AMI study on the mechanism of catalytic hydrogenation of 3-anilinomethylidene-6-alkyl-5,6-2H-dihydropyran-2, 4-diones

3-(p-Methyl)-anilinomethylidene-6-methyl-5, 6-2H-dihydropyran-2, 4-dione wa s selected as model reactant to study the mechanism of catalytic hydrogenat ion of 3-anilinomethylidene-6-alkyl-5, 6-2H-dihydropyran-2,4-diones by mean s of the AM1 and UHF/6-311G methods. The molecular informations such as hea ts of formation, net charges, bond orders, the values of frontier orbital e nergies, composition, their proportion and bonding contribution were acquir ed and analyzed. Thus the possible reactive sites were put forward and the reaction mechanism was postulated via two steps. The postulated intermediat es and products of the two steps were also computed by AM1 method. Their he ats of formation and energies of HOMO/LOMO/LUMO indicate that the mechanism of catalytic hydrogenation of 3-anilinomethylidene-6-alkyl -5, 6-2H-dihydr opyran-2, 4-diones is not only a hydrogenolytic addition on C = C bond but also a hydrogenolytic cleavage of the C-N bond of anilinomethylidene.