Water : A Green Solvent With A Difference

Water : A green solvent with a difference... By Balmukund Thakkar

Contents ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Water : A solvent for chemical reactions ,[object Object],[object Object],[object Object],[object Object],[object Object]

Water : A green solvent ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Water as a solvent with a difference ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Structure of Water molecule ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Hydrogen Bonding in Water ,[object Object],[object Object],[object Object]

Water as dual activator medium ,[object Object],[object Object],[object Object]

Water as dual activator medium ,[object Object],[object Object],Chankeshwara S. V., Rudrawar S., Chakraborti A. K.; 12th ISMAS-WS-2007, March 25-30, 2007, Cidade de Goa, Dona Paula, Goa

Forced hydrophobic interactions ,[object Object],[object Object],[object Object],[object Object],[object Object]

Forced hydrophobic interactions ,[object Object],[object Object]

Acceleration of Diels–Alder reaction in water : Pioneer example of Forced hydrophobic interactions ,[object Object],J. Am. Chem. Soc. , 1980 , 102 , 7816 Solvent Additional component Rate constant K 2 X 10 5 M -1 S -1 Isooctane - 5.94 MeOH - 75.5 Water - 4400 ” LiCl (4.86 M) 10800 ” β -Cyclodextrin 10900 ” α -Cyclodextrin 2610 Solvent Additional component Rate constant K 2 X 10 5 M -1 S -1 Isooctane - 796 MeOH - 666 Water - 22600 ” β -Cyclodextrin 13800

Solvation by water ,[object Object],[object Object],[object Object],[object Object]

Pericyclic reactions ,[object Object],Angew. Chem. Int. Ed. 2005 , 44 , 3275 –3279 trans, trans -2,4-hexadienyl acetate N-propylmaleimide Solvent Conc. (M) Time (h) Yield (%) Toluene 1 144 79 Acetonitrile 1 >144 43 MeOH 1 48 82 Neat 3.7 10 82 Water 3.7 8 81

Pericyclic reactions ,[object Object],[object Object],[object Object],[object Object],J. Am. Chem. Soc ., 1999 , 121 , 6798. J. Am. Chem. Soc., 2000 , 122 , 10418 3-phenyl-1-(2-pyridyl)-2-propen-1-one Solvent ee (%) Acetonitrile 17 THF 24 Ethanol 39 Chloroform 44 Water 74

Pericyclic reactions ,[object Object],Angew. Chem. Int. Ed. 2005, 44, 3275 –3279 Quadricyclane DMAD Solvent Conc. (M) Time (h) Toluene 2 >120 EtOAc 2 >120 Acetonitrile 2 84 DCM 2 72 Dimethyl sulfoxide 2 36 MeOH 2 18 Neat 4.5 48 D 2 O 4.5 3/4 (45 min) C 6 F 14 4.5 36 H 2 O 4.5 1/6 (10 min)

Pericyclic reactions ,[object Object],[object Object],Angew. Chem. Int. Ed. 2005 , 44 , 3275 –3279 Naphthyl ether derivative Solvent Yield (%) Toluene 16 Acetonitrile 27 MeOH 56 DMF 21 Neat 73 H 2 O 100

Reactions of carbanion equivalents ,[object Object],[object Object],[object Object],J. Am. Chem. Soc ., 2003 , 1 25 , 4062.

Reactions of carbanion equivalents ,[object Object],[object Object],[object Object],J. Am. Chem. Soc ., 2003 , 125 , 2958 Solvent Amount (Equivalents) Time Yield %(α : γ ) DMF 6 72 65 (0 : 100) THF 6 72 20 (0 : 100) DCM 6 24 None Ethanol 6 72 97 Neat 24 None H 2 O 2 ml 72 90 (0 : 100) H 2 O 6 24 85 (99 : 1)

[object Object],[object Object],Reactions of carbanion equivalents J. Am. Chem. Soc ., 2003 , 125 , 2958

Reactions of carbocation equivalents ,[object Object],[object Object],[object Object],[object Object],Solvent Yield (%) H 2 O / THF (1 : 4) 91 Dry THF 10

Reactions of carbocation equivalents ,[object Object],[object Object],[object Object],Catalysts / additives Yields (%) Sc(OTf) 3 / -- 3 Sc(OTf) 3 / surfactant (SDS) 88 Sc(DC) 3 / -- 92

Reactions of carbocation equivalents ,[object Object],[object Object],[object Object]

Reactions of carbocation equivalents ,[object Object],[object Object],[object Object],J. Am. Chem. Soc ., 2002 , 124 , 11971

Reactions of radicals A. Lactone formation :- J. Am. Chem. Soc ., 2000 , 122 , 11041 Solvent Yield (%) Hexane 0 Benzene 0 DCM 0 THF 0 Ethanol 3 Methanol 6 2,2,2-trifluoroethanol 18 Acetonitrile 13 DMF 13 Formamide 24 DMSO 37 H 2 O 78 Solvent Yield (%) Hexane (20 ml) 10 Benzene (100 ml) 23 MeOH (20 ml) 0 H 2 O (100 ml) 69 Solvent Yield Benzene 14 Water 70

Reactions of radicals ,[object Object],[object Object],[object Object],[object Object]

Multicomponent reactions ,[object Object],[object Object],Passerini reaction :- Ugi reaction :- β -lactam deri. synthesis :- J. Am. Chem. Soc. 2004 , 126 , 444

Conclusions ,[object Object],[object Object],[object Object],[object Object],[object Object]

References ,[object Object],[object Object],[object Object],[object Object]

Water : A Green Solvent With A Difference

Water : A Green Solvent With A Difference

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