Prepn. of cyclic ester(s) of alpha hydroxy carboxylic acids - by catalytic cracking of oligomers and co:oligomers of the acids

摘要

Cyclic esters of alpha hydroxy carboxylic acids (I) R1 and R2 = H, or one of them is 1-6C alkyl, are prepared by the catalytic cracking of an oligomer or co-oligomer of an alpha hydroxy carboxylic acid, ester, or salt, such that a) the cracking is effected in the presence of a solvent that removes, in the vapour phase, the cyclic esters (I) formed, b) the vapour phase is condensed after the cracking, c) the recovered condensate is separated to remove (I) from the solvent, this solvent optionally being recycled. USE - (I) are intermediates for the preparaton of biocompatible and biodegradable materials (prostheses, sutures) and for controlled release biological systems.