Analysis of isomeric impurities in a synthesis of the novel anti-inflammatory drug, benoxaprofen.

Gas-liquid chromatographic procedures are described for the determination of isomeric impurities in rho-chlorobenzoyl chloride and the intermediates, 2-(rho-nitrophenyl)-proprionitrile and 2-phenylpropionitrile, in a ten-stage synthesis of benoxaprofen, 2-(rho-chlorophenyl)-alpha-methyl-5-benzoxazoleacetic acid.