IDENTIFICATION OF THE ISOMERS FROM MONONITRATION AND DINITRATION OF PHENYLACETIC AND DIPHENYLACETIC ACIDS BY GAS-CHROMATOGRAPHY WITH FOURIER-TRANSFORM INFRARED AND MASS-SPECTROMETRIC DETECTION

The problem of the identification of the isomers from mono- and dinitr ation of diphenylacetic acid prior to their individual separation was investigated by studying the corresponding methyl esters by capillary gas chromatography with Fourier transform infrared detection with the aid of data obtained by gas chromatography-mass spectrometry (GC-MS) i n the positive-ion mode. The isomer assignments were essentially made by extrapolation of the observations of the IR stretching vibrations o f both the nitro group and the benzene ring in the methyl esters of mo nonitrophenylacetic acid isomers. Heteronuclear nitro substitution of diphenylacetic acid was confirmed by GC-MS. The occurrence of products of dinitration on the same benzene ring, if any, was below the observ able limits in the mixtures studied.