Faster Greener Chemistry?

Catalyst synthesis and evaluation

A context based case study in Green / Sustainable Chemistry

What is Context and Problem Based Learning (C/PBL)?

A teaching methodology that aims to increase student engagementUses real-life applications of chemistry principles, techniques and experiments Problem scenarios which are ill-defined, and have a number of satisfactory solutions. Learners collaborate to solve problems, acquire new knowledge and present the outcomes or product. Provides the opportunity to develop valuable transferable skills (see later).Academic staff adopt the role of facilitator or guide.

Module Overview

Session 1: Workshop

Module inductionPlanning laboratory

work

Session 2: Laboratory

Synthesis of catalyst ligand

Session 3: Laboratory

Preparation of catalyst

Session 4: Laboratory

Evaluation of catalyst in

epoxidation step

Session 5: LaboratoryAlternative epoxidation

method

Session 6: Workshop

Cost, performance and environmental impact of reactions

Session 7: Workshop

Feedback clinic

Session 8: Workshop

Group presentations

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Scientific Skills

The scientific skills developed include:• Adaptation of an experimental procedure from the literature.• Effective time planning.• Accurate record keeping in a laboratory notebook.• Interpretation of experimental data and relevant scientific

literature.• Use of chemical databases to find information on raw material

costing and on recent developments to improve the environmental impact of the process (e.g. alternative conditions for oxidation).

• Evaluation of the efficiency, relative costs and environmental impact of the oxidation procedures used.

• Preparation of a scientific report and presentation.

Transferable Skills DevelopedTeam work: work in groups to complete the tasks.

Organisation and planning:

prepare procedures and plan effective use of time in the laboratory.

Communication: oral presentation and report writing.

Drawing conclusions and recommendations:

Justify decisions, assumptions and conclusions with reference to results from other groups and supporting literature.

Numeracy: apply green chemistry metrics to experimental results.

Professional role & responsibilities:

adopt role of a professional chemist to consider the environmental impact & costing

Problem solving: address the brief in the scenario presented.

Information technology skills:

use a wiki to collaborate & develop ability to use word-processing, spreadsheet, presentation, chemical drawing and library database software.

Metacognition: reflect on the case study using the guidelines provided.

You will be asked to summarise your reflections on the development of these transferable skills at

the end of the case study

Tools to help you

You have or will be provided with a Student Guide for this project in which you will find:

• An overview of each workshop or laboratory session and a summary of tasks to be completed during and after it.

• Appendices containing guidelines for various aspects of the work involved and literature review supplied by HugePharma Ltd.

• Details about how the project will be assessed.

Your first task is to read the guide carefully.

Assessment of the Project (see Table 1 in student guide also)

Activity Group / individual

% mark allocation

Contribution to group (based on participation in lab and workshop

sessions, summaries of meetings and contribution to group wiki)

Individual 10

OPTIONAL - Peer assessment by other group members (frequency and quality of

contributions, both online and face-to-face)Individual 5

Lab notebook and individual work submitted on a weekly basis Individual 30

Reflective piece Individual 10

Final wiki report (Criteria - content, accuracy, structure,

clarity, references to the literature)Group 30

Presentation (assessment by tutor, feedback from tutor and peers - peer assessment is optional)

Group 15

Faster Greener Chemistry? - ContextYou will adopt the role of a chemist employed in a campus company that specialises in chemical catalysts, Chem Cat Ltd. The company has been contracted to carry out work for a large pharmaceutical multinational, HugePharma Ltd. Your team will report to your laboratory manager according to the brief outlined in a letter from HugePharma Ltd.

This brief requires that:• a range of Mn-salen catalysts are prepared and

characterised, • their performance in a reference reaction (epoxidation of

trans-stilbene) is evaluated and • the costs and the environmental impact of the process,

and any alternatives suggested are assessed.

Green Chemistry Considerations

The pharmaceutical company have specifically requested that green chemistry (also known as sustainable chemistry) principles be implemented to their full potential in the catalyst synthesis and in the epoxidation process.This is essential as they need to maintain their Integrated Pollution Prevention and Control (IPPC) licence.(more information on the relevant European legislation is available at the following website:http://ec.europa.eu/environment/air/pollutants/stationary/ippc/summary.htm )

What you need to do

Your group will need to devise and perform several laboratory experiments to obtain the results required to make a recommendation to HugePharma Ltd.

You will also need to analyse the results obtained to assess the relative costs and the environmental impact of these processes using suitable metrics.

A report and oral presentation are the means by which your group will communicate your findings and recommendations to HugePharma Ltd.

Green Chemistry and Sustainable Development

In 1987, sustainable development was defined by a United Nations Commission on Environment as “...meeting the needs of the present without compromising the ability of future generations to meet their own needs”.[1]

To achieve sustainable development, synthesis should be optimised to maximise yields, minimise waste and reduce use of toxic reagents or those in short supply. These changes are components of the field of green chemistry.

In 1996, IUPAC defined Green Chemistry as “the invention, design and application of chemical products and processes to reduce or to eliminate the use and generation of hazardous substances”.[2]

[1] M. Lancaster, Green Chemistry : An Introductory Text Cambridge : Royal Society of Chemistry, 2002.[2] P. Anastas and P. Tundo, Green Chemistry: Challenging Perspectives, Oxford University Press, 2000.

Twelve Principles of Green Chemistry

It is better to prevent waste than to treat or clean up waste after it is formed.

Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.

Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.

Chemical products should be designed to preserve efficacy of function while reducing toxicity.

The use of auxiliary substances should be made unnecessary wherever possible, and innocuous when used.

Energy requirements should be recognised for their environmental and economic impacts, and should be minimised. Synthetic methods should be conducted at ambient temperature and pressure.

The aims of green chemistry are summarised in the “Twelve Principles of Green Chemistry”*

Twelve Principles of Green Chemistry* continued

A raw material or feedstock should be renewable rather than depleting wherever technically and economically practicable.

Unnecessary derivatisation should be avoided whenever possible.

Catalytic reagents are superior to stoichiometric reagents.

Chemical products should be designed so that at the end of their function they do not persist in the environment and break down into innocuous degradation products.

Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.

Substances and the form of a substance used in a chemical process should be chosen so as to minimise the potential for chemical accidents.

* P. Anastas and J. Warner, Green Chemistry: Theory and Practice, Oxford University Press, 1998.

The European IPPC Directive requires that industrial and agricultural activities with a high potential to pollute (e.g. energy industries, production and processing of metals, mineral industry, chemical industry, waste management, livestock farming) have a permit.

The conditions for issuing the permit require an organisation to:• use all appropriate pollution-prevention measures, namely the best

available techniques (which produce the least waste, use less hazardous substances, enable the substances generated to be recovered and recycled, etc.);

• prevent all large-scale pollution;• prevent, recycle or dispose of waste in the least polluting way

possible;• use energy efficiently;• ensure accident prevention and damage limitation;• return sites to their original state when the activity is over.

(from Directive 2008/1/EC of the European Parliament 15 January 2008, see http://europa.eu/legislation_summaries/environment/waste_management/l28045_en.htm )

Environmental Legislation

Guidance information on best available techniques (BAT) is available in the form of reference documents for particular activities, e.g. “Reference document on best available techniques for the manufacture of organic fine chemicals”, accessible from http://eippcb.jrc.ec.europa.eu/reference/

Most European countries require that organisations that hold an IPPC licence prepare an Annual Environmental Report (AER). These reports are made available publicly (for example, see http://www.epa.ie/terminalfour/ippc/index.jsp )

Environmental Legislation contd.

The Role of Catalysts

One of the 12 Principles of Green Chemistry is that;Catalytic reagents are superior to stoichiometric reagents.

The benefit of incorporating an efficient catalyst into the process for manufacturing a chemical is very apparent from the accounts from companies who have won Green Chemistry awards;e.g. Development of a catalytic synthesis of a treatment for type 2 diabetes;http://www.epa.gov/greenchemistry/pubs/pgcc/winners/gspa06.html

Manganese-salen Complexes as Catalysts

Salts of Mn(III), particularly those that contain salen type ligands (salen is bis(salicylaldehyde)ethylene diamine), have been found to show catalytic activities of significant interest. These properties have had two main applications to date; 1. asymmetric epoxidation of alkenes (e.g. Jacobsen’s catalyst) and oxidation of a range of organic substrates at commercial scale, 2. development of synthetic enzymes (“synzymes”) which can act either as catalases or superoxide dismutases.

The focus in this case is on the first application, although the ability to effect asymmetric reactions will not be evaluated as chiral substrates will not be employed.

Some Useful Resources• The URL below links to a video in which Professor

Martyn Poliakoff explains the main principles of Green Chemistry;

http://www.youtube.com/watch?v=_KYiLFkMQ_E&feature=player_embedded

• The literature review supplied by HugePharma Ltd., which includes the following;

- Herbert C. Brown Award For Creative Work In Synthetic Methods, Yarnell, A.; Chemical & Engineering News, January 21 2008,86 (3), 57- US Patent No. 6,031,115: Process for Preparing Epoxides and International Patent No. WO 93/1706, D., Fedouloff, M., Turner, G.; 2000; SmithKline Beecham plc, see http://www.everypatent.com/comp/pat6031115.html

Getting Started in Your Group

• Keep an open mind and be prepared to listen.• Avoid being dismissive or judgemental• Be aware of your body language – avoid being

negative

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Stages in the Group Process

• Get to know each other• Establish ground rules• Brainstorm• Agree tasks• Plan your timeline• Keep going• The final product

Guidelines above are based on: Chapter 3 in “Study and Communication Skills for the Chemical Sciences”; Overton, T., Johnson, S., Scott, J.; Oxford University Press (2011)

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Tools to help you : Using a wiki

• Each group will have their own wiki to allow effective collaboration. Guidelines on how to use a wiki are provided in Appendix 1 of your student guide and should be consulted.

• You will add information to the wiki and your group will need to meet face to face at least once in the period between each lab or workshop session.

• At the end of the module, you will publish your final team report directly from your wiki (i.e. your wiki will become your final assignment).

• If you have not already been invited to your group wiki, you need to give your email address to your tutor by the end of Workshop 1.

Introductory text from tutor

Pages created using project headings

Log of recent activity used to monitor student contributions

Create new pages and upload files

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Pages can be edited and linked to other pages throughout the wiki.

Use this space to explain to group members reasoning for changes made

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Using Your Wiki

Reminder:

• Create pages in your wiki corresponding with the sections listed in the Appendix 1 in your student guide.

• You will add information to the wiki during and after each workshop as you complete tasks.

• The wiki enables your tutor to track your progress and give you regular feedback .

• The wiki keeps a record of individual contributions to the group project.

Tools to help you: Oral Presentations

In Session 8, your group will give a presentation.

(see Appendix 6 in your student guide also)

When preparing a presentation, content should:• Suit your audience (for this presentation, the

audience will be peers and academic staff)• Be informative and interesting and a suitable length

In all cases, the presentation should be made as simple and visually engaging as possible.

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• Keep slides simple - too much text turns your audience off• A picture speaks a thousand words• Use simple colours, large font where possible• Don’t (over) animate• Check that the slide can be read in the environment where you are going to speak

• Credit the source that a diagram or image comes from if necessary and include references at the end.

• Face your audience and try not to read from cards

Guidelines

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Structure of Presentation

• Beginning - introduce topic generally, remember your audience

• Core - longest section containing key findings• End - briefly summarise results, emphasising

main point and reflecting on theme

“Tell the audience what you're going to say, say it; then tell them what you've said”.

Dale Carnegie (1888-1955), American writer.

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Tasks to Complete Before Session 2

• Review the assessment criteria and schedule provided (Tables 1- 3).• Read the project briefing pack.• Meet as a group to agree on the list of actions for group. Progress

should then be reported on the wiki by the Recorder for this week by the day specified.

• Become familiar with how to navigate the group wiki and how to add and edit pages, add files and add comments. Add a Table of Contents and a Group Planning and Communication main page (see Appendix 1).

• Submit a group experimental procedure for the preparation of the salen ligand using the wiki.

• Individually submit a short chemical safety assessment.• Add information on the first experiment available in advance

(materials, equipment, literature reference etc.) to your lab notebooks.

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