Process for producing aromatic carboxylic acids and methyl esters thereof

摘要

Disclosed is an improvement in the process for making an aromatic carboxylic acid or its methyl ester from an aromatic compound having at least one methyl or formyl group bonded directly to a nuclear carbon atom of the aromatic ring. The process comprises effecting oxidation of said compound in the liquid phase with molecular oxygen or a gas containing the same with a catalyst comprising a heavy metal compound, and in the substantial absence of an aliphatic carboxylic acid as a solvent, whereby a reaction mixture comprising the acid is formed. If the ester is desired, the acid then is esterified with methanol. The improvement comprises carrying out the oxidation in the co-presence of a lithium compound at a concentration of 0.1-10 moles per mole of heavy metal compound. The lithium compound is at least partly soluble in the reaction mixture or reacts with an acid component of the reaction mixture to form a lithium compound soluble in the reaction mixture.