单取代烷烃生成焓与键能之间的定量关系

Quantitative Relationship Between the Enthaply of Formation and the Bond Energy of Monosubstituted Alkanes

单取代烷烃生成焓的定量估算式与键能的定量估算式中存在相同的电子效应参数,可推断出把电子效应参数作为桥梁,找出单取代烷烃生成焓与其键能之间的定量关系,建立利用生成焓值来确定其键能的新方法.本文用74个单取代烷烃的生成焓ΔfHθ(R—X)结合BDE(X—Me)、NC、h[X]、PEI(R)和ΔPEI(R)对其键能BDE(X─R)实验值进行回归分析,所得回归方程有良好的相关性,相关系数达0.999 9,实验值与计算值之间的平均绝对误差仅3.47 k J,落在实验误差范围内.进而用留一法对其稳定性和预测能力进行验证(R_(CV)=0.999 9),结果表明利用单取代烷烃生成焓建立的键能估算模型是合理并且有效的.本文将看上去相差甚远的两种物理化学性能(键能和生成焓)从理论上探索了它们之间的内在联系,为从同一分子结构基础上理解不同性能之间的联系提供了新的视角和方法.

The study found that the same electronic effect parameter was used in quantitative estimation both for enthaply of formation and bond energy.It can be asserted that we can find the quantitative relationship between the enthaply of formation and the bond energy,andbuild a new model for estimating bond energy by using the electronic effect parameter as a bridge. The ΔfHθ（ R—X）,NC,BDE（ X-Me）,h [X],PEI（ R）,ΔPEI（ R） of 74 monosubstituted alkanes are calculated and used to estimate the BDE（ X ─R） values. The expression has a good correlation,the correlation coefficient is 0.999 9,and the average absolute error between the experimental values and the calculated values is only 3.47 k J,within the experimental uncertainties.Its stability and prediction ability was confirmed by the results of leave-one-out（ LOO） method（ RCV= 0.999 9）.This result shows the estimation model is reasonable and effective. Furthermore,the internal relation between these two physical and chemical properties,which is very diffenent,the enthaply of formation and the bond energy,was explored theoretically.Thus,this paper provides a new approach or method to study the relationship between different properties on the basis of the same molecular structure.