GB841680A - Process for the manufacture of the lower alkyl esters of unsaturated aliphatic acids - Google Patents

Abstract

An unsaturated aliphatic ester is obtained by contacting a vapour-phase mixture comprising an a ,b -unsaturated aliphatic carboxylic acid and at least the stoichiometric proportion of a saturated aliphatic alcohol having not more than 8 carbon atoms with silica gel at a temperature above the boiling-point of the reactants and products in the presence of added water said water being added in a proportion of at least 1 mol. per mol. of said acid. The molar ratio of added water to acid is preferably in the range of 1 : 1 to 8 : 1 and it is preferred to use a stoichiometric excess of the alcohol. Specified alcohols are methanol, ethanol, butanol-1 and 2-ethyl hexanol and specified acids are acrylic and methacrylic acids. Suitable reaction temperatures are from 350 DEG to 750 DEG F. at atmospheric pressure and the process is suitably conducted in a vertical vessel containing a fixed catalyst bed, the reactants being introduced at the bottom of the vessel and the product removed overhead, or vice versa. Preferred contact times are between 15 and 120 seconds. Examples are given for the production of ethyl acrylate, n-butyl acrylate and methyl methacrylate and a comparative example is also given for the production of ethyl acrylate by reacting ethanol and acrylic acid in the vapour phase at 500 DEG F. in the presence of silica gel but without adding water to the reaction.