Green chemistry

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1. Green Chemistry By: Mr. Santosh Damkondwar M. Sc. NET GATE Ph.D. Pursuing Assistant Professor – Engineering Chemistry

2. SOME WELL-PUBLICIZED INCIDENTS FROM THE PAST FEW DECADES … The Cuyahoga River in Ohio became so polluted with chemicals it caught fire .

3. Bhopal Gas Tragedy A plant accident in Bhopal, India, released methyl isocyanate . Nearly 4000 people died.

4. PAUL ANASTAS Father Of Green Chemistry

5. Green Chemistry is the design of chemical products and processes that reduce or eliminate the use and/or generation of hazardous substances.

6. Green Chemistry Is About... Use of Catalyst in place of Reagents Using Non-Toxic Reagents Waste Minimisation at Source Use of Renewable Resources Use of Solvent Free or Recyclable Environmentally Benign Solvent systems Improved Atom Efficiency

7. The 12 Principles of Green Chemistry 1. Prevention It is better to prevent waste than to treat or clean up waste after it has been created. Chemical Process

8. Past The Chemical Industry of the Past(?)

9. The Chemical Industry Today

10. The Chemical Industry Tomorrow(?)

11. Atom Economy : Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product. The 12 Principles of Green Chemistry

12.   Let us consider some common reactions like rearrangement, addition, substitution & elimination to find out which is more atom economical.

13. 3. Less Hazardous Chemical Synthesis: Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to people or the environment . The 12 Principles of Green Chemistry

14. Designing Safer Chemicals: Chemical products should be designed to effect their desired function while minimising their toxicity. The 12 Principles of Green Chemistry

15. EXAMPLES OF GREEN CHEMISTRY Safer dry cleaning Initially gasoline and kerosene were used Chlorinated solvents are now used Supercritical/liquid carbon dioxide (CO 2 )

16. LEAD POLLUTION HAS BEEN DECREASED BY… Replacing tetraethyl lead with less toxic additives (e.g., “lead-free” gasoline ). Such as MTBE & ETBE (ethyl tertiary butyl ether)

17. Safer Solvents & Auxiliaries : The use of auxiliary substances (e.g., solvents or separation agents) should be made unnecessary whenever possible and innocuous when used . Water should be used as a solvent If water is not usable then more ecofriendly solvents like supercritical CO 2 or ionic solvents As far as possible synthesis is carried out without solvents The 12 Principles of Green Chemistry

18. Design for Energy Efficiency : Energy requirements of chemical processes should be recognised for their environmental and economic impacts and should be minimised. If possible, synthetic methods should be conducted at ambient temperature and pressure . This can be achieved by Use of proper catalyst , enzymes Use of micro organisms for organic synthesis Use of renewable materials The 12 Principles of Green Chemistry

19. Use of Renewable Feedstock: A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable. The 12 Principles of Green Chemistry

20. Poly lactic acid (PLA) for plastics production

21. Reduce Derivatives: Unnecessary derivatization (use of blocking groups, protection/de-protection, and temporary modification of physical/chemical processes) should be minimised or avoided if possible, because such steps require additional reagents and can generate waste. The 12 Principles of Green Chemistry

22. Catalysis: Catalytic reagents (as selective as possible) are superior to stoichiometric reagents . Catalysts make the reaction faster decrease the energy requirement can produced single desired product minimize waste. The 12 Principles of Green Chemistry

23. Designing of Degrading Products: Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment . Examples: Polyethylene, polystyrene are not biodegradable but biodegradable polymer like polyhydroxybutyrate-hydroxyvalarate ( PHBV ) Synthetic insecticides remains in the food grains & vegetables & do not get degraded but natural insecticides (chilli, neem etc.) get easily degraded after killing the insect. The 12 Principles of Green Chemistry

24. Polyhydroxyalkanoates (PHA’s)

25. New Analytical Methods: OR Real Time Analysis for Population Prevention: Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances. The 12 Principles of Green Chemistry

26. Safer Chemicals for Accidents Prevention: The 12 Principles of Green Chemistry Analytical Substances and the form of a substance used in a chemical process should be chosen to minimise the potential for chemical accidents, including releases, explosions, and fires . The reagents & reaction should be risk free, in the chemical process, to minimize the chemical accidents, explosion, fires & gas release.

27. Efficiency Parameters

28. Reaction Yield: The reaction should have high % of yield. Efficiency Paramenters

29. Atom Economy: Atom economy (atom efficiency) describes the conversion efficiency of a chemical process in terms of all atoms involved (desired products produced). For the reaction, atom economy should be high i.e. maximum. Efficiency Paramenters

30. Atom Economy: Let us consider some common reactions like rearrangement, addition, substitution & elimination to find out which is more atom economical. Efficiency Paramenters

31. Atom Economy: Efficiency Paramenters

32. Atom Economy: Efficiency Paramenters

33. Conversion: OR Efficiency Paramenters    

34. Reaction Selectivity: Efficiency Paramenters   Environmental Load Factor: It should be minimum .  

35. Traditional & Green Pathways To synthesis

36. Traditional Pathway to Indigo Dye

37. Green Pathway to Indigo Dye

38. Energy Global Change Resource Depletion Food Supply Toxics in the Environment The major uses of GREEN CHEMISTRY

39. Conclusion Green chemistry Not a solution to all environmental problems But the most fundamental approach to prevent pollution.

40. References:

41. Anastas , P.T., and Zimmerman, J.B., “Design through the Twelve Principles of Green Engineering”, Env . Sci. Tech. 2003, 37(5), 94A-101A Green Chemistry: Environmentally Benign Reaction By V. K. Ahluwalia, Ane Books India New Trends in Green Chemistry By V. K. Ahluwalia & M. Kidwai Engineering Chemistry By Jain & Jain Engineering Chemistry By O. G. Palanna http://en.wikipedia.org/wiki/Green_chemistry www.slideshare.net/Santachem

42. Thank you