IONIC LIQUIDS

basic ionic liquid chemistry on how ionic liquids acts as green solvents for organic synthesis.

1. IONIC LIQUIDS AS GREEN SOLVENTS FOR ORGANIC TRANFORMATIONS Submitted by: SANSKRITA MADHUKAILYA M.Sc Dept. of Chemistry, Dibrugarh University

2. TOPICS TO BE COVERED : Green Chemistry & Principles of green chemistry Ionic liquids, Structure & Historical developments Synthesis of ionic liquids Properties of ionic liquids that separates it from other solvents Applications Ionic liquids in different organic solvents Various types of ionic liquids References

3. GREEN CHEMISTRY (Clean Chemistry, Atom Economy, Environmentally benign chemistry, Benign-by-design chemistry) term given by Paul T. Anastas developing chemical products in a safe, environmentally friendly way. defined as “ to promote innovative chemical technologies that reduce or eliminate the use or generation of hazardous substances in the design, manufacture and use of chemical products ” Reducing – -wastes -hazardous reactions -risk -energy -cost

4. Prevention Less hazardous chemical synthesis Designing safer chemicals Design for energy efficiency Use of renewable feed stocks Reduction of derivatives & use of protecting groups Catalysis Design for degradation Real time analysis for pollution prevention Inherently safer chemistry for accident prevention Atom economy Safer solvents and auxiliaries PRINCIPLES OF GREEN CHEMISTRY A. Ivanković , A. Dronjić, A. M. Bevanda, S. Talić. Review of 12 Principles of Green Chemistry in Practice. Int. J. Sustainable and Green Energy , 6(3), 2017 ,49-48.

5. Volatile Organic Compounds (VOCs) PROBLEMS ! REPLACED BY GREEN SOLVENTS: Environmental: Photochemical smog, ozone depletion, greenhouse effect Economic: Cost Hazards: Volatility, Toxicity, Explosive, Cancerous WATER Super-Critical Fluids IONIC LIQUIDS K. Shanab, C. Neudorfer, E. Schirmer, H. Spreitzer, Green Solvents in Organic Synthesis: An Overview, Curr.Org . Chem., 2013 , 17, 1179-1187

6. IONIC LIQUIDS Salt in the liquid state. Ionic Liquids (ILs) consist entirely of ions and being liquid below 100°C. If they are liquid at room temperature, we call them room temperature ionic liquids (RTILs). Also known as room temperature molten salts, Fused salts, ionic fluid, liquid organic salt etc. P. P. Salvi, A Brief Account On: Ionic Liquids with its Applications, Synthesis and applications of task-specific ionic liquids (TSILs) , December 2010

7. Structure of Ionic Liquids Made up of ions: Organic cations & Inorganic/Organic anions Cations are asymmetric, bulky; mostly derivatives of imidazolium, pyridinium, pyrrolidinium, ammonium, phosphonium, sulphonium, thiazolium, pyrazolium, oxazolium etc Common anions: halides, tetrachloroaluminate, hexafluorophosphate, tetrafluoroborate (inorganic) and alkylsulfate, alkylsulfonate, p-toluene sulfonate (tosylate), trifluoroacetate (organic) etc

8. Types of cations & anions constituting Ionic Liquids Cations Anions D. D . Irge . Ionic Liquids: A Review on Greener Chemistry Applications, Quality Ionic Liquid Synthesis and Economical Viability in a Chemical Processes, Am. J. of Phy. Chem., 5 (3), 2016 ,74-79 .

9. HISTORICAL DEVELOPMENTS First report on Room temperature IL reported by Paul Walden in 1914 - ethylammonium nitrate , [C 2 H 5 NH 3 ] NO 3 (m.p. 12 °C) Osteryoung et al, Hussey et al worked on Organic chloride- Aluminium chloride ILs in 1970s-1980s -- First generation ILs Wilkes and Zaworotko, 1992 reported ILs 1-ethyl-3-methyl imidazolium cation with either tetrafluoroborate or hexafluorophosphate anion -- Second generation ILs Development of Modern day ILs – tri-fluoromethane sulphonate, bis-(tri-fluoromethanesulfonyl)imide , tris-(trifluoromethanesulfonyl)methide PAUL WALDEN Mallakpour, Shadpour & Dinari, Mohamad. ( 2012 ). Ionic Liquids As Green Solvents: Progress and Prospects. 10.1007/978-94-007-2891-2_1.

10. SYNTHESIS OF IONIC LIQUIDS Two step synthesis: (1) The formation of the Desired Cation, (2) Anion Exchange Common alkylating agents: Methyl triflate Methyl tosylate Octyl tosylate R. Ratti , Ionic Liquids: Synthesis and Applications in Catalysis, Hindawi Pub. Corporation, Adv. in Chem. , 2014, Art. ID 729842, 16

11. Properties of ILs that distinguishes them from other solvents Zero or no vapor pressure, i.e. they do not evaporate easily Non-flammable High thermal stability Immiscible in majority of org. solvents Easily recyclable have good solubility of gases Large electrochemical window Other properties include: Low melting point Good ionic conductors Viscous Non-toxic since non-volatile, however causing considerable water pollution. Mallakpour , Shadpour & Dinari , Mohamad . ( 2012 ). Ionic Liquids As Green Solvents: Progress and Prospects. 10.1007/978-94-007-2891-2_1 D. D . Irge . Ionic Liquids: A Review on Greener Chemistry Applications, Quality Ionic Liquid Synthesis and Economical Viability in a Chemical Processes. American Journal of Physical Chemistry, 5(3), 2016 , 74-79.

12. Applications of Ionic Liquids analytical chemistry Photochemistry electrochemistry separation chemistry organic synthesis and catalysis Biological uses

13. Use of ionic liquids in organic synthesis & catalysis as green solvents.

14. IONIC LIQUIDS IN DIFFERENT ORGANIC REACTIONS 1. Diels Alder Reaction Reaction proceeds in an almost fully endo-selective manner. Ratio of endo/ exo product depends on the lewis acidity of the IL, more the acidity, more is the ratio of endo / exo product.

15. 2. Heck reaction Reaction of aryl halide & styrene using Pd-catalyst in polar solvent. If less reactive ArBr or ArCl is used, Phosphine ligand is added In ILs as solvents, addition of ligand is not necessary; high yield

16. 3. Wittig Reaction Classic problem: separation of the product and the by-product. Separation and purification usually carried out by crystallization or chromatography. When ionic liquid used as solvent, the product and phosphine oxide can be easily separated by combining an ether extraction and a toluene extraction after the reaction is complete. The ionic liquid is reused.

17. 4. Friedal Craft acylation Product obtained quantitatively within 1h; p -/ o -product ratio of 96% Using acetonitrile - lower conversion of 64% at 1h; reduced  p -/ o -product ratio 93% High yield & high selectivity

18. 5. Reduction ionic liquid temp. ( o C ) time (h) Y. (%) bmimBF 4 100 16 93 emimBF 4 100 16 90 emimPF 6 100 16 96 emimPF 6 r.t. 48 94 Reductions using simple trialkylboranes generally require reaction temperatures in excess of 150 o C.

19. 6. Hydrogenation Product exists in the alcoholic phase; Catalyst in the ionic liquid phase. Separated by decantation. Catalyst is reused without loss in activity.

20. 7. Stille Reactions iodocyclohexeneone vinylbutyltin Product separation is easier Catalyst can be reused ionic liquid/catalyst phase is air and moisture stable

21. 8. Ring opening reaction Reaction in presence of ionic liquids proceeds at room temperature to give β- aminoalcohols in high yield. The product is extracted with ether. Ionic liquid is reused.

22. VARIOUS TYPES OF IONIC LIQUIDS Functional Ionic Liquid/ Task-specific ionic liquids (TSILs): Possess functional groups covalently bonded to IL ions. Example- IL bearing appended amines, can separate CO 2  from gas streams, IL with hydroxyl groups can act as phase transfer catalyst in the synthesis of ethoxybenzene etc. Deep Eutectic solvents ( DES): Mixture of two components- a quaternary ammonium halide salt+ a hydrogen bond donor. M.P of the mixture is less than the M.P. of the individual components. Example- mixture of choline chloride & urea. ease of preparation, and easy availability from relatively inexpensive components: Advantages over ILs. E.L. Smith, A. P. Abbott , , K. S. Ryder, Deep Eutectic Solvents (DESs) and Their Applications, Chem. Rev. ,  2014 ,  114  (21), 11060–11082

23. REFERENCES A. Ivanković, A. Dronjić, A. M. Bevanda, S. Talić. Review of 12 Principles of Green Chemistry in Practice. Int. J. Sustainable and Green Energy , 6(3), 2017 , 49-48. K. Shanab, C. Neudorfer, E. Schirmer , H. Spreitzer , Green Solvents in Organic Synthesis: An Overview, Curr.Org . Chem., 2013 , 17, 1179-1187 D. D. Irge . Ionic Liquids : A Review on Greener Chemistry Applications, Quality Ionic Liquid Synthesis and Economical Viability in a Chemical Processes , Am. J. of Phy . Chem ., 5 (3), 2016 , 74-79. R. Ratti , Ionic Liquids: Synthesis and Applications in Catalysis, Hindawi Pub. Corporation, Adv. in Chem. , 2014 , Art. ID 729842, 16 Mallakpour , Shadpour & Dinari , Mohamad. ( 2012 ). Ionic Liquids As Green Solvents : Progress and Prospects. 10.1007/978-94-007-2891-2_1. P. P. Salvi, A Brief Account On: Ionic Liquids with its Applications, Synthesis and applications of task - specific ionic liquids ( TSILs ) , December 2010 Rekha Devi al. Ionic liquids - Useful Reaction Green Solvents for the Future (A Review ) Int. J. of Recent Research Aspects ISSN: 2349-7688, 2, Issue 2, June 2015 , 26-29 E.L. Smith, A. P. Abbott , , K. S. Ryder, Deep Eutectic Solvents (DESs) and Their Applications, Chem. Rev. ,  2014 ,  114  (21), 11060–11082