GB917568A - Process for the production of esters - Google Patents

Abstract

Esters of dicarboxylic acids are produced by hydrobrominating a terminal olefin to produce a terminal bromide, contacting the terminal bromide with an inorganic salt of a dicarboxylic acid in the presence of an organic base, preferably under an inert atmosphere, to produce an ester, reacting the inorganic bromide also produced with sulphuric acid to form HBr, and recycling recovered HBr to the hydrobromination stage. The terminal olefin preferably contains 6 to 20 carbon atoms and may be, for example, hexene, 2-ethylhexene, octene, decene, hexadecene or styrene. Dicarboxylic acids specified are phthalic, isophthalic, terephthalic, sebacic, maleic and isosebacic acids. The hydrobromination may be carried out by reacting the terminal olefin with HBr in the presence of a free radical initiator, e.g. oxygen, ozonised air, ozonised oxygen, a peroxide or ultra-violet light. The organic base present during the reaction between the terminal bromide and the dicarboxylic acid salt, a tertiary base, e.g. trimethylamine or triethylamine, or a quaternary ammonium salt, e.g. the product of triethylamine or triethylamine with the terminal bromide, although N-methyl morpholine, N-ethyl piperidine, piperidine, dimethyl formamide, N : N-dimethylcyclohexylamine are also used in the examples. The proportion of catalyst may vary from 0.01% to 10% by weight of the total weight of the reactants.