Ionic Liquid Oxidant for Efficient and Selective Oxidation of Benzylic Alcohols

Abstract

Hexamethylenebis (N-methylimidazolium) dichlorochromate was easily prepared by addition of N-methylimidazole to 1,6-dibromohexane to form the corresponding dibromide salt and subsequent treatment with CrO₃ in 6 N HCl solution. It is a low-melting orange salt that selectively oxidized benzylic alcohols.

Keywords:

• Benzylic alcohols
• hexamethylenebis (N-methylimidazolium) dichlorochromate
• ionic liquid
• oxidation

ACKNOWLEDGMENT

Financial support from the research council of the University of Mazandaran is gratefully acknowledged.

Notes

^a Yields refer to isolated products.

^b All products were identified by comparing IR, NMR, and TLC with those of authentic samples reported in literature.

^a Hexamethylenebis(N-methylimidazolium) dichlorochromate.

^b Pyridinium chlorochromate.

^c Ethylenebis(N-methylimidazolium) chlorochromate.

^d N-Methyl piperidinium chlorochromate.

^e 1-(Benzoylamino)-3-methylimidazolium chlorochromate.

^f n-Buthylammonium chlorochromate.