GB520164A - Improvements in or relating to the alcoholysis of polymerisable esters - Google Patents

Abstract

520,164. Esters of unsaturated acids. ROHM & HAAS AKT.-GES. Oct. 13, 1938, No. 29716. Convention date, Oct. 13, 1937. [Class 2 (iii)] Esters of unsaturated polymerizable acids are manufactured by reacting esters from such acids and alcohols of relatively' low molecular weight with alcohols of relatively high molecular weight, or with phenols, and continuously removing from the reaction zone the lower alcohols set free and the esters of higher alcohols or phenols formed. Preferably the reacting substances are so selected that the boiling points of the higher ester, the lower alcohol and the reaction mixture differ sufficiently for their separation to be effected by distillation. The reaction may be carried out in a tower in which the temperature gradient is such that essentially only the substances formed can leave the tower, the readily volatile substance leaving at the top as vapour, the difficulty volatile substances leaving the foot as liquid, whilst mixtures of the starting materials are found in the centre parts of the tower. The reaction may be carried out in the presence of acid, alkaline or alkalinereacting catalysts, e.g., sulphuric or phosphoric acid, aromatic sulphonic acids such as ptoluenesulphonic acid, or alcohols, and, if desired, with the addition of solvents, which in some cases may form an azeotropic mixture with the lower alcohol formed in the reaction or may act as boiling promoters for the higher ester. Suitable starting materials are, on the one hand, the lower esters, e.g., methyl and ethyl esters, of acrylic acid, its homologues, e.g., methacrylic acid, or it substitution products, e.g., α-chloracrylic acid, and, on the other hand, saturated or unsaturated aliphatic, alicyclic, aromatic or heterocyclic alcohols, polyhydric alcohols, e.g., glycol, alcohols of mixed functions such as ether alcohols or halogen alcohols, or phenols. In an example, n-butanol and methyl methacrylate are reacted in a tower in the presence of sulphuric acid and of sulphur as a polymerization retardant, and advantageously in the presence of a boiling liquid, e.g., a lubricating oil of high boiling point. A mixture of methanol and methyl methacrylate leaves the top of the tower, and crude n-butyl methacrylate is withdrawn at the bottom. The n-butanol may be replaced by n-hexyl alcohol and the sulphuric acid by p-toluenesulphonic acid.