Reactions of acetophenone with alcohols over oxide catalysts: Alkylation of ketones by alcohols

Abstract

As part of a study of hydrogen transfer reactions over alumina, the reactions of acetophenone with methanol over η-alumina at 300–500 °C were studied. In addition to styrene arising from reductive dehydration, products arising from methylation (propiophenone, β-methylstyrene) were also observed. At higher conversion, secondary reactions like dealkylation of higher ketones and alkylation, dealkylation, and hydrogenation of olefins were also observed. Reactions have also been carried out with modified alumina (fluorided and Na+-doped) catalysts, HY-zeolite, phosphotungstic acid, and silicotungstic acid to study the effect of acidity on the selectivity for these reactions. Reactions of methanol with aralkyl ketones and with olefins were also studied. Acetophenone conversion was found to increase with increasing catalyst basicity while the selectivity for reductive dehydration decreased. Conclusions have also been drawn, on the basis of these studies, regarding the nature of the active catalytic sites responsible for the different reactions and mechanisms have been proposed for the surface reactions.