Vapour-Phase Reaction of Acetophenone with Methanol or Dimethyl Carbonate on Magnesium Oxide and Magnesium Phosphates

Abstract

The vapour-phase reaction of acetophenone with methanol on magnesium oxide, various magnesium phosphates, and combinations of the two types of catalysts was studied. The process was found to involve the Meerwein–Ponndorf–Verley reaction, aldol condensations, dehydrations, and hydrogenations. The presence of basic sites is indispensable for the reaction to develop; however, acid sites also play an active role. The selectivity for each reaction product depends on the particular catalyst used. The total conversion is maximal with the catalysts containing the largest populations of acid and basic sites. Also, catalysts with large numbers of acid sites exhibit an increased selectivity towards the corresponding alkenes. The use of dimethyl carbonate instead of methanol alters the reaction selectivity to an extent dependent on the particular catalyst and operating conditions. However, this also results in markedly decreased total conversion in some instances.