This presentation is for those who have the propensity and predilection for GREEN SOLVENTS !!!

1. Solvents in Green Chemistry Compiled by :- Pratul Yadav XB4 - COE - 068

2. What is Green Chemistry ? Green Chemistry , also called Sustainable Chemistry, is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances. OR Green Chemistry is the design , development , and implementation of chemical products and processes to reduce or eliminate the use and generation of substances hazardous to human health and the environment.

3. Need for Green Chemistry Energy efficient Viable Liveable G Economic Ecofriendly Sustainable

4. Green Chemistry as a Reduction Process Cost Waste REDUCING Materials Energy Risk & Hazard

5. SUSTAINABILITY Efficient use of resources Protect employees Competitive benefits Minimized harm EHS Policy EnvironmentalIntegrity Social Responsibility Climate Change Social cohesion Codes of Conduct Mission , Vision , Values Biodiversity Dividends Share price Capital growth Profitability Economic Viability

6. PRINC IPLES Prevention 1 Use of Renewable Feedstocks 7 Atom Economy 2 8 Reduce Derivatives Less Hazardous Chemical Synthesis Catalysis 3 9 Designing Safer Chemicals Design for Degradation 10 4 Real time analysis for Pollution Prevention Safer Solvents & Auxiliaries 11 5 Safer Chemistry for Accident Prevention Design for Energy Efficiency 12 6

7. Solvents in Green Chemistry Solvents define a major part of the environmental performance of processes in chemical industry and also impact on cost, safety and health issues. The idea of “green” solvents expresses the goal to minimize the environmental impact resulting from the use of solvents in chemical production.

8. Greener Solvent Alternatives Supercritical fluids Water Ionic liquids No Solvent Lactate esters Perfluorinated hydrocarbons

9. Water : AGreen Solvent With A Difference…….. Water is the best solvent among all the green solvents because of its many advantages such as….. * Environmental benefits * Safety * Synthetic efficiency * Simple operation * Cost effective * Potential for new synthetic methodologies

10. Water as dual activator medium * Hydrogen bonding in water endows a unique characteristic - dual activator property. * Water can activate both – nucleophiles & electrophiles, and hence accelerates polar reactions. For example , the role of water in the reaction of an aldehyde with 2-aminothiophenol for benzothiozole synthesis.

11. Supercritical Fluids (SCFs) A pure fluid is supercritical when it is above its Tc & Pc. In the Supercritical region the substance is neither a gas nor a liquid – it is a fluid that has properties of both. There are no sharp boundaries between gas and liquid. Properties of SCFs can be very different from the normal liquid phase.

12. Possible advantages of supercritical fluids * increased solubilities of reactants or products * single homogeneous phase, no transport limitations * SCFs such as water, CO2 can be recovered, or disposed of with little or no environmental impact * reaction conditions can be fine-tuned by varying pressure and/or temperature * separation step can be eliminated * organic compounds are soluble in SCW, inorganic salts are insoluble  SCWO

13. Phase diagram for pure CO2 © Monterey Bay Aquarium Research Institute SOLID SUPERCRITICAL FLUID Critical • point Pressure (bar) 74 LIQUID Triple • point 5.1 GAS 1 31.1ºC -56.3ºC -78 ºC Temperature (ºC)

14. Advantages of ScCO2 *High compressibility *Large change in solvent properties for relatively small change in pressure – infinite range of solvent properties available *Ability to tune solvent to favour a particular reaction pathway simply by optimising temperature or pressure *Small amounts of cosolvents can further modify solvent properties *High diffusion rates offer potential for increased reaction rates. *Potential for homogeneous catalytic processes. *High solubility of light gases, some catalysts and substrates; bring all together in single homogeneous phase *Inert to oxidation; resistant to reduction *Excellent medium for oxidation and reduction reactions.

15. Extraction using ScCO2 *Extensively used for ‘natural’ coffee decaffeination; alternative uses CH2Cl2(also tea) *Extraction of Hops for Brewing *Many other extraction processes *Often use liquid rather than supercritical CO2. *Spices *Essential oils and fragrances *Simple product isolation by evaporation, to 100% dryness. *No solvent residues or effluent

17. Epoxidation

18. Radical reactions

19. Pd-mediated C-C bond formation

20. Ring closing metathesis

21. Biotransformations

23. Highly polar

24. Consist of loosely co-ordinating bulky ions

25. Very low vapor pressure

26. Liquid window of up to 300 ºC enabling wide kinetic control

27. Most liquids thermally stable >200 ºC

28. Immiscible with many organic solvents

29. Non-aqueous polar alternatives for phase transfer processes

30. Relatively inexpensive

32. Biocatalysis in IL’s using scCO2 as mobile phase Continuous process reported by Reetz and Leitner, combines green solvents: * Enzyme suspended in IL phase * Substrates injected using flow of scCO2 * Substrate more soluble in IL than in scCO2 * Product has good solubility in scCO2 and readily extracted * IL and enzyme reused * IL does not dissolve in scCO2

33. Fluoropolymer synthesis *Dupont $275M facility *Replaces CFCs used previously (now banned by Montreal Protocol) *Initially used for fluorinated ethylene-propylene and perfluoroalkoxy resins *Easy polymer isolation and drying, and minimal waste

34. Diastereoselective Sulphur Oxidation * By modification of the density, selectivity was enhanced to a maximum d.e. of >95%. No d.e. is observed in conventional solvent. No diastereoselectivity observed in conventional solvent! Optimumdensity is ca. 0.7g/ml

35. Ethyl Lactate : A Renewable Solvent *Derived from processing corn *Variety of lactate esters possible *Renewable source (non-petrochemical) *Attractive solvent properties *Biodegradable, *Easy to recycle, *Non-corrosive, *Non-carcinogenic *Non-ozone depleting *Good solvent for variety of processes *Commonly used in the paint and coatings industry *Potentially has many other applications.

36. … and if you can find a way to use no solvent at all, that may even be better!