The Bombay Technologist

Ionic Liquid as a Green Catalyst and Solvent Media for Friedel-Craft Acylation Reaction

Dinesh D. Thakare

Green Technology

Nikhil N. Gharat

Green Technology

Keywords: Ionic Liquids, [bmim]Cl/AlCl₃, [bmIm][dca], [emIm][dca], ([bmim][BF₄]-), ([bmim][PF₆]-), Friedel–Crafts Acylation.

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Abstract

Ionic liquids, being composed entirely of ions, their lack of measurable vapor pressure characterizes them as green solvents, and that a wide range of chemical reactions can be performed in them. Friedel-Crafts acylation reactions are of great importance in both laboratory work and industry processes to synthesize aromatic ketones. AlCl₃, H₂SO₄, HF or other Lewis acid can be used as catalyst in Friedel-Crafts reactions. However, these catalysts can cause a serious environmental problem during purification, and are very difficult to reuse. Therefore, it is important to replace these highly corrosive and hazardous acid catalysts with environmentally friendly catalysts which are active under mild conditions and can be easily regenerated after reaction. In recent years, ionic liquids have shown great promise as an attractive alternative to conventional catalysts and solvents for synthesizing organic chemicals. The Friedel-Crafts acylation using ionic liquids have been reviewed in this article.