摘要
提出了一个用取代基效应预测吡啶衍生物的气相标准生成焓的经验公式：△ｆＨ—ｍ（ｇ）／ｋＪ·ｍｏｌ－１＝ａ＋ｃｉｘｉ＋ｎ１ｏ＋ｎ２ｍ＋ｎ３ｐ＋ｎ′１ｏ′＋ｎ′２ｍ′＋ｎ′３ｐ′＋７ｂ．其中，ａ是吡啶（母体）的气相标准生成焓；ｃｉ和ｘｉ分别表示每类取代基的数目及其初级效应；ｎ１，ｎ２，ｎ３和ｏ，ｍ，ｐ分别表示吡啶Ｎ原子的邻、间、对位上取代基的数目及其次级效应；ｎ′１，ｎ′２，ｎ′３和ｏ′，ｍ′，ｐ′分别表示取代基之间互为邻、间对位的数目及其次级效应；ｂ是甲基的障碍点数．经验公式计算结果表明２５个已知化合物的平均相对误差为±０．４７８％，平均标准偏差为０．９８７，复相关系数ｒ１．０００（实际为０．９９９８）．
An empiric formula predicting gas phase standard formation enthalpies of pyridine derivates with effect of substituent is proposed in this paper as follows:△ fH ? 璵(g)/ kJ·mol -1 =a+c ix i+n 1o+n 2m+n 3p+n′ 1o′+n′ 2m′+n′ 3p′+7b.Here , a /kJ·mol -1 is gas phase standard enthalpies of pyridine (parent substance).c i and x i are respectively the numbers of substituents and their primary effect.n 1,n 2,n 3 and o,m,p are respectviely the numbers between substituents and N (on pyridine) in adjacent position,meta—postiton,para—postiton and their secondary effect.n′ 1,n′ 2,n′ 3 and o′,m′,p′ are respectively the numbers between one substituent and other ones in adjacent position,meta—position,para—position and thier secondary effect. b is number of barrier point. The calculated results show that mean related errors and meam standard deviation of twenty—five known compounds is ± 0.47% and 0.987 respectively with relative coefficient r1.000.
基金
湖北省教委科研基金
