GC/MS characterization of monosubstituted hydrazones of glyoxylic acid ethyl ester

Electron ionization mass spectra and gas chromatographic retention indices of a series of newly synthesized N -monosubstituted (alkyl, aryl, allyl) hydrazones of glyoxylic acid ethyl ester RNHN=CHCO 2 C 2 H 5 were considered. It was shown the hydrazones were partially converted into isomeric (ethoxycarbonyl)methyl diimides during their GC separation (mostly in the heated injector port of the gas chromatograph). The retention indices of these diimides are lower than those of initial hydrazones by 268 ± 26 i.u. The most remarkable feature of these isomers appeared to be the high identity of their mass spectra because of similar rearrangements in molecular ions.