, Alan H. TkaczykSTRUCTURE OF TRAINING AND PREPARATION OF NATIONAL INDUSTRY FOR NUCLEAR POWER PLANT CONSTRUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Līga Avotiņa, Dāvis Čonka, Andris Leščinskis, Elīna Pajuste, Larisa Baumane, Arnis Supe, Gunta Ķizāne and JET ContributorsANALYSIS OF PARAMAGNETIC CENTERS IN CARBON BASED DIVERTOR MATERIALS . . . . . . . . . 12Ilze Blūma, Agnese OsīteANALYSIS OF PARTICULATE MATTER ORIGINATED DURING BURNING OF SCENTED CANDLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Estefanija Bogdanova, Irina Rozentale, Iveta Pugajeva, Emeka E. Emecheta, Ingars Reinholds, Vadims BartkevicsTHE OCCURENCE AND RISK ASSESSMENT OF MYCOTOXINS, ACRYLAMIDE AND FURAN IN BEER PRODUCED IN LATVIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Lauma Buša, Krišs Dāvids Labsvārds, Arturs VīksnaPRELIMINARY RESULTS IN USE OF SIRMS TO DETERMINE LATVIAN AND GEORGIAN HONEY AUTHENTICITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Lauma Buša, Dmitrijs Ponomarjovs, Arturs Vīksnaδ15N AND δ13C VALUES AS POSSIBLE MARKERS FOR DISTINGUISHING BETWEEN ORGANIC AND CONVENTIONAL GRAINS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Vladlens Grebņevs, Arturs Vīksna, Oskars Purmalis, Liene PlūdumaANALYTICAL CHARACTERIZATION OF HYDROXYAPATITES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Ieva Igaune, Elīna Pajuste, Gunta ĶizāneCOMPARISON OF THE STRUCTURE OF THE PLASMA-FACEING SURFACE AND TRITIUM ACCUMULATION IN BERYLLIUM TILES FROM JET ILW CAMPAIGNS 2011–2012 AND 2013–2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Mārtiņš Jansons, Iveta Pugajeva, Vadims BartkevičsOCCURRENCE OF GLYPHOSATE IN BEER FROM THE LATVIAN MARKET . . . . . . . . . . . . . . . . . . . . . . . 20Marta Kāne, Deniss Fedorenko, Guntars VaivarsION CONDUCTING MODIFIED SPEEK MEMBRANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Anna Lankovska, Līga Avotiņa, Pēteris Mekšs, Valentīna Kinerte, Gunta ĶizāneAPPLICATION OF ELECTRON IRRADIATION FOR DEVULCANIZATION OF TYRE MATERIAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Māris Lauberts, Tatjana Dižbite, Arturs Vīksna, Gaļina TeliševaISOLATION OF POLYPHENOLS FROM DIFFERENT PLANT BIOMASS PROCESSING RESIDUES APPLIED ENVIRONMENTALLY FRIENDLY EXTRACTION METHODS AND COMPREHENSIVE CHARACTERIZATION OF THE PRODUCTS OBTAINED . . . . . . . . . . . . . . . . . . . . . . 24Laura Elina Ikkere, Ingus Pērkons, Vadims BartkevicsPERSISTENT ORGANIC POLLUTANTS IN FRESHWATER MUSSELS FROM THE LATVIAN ENVIRONMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Vitālijs Lazarenko, Zenta Balcerbule, Egita ĒrmaneTHE VARIATION OF PHOSPHORUS, SULFUR AND NITROGEN IN LICHENS DEPENDING ON LOCATION AREA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Kristīne Meile, Daniela Godiņa, Arturs Vīksna, Aivars ŽūriņšDETERMINATION OF THE PURITY OF BIOMASS-BASED LEVOGLUCOSAN . . . . . . . . . . . . . . . . . . . . . . 27

Matīss Pāls, Līga Lauberte, Galina Teliševa, Arturs Viksna, Ilva NakurteDETERMINATION OF OLIGOMERIC PROANTHOCYANIDINS IN WILLOW BARK BY UPLC-MS/MS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Elīna Sala, Toms Rēķis, Agris BērziņšEXPERIMENTAL AND COMPUTATIONAL STUDY OF SOLID SOLUTIONS FORMED BY MALIC ACID ENANTIOMERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Anna Trubača-Boginska, Andris Actiņš, Jānis Švirksts, Anda PrikšāneILLITE CLAY MINERAL ION EXCHANGE AND APPLYING OF THIS PHENOMENON IN PRACTICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Dārta Ūbele, Liene Plūduma, Kārlis Agris GrossINCREASING HYDROXYL ION CONCENTRATION OF THERMALLY SPRAYED HYDROXYAPATITE COATINGS BY HYDROTHERMAL TREATMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Valda Valkovska, Agnese Osīte, Vizma NikolajevaTHE EFFECTS OF HYDROTHERMAL PROCESSING IN PRESENCE OF H2O2 ON ANTIBACTERIAL ACTIVITY OF STRONTIUM SUBSTITUTED APATITE . . . . . . . . . . . . . . . . . . . . . . . . . 33Vanda Voikiva, Liga Avotina, Valentina Kinerte, Gunta Kizane, Larisa BaumaneANALYSIS CHEMICAL BONDS AND FREE RADICALS IN RADIATION MODIFICATED LATVIAN SHEEP WOOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

ORGANISKĀS ĶĪMIJAS SEKCIJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Simonas Balkaitis, Inga ČikotienėSYNTHESIS AND CYCLISATIONS OF N-(3-ARYLPROP-2-YNYL) DERIVATIVES OF BENZAMIDES, CARBAMATES AND THIOUREAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Haralds Baunis, Olesja KoledaDDQ MEDIATED ELECTROCHEMICAL CLEAVAGE OF THE PARA-METHOXYBENZYL PROTECTING GROUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Rūdolfs Beļaunieks, Andis Melderis, Uldis Peipiņš, Māris TurksSYNTHESIS OF NOVEL TRITERPENOID-1,2,3-TRIAZOLE CONJUGATES . . . . . . . . . . . . . . . . . . . . . . . . . 38Toms IzmailovsSYNTHESIS OF HETEROCYCLIC KETONES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Mantas Jonušis, Kaspars LeduskrastsSYNTHESIS AND PHOTOPHYSICAL PROPERTIES OF SOME 2,3,5-TRISUBSTITUTED THIOPHENE DERIVATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Zigfrīds Kapilinskis, Armands Sebris, Irina Novosjolova, Māris TurksSYNTHESIS AND PHOTOPHYSICAL PROPERTIES OF N(9)-ALKYLATED PURINE DERIVATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Sindija LapčinskaSYNTHETIC ROUTE TOWARDS LEPADINS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Linda PudnikaSYNTHESIS OF BENZO[B]OXEPIN-2-(3H)-ONE DERIVATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Mikus Puriņš, Māris TurksBRØNSTED ACID CATALYSED 1,2-SILYL SHIFT IN PROPARGYL SILANES . . . . . . . . . . . . . . . . . . . . . . . . 44Mārcis SējējsPARALLEL KINETIC RESOLUTION OF TETRAZOLE HEMIAMINAL ENOLATES . . . . . . . . . . . . . . . . . . 45Anda Sīpola, Unda Nelda DubovaDESIGN AND SYNTHESIS OF SMALL-MOLECULE HEPATITIS B VIRUS CAPSID SELF-ASSEMBLY INHIBITORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Krista Suta, Jevgeņija Lugiņina, Māris TurksSTUDY ON GLYCOSYLATION OF ALCOHOLS AND THIOLS IN LIQUID SO2 . . . . . . . . . . . . . . . . . . . . . . 47

PLENĀRREFERĀTI ĶĪMIJAS NOZARĒ

6 LATVIJAS UNIVERSITĀTES 76. STARPTAUTISKĀ KONFERENCE

CHEMICAL SOLUTION DEPOSITION OF FUNCTIONAL OXIDE THIN FILMSAleksej Zarkov1, Andrius Stanulis2, Matas Grigaliunas1, Aivaras Kareiva1

1 Institute of Chemistry, Vilnius University, Naugarduko 24, Vilnius, LT-03225, Lithuania 2 Institute of Chemistry, Center for Physical Sciences and Technology, Sauletekio av. 3, Vilnius, LT10257, Lithuania E-mail: [email protected]

Low-dimensional systems such as thin films, two-dimensional heterostructures and surface layers attract a considerable attention because of their chemical, physical, and functional properties different from those of the conventional bulk materials. Consequently, a large number of studies are devoted to nanostructured thin films due to their wide range of applications. Chemical solution deposition (CSD) is widely employed as a relatively easy, flexible and cost-effective method of thin film fabrication. This technique consists of depositing a precursor solution by dip or spin coating followed by a thermal treatment to crystallize the desired phase. The use of a simple equipment, homogeneity at the solution, high reactivity of starting materials, a wide flexibility in choice of the chemicals, capability for uniform large-area coatings are the advantages of CSD compared to physical coating methods [1, 2]. Contrary to some vacuum deposition techniques, where chemical composition of the films can differ from the target stoichiometry, CSD provides mixing of the elements on atomic level and guarantees stoichiometric accuracy of the final product. Deposition of thin films can be performed from both aqueous and organic solutions.

Due to the high ionic conductivity in 500–700 °C temperature range, Gd-doped ceria (GDC) is considered to be one of the most promising materials for intermedia-te temperature solid oxide fuel cells (SOFCs) [3]. Application of this material in the form of thin films is of particular interest in terms of miniaturizing of electroche-mical devices. Micro SOFCs systems based on thin films are predicted to show the highest specific energy and energy density [4].

Tin dioxide (SnO2) is one of the most important wide band gap semiconducting materials, which attracts scientific interest since it combines important physical properties such as a high optical transparency in the visible spectrum, a low electri-cal resistance, good chemical and thermal stability.

In the present study we report on the synthesis of GDC thin films from organic solution and fully organic-free deposition of SnO2 thin films from aqueous solution.

References:[1] Simon, Q., Bouquet, V., Perrin, A., Guilloux-Viry, M. Synthesis of KTaxNb1−xO3 (KTN)

powders and thin films by polymeric precursor method. Solid State Sciences. 2009, 91–95.[2] Schwartz, R. W. Chemical solution deposition of perovskite thin films. Chemistry of Materials.

1997, 2325–2340.[3] Sinha, A., Miller, D. N., Irvine, J. T. S. Development of novel anode material for intermediate

temperature SOFC (IT-SOFC). Journal of Materials Chemistry A. 2016, 11117–11123.[4] Evans, A., Bieberle-Hütter, A., Rupp, J. L. M., Gauckler, L. J. Review on microfabricated micro-

solid oxide fuel cell membranes. Journal of Power Sources. 2009, 119–129.

PLENĀRREFERĀTI ĶĪMIJAS NOZARĒ 7

3D RECONSTRUCTION OF SEM IMAGES OF ADIPOSE TISSUEVilma Brimiene1, Ramūnas Skaudzius2, Martynas Misevicius2, Gintautas Brimas3, Edvardas Brimas3, Algirdas Selskis4 and Aivaras Kareiva2

1 Center of Abdominal Surgery, Vilnius University, Vilnius, LT-08661, Lithuania 2 Department of Inorganic Chemistry, Vilnius University, Vilnius, LT-03225, Lithuania 3 Department of General Surgery, Vilnius University, Vilnius, LT-04130, Lithuania 4 Center for Physical Sciences and Technology, Vilnius, LT-02300, Lithuania E-mail: [email protected]

Adipose tissue has recently been described as an endocrine organ. The develop-ment of it characterization is still a challenging issue. The improvements in the de-tection of microstructures of varied materials with opening the new areas of applica-tions provide a strong motivation for studying electron microscopy data processing possibilities. Till now the suitable models for the extrapolation of three‐dimensional sample data out of the SEM images are lacking, and consequently, the precise quali-tative and quantitative microstructural analysis is still an open question.

Fig. 1. 3D view of reconstructed SEM images of adipose tissue

In the present work SEM images were used to reconstruct 3D view with an open source software VisualSFM. For the primary work, very characteristic AgNO3 par-ticles (cubes and tetrapods) were selected to get acquainted with the software. Then the database of SEM images of the adipose tissue taken from 3 layers of adipose tis-sue (subcutaneous, preperitoneal and visceral) was collected. The most characteristic examples were selected for 3D reconstruction. The key steps and 3D reconstruction model will be presented during the talk.

This research was supported by the National Research Programme “Healthy ageing” funded by Research Council of Lithuania (No. SEN‐16014).


INNOVATIVE ADVANCED MATERIALS USING MODIFIED SPEEK MEMBRANESJAUNU MATERIĀLU IESPĒJAS, MODIFICĒJOT SPEEK MEMBRĀNAS

Guntars VaivarsFaculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, Riga, LV-1063, Latvia

The interest of the research, in particular during the last 20 years, was addressed to the improvement of existing polymer electrolyte membranes for fuel cells and the development of new ones [1] due to the need to develop alternative energy systems. One of the most used and widely considered is sulfonated poly(ether ether ketone) (SPEEK) because of its many advantages [2]. Actually, the main problem accelara-ting the new technology development is related to CO2 emissions and climate chan-ges. For this reason, the focus of research is changing to direct methods reversing CO2 emissions. Availability of local alternative energy sources (wind, solar) makes it possible to discuss the electrochemical CO2 transformation to useful chemicals – methanol, acetic acid, carbohydrates, etc (Fig. 1). Ionic liquids attracted research interest as electrolytes and possible agents for activating cathode material (current-ly, most popular – copper on nanostructured carbon) – highly polar ionic liquids might increase the cathode adsorption capacity. Different other applications of ionic liquids will be discussed.

Fig. 1. The electrochemical CO2 transformation to useful chemicals – methanol etc.

References:[1] Carbone, A., Pedicini, R., Portale, G., Longo, A., D`Ilario, L., Passalacqua, E. J. Power Sources.

2006, 163, 18–26.[2] Hou, H., Maranesi, B., Chailan, J.-F., Khadhraoui, M., Polini, R., Di Vona, M. L., Knauth, P.

J. Mater. Res. 2012, 27, 1950–1957. [3] Reesa, N. V., Compton, R. G. Energy & Environmental Science. 2011, 2, 403–408.

PLENĀRREFERĀTI ĶĪMIJAS NOZARĒ 9

ANALĪTISKĀS UN FIZIKĀLĀS

ĶĪMIJAS SEKCIJA


STRUCTURE OF TRAINING AND PREPARATION OF NATIONAL INDUSTRY FOR NUCLEAR POWER PLANT CONSTRUCTIONAPMĀCĪBU STRUKTŪRA NACIONĀLĀS INDUSTRIJAS SAGATAVOŠANAI DALĪBAI AES BŪVNIECĪBĀ

Agris Auce1, Indulis Andris Horns1, C. Ipbüker2, Alan H. Tkaczyk2

1 Institute of Chemical Physics, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Institute of Physics, University of Tartu, W. Ostwaldi 1, Tartu, 50411, Estonia E-mail: [email protected]

Construction of a nuclear power plant (NPP) is a high-cost, time-consuming and complex megaproject. Due to high quality and safety standards NPP is subjected to, it falls under the category of special engineering and construction. It is estimated that a new NPP is among the most complex construction and design projects in the world, and has surpassed only by for example the international space station, and by some other unusual megaprojects.

There are special requirements for the safety and reliability of NPP over its exten-ded time of the operation, which is more than 60 years for a modern nuclear reactor (NR) [1]. These demands put special and distinct prerequisites for the design, materials and construction process of the NR. These requirements are applied through the who-le supply chain, from the engineering company to even the smallest subcontractor.

The key criteria for a company to be part of the nuclear supply chain are to de-monstrate that the product and/or service supplied by the supplier is guaranteed to comply with the quality requirements specified for each of the details and proces-ses that is part of the construction of the NR. Quality control is an essential part of the construction process and it generally does not leave the option of replacing faulty parts as it is considered to be an unacceptable practice. For this reason, the quality assurance system is vital and as such it is the first criteria a potential con-tractor has to fulfil. The traceability of supplies is another very important criteria that every supplier must provide. Quality assurance mean more than just delivering correct components, the delivery must also be guaranteed to be on time, so that the overall management system works efficiently with the desired performance. In order to fulfill these criteria a potential supplier should have both technical capabilities and adequately trained and certified personnel, in terms of both workers and ma-nagement. In this respect NPP construction is similar to pharmaceutical, aviation, offshore energy and some other similar industries that require robust and reliable quality assurance systems.

The specific training of personnel, and the creation and installation of adequate management systems is a complex task that few companies are able to accomplish with their existing resources. Therefore, there is a need for improved infrastructure that can provide training and support for the companies so that they acquire the necessary skills, understand and implement the required quality assurance and ma-nagement systems. For workers there is a need for specific training programs, for example in welding, quality management and other areas that are part of nuclear power plant construction process.

In the EU there has been a 20-year gap in the NPP construction and much of the skills and expertise in the industries has been lost and has to be developed again.

ANALĪTISKĀS UN FIZIKĀLĀS ĶĪMIJAS SEKCIJA 11

The process of how to bring companies and personal to the necessary technical level differs from country to country. In countries with no previous nuclear experience the state coordinated support is very important. Usually the supplier of the NR tech-nology takes charge in the creation of supply chain by creating the training centers and providing support. This has been happening in the United Kingdom in the construction of the Hinckley Point C. The UK Government has also sharply increa-sed the allocation of resources for the nuclear R&D and nuclear training [2].

Lithuania used to be an established nuclear energy country. In preparation for the new Visaginas NPP Lithuania started an extensive nuclear education and trai-ning program in some of the major universities. The education and training were supported by the potential supplier of technology, Hitachi-GE Nuclear Energy.

In Estonia in accordance with the Estonian National Development Plan for the Energy Sector until 2020, the University of Tartu (UT) and Tallinn University of Technology (TUT) formed a curriculum development committee for the forma-tion of a new master’s program entitled “Nuclear Energetics and Nuclear Safety”. A strategic partnership was developed with the main Estonian energy company Eesti Energia, the Estonian Environmental Board Radiation Department, and internatio-nal partners including KTH Royal Institute of Technology. Dr. Alan Tkaczyk was assigned to be the programme manager of this new curriculum, and the UT and TUT University Councils approved the initiation of this curriculum. The curricu-lum comprehensively addressed physical, chemical, environmental, ecological, geo-logical, economical, legal and political aspects of nuclear power.

Changes in Estonia’s long-term energy strategy caused the curriculum to become inactive. The curriculum sequence and associated course descriptions still exist, and the curriculum could be revived if market needs for accordingly trained graduates increase. To maintain student interest in the topic, in some years an elective course in “Nuclear Engineering” is teached within the physics curriculum. As interest inc-reases, this course could be expanded into an appropriate specialization or indepen-dent master’s program.

In Latvia there has been no formal “nuclear technology curriculum” aimed at NPP construction.

In Poland there is a government supported education and training process to bring out the information to the companies interested to participate in the nuclear energy supply chain and prepare the industry. Many Polish companies were success-ful in participating in the construction of Olkiluoto 3 NPP in Finland.

For a successful preparation of industry for the participation in the international nuclear supply chain, it is important that the companies have access to national trai-ning infrastructure and that there is a coordinating center that helps the companies in their attempts. Competence centers can fill the role of the coordinating center with the universities being one of the players in this process.

This work has received funding from the EURATOM research and training programme 2014–2018 under grant agreement no. 662167 (BRILLIANT project).

References:[1] UK ABWR Generic Design Assessment. http://www.hitachi-hgne-uk-abwr.com/down-

loads/2015-10-30/UKABWR-GA91-9101-0101-11000-RevB-PB.pdf[2] http://www.world-nuclear.org/information-library/country-profiles/countries-t-z/united-

kingdom.aspx


ANALYSIS OF PARAMAGNETIC CENTERS IN CARBON BASED DIVERTOR MATERIALSPARAMAGNĒTISKO CENTRU ANALĪZE OGLEKĻA DIVERTORA MATERIĀLOS

Līga Avotiņa1, Dāvis Čonka1, 2, Andris Leščinskis1, 2, Elīna Pajuste1, Larisa Baumane1, 3, Arnis Supe1, Gunta Ķizāne1 and JET Contributors4*

1 Institute of Chemical Physics, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 3 Latvian Institute of Organic Synthesis, Dzerbenes Street 21, Riga, LV-1006, Latvia 4 EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK E-mail: [email protected]

Carbon based materials, carbon fiber composites (CFC) in particular, are suitab-le to be used in tokamak and stellarator type fusion devices as divertor and plasma facing materials [1, 2]. However, during plasma operations, plasma-wall interacti-ons (PWI) occur: erosion, re-deposition of plasma facing materials, accumulation of hydrogen isotopes takes place [3] and limits the lifetime of divertor materials. In plasma non-exposed CFC there are paramagnetic centers (PMC) due unpaired electrons in graphite. To estimate the PWI caused damage in PMC of the CFC, electron spin resonance spectrometry (ESR) is used.

In this work PMC in CFC from Joint European Torus vacuum vessel, High field gap closure (HFGC; campaign 2010–2012) tile are analyzed and compared with plas-ma non-exposed CFC. Paramagnetic cen-ters, determined in plasma non-exposed CFC are with g-factor 2.0087 ± 0.0005, plasma exposed divertor materials the g = 2.0084 ± 0.0005. The PMC are similar to those described in other carbon con-taining materials [4]. The differences be-tween plasma exposed and non-exposed samples could be due variations in composition of aromatic carbon structures.

References:[1] Wisen, S. et al. Impact of the JET ITER-like wall on H-mode plasma fueling. Nuclear Fusion.

2017, 57, 066024, p. 9.[2] Firdaouss, M. et al. Tungsten coating by ATC plasma spraying on CFC for WEST tokamak.

Physica Scripta. 2017, T170, 014008, p. 6.[3] Catarino, N. et al. Assesment of erosion, deposition and fuel retention in the JET-ILW divertor

from ion beam analysis data. Nuclear Materials Energy. 2017, 12, 559–563.[4] Liu, J. et al. Chemical properties of superfine pulverized coal particles. Part 1. Electron para-

magnetic resonance analysis of free radical characteristics. Advanced Powder Technology. 2014, 25, 916–925.

*See author list in the paper: Litaudon, X. et al. Nucl. Fusion. 2017, 57, 102001

Fig. 1. ESR spectra of plasma non-exposed and tokamak plasma exposed CFC


ANALYSIS OF PARTICULATE MATTER ORIGINATED DURING BURNING OF SCENTED CANDLES AROMĀTISKO SVEČU DEDZINĀŠANAS REZULTĀTĀ RADUŠOS AEROSOLU DAĻIŅU ANALĪZE

Ilze Blūma, Agnese OsīteFaculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Indoor air pollution – mainly increased concentrations of particulate matter still continues to be a challenging issue for scientists. Combustion process, e.g. cooking, smoking, candle and incense burning, is associated as one of the most common emission sources for small size particles (diameter less than 1 µm). Particularly small size particles from combustion processes are considered with significant im-pact on the health effects due to their alveolar deposition, high surface reactivity, chemical composition and inflammogenic potential. There is strong evidence from the literature data that exposure to particles pollution is associated with inflamma-tion, oxidative stress and elevated levels of oxidatively damaged DNA in cultured cells of animals and humans [1]. Candles have been used since ancient times as a source of light and in our everyday life they are frequently used for decorative and religious purposes in various indoor environments. Over the past 30 years scented candles have become more popular which is the result of the growing popularity of aromatherapy and the current abundance of candle shops [2].

During the current research a close test chamber with clean air supply was for-med for combustion experiments. Sampling and analysis of particulate matter was realized by Grimm Aerosol Spectrometer EDM 365. Different types of scented candles (containing soya, stearin, paraffin, wax) were used. Experimental results showed a rapid increase of both – fine and coarse particulate matter concentrations during scented candles burning.

Fig. 1. PM mass concentrations during burning Tromborg scented candleMass concentrations of particulate matter during burning time exceeded values

over 300 µm/m3 and from the Fig. 1. it is seen that PM concentrations continue to increase (reaching 500 µm/m3) even after candle burning.

References:[1] Skovmand, A., Gouveia, A. C. D., Koponen, I. K., Moller, P., Loft, S., Roursgaard, M. Lung

inflammation and genotoxicity in mice lungs after pulmonary exposure to candle light com-bustion particles. Toxicology Letters. 2017, 276, 31–38.

[2] Orecchio, S. Polycyclic aromatic hydrocarbons (PAHs) in indoor emission from decorative candles. Atmospheric Environment. 2011, 45, 1888–1895.


THE OCCURENCE AND RISK ASSESSMENT OF MYCOTOXINS, ACRYLAMIDE AND FURAN IN BEER PRODUCED IN LATVIAMIKOTOKSĪNU, AKRILAMĪDA UN FURĀNA SASTOPAMĪBA LATVIJĀ RAŽOTAJĀ ALŪ UN RISKA NOVĒRTĒJUMS

Estefanija Bogdanova1, 2, Irina Rozentale1, Iveta Pugajeva1, Emeka E. Emecheta3, Ingars Reinholds1, 2, Vadims Bartkevics1, 2

1 Institute of Food Safety, Animal Health and Environment “BIOR”, Lejupes Street 3, Riga, LV-1076, Latvia 2 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 3 University of Tartu, Ülikooli 18, Tartu, Estonia E-mail: [email protected]

Beer is one of the most consumed cereal-based alcoholic beverages in a number of EU countries, including Latvia [1]. Usually industrial beer is produced by fermen-ting different starch-rich grains such as malted barley and wheat, nevertheless, the-re are also many other sources of fermentable sugars for the yeast like maize, oats, unmalted barley, rice and a large amount of different other cereals, depending on economics and location of a direct beer producing county. These raw materials can contain various contaminants such as mycotoxins [2], pesticides [3] and others that inevitably are transferred to the final product.

This work reports data on the occurrence of 9 mostly common mycotoxins and two food processing contaminants – acrylamide and furan in a total of 100 beer samples produced in Latvia. Mycotoxins were detected by high performance liquid chromatography (HPLC) coupled with time-of-flight mass spectrometry, acrylamide by HPLC coupled with quadrupole – Orbitrap mass spectrometry and furan by he-adspace gas chromatography tandem mass spectrometry.

The most frequent occurrence among mycotoxins was determined for HT-2 toxin and deoxynivalenol (DON) appearing in 52% and 51% of the analysed samples. The highest content was observed for DON reaching the maximum of 248 µg kg-1. The presence of furan was absolute (100%) and 74% of analysed samples contained acrylamide. By the estimated exposure, the biggest possible health risk was detected for HT-2 representing more than 11% of tolerable weekly intake (TWI). The margin of exposure (MOE) approach indicates the exposure to furan through beer being significant because of MOE values being close to the critical limit.

References:[1] WHO (World Health Organization). Alcohol consumption. In: V. Poznyak & D. Rekve

(Eds.). Global status report on alcohol and health. Geneva: World Health Organization, 2014, pp. 27–42.

[2] Liu, Z., Wu, H. L., Xie, L. X. et al. Chemometrics-enhanced liquid chromatography-full scan-mass spectrometry for interference-free analysis of multi-class mycotoxins in cereal samples. Chemometr Intell Lab. 2017, 160, 125–138.

[3] Bordin, A. B., Minetto, L., do Nascimento Filho, I. et al. Determination of pesticides residues in whole wheat flour using modified QuEChERS and LC-MS/MS. Food Anal. Methods. 2017, 10(1), 1–9.


PRELIMINARY RESULTS IN USE OF SIRMS TO DETERMINE LATVIAN AND GEORGIAN HONEY AUTHENTICITYLATVIJAS UN GRUZIJAS MEDUS AUTENTISKUMA NOTEIKŠANAS SĀKOTNĒJIE REZULTĀTI, IZMANTOJOT SIRMS METODI

Lauma Buša, Krišs Dāvids Labsvārds, Arturs VīksnaUniversity of Latvia, Faculty of Chemistry, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Honey is a sweet, viscous food substance produced by bees from floral nectar. Natural bee honey is a unique sweetening agent that can be used by humans without processing. However, honey can easily be adulterated with various cheaper sweete-ners, resulting in higher commercial profits [1]. Commonly used adulterants inclu-de high fructose corn syrup, maltose syrup, refined beet and cane sugar etc. Stable isotope ratio mass spectrometry (SIRMS) can be used to determine the adulteration of honey with corn or cane sugar (C4 plants), comparing the extracted protein and honey δ13C values [2].

Four honey samples form Latvia and three honey samples from Georgia were selected for the analysis. The protein from the honey was extracted using dialysis membrane with MWCO 12 kDa. Determination of δ13C ratios in protein and honey was carried out with Nu Horizon SIRMS at the University of Latvia, using certified inorganic reference materials USGS-40 and USGS-41 (L-Glutamic acid). The δ13C values are expressed relative to VPDB.

Table 1Honey and extracted protein δ13C values of selected Latvian and Georgian honeys

Country of origin Sample

δ13CVPDB, ‰Honey Protein Difference (protein-honey)

Latvia

LV 1 -26.586 -26.720 ± 0.007 -0.134 ± 0.007LV 2 -27.374 ± 0.006 -26.29 ± 0.02 1.09 ± 0.02LV 3 -27.767 ± 0.016 -26.52 ± 0.02 1.25 ± 0.03LV 4 -28.706 ± 0.003 -27.81 ± 0.03 0.89 ± 0.03

GeorgiaGE 1 -26.661 ± 0.017 -26.342 ± 0.006 0.32 ± 0.02GE 2 -25.15 ± 0.03 -22.49 ± 0.05 2.67 ± 0.06GE 3 -26.594 ± 0.013 -26.957 ± 0.016 -0.36 ± 0.02

Only two of the seven samples have the values lower that 0, that suggest possible use of C4 plant nectar source or adulteration of honey with corn or cane sugar, but to an extent which does not exceed 7% [3]. However, this method does not provide any information about adulteration with beet sugar. Other analytical methods have to be selected and used in order to determine adulteration with C3 plant sugars.

References:[1] Oroian, M., Ropciuc, S., Paduret, S. Food Anal. Methods. 2017, 1–10 (in Press).[2] Chua, L. S., Lee, J. Y., Chan, G. F. Anal. Bioanal. Chem. 2013, 405, 3063–3074.[3] Tosun, M. Food Chem. 2013, 138, 1629–1632.


δ15N AND δ13C VALUES AS POSSIBLE MARKERS FOR DISTINGUISHING BETWEEN ORGANIC AND CONVENTIONAL GRAINSδ15N UN δ13C VĒRTĪBAS KĀ POTENCIĀLI MARĶIERI BIOLOĢISKI UN KONVENCIONĀLI AUDZĒTU GRAUDU ATŠĶIRŠANAI

Lauma Buša, Dmitrijs Ponomarjovs, Arturs VīksnaUniversity of Latvia, Faculty of Chemistry, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Organic plant products are believed to be safer, healthier and environmentally friendlier than conventionally grown ones. However, it is still challenging to distin-guish between organic and conventional products using everyday methods. Stable isotope ratio mass spectrometry (SIRMS) is offered as an alternative method [1].

In the research wheat and barley samples from conventional and organic corn-fields were analysed. The conventional grain samples were collected form commer-cial mills all over the country, whereas the organic grain samples were obtained from Latvia State Institute of Agrarian Economics, State Stende Cereals Breeding Institute.

The analyses were carried out with Nu Horizon SIRMS at the University of Lat-via, using certified inorganic reference materials USGS-40 and USGS-41 (L-Gluta-mic acid). The δ13C values are expressed relative to VPDB and the δ15N values relati-ve to AIR.

-1012345

δ15N

AIR, ‰

Fig. 1. δ15N values of conventional and organic wheat grainsThe preliminary results show that the δ15N values of some biological wheat sam-

ples are enriched, compared to conventionally grown wheat, as the cornfields are usually fertilized using organic manures that have significantly higher δ15N values that synthetic fertilizers [1].

Reference:[1] Laursen, K. H., Mihailova, A., Kelly, S. D., Epov, V. N., Bérail, S., Schjoerring, J. K., Do-

nard, O. F. X., Larsen, E. H., Pedentchouk, N., Marca-Bell, A. D., Halekoh, U., Olesen, J. E., Husted, S. Food Chem. 2013, 141, 2812–2820.


ANALYTICAL CHARACTERIZATION OF HYDROXYAPATITESHIDROKSILAPATĪTU ANALĪTISKĀ RAKSTUROŠANA

Vladlens Grebņevs1, Arturs Vīksna1, Oskars Purmalis2, Liene Plūduma3

1 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Faculty of Geography and Earth Sciences, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 3 Biomaterials Research Laboratory, Riga TU, Paula Valdena Street 3/7, Riga, LV-1048, Latvia E-mail: [email protected]

Due to a tendence of rapid ageing of population taking place nowadays in several countries, an increasing demand for orthopedical implant development with impro-ved properties appears. Calcium phosphates (mainly hydroxyapatite – HAp), being similar to a chemical structure of human bone inorganic constituents, are mostly recognized biomaterials for bone and teeth renewal. HAp-based biomaterial major advantages are high biocompatibility, osteoconductivity and non-toxicity.

One of the most essential parameters characterizing HAp is Ca/P ratio. It pri-marily depends on synthesis conditions such as pH, stirring and reagent addition rate. Practice shows that properties of commercially available HAp tend not to mat-ch with those defined by the manufacturer, also the information about the product may be indistinct and imprecise. Furthermore, in case of synthesized HAp, several unexpected deviations from normal reaction progress periodically occurs.

A lack of information about complete HAp composition makes it impossible to obtain high quality implants. Stoichiometry mismatch is often accomponied by HAp unpredicted properties after high temperature treatment what results in chan-ges of thermal stability. In order to prevent appearance of HAp-based material de-fects, Ca/P ratio must be strictly controlled [1].

In this research for determination of HAp Ca/P ratio X-ray methods (TXRF, PXRD, WDXRF), atomic absorption spectroscopy and gravimetry were used. Accu-racy, sensitivity and suitability for HAp analysis of selected analytical methodes have been estimated as well as conclusions about their potential in routine analyses have been made.

Reference:[1] Demirchan, A. C. Hydroxyapatite: Synthesis, Properties, and Applications. Nova Science Pub-

lishers. 2012, 7–11.


COMPARISON OF THE STRUCTURE OF THE PLASMA-FACEING SURFACE AND TRITIUM ACCUMULATION IN BERYLLIUM TILES FROM JET ILW CAMPAIGNS 2011–2012 AND 2013–2014PLAZMAS SASKARES VIRSMAS UN TRITIJA UZKRĀŠANĀS SALĪDZINĀJUMS BERILIJA ĶIEĢEĻOS NO JET ILW 2011–2012 UN 2013–2014 GADA DARBĪBAS PERIODIEM

Ieva Igaune1, 2, Elīna Pajuste1, Gunta Ķizāne1

1 Institute of Chemical Physics, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

ITER-Like-Wall project has been carried out at Joint European Torus to test plasma facing materials relevant to International Thermonuclear Experimental Reactor – ITER. The first wall of the vacuum vessel is made of bulk beryllium tiles [1]. Material erosion and tritium accumulation are the main issues related to perfor-mance of plasma facing materials in the vacuum vessel of fusion reactors. Thermal transient loads cause heating of beryllium surface and results in significant chan-ges – material loss, melting, cracking, evaporation, formation of dust. Moreover, hydrogen isotopes retention in the wall materials and erosion product also takes place [2].

During the shutdowns in 2012 and 2014, selected beryllium tiles were removed from the vacuum vessel. Tiles were from the inner wall, outer wall, and upper region of the vessel.

Two methods were used to determine tritium content in the samples – dissolu-tion under controlled conditions and tritium thermodesorption. Prior to tritium determination, scanning electron microscopy and energy dispersive x-ray spectro-scopy were used to study structure and chemical composition of the plasma-facing-surfaces of the beryllium samples.

Fig. 1. Tritium bulk distribution (gasous phase) in the samples nr. 60 and 75 from the IWGL tile 2XR10


Experimental results revealed that total tritium activity in the samples obtained is in range of several kilo Becquerel per square centimetre of the surface area. For example, in beryllium tiles from the shutdown in 2012 the largest tritium activity was found in the samples from outer wall 3.3–31.9 kBq/cm2, activity decreases in inner wall 1.0–6.4 kBq/cm2 and the least from the upper region tile middle part has tritium activity of 3.3 kBq/cm2.

Results obtained from scanning electron microscopy has shown that samples surface morphology for beryllium tiles obtained during shutdown in 2014 are simi-lar to samples surface morphology for beryllium tiles obtained in 2012.

References:[1] Guillemaut, C., Drewelow, P., Matthews, F. G. et al. Main chamber wall plasma loads in JET-

ITER-like wall at high radiated fraction. Nuclear Materials and Energy. 2017, August, 234–240.[2] Brezinsek, S. et al. Beryllium mitigation in JET ITER-like wall plasmas. Nuclear Fusion. 2015,

55(6).


OCCURRENCE OF GLYPHOSATE IN BEER FROM THE LATVIAN MARKETGLIFOSĀTA IZPLATĪBA ALŪ LATVIJAS TIRGŪ

Mārtiņš Jansons1, 2, Iveta Pugajeva2, Vadims Bartkevičs1, 2

1 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Institute of Food Safety, Animal Health and Environment “BIOR”, Lejupes Street 3, Riga, LV-1076, Latvia E-mail: [email protected]

Glyphosate is the most widely used herbicide. Due to farmers adopting glypho-sate tolerant GMO’s, the global consumption grew 12-fold up to 826 thousand tons over 10 years – sufficient for treating 20–30% of global cropland. Due to restricted GMO’s in the EU, preharvest applications probably are the main source of glypho-sate in cereal products in Latvia. These applications may be carried out to control weeds, but not to desiccate crops or control the time and conditions of harvest. Re-cent studies suggested new health effects of glyphosate – an increase in lymphoma in mice, reproductive development disruption in rats and fish, and possible endocrine activity. Links between exposure to glyphosate herbicides and lymphoma and kid-ney disease have been proposed. The International Agency for Research on Cancer concluded in 2015 that glyphosate is probably carcinogenic [1].

0

20

40

60

80

100

120

0 5 10 15 20

Inte

nsity

, cps

Time, min

Glyphosate10.8 min

Blank + 0.2 μg kg-1

MRM, 168/63 m/zArea: 2.57e+003 countsHeight: 1.06e+002 cpsRT: 10.8 min

AFig. 1. Histogram of glyphosate in 100 beer samples from the Latvian market and a

chromatogram of blank beer sample spiked to 0.2 µg kg1

Sensitive LC-MS/MS method for determination of glyphosate in beer consisting of solid phase extraction, separation on aminopropyl phase and MS/MS detection was developed and applied to analyze 100 beer samples representative of most brands and varieties in local supermarkets from 24 producers and distributors in Latvia. Different methods of determination were compared [2]. The concentration of glyphosate in beer varied from below the LOQ of 0.2 μg kg1 up to 150 μg kg1 – higher than previously reported. Significantly higher (p < 0.01) content of glyphosate was observed in beers with no country of production marked on the label (1.8 μg kg1 median in local, 6.7 μg kg1 median in beer of undisclosed origin).


References:[1] Pflaum, T., Hausler, T., Baumung, C., Ackermann, S., Kuballa, T., Rehm, J., Lachen-

meier, D. W. Carcinogenic compounds in alcoholic beverages: an update. Arch. Toxicol. 2016, 90, 2349–2367.

[2] Nagatomi, Y., Yoshioka, T., Yanagisawa, M., Uyama, A., Mochizuki, N. Simultaneous LC-MS/MS Analysis of Glyphosate, Glufosinate, and Their Metabolic Products in Beer, Barley Tea, and Their Ingredients. Biosci., Biotechnol., Biochem. 2013, 77, 2218–2221.


ION CONDUCTING MODIFIED SPEEK MEMBRANESMODIFICĒTAS SPĒĒK MEMBRĀNAS AR JONU VADĪTSPĒJU

Marta Kāne1, Deniss Fedorenko1, Guntars Vaivars1, 2

1 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, Riga, LV-1063, Latvia

Polymer electrolyte membranes are finding potential application in a number of advanced devices – fuel cells, carbon dioxide convertors, batteries etc. One of the most used and widely considered is sulfonated poly(ether ether ketone) (SPEEK) be-cause of its many advantages [1, 2]. The membrane properties might be changed by using different modification techniques. In this work, the adding of ionic liquids was used [3]. However, the interaction between the sulphonated membrane and modi-fying agent is not well understood. In this work, SPEEK membranes with different sulphonation degree was synthesized and investigated (Fig. 1).

Fig. 1. Kinetics of SPEEK sulphonation Electroconductivity was obtained from impedance measurements. Impedan-

ce analysis was performed using Autolab potentiostat/ galvanostat instrument in a frequency range 50 kHz to 100 Hz (with 10 mV signal amplitude).

References:[1] Boaretti, C., Pasquini, L., Sood, R., Giancola, S., Donnadio, A., Roso, M., Modesti, M., Cava-

liere, S. 2018, 545, 66–74.[2] Hou, H., Maranesi, B., Chailan, J.-F., Khadhraoui, M., Polini, R., Di Vona, M. L., Knauth, P.

J. Mater. Res. 2012, 27, 1950–1957. [3] Olivier-Bourbigou, H., Magna, L., Morvan, D. Appl. Catalysis A: General. 2010, 373, 1–56.


APPLICATION OF ELECTRON IRRADIATION FOR DEVULCANIZATION OF TYRE MATERIALRIEPU MATERIĀLU DEVULKANIZĀCIJA PAĀTRINĀTU ELEKTRONU IETEKMĒAnna Lankovska1, 2, Līga Avotiņa2, Pēteris Mekšs1, Valentīna Kinerte2, Gunta Ķizāne2

1 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Institute of Chemical Physics, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Waste car tyre materials and pyrolysis products modification with ionizing ra-diation is an advanced solution for waste car tyres reuse. There are several researc-hes works for high energy radiation (gamma irradiation) uses in tyre material modi-fication [1, 2]. Perspective direction of tyre materials modification is irradiation with accelerated electrons. To evaluate ionizing radiation influence on tyre materials, it is necessary to study radiation induced changes. Therefore, analysis of chemical com-position, chemical bonds as well as free radicals is needed.

Fig. 1. Non-irradia-ted and irradiated tyre materials FT-IR absorption spectra

In this work are analysed tyre material and pyrolysis products, irradiated with accelerated electrons in different doses (20–1000 kGy) using 5 MeV electron acce-lerator ELU-4. Non-irradiated and irradiated samples are analysed by using me-ans of Fourier transformation infrared spectrometry attenuated total reflection (FT-IR-ATR) and chromatography. The most intense signals in FT-IR spectra are at 500–1600 cm-1, indicating on presence of C-H; CH=CH2; -CH=; C-C; C-S [3, 4]. Electron irradiation causes changes in the intensity of the C-S [4] bonds. Chromato-graphy results show that non-irradiated and irradiated products of pyrolysis mostly contain toluene and p-xylene. The results will be used to develop recommendations for the use of electron irradiation technology in tire material modification.References:[1] Grohens, Y. et al. Recycling And Reuse Of Materials And Their Products. Oakville, 2013. [2] Moustafa, A. B. et al. Effect of gamma irradiation on the properties of natural rubber/styrene

butadiene rubber blends. Arabian Journal of Chemistry. 2016, 9, 124–129.[3] Colom, X. et al. FTIR spectroscopic and thermogravimetric characterization of ground tyre

rubber devulcanized by microwave treatment. Polymer Testing. 2016, 52, 200–208.[4] Karabork, F. et al. Characterization of styrene butadiene rubber and microwave devulcanized

ground tire rubber composites. Journal of Polymer Engineering. 2014, 34, 543–554.


ISOLATION OF POLYPHENOLS FROM DIFFERENT PLANT BIOMASS PROCESSING RESIDUES APPLIED ENVIRONMENTALLY FRIENDLY EXTRACTION METHODS AND COMPREHENSIVE CHARACTERIZATION OF THE PRODUCTS OBTAINED POLIFENOLU IZDALĪŠANA NO DAŽĀDIEM AUGU BIOMASAS PĀRSTRĀDES ATLIKUMIEM AR VIDEI DRAUDZĪGĀM EKSTRAKCIJAS METODĒM UN IEGŪTO PRODUKTU VISPUSĪGA RAKSTUROŠANA

Māris Lauberts1, 2, Tatjana Dižbite2, Arturs Vīksna1, Gaļina Teliševa2

1 Faculty of Chemistry,University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga, LV-1006, Latvia E-mail:[email protected]

Orientation of society on creation of bioeconomy requires re-valorization of re-newables. In Institute of Wood chemistry (IWC) the biorefinery scheme for decidu-ous tree bark processing without residue is developed (Fig. 1). The extractives, inclu-ding polyphenol extraction, are integrated as integral part for value-added product obtaining.

Fig. 1. Principal scheme of hardwood bark biorefinery proposed by IWCIn this research the methodology for the extraction of plant polyphenol com-

pounds from various plant biomass residues: bark, wood residues and by-products of biomass chemical processing, was developed. The optimal conditions for extrac-ting polyphenols from pine wood and alder bark were determined using different extraction methods (Soxhlet, ASE, SLE, FBE, ME maceration). A comprehensive and detailed description of the polyphenol target compounds (mainly diarylhepta-noids, stilbenes, lignins) has been developed. The obtained characterization is used for development of analytical analysis complex, which is further used as a tool for evaluation of polyphenols. The work shows the whole chain of analytical process performed, from sampling to full analysis, emphasizing the evaluation of the effect of the extraction process on the target polyphenol compounds, their composition and antioxidant activity. In addition, the analytical process integrates sustainable development, which reduces the use of toxic and hazardous substances in extraction processes, replacing them with more environmentally friendly ones.


PERSISTENT ORGANIC POLLUTANTS IN FRESHWATER MUSSELS FROM THE LATVIAN ENVIRONMENTNOTURĪGIE ORGANISKIE PIESĀRŅOTĀJI SALDŪDENS GLIEMENĒS LATVIJAS APKĀRTĒJĀ VIDĒ

Laura Elina Ikkere1, 2, Ingus Pērkons1, 2, Vadims Bartkevics1, 2

1 Institute of Food Safety, Animal Health and Environment – “BIOR”, Lejupes Street 3, Riga, LV-1076, Latvia 2 University of Latvia, Faculty of Chemistry, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Both freshwater and marine mussels are widely used as indicator organisms across the world. The popularity of mussels as environmental sentinels stems from their biological and ecological characteristics which make them virtually ideal for pollution monitoring. They are filter feeders and therefore are able efficiently to accumulate pollutant chemicals from water, thereby providing an integrative measu-re of the concentration and bioavailability of water pollutants in situ. Furthermore, mussels are sessile organisms, which provides area specific information [1].

To our knowledge the contamination status of Latvian mussels has not been re-ported before. However, notable concentrations of flame retardants have been repor-ted in game meat and eels indicating environmental contamination levels in Latvia [2, 3].

In this study occurrence of PAHs, pharmaceuticals and several classes of POPs, such as PBDEs, PFCs were evaluated in freshwater mussels. The highest contami-nation levels and detection frequencies were observed for PBDEs, namely BDE-47, BDE-99 and BDE-100, which is in a good agreement with PBDE congener distribu-tion in mussels reported in other studies [4]. Levels of all analysed contaminants were generally low, when compared to other studies, indicating the low industrial and anthropogenic pollution level in Latvia.

References:[1] Beyer, J., Green, N. W., Brooks, S., Allan, I. J., Ruus, A., Gomes, T., Brate, I. L. N., Schoyen, M.

Blue mussels (Mytilus edulis spp.) as sentinel organisms in coastal pollution monitoring: A re-view. Mar. Environ. Res. 2017, 130, 338–365.

[2] Zacs, D., Rjabova, J., Ikkere, L. E., Bavrins, K., Bartkevics, V. Brominated flame retardants and toxic elements in the meat and liver of red deer (Cervus elaphus), wild boar (Sus scrofa), and moose (Alces alces) from Latvian wildlife. Sci. Total Environ. 2018, 621, 308–316.

[3] Zacs, D., Rjabova, J., Fernandes, A., Bartkevics, V. Brominated, chlorinated and mixed bro-minated/chlorinated persistent organic pollutants in European eels (Anquilla anquilla) from Latvian lakes. Food Addit. Contam. Part A. 2016, 33, 460–672.

[4] Bianco, G., Novario, G., Anzilotta, G., Palma, A., Mangone, A., Cataldi, T. R. I. Polybrominated diphenyl ethers (PBDEs) in Mediterranean mussels (Mytilus galloprovincialis) from selected Apulia coastal sites evaluated by GC–HRMS. J. Mass. Spectrom. 2010, 45, 1046–1055.


THE VARIATION OF PHOSPHORUS, SULFUR AND NITROGEN IN LICHENS DEPENDING ON LOCATION AREAFOSFORA, SĒRA UN SLĀPEKĻA VARIĀCIJAS ĶĒRPJOS ATKARĪBĀ NO TO AUGŠANAS VIETAS

Vitālijs Lazarenko, Zenta Balcerbule, Egita ĒrmaneFaculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Lichens (lichenes) belong to the group of symbiotic organisms which consist of two components: fungi and algae. There are about 25 thousand lichens species found all over the world even in Antarctica [1]. In the territory of Latvia, by the year 2015, 687 lichen species have been identified and more than 60 of them are included in the list of specially protected species [2].

In various environmental pollutants, lichens are used as biological indicators, as they can be found in a wide geographical area (they are able to grow even on bare rocks and stones). They are sensitive to air pollution, in particularly to sulfur dioxide and able to accumulate metallic elements.

Based on appearances, lichens are categorized as follows: crustose (crusty), fo-liose (leafy) and fruticose (shrubby). Foliose and fruticose lichens are recognized as one of the best biological indicators [3].

In Balvi and Vilaka districts, 3 different places with a distance of 10–30 km be-tween them were chosen to collect lichens:

• the territory of the former Kuprava brick factory (Kuprava parish),• the territory of the former landfill (Kubuli parish),• Sitas forest (Kubuli parish).The collected lichens were subjected to mineralization and phosphorus, sulfur

and nitrogen content was determined in the samples.The obtained results show that the content of phosphorus, sulfur and nitrogen in

the lichens depends not only on the place where lichens were collected, but also on the growth site (land, tree, stone) and the lichen species itself. There is a tendency that the amount of sulfur and nitrogen in the lichens collected on the trees depends on whether the tree is greenish or dried out. It has been observed that for the lichens grown on the ground, the nitrogen content depends on the soil type. When determi-ning the amount of phosphorous, the increment of the content was observed depen-ding on the lichens growth site according to the following order: land→tree→stone.

References:[1] Зенова, Г. М. Лишайники. Московский государственный университет им. М. В. Ломо-

носова, 1999, 2–3.[2] Moisejevs, R. Ķērpju indikatorsugu rokasgrāmata dabas pētniekiem. Daugavpils Universitāte,

2016, 1.[3] Kuldeep, S., Prodyut, B. Lichen as a Bio-Indicator Tool for Assessment of Climate and Air

Pollution Vulnerability. International Research Journal of Environment Sciences. 2015, 3–4.


DETERMINATION OF THE PURITY OF BIOMASS-BASED LEVOGLUCOSANNO BIOMASAS IEGŪTA LEVOGLIKOZĀNA TĪRĪBAS NOTEIKŠANA

Kristīne Meile1, 2, Daniela Godiņa1, 2, Arturs Vīksna1, Aivars Žūriņš2

1 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga, LV-1006, Latvia E-mail: [email protected]

Levoglucosan or 1,6-anhydro-β-D-glucopyranose is among the Top 30 building block chemicals which can be produced from saccharides and subsequently conver-ted to high-value renewable chemicals or materials [1]. Previous work [2] has shown that preparative column chromatography can be used to separate levoglucosan from the heterogeneous mixture of wood pyrolysis products and further purifica-tion by crystallization can be done to obtain levoglucosan with >90 % purity. When levoglucosan is the main compound a broad range of methods for its quantitative analysis are available, including spectrophotometry, titration, gas chromatography with flame ionization detection, and liquid chromatography with refraction index or evaporative light scattering detection. Furthermore, the identity and purity of levoglucosan can be tested by NMR spectroscopy, X-ray diffractometry, as well as measuring such physicochemical properties as the solubility, melting point and op-tical rotation. The purpose of this study was to determine the purity of levoglucosan obtained from birch (Betula pendula) wood by fast pyrolysis.

X-ray diffraction and 1H NMR spectroscopy both confirmed that the obtained white crystalline product by fast pyrolysis of birch wood was levoglucosan. The op-tical rotation of the product was -72 ± 2, the melting point was 180.6 ± 1.2 °C, and the solubility in water at 20 °C was 1000 ± 40 mg/mL. The purity of the obtained levoglucosan was >95%. According to ICUMSA methodology [3] the color of the purified levoglucosan was 225. UV-Vis spectrometry showed the presence of some impurities with absorption maximum at 275 nm wavelength.

The study was implemented within the National Research Programme “Forest and earth entrails resources: research and sustainable utilization – new products and technologies” (ResProd) Project Nr.3 “Biomaterials and products from forest resources with versatile applicability’’.

References:[1] Werpy, T., Petersen, G. Top Value Added Chemicals From Biomass. NREL. 2004.[2] Meile, K., Zhurinsh, A., Spince, B., Dobele, G. Key Engineering Materials. 2014, 604, 232.[3] https://www.sigmaaldrich.com/technical-documents/articles/analytical-applications/

photometry/determination-of-white-sugar-solution-color-according-to-icumsa-method-gs2-3-10.html


DETERMINATION OF OLIGOMERIC PROANTHOCYANIDINS IN WILLOW BARK BY UPLC-MS/MSOLIGOMĒRU PROANTOCIANIDĪNU NOTEIKŠANA KĀRKLU MIZĀS, IZMANTOJOT UPLC-MS/MS

Matīss Pāls1, 2, Līga Lauberte2, Galina Teliševa2, Arturs Vīksna1, Ilva Nakurte1

1 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga, LV-1006, Latvia E-mail: [email protected]

Proanthocyanidins, constituted by condensed flavan-3-ols units, have been the object of different studies due to their potential health benefits. They have been used in the leather industry, foods, livestock feeds, beverages (such as wine and tea) and herbal preparations [1]. Analysis of condensed tannins in plant material is a very di-fficult task because these phenolic compounds are characterized by heterogeneous character and different degrees of polymerization. Furthermore, no group-specific method for the qualitative and quantitative determination of all proanthocyanidin sizes in plant samples has been reported. In this study the UPLC-MS/MS method for proanthocyanidin qualitative and quantitative detection was experimentally estab-lished and results were compared with vanillin and acid-butanol methods.

0.00

0.50

1.00

1.50

2.00

Dimer Trimer Tetramer Dimer Trimer Tetramer

Crude Salix Extract Frac on obtained with Sephadex LH-20

Con

tent

in o

.v.d

. sa

mpl

e, %

Fig. 1. The content of proanthocyanidin B type dimers, trimers and tetramers in Salix Klara bark

The obtained results showed that crude willow bark extract contains 0,63% pro-anthocyanidin B type oligomers in total, while purified sample contains 2,89% oli-gomers in total. These results are smaller than those obtained from acid-butanol and vanillin methods, since used UPLC-MS/MS method is specific to B type epicatechin oligomers, while acid-butanol and vanillin methods shows all types of proanthocya-nidins including A type oligomers and gallocatechin-containing oligomers.

Reference:[1] Dooren, I., Foubert, K., Theunis, M., Naessens, T., Pieters, L., Apers, S. Advantages of a vali-

dated UPLC-MS/MS standard addition method for the quantification of A-type dimeric and trimeric proanthocyanidins in cranberry extracts in comparison with well-known quantifica-tion methods. Journal of Pharmaceutical and Biomedical Analysis. 2018, 148, 32–41.


EXPERIMENTAL AND COMPUTATIONAL STUDY OF SOLID SOLUTIONS FORMED BY MALIC ACID ENANTIOMERSĀBOLSKĀBES ENANTIOMĒRU VEIDOTO CIETO ŠĶĪDUMU EKSPERIMENTĀLIE UN TEORĒTISKIE PĒTĪJUMIElīna Sala, Toms Rēķis, Agris BērziņšFaculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Organic solids are able to form a very wide range of crystalline structures of di-fferent compositions – polymorphs, solvates, co-crystals and solid solutions. Both geometric and chemical aspects as molecules dimension, form, symmetry, and inter-molecular interactions are important in determining solid state properties of all the-se phases. In last decade while analyzing enantiomeric solid compound molecular packing more and more attention is paid to geometric / stereochemical aspects, such as molecule chirality and configuration. Since chiral solids have wide use in various industries (pharmacy and medicine, biochemistry, geology), interest in these solids is only growing.

In this research aspects responsible for formation of solid solutions of enantio-meric solids using model compound malic acid was studied.

New alternative two-component phase diagram was constructed for malic acid. It was revealed that eutectic region exists in much narrower range than previously believed, and previously reported discrete S3R phase is metastable with respect to solid solution with the same enantiomeric composition, which is isostructural to thermodynamically stable racemic form RSI. Solid solution in racemic composition may occur, when configuration of hydroxyl group of the chiral center is changed. Despite this is associated with loss of hydrogen bond present in RSI structure, a po-tential to create three other different hydrogen bounds with the nearby oxygen atoms is present. Different methods (DSC and PXRD) were used to determine and interpret the two-component phase diagram, while computational calculations were used to analyze structural and energy related aspect of solid solution formation of malic acid.

Fig. 1. Malic acid two-component phase diagram (solid solution in racemic composition (squ-are); solid solution in enantiomerically pure compositon (light circle); S3R phase (dark circle)


ILLITE CLAY MINERAL ION EXCHANGE AND APPLYING OF THIS PHENOMENON IN PRACTICEILLĪTU MĀLU MINERĀLU JONU APMAIŅA UN ŠĪS PARĀDĪBAS PIELIETOŠANA PRAKSĒ

Anna Trubača-Boginska, Andris Actiņš, Jānis Švirksts, Anda PrikšāneFaculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia

E-mail: [email protected]

Illites are non-swelling 2:1 type clay minerals consisting of one Al - O octahedral sheet condensed with two Si - O tetrahedral sheets (the schematic representation of illite structure shown in Fig. 1.). In illite minerals isomorphic substitution mainly occurs in the tetrahedral sheets where negative layer charge is compensated by po-tassium ions [1].

Fig. 1. Schematic representation of illite structureIllite clay minerals can usually occur two ion exchange processes. The most com-

mon is the replacement of flat-layer surface K+ ions by other types of inorganic or organics cations. The less common is anion exchange on the edge surfaces of the clay plates [1].

The anion and cation exchange process was successfully applied to extract illite clay minerals from Latvian Devonian clay samples. As a result, the developed met-hod was patented [2] in 2015.

Despite the fact that extracted illite clay mineral fraction cation exchange capaci-ty is low (28 meq/ 100 g), the study was carried out on the modification of illite clay surface with Brönsted acidic ionic liquids.

The use of acidic ionic liquids is mainly related to the attraction of a certain functional group to the clay mineral surface. In this case, sulfonic acid groups may influence the clay mineral proton conductivity properties.


The study will discuss the importance of anion and cation exchange in illite clay mineral extraction process as well as the surface modification with organic salts. The cation exchange will be studied by X-ray powder diffraction, X-ray fluorescence spectrometry, and thermogravimetric analysis.

This work was supported by University of Latvia, grant No. 6012-A55.2/48.

References:[1] Van Olphen, H. An Introduction to Clay Colloid Chemistry, 2nd ed. John Wiley & Sons, 1977.[2] Kostjukovs, J., Trubača-Boginska, A., Actiņš, A. Method for separation of submicrone par-

ticles of illite mineral fro illite clay. European Patent Office, EP 2840063 B1, February 25, 2015.


INCREASING HYDROXYL ION CONCENTRATION OF THERMALLY SPRAYED HYDROXYAPATITE COATINGS BY HYDROTHERMAL TREATMENTHIDROKSILJONU KONCENTRĀCIJAS PAAUGSTINĀŠANA TERMISKI SMIDZINĀTOS HIDROKSILAPATĪTA PĀRKLĀJUMOS AR HIDROTERMISKO METODI

Dārta Ūbele, Liene Plūduma, Kārlis Agris GrossBiomaterials Research Laboratory, Riga Technical University, Paula Valdena Street 3/7, Riga, LV-1048, Latvia E-mail: [email protected]

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) because of its similarity to the inorga-nic component of natural bone, is widely used as an implant material [1]. Hydroxya-patite has good biocompatibility, but poor mechanical properties, and so it is neces-sary to improve these properties by combining bioactive HAp on mechanical strong titanium (Ti). Thermal spraying is commercially the most widely used method for producing HAp coatings on metal implants, but it is well known that hydroxyl ions (OH-) are depleted from the HAp structure after thermal spraying [2]. Therefore, hydrothermal treatment (HT) in watter vapour could be used to return the thermal-ly damaged material to hydroxyapatite crystalline phase [3]. While previous work has only shown qualitative improements, here we shall show quantitative measures of the hydroxyl ion content.

In this research, the effect of HT on the OH- content was investigated in thermal-ly sprayed HAp coatings. HT was conducted at different temperatures (100–250 °C) and at different times (6–70 h) by placing the HAp coating into a hydrothermal pres-sure vessel.

Chemical phases and functional groups were obtained with X-ray diffraction and Fourier transform infra-red spectroscopy (FTIR), respectively. The changes in OH- concentration were detected by calculating the OH/PO4 area ratio in the 500–700 cm-1 FTIR spectral region. Results showed an increase in the OH- con-centration from 2% for as-sprayed coatings to 83% when hydrothermally treated at 200 °C for 12 h). Also, it was determined that the efficiency of HT conversion de-pends on the phase composition of the coating.

This work was supported by the European Union’s FP7 research and innovation programme M-ERA.NET project “Implants signal to bone for bone growth and at-tachment” No. ESRTD/2017/4.

References:[1] Kolmas, J., Krukowski, S., Laskus, A., Jurkitewicz, M. Synthetic hydroxyapatite in pharmaceu-

tical applications. Ceramics International. 2016, 42, 2472–2487.[2] Demnati, I., Parco, M., Grossin, D., Fagoaga, I., Drouet, C., Barykin, G., Combes, C.,

Bra ceras, I., Goncalves, S., Rey, C. Hydroxyapatite coating on titanium by a low energy plasma spraying mini-gun. Surface & Coatings Technology. 2012, 206, 2346–2353.

[3] Cao, Y., Weng, J., Chen, J., Feng, J., Yang, Z., Zhang, X. Water vapour-treated hydroxyapatite coatings after plasma spraying and their characteristics. Biomaterials. 1996, 17, 419–424.


THE EFFECTS OF HYDROTHERMAL PROCESSING IN PRESENCE OF H2O2 ON ANTIBACTERIAL ACTIVITY OF STRONTIUM SUBSTITUTED APATITEHIDROTERMISKĀS APSTRĀDES H2O2 KLĀTBŪTNĒ IETEKME UZ STRONCIJU AIZVIETOTU APATĪTU ANTIBAKTERIĀLO AKTIVITĀTI

Valda Valkovska1, Agnese Osīte1, Vizma Nikolajeva2

1 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Faculty of Biology, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Hydroxyapatite (HAp) is a biocompatible material, which is widely used for bio-medical applications – usually for coatings of metallic implants and bone substitute. Synthetic HAp is chemically similar to the inorganic phase of vertebrate bones. Still some disadvantages of biomaterial are highlighted – weak antibacterial and mechanical properties. Cationic and anionic substitutions of HAp are assumed as one of the most appropriate strategies to improve these properties [1, 2].

The aim of the current research is to improve antibacterial activity of HAp by the cationic substitution and the peroxide ion incorporation in CaHAp and parti-ally substituted strontium hydroxyapatite (SrCaHAp). The synthesized samples displayed antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa bacteria. The hydrothermal processing of HAp and SrCaHAp increases the antibacterial activity against both types of bacteria. Minimal inhibitory concen-tration (MIC) and minimal bactericidal concentration (MBC) of microbiology tests are shown in Table 1.

Table 1The MIC, MBC and values of the synthesized apatites

Sample S. aureusMIC, MBC, [mg/mL]

P. aeruginosa MIC, MBC, [mg/mL] ωH2O2

, [%]

CaHAp – >107 –CaPerAp (100 °C) 54 54 1.32 ± 0.08CaPerAp (150 °C) 54 54 0.98 ± 0.0725%-SrCaHAp 121 120 –25%-SrCaPerAp (100 °C) 40 26 1.80 ± 0.1125%-SrCaPerAp (150 °C) 54 1.18 ± 0.0575%-SrCaHAp 193 >220 –75%-SrCaPerAp (100 °C) 63 33 1.44 ± 0.0975%-SrCaPerAp (150 °C) 52 52 0.67 ± 0.07

References: [1] Mucalo, M. Hydroxyapatite (HAp) for biomedical applications. 2015, 3–155.[2] Šupová, M. Substituted hydroxyapatites for biomedical applications: A review. Ceram. Int.

2015, 41, 9203–9231.


ANALYSIS CHEMICAL BONDS AND FREE RADICALS IN RADIATION MODIFICATED LATVIAN SHEEP WOOLĶĪMISKO SAIŠU UN BRĪVO RADIKĀĻU ANALĪZE RADIĀCIJAS MODIFICĒTĀ LATVIJAS AITU VILNĀ

Vanda Voikiva1, 2, Liga Avotina1, Valentina Kinerte1, Gunta Kizane1, Larisa Baumane1, 3

1 University of Latvia, Institute of Chemical Physics, Jelgavas Street 1, Riga, LV-1004, Latvia 2 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 3 Latvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia E-mail: [email protected]

The sheep sector is developing in Latvia and the future of this sector is predicted to be positive. One of the most important sheep products is wool, which is used for insulation, construction materials; manufacture of yarns, blankets, clothes, rugs, packaging materials. Sheep wool contains a lot of different useful substances and items, such as lanolin [1]. Lanolin is a valuable raw material for the production of cosmetics, lubricants and rust protectors. It is proposed that radiation modification can influence lanolin extraction from wool [2].

Fig. 1. FT-IR absorption spectra of non-irradiated and irradiated sheep woolIn this work we irradiate sheep wool with accelerated electrons, modification is

carried out using ELU-4. Chemical bonds and free radicals in nonradiated and irra-diated wool are mesured by means of infrared and electron spin resonance spectro-metry (ESR). Doses up the 200 kGy do not significaly affect chemical composition of the wool. Due to irradiation decreases intensity of whole spectrum.

In the ESR spectra occur presence of several radicals, that show a dependency on irradiaton dose. However, further invetstigations are needed, to undertand the irrdiation caused changes in the sheep wool.

References:[1] Coleman, G. Consumer and societal expectations for sheep products. Advances in Sheep Wel-

fare. 2017, 37–51.[2] Hanzlikova, Z., Porubska, M., Jomova, K. Irradiated lanoline as a prospective substance for

biomedical applications: A spectroscopic and thermal study. Radiation Physics and Chemistry. 2015, 113, 41–46.

ORGANISKĀS ĶĪMIJAS SEKCIJA 35

ORGANISKĀS ĶĪMIJAS SEKCIJA


SYNTHESIS AND CYCLISATIONS OF N-(3-ARYLPROP-2-YNYL) DERIVATIVES OF BENZAMIDES, CARBAMATES AND THIOUREASSimonas Balkaitis1, 2, Inga Čikotienė3

1 Latvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia 2 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 3 Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko Street 24, Vilnius, LT-03225, Lithuania E-mail: [email protected]

Molecules containing oxazinone and thiazine rings have long attracted attention [1] and are found in many drugs, pro-drugs, insecticides and other demanded pro-ducts. Typically, these heterocycles are assembled with the help of Pd, Cu and other transition metal catalysts [2] in presence of ligands. However, this classical synthe-tic pathway has its limitations: use of precious metals and environmental concerns are rather discouraging, products have none or limited variety of substituents, thus leaving less potential for further functionalisation. On the contrary, cyclisations mediated by electrophilic reagents yield variously functionalised products, opening possibility for consecutive reactions. This work is devoted to the synthesis of alkynes (I-II, scheme 1) and investigation of their reactivity with selected electrophiles: I2, NBS, PhSeCl, 1-methoxy-isochroman and acyclic acetals.

NH

XR

E+

NH

XRE

R'' R' R'R''

X= O (I), S (II)

Scheme 1. General electrophile mediated cyclisation reaction investigated in this work

Synthesis of tert-butyl 3-arylprop-2-ynylcarbamates and N-(3-arylprop-2-ynyl-carbamothioyl)benzamides went as expected and subsequent cyclisations yielded 6-endo-dig products, as determined by double-resonance NMR experiments. On the other hand, 1-benzyl-3-(3-arylprop-2-ynyl)thioureas and 1-benzyl-3-(prop-2-ynyl)thiourea (intermediates in reactions of propargylic amines and ben-zyl isothiocyanate) instantly formed 5-exo-dig cyclisation products. A series of 19 (15 cyclic, 4 acyclic) compounds were synthesised via electrophilic cyclisations of alkynes. Overall, 27 new compounds were synthesised and identified.

References:[1] Didwagh, S. S., Piste, P. B. Int. J. Pharm. Sci. Res. 2013, 4, 2045–2061.[2] General reviews: Hu, Y., Xin, X., Wan, B. Tet. Lett. 2015, 56, 32–52; Lessing, T., Muller, T. J. J.

Appl. Sci. 2015, 5, 1803–1836. Other examples: Hashmi, A. S. K., Schuster, A. M., Schmuck, M., Rominger, F. Eur. J. Org. Chem. 2011, 24, 4595–4602; Chu, J.-J., Hu, B.-L., Liao, Z.-Y., Zhang, X.-G. J. Org. Chem. 2016, 81, 8647–8652.


DDQ MEDIATED ELECTROCHEMICAL CLEAVAGE OF THE PARA-METHOXYBENZYL PROTECTING GROUPHaralds Baunis, Olesja KoledaLatvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Para-methoxybenzyl (PMB) protecting group is a useful protecting group em-ployed in organic synthesis to protect alcohols, carboxylic acids, and nitrogen con-taining compounds [1, 2]. This protecting group can be cleaved under relatively mild conditions, using stoichiometric amounts of DDQ or CAN, or using TFA. However, other methods have also been reported [1, 3, 4].

Deprotection of alcohols by means of DDQ is an easy and relatively cheap met-hod, however, it is considerably slow and employs multiple equivalents of DDQ, re-sulting in poor atom efficiency. What’s more, DDQ hydrolyses in water, releasing the toxic HCN gas [5].

Organic electrosynthesis, on the other hand, is a green synthetic method, which greatly increases atom efficiency. It is innately scalable, features high chemoselec-tivity and functional group tolerance [6]. It is because of these reasons that a new electrochemical approach to cleavage of the PMB protecting group was explored.

RO

O

ROH

O

O

H

0.025 eq DDQ0.05 M Bu4NClO4

HFiP:H2O 9:10.8V vs Ag/AgNO3

WE: Graphite; CE: Graphite

+

Scheme 1. Electrochemical cleavage of the PMB protecting group

A novel synthetic approach for deprotection of PMB ethers was developed (Scheme 1), using a mixture of 1,1,1,3,3,3-hexafluoroisopropanol (HFiP) and water as a solvent and a catalytic amount of DDQ, significantly reducing amounts of the toxic reagent necessary. Furthermore, it employed the relatively inexpensive and commercially available graphite as the electrode material. The scope of the reaction was also explored, applying it for different substrates.

Supervisor: Prof. E. Suna.

References:[1] Wuts, P. G. M. Protection of the Hydroxyl Group, Including 1,2- and 1,3-Diols. In: Greene’s

Protective Groups in Organic Synthesis, 5th ed. New York: John Wiley & Sons, 2014, pp. 17−471.[2] Owen, D. R., Bull, D. J., Bunnage, M. E., Glossop, M. S., Maguire, R. J., Strang, R. S. Bioorg.

Med. Chem. Lett. 2010, 20(1), 92–96.[3] Ilangovana, A., Anandhana, K., Kaushik, M. P. Tet. Lett. 2015, 56(9), 1080–1084.[4] Kern, N., Dombrav, T., Blanc, A., Weibel, J. M., Pale, P. J. Org. Chem. 2012, 77(20), 9227–9235.[5] Chen, L., Liu, S., Zhao, L., Zhao, Y. M. Electrochimica Acta. 2017, 258, 677–683.[6] Horn, E. J., Rosen, B. R., Baran, P. S. ACS Cent. Sci. 2016, 2, 301.


SYNTHESIS OF NOVEL TRITERPENOID-1,2,3-TRIAZOLE CONJUGATESRūdolfs Beļaunieks, Andis Melderis, Uldis Peipiņš, Māris TurksInstitute of Technology of Organic Chemistry, Faculty of Materials Science and Applied Chemistry, Riga Technical University, P. Valdena Street 3, Riga, LV-1048, Latvia E-mail: [email protected]

Betulin is an abundant naturally occurring triterpene, most commonly found in birch bark. Research shows, that betulin and its derrivatives possess wide spectrum of biological activities such as anti-HIV, antiinflammatory and anticancer [1, 2]. Use of betulin is limited by its low solubility in water. Therefore, to improve properties of betulin, structural modifications with new biological activity simultaneously impro-ving solubility in water are being made [3].

HOH

OHH

H

HHO

H

NH

H

H

NNR

HOH

NH

H

H

NNR

1 2 3

29

28

3

20

Scheme 1. Synthesis of lupan-3β-ol and betulin-1,2,3-triazole conjugates

In this work, betulin (2) and lupan-3β-ol (3) conjugates were obtained in 5 step synthesis from betulin (1). Betulinaldehyde was obtained by chemoselective pri-mary alcohol oxidation followed by reaction with hydroxylamine hydrochloride that provided betulinaldoxime. Following catalytic hydrogenation under certain conditions gave amines with or without reduced double bond between C(20) and C(29). From the obtained amines respective azides were synthesised in diazotransfer reactions using trifluoromethanesulfonic azide. The latter were employed in Cu(I) catalyzed 1,3-dipolar azide-alkyne cycloaddition reactions to obtain betulin and lupan-3β-ol-triazole conjugates.

References:[1] Alakurtti, S., Makela, T., Koskimies, S., Yli-Kauhaluoma, J. Eur. J. Pharm. Sci. 2006, 29, 1–13.[2] Murniece, R., Namniece, J., Nakurte, I., Jekabsons, K., Rieksina, U., Jansone, B. Pharmacol. Res.

2016, 113, 760–770.[3] Khlebnicova, T. S., Piven, Y. A., Baranovsky, A. V., Lakhvich, F. A., Shishkina, S. V., Zicāne, D.,

Tetere, Z., Rāviņa, I., Kumpiņš, V., Rijkure, I., Mieriņa, I., Peipiņš, U., Turks, M. Steroids. 2017, 117, 77–89.


SYNTHESIS OF HETEROCYCLIC KETONESToms IzmailovsLatvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Heterocyclic ketones are important building blocks in medical chemistry. There-fore, the development of synthetic methods for synthesis of heterocyclic ketones is of great importance. Herein we report a novel approach to the synthesis of azole-con-taining ketones from readily available azole hemiaminals such as 2.

Ph

NH

N

AcetaldehydeBz2ODMAP

MTBE, RT

Ph

N

N

O

RO

i-Pr2NHn-BuLi

THF, -78 oC

Ph

NH

N O

R

1 2 452-86% 18-30%

+Ph

NH

N

R N

HNHO

Ph

50%

R = Ph, Bn, t-Bu

OR

O-

N

N-

Ph

Li+

NN

Ph 3

Scheme 1. Synthesis of heterocyclic ketone 4

Imidazole hemiaminal 2 was obtained from imidazole, acetaldehyde and benzoic anhydride as described in the literature [1]. Lithiation of imidazole hemiaminal 2 with LDA at 78 °C yielded ketone 4 in moderate yields (18–30%) (Scheme 1). Notab-ly, the formation of alcohol 5, a by-product resulting from a double addition of lithi-ated imidazole to the ketone intermediate 4 was not observed (Fig. 1). This points to the formation of stable tetrahedral intermediate 3 after the first addition step. In a cross-experiment an equimolar mixture of hemiaminals 6, 7 was treated with LDA under standard conditions (Scheme 2). The observed formation of cross-products 9, 11 together with the desired ketones 8, 10 points to an intermolecular nucleophilic attack of the lithiated imidazole species on the hemiaminal ester group as the most likely mechanism for the formation of heterocyclic ketones.

N

N

O

Ot-Bu

Ph

N

N

O

O Ph

i-Pr2NHn-BuLi

THF, -78 oC

NH

N O

t-Bu

Ph

NH

N O

Ph

Ph

NH

N

t-Bu

O

NH

N O

Ph

6

7

8 9

10 11

20% 13%

4% 4%

Scheme 2. Synthesis of ketones 8 and 10 in a cross-experiment (LCMS yields)

Reference:[1] Kinens, A., Sejejs, M., Kamlet, A. S., Piotrowski, D. W., Vedejs, E., Suna, E. J. Org. Chem. 2017,

82, 869–886.


SYNTHESIS AND PHOTOPHYSICAL PROPERTIES OF SOME 2,3,5-TRISUBSTITUTED THIOPHENE DERIVATIVESMantas Jonušis1, Kaspars Leduskrasts2, 31 Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko Street 24, Vilnius, LT-03225, Lithuania 2 Latvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia 3 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

By establishing Fiesselmann [1] thiophene synthesis we have synthesized series of substituted thiophenes from 1,3-diarylprop-2-yn-1-ones and corresponding thiols or thioureas [2].

SR

R

O

R1 SR

R

HN

N R1

SR

R

S

R

R1

SR

R

O N

R

SR

R

HN N

R

1 2 3

4 5

Scheme 1. Structures of synthesized thiop-hene derivatives

All of the synthesized compounds were characterized by spectral analysis. Moreover, Absorbance, emission, Quantum Yield in MeCN and in the solid state were measured. While most of the compounds showed quite low quantum yields (in the range of 0.2–4.3%) and fluorescence lifetimes are in nanosecond range, compounds 2 and 4 (Table 1) possessed quantum yields in the range of 25–42% what is likely due to thermally activated delayed fluorescence.

Table 1Photophysical properties of compounds

Nr. Abs., nm Em., nm

QY, % (MeCN)

QY, % (solid) Comp. R R1

1 264, 408 516 0.2 6.9 1 Ph 4-CN-Ph2 234, 280, 360 445 42.5 11.6 2 4-OMe-Ph Cl3 240, 266, 322, 364 466 4.3 1.69 3 Ph 2-Benzimidazolyl4 234, 280, 356 441 33.8 1.8 2 4-OPent-Ph H5 258, 322 394 2.7 1.7 5 Ph Ph6 262, 336 419 2.3 26.2 4 Ph Ph7 240, 264, 312 474 2.1 1.6 3 Ph 4-Py8 264, 430 562 1.8 4.6 1 4-OMe-Ph 4-CN-Ph9 240, 296, 410 523 0.4 2.9 1 4-OMe-Ph 4-OMe-Ph

10 240, 262, 282, 420 536 0.7 10.1 1 4-OMe-Ph 4-Br-Ph11 240, 262, 282, 360 537 0.5 14.9 1 4-OMe-Ph 4-Cl-Ph12 254, 422 538 0.4 8.9 1 4-OMe-Ph 4-Py

Supervisors: Prof. Inga Čikotienė, Prof. Edgars Suna.References:[1] Li, J. J. Name Reactions: A Collection of Detailed Mechanisms and Synthetic Applications.

Switzerland: Springer International Publishing, 2014.[2] Tamas, K., Jozsef, J., Erzsebet, O., Kalman, H. Synthetic Communications. 2003, 33(9),

1433–1442.


SYNTHESIS AND PHOTOPHYSICAL PROPERTIES OF N(9)-ALKYLATED PURINE DERIVATIVESZigfrīds Kapilinskis, Armands Sebris, Irina Novosjolova, Māris TurksInstitute of Technology of Organic Chemistry, Faculty of Materials Science and Applied Chemistry, Riga Technical University, P. Valdena Street 3, Riga, LV-1048, Latvia E-mail: [email protected]; [email protected]

Earlier we reported the synthesis of fluorescent 6-triazolyl purine nucleosides [1]. Now we developed the synthesis of 2/6-triazolyl purine derivatives with amorphous groups at N(9) position. Different electron-donor and electron-acceptor groups were introduced in the purine structure and enhanced fluorescent properties, while the trityl group increased amorphous properties [2].

In this work, the synthetic routes for C(6) and C(2) substituted purines were de-signed. Final products have been obtained with 19‒34% total yield. The fluorescent properties were studied in the solution and in the film. Quantum yields in DCM reached up to 91%. Compounds 5, 6, 10 had quantum yields up to 59% in the films.

N

N NH

N

Cl

Cl

N

N N

N

N

NR1

NN

R2

N

N N

N

R1

N

NN

R2

N15, 48-91%

10, 42-88%

N

N N

N

Cl

ClR1

NaN3 N

N N

N

N3

N3R1

NH N

N N

N

N3

NR1

[Cu(I)]

R2

N

N NH

N

N3

N3

NaN3

NH N

N NH

N

N

N3

N

N N

N

N

N3R1

[Cu(I)]

R2

3, 94-98% 4, 52-74%

7, 75% 8, 52% 9, 71-78%

N

N N

N

N

N OR3

n

NN

R2

6, 56-68%

R1: a) c)Ph

PhPh

O3

OTHP

R3:

b)

O

Ph

PhPh

2, 58-87%

Ph

PhPh

O

d) O5

OTHPO Ph

PhPh

O

b)

n=4,6

H

b)

c)d)e)

f)h)

i)

Ph3PDIADTHF acetone DCM

EtOH

H2O

Ph3PDIADTHF DCM

DMF

1)p-TsOHMeOH

R2:

2) EDC, DMAP, DCM

a)

C6H5

p-C6H4OMe

p-C6H4N(Me)2

a)

p-C6H4CNp-C6H4NO2

CH2OH

O O

Ph

PhPh

Scheme 1. General scheme for 2/6-amino-6/2-triazolyl purine derivatives

Acknowledgements:This work was supported by ERDF project Nr. 1.1.1.1/16/A/131. Dr. K. Traskovskis and

Dr. A. Vembris are acknowledged for the photophysical measurements and calculations.

References:[1] Kovaļovs, A., Novosjolova, I., Bizdēna, Ē., Bižāne, I., Skardziute, L., Kazlauskas, K., Jursenas, S.,

Turks, M. Tetrahedron Lett. 2013, 54, 850.[2] Traskovskis, K., Mihailovs, I., Tokmakovs, A., Kokars, V., Rutkis, M. Proceedings of SPIE. 2012,

8434: Nonlinear Optics and Applications VI, 1.


SYNTHETIC ROUTE TOWARDS LEPADINSSindija LapčinskaLatvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia Faculty of Materials Science and Applied Chemistry, Riga Technical University, Paula Valdena Street 3/7, Riga, LV-1048, Latvia E-mail: [email protected]

Lepadins are a class of cis-decahydroquinoline alkaloids isolated from several marine organisms: Clavelina lepadiformis, Protheceraeus vittatus, Didemnum sp., Aplidium tabascum. Eight representatives have been isolated during the period 1991–2002 [1, 2]. The lepadin alkaloids are characterized by a cis-decahydroqui-noline ring containing a C-2 methyl group, a C-3 oxygenated (hydroxy or acyloxy) group and a C-5 eight carbon side chain.

Lepadins exhibit biological activity: cytotoxic, antiplasmodial, antitrypanosomal and neurological properties [3]. Further pharmacological research has been limited by the low quantities of samples available from natural sources. Previous syntheses of lepadins require many steps (18–40 steps) and that is why development of practi-cal synthetic route towards these compounds is required.

We investigated a modular synthetic approach towards decahydroquinoline al-kaloids. The main stages of our synthesis include epoxide preparation from ortho-gonally protected alanine methyl ester, the next stage is copper catalyzed epoxide coupling with bromo-cyclohexene derivative. Synthesis of octahydroquinoline core required development of novel Pd catalyzed amino-cyclization reaction.

O

NBnR1OMe

NBnR1

OOR3

BnN

OR2

NBn

OR2

HNBn

OR3

H

HBPin

NH

OH

H

H

R1

C4H9

O

NB R1OMe

NB R1

OOR3

B N

OR2

NBn

OR2

HNBn

OR3

H

HBPin

NH

OH

H

H

C4H9

Scheme 1. Retrosynthetic analysis of lepadin B

Supervisor: Dr. chem. A. Pelšs

References:[1] Kubanek, J., Williams, D. E., Dilip de Silva, E., Allen, T., Andersen, J. Tetrahedron Lett. 1995,

35, 6189–6192.[2] Wright, A. D., Goclik, E., Konig, G. M., Kaminsky, R. J. Med. Chem. 2002, 22, 3067–3072.[3] Davis, R. A., Carrol, A. R., Quinn, R. J. J. Nat. Prod. 2002, 65, 454–457.


SYNTHESIS OF BENZO[B]OXEPIN-2-(3H)-ONE DERIVATIVESLinda PudnikaLatvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

α-Carbonic anhydrases (CA) are zinc – containing enzymes whose main funcion is pH regulation in cells. Of the 15 α-CA isoforms found in human body, CA IX and CA XII are highly expressed in tumor cells, and therefore selective inhibition of the-se isoforms is required [1, 2].

It was found that coumarins (1) are selective inhibitors of CA IX [3]. To improve biological activities it was necessary to obtain a series of benzo[b]oxepin-2(3H)-one (2) derivatives.

O O1

OO2

Scheme 1. Coumarin (1) and benzo[b]oxepin-2(3H)-one (2)

OO

5R

OBrO

OOMe

4

Br

O

O

OOMe

O3

OOMe

Scheme 2. Synthesis of 8-aryl benzo[b]oxepin-2(3H)-one derivatives 5

8-Aryl benzo[b]oxepin-2(3H)-ones 5 were synthesized in two steps from com-pound 3 by catalytic Wittig reaction, then compound 4 was further converted to target compounds 5 by Suzuki reaction.

Supervisor: Dr. chem. A. Grandāne

References:[1] Supuran, C. T. Carbonic Anhydrase Inhibition/Activation: Trip of a Scientist Around the World

in the Search of Novel Chemotypes and Drug Tarfets. Curr. Pharm. Des. 2010, 16, 3233–3245.[2] Aterio, V., Fiore, A., D’Ambrosio, K., Supuran, C. T., De Simone, G. Multiple Binding Modes

of Inhibitors o Carbonic Anhydrases: How to Design Specific Drugs Targeting 15 Different Isoforms? Chem. Rev. 2012, 112, 4421–4468.

[3] Maresca, A., Tempertini, C., Vu, H., Pham, N. B., Poulsen, S. A., Scozzafava, A., Quinn, R. J., Supuran, C. T. Non – Zinc Mediated Inhibition of Carbonic Anhydrases: Coumarins Are a New Class of Suicide Inhibitors. J. Am. Chem. Soc. 2009, 131, 3057–3062.


BRØNSTED ACID CATALYSED 1,2-SILYL SHIFT IN PROPARGYL SILANESMikus Puriņš, Māris TurksInstitute of Technology of Organic Chemistry, Faculty of Materials Science and Applied Chemistry, Riga Technical University, P. Valdena Street 3, Riga, LV-1048, Latvia E-mail: [email protected]

There are two possible pathways for propargyl silane reactions with electrophiles. The first involves Hosomi-Sakurai type aditition to aldehydes and imines. However, the second pathway involves migration of silyl group in the intermediate β-silyl vi-nyl carbenium ion and subsequent cyclization [1]. In such cases propargyl silanes act a 3-carbon unit in [3+2] annulation reactions.

Silyl dienes have proven to be versatile substrates, as they readily undergo cyclo-addition reactions yielding vinyl silane moiety. Furthermore such products can par-ticipate in HiyamaDenmark cross-coupling reactions by transmetalation of the silyl group [2].

SiR2

R2

Si

SO2

OSi

R2O

O

H

H

SO

O

R2

Si

O

O

O 5, 19 - 70 %

6, 64-69 %

R1 R1

R1

R1

HA

SiR2

R1 R2

Si

R1H

AA

Si = SiMe3, SiEt3, SitBuMe2, Si(iPr)2OMe

4, up to 88 %dr > 10:1

1

23

Scheme 1. Mechanism 1,2-silyl shift

Here we report the use of strong Brønsted acids such as triflic acid to activate the triple bond and promote 1,2-silyl shift in propargyl silanes. Deprotonation of the resulting allyl carbenium ion provides 2-silyl-1,3-dienes in good yields. Addi-tion of dienophiles to silyl dienes yields Diels-Alder adducts in one pot procedure. Performing this rearrangement in liquid sulfur dioxide as a polar reaction medium [3, 4, 5], it is possible to activate the triple bond even with weak Brønsted acids such as benzoic acid.

References:[1] Danheiser, R. L., Dixon, B. R., Gleason, R. W. J. Org. Chem. 1992, 57(23), 6094–6097.[2] Choudhury, P., Welker, M. Molecules. 2015, 20(9), 16892–16907.[3] Posevins, D., Suta, K., Turks, M. Eur. J. Org. Chem. 2016, 2016(7), 1414–1419.[4] Lugiņina, J., Uzuleņa, J., Posevins, D., Turks, M. Eur. J. Org. Chem. 2016, 2016(9), 1760–1771.[5] Lugiņina, J., Turks, M. Synlett. 2017, 28(8), 939–943.


PARALLEL KINETIC RESOLUTION OF TETRAZOLE HEMIAMINAL ENOLATESMārcis SējējsLatvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia University of Latvia, Faculty of Chemistry, Jelgavas Street 1, Riga, LV-1004, Latvia E-mail: [email protected]

Incomplete E/Z selectivity of enolization is frequently one of the main hurdles for achieving stereoselective reactions with ester enolates. Herein we report a way of im-proving the E/Z ratio of ester enolates by parallel kinetic resolution (PKR) of lithium enolates. The developed PKR conditions allows for achieving high diastereoselecti-vity in reactions of tetrazole hemiaminal-derived lithium enolates 2 with a series of electrophiles.

It was observed that diastereoselectivity of fluorination of chiral tetrazole hemia-minal 1 was increased from 85:15 to 97:3 d.r. if TMSCl was used as an additive [1]. Investigation of this reactions kinetics indicated that PKR of enolate E/Z isomers is responsible for improved diastereoselectivity. Accordingly, isomer (E)-2 reacts fas-ter with TMSCl whereas isomer (Z)-2 reacts faster with electrophile. The concept of PKR of lithium enolates was successfully exploited with a variety of electrophiles such as NFSI, nitrosobenzene and benzaldehyde dimethyl acetal.

N

NN

N

Ph

OO

R

N

NN

N

Ph

OOLi

R

N

NN

N

Ph

OOLi

R

N

NN

N

Ph

OOTMS

R

N

NN

N

Ph

OO

RE

E+

TMSCl

LiHMDS

1

(E)-2

(Z)-2

3

4

R=Aromatic, aliphaticE+=NFSI, PhNO, benzaldehyde dimethyl acetal

Scheme 1. PKR of tetrazole hemiaminal enolate

Supervisor: Prof. E. Sūna

Reference:[1] Kinens, A., Sejejs, M., Kamlet, A. S., Piotrowski, D. W., Vedejs, E., Suna, E. J. Org. Chem.

2017, 82(2), 869–886.


DESIGN AND SYNTHESIS OF SMALL-MOLECULE HEPATITIS B VIRUS CAPSID SELF-ASSEMBLY INHIBITORS Anda Sīpola1, 2, Unda Nelda Dubova3

1 Latvian Institute of Organic Synthesis, Aizkraukles Street 21, Riga, LV-1006, Latvia 2 Faculty of Chemistry, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia 3 Latvian Biomedical Research and Study Centre, Ratsupites Street 1, Riga, LV-1067, Latvia E-mail: [email protected]

An estimated 240 million persons worldwide are chronically infected with he-patitis B virus (HBV). Chronic hepatitis B (CHB) in up to 40% of cases progresses to liver cirrhosis, hepatic decompensation, and hepatocellular carcinoma, a leading cause of cancer-related morbidity and mortality worldwide [1]. We are focused on original antiviral strategy intended to suppress the self-assembly process of HBV core (HBc) protein as one of the promising ways to cure CHB without induction of drug resistance. Targeting the capsid protein of HBV and thus interrupting normal capsid formation have been an attractive approach to block the replication of HBV.

Heteroaryldihydropyrimidines (HAPs) were shown to bind the HBV core pro-teins and misdirect the assembly of the capsid in vitro. We carried out structural optimizations based on HAPs analogue Bay 41-4109 and structure-activity relati-onship studies [2].

Newly synthesized HAPs 1 and 2 were evaluated for their ability to disrupt the capsid assembly in cell culture, and promising candidates were selected for further evaluation of antiviral activity and discovery of mechanisms of compound action.

Supervisors: Dr. chem. B. Vīgante, Dr. habil. chem. G. Duburs

References: [1] WHO Hepatitis B Fact Sheet. Geneva: World Health Organization, 2016.[2] Qiu, Z. et al. Design and Synthesis of Orally Bioavailable 4-Methyl Heteroaryl-dihydropyrim-

idine Based Hepatitis B Virus (HBV) Capsid Inhibitors. J. Med. Chem. 2016, 59, 7651–7666.


STUDY ON GLYCOSYLATION OF ALCOHOLS AND THIOLS IN LIQUID SO2

Krista Suta, Jevgeņija Lugiņina, Māris TurksFaculty of Materials Science and Applied Chemistry, Riga Technical University, P. Valdena Street 3, Riga, LV-1048, Latvia E-mail: [email protected]

Glycosylation is one of the most important strategy towards glycosidic bond formation in carbohydrate chemistry. Still, there is no universal conditions for glycosylation reaction. Yield, regio- and stereoselectivity are the main criteria that determinate application limits of known glycosylation methods. Appropriate, even specific, combination of glycosyl donor and its activator, glycosyl acceptor and sol-vent has to be developed to reach optimal results [1]. Glycosyl halides are widely used glycosyl donors with glycosyl fluorides being the most stable ones [2]. Based on Lewis acid properties of liquid SO2 as well as Eisfeld study on solvation of fluoride ion by this unconventional solvent [3], we decided to explore glycosylation reaction in liquid SO2 by employing glycosyl fluorides as glycosyl donors.

Herein we report new conditions for synthesis of O- and S-glycosides from gly-cosyl fluorides by glycosylation of alcohols and thiols in liquid SO2 in the absence of any additional activator. Method is applicable only for glycosyl donors with protec-ting groups that are stable in acidic media, otherwise deprotection occurs leading to inseparable mixture of monosaccharides. Reactivity of nucleophiles under these conditions corresponds to the theory and isolated yields of desired glycosides reach up to 96%, while stereoselectivity highly depends on substrate steric effects.

O

SO2

SOO

n*F

O

oxocarbenium ion-SO2 solvate

NuH(ROH or RSH) O

NuPGO

FPGO

PGO

PG = Piv or Bn

F ⋅(SO2)n

FS

O

O

*

OPivO

PivOOPiv

F

OPivOBnO

BnOBnO

OBn

F

OPivOPivO

OPiv

F

OPiv

8 examples47-96%

α > β for ROHα/β ∼70:30 for RSH

11 examples34-96%

α/β 80:20 to 100:0

5 examples33-72%

α/β 19:81 to 62:38

SH

ClOH

10

OH

Glycosyl donorsNuH (ROH or RSH)

R:

References:[1] Toshima, K. Glycoscience, 2nd ed. B. O. Fraser-Reid, K. Tatsuta, J. Thiem (Eds.). Berlin: Spring-

er, 2008.[2] Robina, I., Carmona, A. T., Moreno-Vargas, A. J. Curr. Org. Synth. 2008, 11, 33.[3] Eisfeld, W., Regitz, M. J. Am. Chem. Soc. 1996, 118, 11918.

ĶĪMIJAS SEKCIJA - LU

Documents

Transcript of ĶĪMIJAS SEKCIJA - LU