The ion pair mechanism in the thermal deamination of primary amines catalyzed by HBr in the gas phase: DFT and AIM analysis

Abstract The possible reaction mechanisms for the gas-phase thermal deamination of isopropylamine, tert- butylamine, and dextroamphetamine in the presence of hydrogen bromide are investigated by DFT calculations with several functionals. In each case, QTAIM analysis supports the formation of an ion-pair complex, which subsequently decays through a six-membered cyclic transition state (TS). NBO charges and interatomic lengths suggest the polarization of the N 1 δ− ··· δ+ C 2 bond in the TS is rate determining.