Aromatics formation from alumina-catalyzed reactions of methanol with aliphatic and alicyclic carbonyl compounds

Abstract

Reactions of aliphatic and alicyclic carbonyl compounds with methanol over alumina and modified alumina (fluorided and Na+-doped) catalysts have been studied. At 250–260 °C (low conversions) all carbonyl compounds, by a series of alkylation, dealkylation, condensation, and cleavage processes, lead to similar mixtures of simple ketones and products arising from them. At 350 °C (100% conversion) hexamethylbenzene is formed in very good yield. In the absence of methanol, 3,5-dimethylphenol is the major product. Mechanistic studies have been carried out and the evidence for the reaction route carbonyl compounds → acetone → isophorone → 3,5-dimethylphenol → hexamethylbenzene is presented. Efficient and simple methods for the preparation of 3,5-dimethylphenol and HMB are also described.