Catalysts for Carbonylation of Alcohols to Obtain Carboxylic Acids and Esters

Abstract Carbonylation of alcohols with CO is one of synthetic routes to carboxylic acids and esters, which are demanded by chemical and pharmaceutical industry. The existing commercial processes for methanol carbonylation under the conditions of homogeneous catalysis with rhodium (Monsanto process) and iridium (Cativa process) compounds involve the addition of corrosion-active iodides. The development of catalysts that desirably do not contain expensive platinum metals and preserve the activity in a large number of recycles is topical from the economical viewpoint. The review systematizes the results of studies performed since 2011 on carbonylation of various alcohols with СО in the presence of novel homogeneous and heterogeneous catalysts. The majority of studies deal with the methanol carbonylation to obtain acetic acid and methyl acetate. To this end, novel homogeneous rhodium–ruthenium and iridium catalysts, heterogeneous catalysts containing Ir, Rh, Cu, Ni, and Re on various supports, and a zeolite catalyst containing no supported metals have been suggested. The ethanol carbonylation to obtain propanoic acid and ethyl propanoate was performed in the presence of homogeneous rhodium and nickel catalysts and of heterogeneous catalysts containing Rh. The carbonylation of other saturated aliphatic and alicyclic alcohols to obtain the corresponding carboxylic acids and esters was performed using homogeneous nickel catalytic systems. The carbonylation of saturated aliphatic polyhydric alcohols to obtain monocarboxylic acids was performed using homogeneous rhodium and iridium catalysts. In some cases, the authors were able to perform carbonylation of alcohols without iodide additions. Homogeneous and heterogeneous palladium catalysts were suggested for preparing unsaturated carboxylic acids and esters by carbonylation of allyl alcohols. Homogeneous nickel and palladium catalytic systems were developed for the synthesis of aryl-substituted carboxylic acids and esters by carbonylation of aromatic alcohols. The carbonylation of propargyl alcohols was performed under the conditions of homogeneous catalysis with palladium systems.