Abstract:The kinetic parameters for decomposition of allicin in pentane or ethanol were determined. The activation energies and pre-exponential factors were separately 56.0 kJ/mol and 9.2×105 in pentane as well as 72.0 kJ/mol and 1.5×106 in ethanol. The intermolecular interaction energy between allicin and solvent was calculated by density functional theory (DFT) at the B3LYP/6-31+G(d+P) leve1. The results showed that the intermolecular interaction energy between allicin and ethanol (31.18 kJ/mol) was higher than that between allicin and pentane (1.12 kJ/mol). Natural orbital theory (NBO) analysis showed that the anti-bonding orbital stabilization energy between the lone pairs of O (13) in allicin and hydroxyl (O(21)-H(20)) in ethanol molecule was 45.45 kJ/mol, which illustrated that strong hydrogen bonding interaction between them dispersed the negative charges in O atom of allicin. Therefore it became more difficult in the intramolecular to transfer H atom during decomposition of allicin in ethanol.
