SJSU Undergraduate Research Grants Olefin Metathesis with ...SJSU Undergraduate Research Grants...
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SJSU Undergraduate Research Grants Olefin Metathesis with a Polymer Supported Ruthenium Catalyst Complex Tyler Devincenzi and Prof. Madalyn Radlauer Department of Chemistry, College of Science Citations Ruthenium catalysts for olefin metathesis are known to be tolerant of various functionalities and conditions, but over longer periods of time and especially at elevated temperatures, these catalysts will degrade. Our initial research objective has been the integration a ruthenium catalyst into the framework of a linear polymer with the intent of increasing stability and recyclability. In order to incorporate the catalyst in a such a framework, we have synthesized a hydroxyl substituted N-heterocyclic carbene (NHC) ligand precursor. A nucleophilic substitution with mesylated poly(ethylene glycol) monomethyl ether couples the NHC ligand precursor to the linear polymer. A ruthenium precursor (Grubbs or Grubbs-Hoveyda 1 st generation catalyst) added to this poly(ethylene glycol) ligand produces the polymer-supported catalyst complex, which can catalyze cross metathesis (and other olefin metathesis reactions). Commercially available Grubbs and Grubbs-Hoveyda 2 nd generation catalysts have been utilized as benchmarks. We will expand on these results by incorporating the ruthenium catalyst into a structured polymer and determining if reaction selectivity could be affected by the steric environment of the material. Abstract Catalytic runs: Cross metathesis Research questions Acknowledgements Current work: Linear polymer support Next steps: More catalysis and polymer architecture studies Ruthenium Catalysis Team • Juan Moreno • Zehra Hamidi Funding Sources Radlauer Research Group College of Science Department of Chemistry Office of Research Center for Faculty Development Type 1 2 3 1 97% 2 3 0% Type 1: Hexene Type 3: Tert-butylethylene Olefins have been classified into 4 types of olefins based on their likelihood to homodimerize with the ruthenium catalyst. 2 In general, Type 1 olefins readily homodimerize (green), Type 2 will slowly homodimerize (yellow), Type 3 will not homodimerize (red), but will react with Type 1, and Type 4 will not react (thus these were left off of the table. The olefins listed on the right are classified based on expected reactivity using Grubbs 2 nd Generation catalyst. The percentages in the boxes of the table indicate %conversion in the homodimerization benchmarking reaction we ran with Grubbs 2 nd Generation catalyst. Starting from 2,4,6-trimethylaniline, we can synthesize a ruthenium catalyst supported by linear poly(ethylene glycol) (PEG). 3 We will compare its reactivity with that of the commercial catalyst. Currently, we are two steps from the ruthenium complex. We are also looking into star polymer architectures. A star polymer would introduce a more sterically hindered environment for the catalyst to work in. The structure it provides may also lead to a more stable catalyst at higher temperatures. Type 2: Ethyl acrylate • How do we synthesize a catalyst with a polymer support? • Will the sterically crowded environment produced by the polymer around the catalytic metal species lead to an effectively site-isolated reaction? • Will the presence of the polymer support lead to a more stable catalyst at higher temperatures? • Will all types of metathesis reactions be affected by changing from a small molecule catalyst to a supported catalyst? • Is a linear polymer architecture sufficient to change reactivity and stability or will a more structured polymer support be necessary to observe the desired effects? 1. Mugemana, C.; Bukhryakov, K. V.; Bertrand, O.; Vu, K. B.; Gohy, J.; Hadjichristidis, N.; Rodionov, V. O. Ring opening metathesis polymerization of cyclopentene using a ruthenium catalyst confined by a branched polymer architecture. Polym. Chem. 2016, 7, 2923–2928. 2. Chatterjee, A. K.; Choi, T.; Sanders, D. P.; Grubbs, R. H. A General Model for Selectivity in Olefin Cross Metathesis. J. Am. Chem. Soc. 2003, 125, 11360–11370. 3. Hong, S. H.; Grubbs, R. H. Highly active water-soluble olefin metathesis catalyst. J. Am. Chem. Soc. 2006, 128, 3508–3509. O O The last step to make the linear polymer appended catalyst will be the attachment of the ruthenium to our polymeric precursor. Once this is done, we can run the catalytic trials with our polymeric supported catalyst and compare the results to our benchmarking reactions. 1 2 3 4 General cross metathesis reaction 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 f1 (ppm) 1 2 3 4 Me O O S O O Me + DMF, 60ºC, 48hrs KOtBu 2 (added in step 2) R1 + R2 R1 R2 1 mol% catalyst 45 ºC 15hrs 4 1 3
Transcript of SJSU Undergraduate Research Grants Olefin Metathesis with ...SJSU Undergraduate Research Grants...
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SJSU Undergraduate Research Grants
Olefin Metathesis with a Polymer Supported Ruthenium Catalyst Complex
Tyler Devincenzi and Prof. Madalyn RadlauerDepartment of Chemistry, College of Science
Citations
Ruthenium catalysts for olefin metathesis are known to be tolerant of variousfunctionalities and conditions, but over longer periods of time and especially atelevated temperatures, these catalysts will degrade. Our initial research objective hasbeen the integration a ruthenium catalyst into the framework of a linear polymer withthe intent of increasing stability and recyclability. In order to incorporate the catalyst ina such a framework, we have synthesized a hydroxyl substituted N-heterocycliccarbene (NHC) ligand precursor. A nucleophilic substitution with mesylatedpoly(ethylene glycol) monomethyl ether couples the NHC ligand precursor to the linearpolymer. A ruthenium precursor (Grubbs or Grubbs-Hoveyda 1st generation catalyst)added to this poly(ethylene glycol) ligand produces the polymer-supported catalystcomplex, which can catalyze cross metathesis (and other olefin metathesis reactions).Commercially available Grubbs and Grubbs-Hoveyda 2nd generation catalysts have beenutilized as benchmarks. We will expand on these results by incorporating theruthenium catalyst into a structured polymer and determining if reaction selectivitycould be affected by the steric environment of the material.
Abstract Catalytic runs: Cross metathesis
Research questions
Acknowledgements
Current work: Linear polymer support Next steps: More catalysis and polymer architecture studies
Ruthenium Catalysis Team• Juan Moreno• Zehra Hamidi
Funding Sources
Radlauer Research Group
College of ScienceDepartment of ChemistryOffice of ResearchCenter for Faculty Development
Type 1 2 3
1 97%
2
3 0%
Type 1: Hexene
Type 3: Tert-butylethylene
Olefins have been classified into 4 types of olefins based on their likelihood tohomodimerize with the ruthenium catalyst.2 In general, Type 1 olefins readilyhomodimerize (green), Type 2 will slowly homodimerize (yellow), Type 3 will nothomodimerize (red), but will react with Type 1, and Type 4 will not react (thus thesewere left off of the table. The olefins listed on the right are classified based onexpected reactivity using Grubbs 2nd Generation catalyst. The percentages in the boxesof the table indicate %conversion in the homodimerization benchmarking reaction weran with Grubbs 2nd Generation catalyst.
Starting from 2,4,6-trimethylaniline,we can synthesize a rutheniumcatalyst supported by linearpoly(ethylene glycol) (PEG).3 We willcompare its reactivity with that ofthe commercial catalyst. Currently,we are two steps from theruthenium complex.
We are also lookinginto star polymerarchitectures. A starpolymer wouldintroduce a moresterically hinderedenvironment for thecatalyst to work in. Thestructure it providesmay also lead to amore stable catalyst athigher temperatures.
Type 2: Ethyl acrylate
• How do we synthesize a catalyst with a polymer support?
• Will the sterically crowded environment produced by the polymer around the catalytic metal species lead to an effectively site-isolated reaction?
• Will the presence of the polymer support lead to a more stable catalyst at higher temperatures?
• Will all types of metathesis reactions be affected by changing from a small molecule catalyst to a supported catalyst?
• Is a linear polymer architecture sufficient to change reactivity and stability or will a more structured polymer support be necessary to observe the desired effects?
1. Mugemana, C.; Bukhryakov, K. V.; Bertrand, O.; Vu, K. B.; Gohy, J.; Hadjichristidis, N.; Rodionov, V. O. Ring opening metathesis polymerization of cyclopentene using a ruthenium catalyst confined by a branched polymer architecture. Polym. Chem. 2016, 7, 2923–2928.
2. Chatterjee, A. K.; Choi, T.; Sanders, D. P.; Grubbs, R. H. A General Model for Selectivity in Olefin Cross Metathesis. J. Am. Chem. Soc. 2003, 125, 11360–11370.
3. Hong, S. H.; Grubbs, R. H. Highly active water-soluble olefin metathesis catalyst. J. Am. Chem. Soc. 2006, 128, 3508–3509.
O
O
The last step to make the linear polymerappended catalyst will be the attachment ofthe ruthenium to our polymeric precursor.Once this is done, we can run the catalytictrials with our polymeric supported catalystand compare the results to our benchmarkingreactions.
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General cross metathesis reaction
0.51.01.52.02.53.03.54.04.55.05.56.06.57.07.5
f1(ppm)
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MeO
O SO
OMe + DMF, 60ºC, 48hrs
KOtBu
2(added in step 2)
R1+
R2 R1
R21 mol% catalyst
45 ºC 15hrs
4
1 3
