Towards an understanding of the molecular mechanism of the unimolecular decomposition of the N-chloro-α-amino acids on the ground and excited states surfaces in aqueous medium

Two molecular mechanisms for the decomposition of N-chloro-α-amino acids in aqueous solution can be proposed: the first one takes place in the singlet electronic state; the second one, through a vertical excitation of the N-chloro-α-amino acid from the singlet to the triplet electronic state, takes place on the triplet state by means of a heterolytic breaking process of the N–Cl bond without an energy barrier, leading to a nitrenium system (zwitter). These results reveal that intersystem crossing processes are possible, thus a single isolated adiabatic surface is not appropriate for the study of the decomposition process.