有机化合物的键裂能及自由基的生成热

BOND DISSOCIATION ENERGIES OF ORGANIC COMPOUNDS AND HEATS OF FORMATION OF RADICALS

本文发现了键裂能的差值△DH^0(Me-X/R-X)与基团电负性的线性关系,从而建立了一个计算R-X键键裂能的简单方法:DH^0(R-X)=DH^0(CH_3-X)-(a_mx_G+c_m)式中,R为烷基;X代表CI、Br、I、OH、NH_2、SH、CH_3;X_G是作者前一工作建立的基团电负性:a_m和c_m是与烷基结构因素相关的常数.对于14个可比较的值,其平均偏差为1.30kJ/mol,最大偏差为3.01kJ/mol.同时,烷基和烷氧基自由基的标准生成热也被准确地估算,9个自由基估算的平均偏差为1.63kJ/mol,最大偏差也只有3.54kJ/mol.

Linear relations between the differences in bond dissociation energies △DH^0(CH_3-X / R-X) and the group electronegativities have been found. We have built up a formula for calculating the bond dissociation energies of R-X: DH^0(R-X) =DH^0(CH_3-X)-(α_mX_G-c_m Here, R is alkyl; X is Cl, Br, I, OH,NH_2, SH and CH_3; X_G is group electronegativity; a_mand c_mare constants related to the structure of R. The average deviation from observed bond dissociation energies of the estimated ones for 14 bonds is only 0.31 kcal / mol with the maximum deviation 0.72 kcal / mol. The heats of formation of alkly radicals and alkoxyl radicals are estimated accurately in this work. For the 9 radicals available average deviation is 0.39 kcal / mol with the maximum deviation 0.84 kcal / mol.