Amino-reductones. Formation mechanisms and structural characteristics.

Various types of amino-reductones are known to be involved in process-induced chemical changes in foods. Since most amino-reductones, especially enaminol compounds are unstable reaction intermediates and are difficult to isolate, their structural characteristics are still unclear. In order to obtain more precise structural information about amino-reductones, the structures of the enaminol form of fructoseglysine (D-fructoseglycine = FG) and scorbamic acid (L-scorbamic acid = SCA), a relatively stable cyclic enaminol compound were examined by the use of a semi-empirical molecular orbital method. Optimized structures, heat of formations and charge distributions of various enol forms of FG were obtained. Heat of formations of the non-dissociated, mono-anion, and di-anion forms of FG were estimated to be about -302, -347 and -308 kcal/mol, respectively. Optimized structures of non-dissociated, anion, and dipolar ion forms of SCA were also obtained and their heat of formations were estimated to be about -197, -204 and -248 kcal/mol, respectively. The nitrogen atom of the enaminol group in the SCA molecule was found to be positively charged.