Manikrao M. Salunkhe

Lewis acidic ionic liquids for the synthesis of electrophilic alkenes via the Knoevenagel condensation

1-Butyl-3-methylimidazolium chloroaluminate, [bmim]Cl·AlCl3, N=0.67 and 1-butylpyridinium chloroaluminate, [bpy]Cl·AlCl3, N=0.67 ionic liquids were found to work well as the Lewis acid catalyst and solvent in the Knoevenagel condensations of benzaldehyde and substituted benzaldehydes with diethyl malonate to give benzylidene malonates. The benzylidene malonates subsequently underwent Michael additions with diethyl malonate. The extent of Michael product formed during the reaction was found to vary with the Lewis acidity and the molar proportion of ionic liquid. The influence of Lewis acidity of the ionic liquid on the Knoevenagel and Michael products is demonstrated. In the case of 2-hydroxyarylaldehydes, the reactions led to the formation of 3-ethoxycarbonyl coumarins under ambient conditions.

Coumarin syntheses via Pechmann condensation in Lewis acidic chloroaluminate ionic liquid

Butyl-3-methylimidazolium chloroaluminate, (bmim)Cl·2AlCl3 ionic liquid is used as an alternative to conventional acid catalysts in the Pechmann condensation of phenols with ethyl acetoacetate leading to the formation of coumarin derivatives. The reaction time is reduced drastically even at ambient conditions. The ionic liquid plays the dual role of solvent and Lewis acid catalyst providing a quick and efficient route to the syntheses of coumarins.

Lipase-catalysed transesterification in ionic liquids and organic solvents: a comparative study

Abstract The lipase-catalysed transesterifications of 2-hydroxymethyl-1,4-benzodioxane in two different ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim]PF 6 and 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim]BF 4 and different organic solvents was studied. The hydrophobic and hydrophilic properties of ionic liquids and organic solvents do influence the lipase activity as illustrated from the results. The influence of the ionic liquid as an additive in an organic solvent on this reaction has been demonstrated. The enzymes in ionic liquids in combination can be recycled for several runs without substantial diminution in the lipase activity.

Influence of ionic liquids on the phase transfer-catalysed enantioselective Michael reaction

Abstract The enantioselective Michael addition of dimethyl malonate to 1,3-diphenylprop-2-en-1-one promoted by a quaternary derived ammonium salt from quinine as a phase transfer catalyst in different ionic liquids, 1-butyl-3-methyl imidazolium hexafluorophosphate, [bmim]PF 6 , 1-butyl-3-methyl pyridinium tetrafluoroborate, [bpy]BF 4 , 1-butyl-3-methyl imidazolium tetrafluoroborate [bmim]BF 4 as well as in conventional organic solvents was studied.

Borohydride reducing agent derived from anion exchange resin: selective reduction of α, β-unsaturated carbonyl compounds.

Abstract Borohydride exchange resin (BER) exhibited selectivity in the reduction of α, β-unsaturated carbonyl compounds to the corresponding unsaturated alcohols.

Lipase-catalysed polyester synthesis in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid

1-Butyl-3-methylimidazolium hexafluorophosphate ionic liquid was employed as a reaction medium for lipase-catalysed aliphatic polyester synthesis. Lipase PS-C exhibited excellent catalysis in polycondensation of diethyl octane-1,8-dicarboxylate and 1,4-butanediol at room temperature and at 60°C. A relatively high molecular weight polymer was obtained at 60°C.

Polyamides containing s-triazine rings and fluorene “cardo”groups: synthesis and characterization

Abstract Two new polyamides containing s-triazine rings and fluorene “cardo” groups were synthesized by low temperature interfacial polycondensation of two s-triazine ring containing diacyl chlorides viz. 2,4-bis(4-chlorocarbonylphenoxy)-6-methoxy-s-triazine and 2,4-bis(3-chlorocarbonylphenoxy)-6-methoxy-s-triazine with a cardo diamine viz. 9,9-bis(4-aminophenyl) fluorene. The resulting polyamides were characterized by elemental analysis, viscosity measurements, X-ray diffraction studies, thermogravimetry and IR, 1 H- and 13 C-NMR spectroscopy. The polyamides PA-1 and PA-2 had inherent viscosity values 0.52 and 0.60 dl/g respectively in N,N-dimethylacetamide (DMAc) at 30°C. Both the polyamides were found to be readily soluble at room temperature in polar solvents such as dimethylsulfoxide, DMAc, N,N-dimethylformamide, N-methyl-2-pyrrolidone and m-cresol. Transparent, tough and flexible films of polyamides could be cast from DMAc solution. Thermogravimetric analysis of the polyamides indicated no weight loss below 360°C under nitrogen atmosphere.

Ionic Liquid–Mediated Knoevenagel Condensation of Meldrum's Acid and Aldehydes

Abstract A simple, efficient, and green protocol for Knoevenagel condensation of Meldrums acid and aldehydes in ionic liquid at room temperature without any catalyst is described. The reaction has been performed in different ionic liquids. The enhancement in the rate is observed in Brönsted acidic ionic liquid 1‐methylimidazolium trifluoroacetate [Hmim]Tfa, which furnishes quantitative yields with 4–30 min in most of the cases. Furthermore, ionic liquid is easily reused without any appreciable loss in activity.

Application of ionic liquid 1-methoxyethyl-3-methyl imidazolium methanesulfonate in nucleoside chemistry

The ionic liquid 1-methoxyethyl-3-methyl imidazolium methanesulfonate (MOEMIM.OMs) is employed as a ‘green’ alternative to the conventional organic solvents used as a reaction medium in nucleoside chemistry.

Fries rearrangement in ionic melts

Abstract 1-Butyl-3-methylimidazolium chloroaluminate, [BMIm] + Al 2 Cl 7 − , was used as a solvent as well as a Lewis acid catalyst in Fries rearrangement reactions of phenyl benzoates. The rate of consumption of phenyl benzoate obeyed first-order kinetics. Good yields and high selectivity are the features observed in this unconventional but interesting aprotic solvent.