物理化学学报 >> 2013, Vol. 29 >> Issue (01): 35-42.doi: 10.3866/PKU.WHXB201210261

理论与计算化学 上一篇    下一篇

用扩展的Istomin-Palm模型估算双向延伸化合物R1-Y-R2生成焓

曹晨忠1, 武亚新1,2   

  1. 1 湖南科技大学化学化工学院, 理论化学与分子模拟教育部重点实验室, 分子构效关系湖南省普通高校重点实验室, 湖南 湘潭 411201;
    2 中南大学化学化工学院, 长沙 410083
  • 收稿日期:2012-07-03 修回日期:2012-10-24 发布日期:2012-12-14
  • 通讯作者: 曹晨忠 E-mail:czcao@hnust.edu.cn
  • 基金资助:

    国家自然科学基金(21072053)和湖南省教育厅科研基金(10K025)资助项目

An Extended Istomin-Palm Model for Estimating the Enthalpies of Formation of the Two-Direction Extending Compounds R1-Y-R2

CAO Chen-Zhong1, WU Ya-Xin1,2   

  1. 1 Hunan Provincial University Key Laboratory of QSAR/QSPR, Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, Hunan Province, P. R. China;
    2 School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
  • Received:2012-07-03 Revised:2012-10-24 Published:2012-12-14
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21072053) and Scientific Research Fund of Hunan Provincial Education Department, China (10K025).

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摘要：

Istomin和Palm曾提出用模型ΔfH0(RX)=h[R]+h[X]+φ[R]φ[X](式中h[R]和h[X]分别为烷基R 和取代基X对单取代烷烃生成焓ΔfH0(RX)的贡献, φ[R]φ[X]则表示R与X之间的相互作用对ΔfH0(RX)的贡献)来表示单取代烷烃生成焓ΔfH0(RX). 对于双向延伸化合物R1-Y-R2, 其取代基Y位于分子链的中间, 与两个烷基(R1和R2)相连. 此类化合物分子内取代基与烷基之间的相互作用, 较单取代烷烃的相比更为复杂. 因此, Istomin-Palm模型在R1-Y-R2体系中应用必须进行修正. 本文把取代基Y、烷基R1和R2三者之间的相互作用对R1-Y-R2类化合物生成焓ΔfH0(R1-Y-R2)的贡献分为三部分: R1Y与R2之间的相互作用(φ[R2]φ[R1Y]), YR2与R1之间的相互作用(φ[R1]φ[YR2]), 以及两烷基R1与R2之间的相互作用(ψ[R1]ψ[R2]). 用以上三项替换φ[R]φ[X], 扩展Istomin-Palm模型, 建立一个新的经验模型ΔfH0(R1-Y-R2)=h[R1]+h[R2]+h[Y]+φ[R1]φ[YR2]+φ[R2]φ[R1Y]+ψ[R1]ψ[R2], 来表示ΔfH0(R1-Y-R2)(式中h[R1]、h[R2]和h[Y]分别为烷基R1、R2和取代基Y对ΔfH0(R1-Y-R2)的贡献, 后三项则表示烷基R1、R2和取代基Y两两之间相互作用对ΔfH0(R1-Y-R2)的贡献). 进而, 采用本研究组最近报道的相互作用势指数IPI(X)(Wu, Y. X.; Cao, C. Z.; Yuan, H. Chin. J. Chem. Phys. 2012,25 (2), 153.)表示取代基Y对烷基的固有作用(φ[Y]), 从而建立两个定量估算生成焓的通用模型. 其中, 一个用于估算硫醚、仲胺、醚和酮类化合物生成焓, 另一个用于估算酯类化合物生成焓. 这两个模型均得到良好的结果, 与采用G3和G3MP2方法相比具有同样的精度, 还可以避免大量繁琐的计算.

关键词: 生成焓, 取代基, 相互作用, 双向延伸化合物, 相互作用势指数

Abstract:

Istomin and Palm proposed a model, ΔfH0(RX)=h[R]+h[X]+φ[R]φ[X], (the h[R] and h[X] are the contributions of alkyl R and substituent X to the ΔfH0(RX), respectively. φ[R]φ[X] represents the interaction of alkyl R and substituent X), to express the enthalpies of formation of monoderivatives of hydrocarbons ΔfH0(RX). However, in two-direction extending compounds R1-Y-R2, the Y substituent is attached to two alkyl groups (R1 and R2), and the intramolecular interactions are more complicated than that in monosubstituted alkanes. Thus, the Istomin-Palm model must be modified. In this work, the interactions among Y, R1, and R2 contributing to the enthalpy of formation, ΔfH0(R1-Y-R2), are divided into three parts: the interaction between R1Y and R2(φ[R2]φ[R1Y]), the interaction between YR2 and R1 (φ[R1]φ[YR2]), and the interaction between R1 and R2 (ψ[R1]ψ[R2]). These three interactions replace the φ[R]φ[X] term, and a new extended Istomin-Palm model, ΔfH0(R1-Y-R2)=h[R1]+h[R2]+h[Y] +φ[R1]φ[YR2]+φ[R2]φ[R1Y]+ψ[R1]ψ[R2], is proposed. In this model, h[Y] is the contribution of substituent Y to ΔfH0(R1-Y-R2). The h[R1] and h[R2] terms are the contributions of alkyls R1 and R2 to ΔfH0(R1-Y-R2). The last three terms are the total contribution of interactions among Y, R1, and R2. Furthermore, the interaction potential index IPI(X) reported in our recent work (Wu, Y. X.; Cao, C. Z.; Yuan, H. Chin. J. Chem. Phys. 2012, 25 (2), 153.) was employed to express the intrinsic interaction of Y with alkyl groups (φ[Y]), and two general expressions were established to estimate ΔfH0, in which one is for thioethers, secondary amines, ethers, and ketones, and the other is for esters. These two estimating equations give results, which are as accurate as G3 and G3MP2 models in calculating ΔfH0 for R1-Y-R2 compounds. Moreover, our method avoids time consuming calculations.

Key words: Enthalpy of formation, Substituent, Interaction, Two-direction extending compound, Interaction potential index