The Substitution Effects on Dissociation and Isomerization of HXCO(X=F,Cl)

The changes of Gibbs' free energy (△G°), heat of reaction (△H °), rate constants, and Wigner's correCtion for dissociation and isomerization of HXCO, XCOH and HCOX have been calculated over the temperature interval 200-1300K.The influence of the substitute on the thermodynamic and kinetic properties has been analysed. Main results are as follows:(1)the substitute has great influence on the △G°, △H°,and the rate, the effects varing with the mechanism of reaction.(2)If the reaction do not involve the chemical bond which links the substitute, the suboitution effect on tunneling is much weak.(3)the molecular stability judged only by electronic energy is unreliable.