GB687902A - Improvements in or relating to processes for the hydrolysis of methyl acetate and the treatment of aqueous mixtures of methyl acetate, methyl alcohol and acetic acid so obtained - Google Patents

Abstract

Methyl acetate is hydrolysed with water in the presence of a hydrolysation catalyst at a pressure above atmospheric and an elevated temperature below the boiling-point of the mixture at said pressure. The catalyst may be a strong acid, e.g. sulphuric acid equivalent to 0.05-2, preferably about 1 per cent by weight of the reactants. Temperature may be 48-140 DEG C. and pressure up to 10 atm., e.g. 100 DEG C. at 3 atm., or 115 DEG C. at 6 atm. The ratio of water to ester is preferably such that only 20-70 per cent is hydrolysed, viz. 0.3-2 : 1. The hydrolysis mixture is preferably subjected to the reaction conditions for 10-45 minutes. The mixture of acetic acid, methanol, methyl acetate and water obtained by said hydrolysis is distilled, the overhead of methanol and methyl acetate being in part returned as reflux, and in part scrubbed with water to give aqueous methanol and the ester. The bottoms of aqueous acetic acid is extracted with methyl acetate which may contain 10-25 per cent of cyclohexane, the extract then being distilled to drive off solvent and water and recover anhydrous acid. The methyl acetate for the extraction may be part of the feed to the hydrolysis or the product of the water scrubbing.