New concept of organic homo‐rank compounds and its application in estimating enthalpy of formation of mono‐substituted alkanes |
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| Authors: | Chao‐Tun Cao Hua Yuan Chenzhong Cao |
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| Affiliation: | School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Key Laboratory of Theoretical Organic Chemistry and Function Molecule (Hunan University of Science and Technology), Ministry of Education, Hunan Provincial University Key Laboratory of QSAR/QSPR, Xiangtan, China |
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| Abstract: | Based on the topological characteristics of distance matrices and adjacency matrices of molecular graphs, a new concept of organic homo‐rank compounds was proposed. Based on this concept, compounds can be classified into new groups other than the traditional homologues. Furthermore, novel structure–property relationship approach named as homo‐rank compounds method can be developed. The feasibility of homo‐rank compounds method was explored by estimating the enthalpy of formation of organic compounds. The group contribution index (GCIX) and group polarizability potential index (GPIX) of substituents X were defined and determined for mono‐substituted alkanes RX (X includes 20 substituents). The research results show that the enthalpies of formation of organic homo‐rank compounds and their isomers can be correlated very well with the parameters GCIX and GPIX. Combining the method of homologues with that of homo‐rank compounds, a general and simple quantitative correlation equation (8) was established to estimate the enthalpy of formation for RX, and the calculation precision is within the chemical accuracy ‘1 kcal/mol’. For 242 samples of RX, the average absolute deviation between the experimental and the calculated values is 2.42 kJ/mol. In addition, the enthalpies of formation of more than 2800 samples of RX were estimated. The approaches of organic homo‐rank compounds and organic homologues are independent of but complementary to each other. The combination of these two methods can help us to understand the organic molecular structure–property relationships more deeply, and to investigate these relationships more conveniently and accurately. Copyright © 2015 John Wiley & Sons, Ltd. |
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| Keywords: | enthalpy of formation group contribution index group polarizability potential index mono‐substituted alkane organic homo‐rank compounds |
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