Transposition des cations radicaux aminés en spectrométrie de masse

Abstract

It is demonstrated in mass spectrometry that alkylamines substituted at C2 and containing weak internal energy isomerize in the gas phase into intermediary ions composed of ionized cyclopropanes complexed with an ammonia molecule. This process is induced by a C3 hydrogen shift on the nitrogen atom. After opening of the cyclopropane, the dissociation of these complexes leads to m/z 44, 58, and 72 ions having [CH3(CH2)nCH NH2] structures. The mechanism of their formation is demonstrated by the MIKE spectra of 13C and deuterium labelled compounds. The experimental results are in good agreement with those described by Gross etal., who studied the fragmentation of the complexes formed during the reaction between substituted ionized cyclopropanes and ammonia in the gas phase.