A general homogeneous catalytic method for the homologation of methanol to ethanol

Abstract

The direct conversion of synthesis gas to ethanol and the indirect reaction of synthesis gas with methanol to yield ethanol (homologation) have been studied as possible alternative processes for the production of ethanol from coal. Experimental evidence indicates an unusually general catalytic method for methanol homologation occurring in methanol solutions of amines at synthesis gas pressures near 300 atm and temperatures near 200/sup 0/C. Significantly, methanol is homologated while ethanol is essentially unaffected. In each case, carbon dioxide is the oxygenated byproduct, and ethanol is formed. Since observation of this type of reaction using Fe(CO)/sub 5/ catalyst, we have become aware of the method's generality extending to several diverse metal centers. This study represents an accumulated detailed knowledge of the mechanism for the iron carbonyl system. More important, however, a clear picture of a common pathway of a number of the complexes has emerged. In general, all of the catalytic reactions use methyl-ammonium ions as methyl carriers, transition-metal complex anions as nucleophilic methyl acceptors, and catalytic decomposition of formic acid to remove protons generated in hydrogen activation steps.