Molecular structure parameters and thermal stabilities of benzocarbazoles

• Published in: Acta geochimica Vol. 27; no. 2; pp. 135 - 139
• Main Authors: Chen, Chuanping, Liu, Jianping, Gu, Xu, Zhou, Sumin
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science Press 01.06.2008; Springer Nature B.V; School of Life Science and Chemical Engineering,Huaiyin Institute of Technology,Huai'an 223000,China%School of Chemistry,Huazhong Normal University,Wuhan 430000,China
• Subjects: Benzene; Earth and Environmental Science; Earth Sciences; Geochemistry; Hydrocarbons; Molecular structure; Sediments; 分子结构; 成熟度; 热稳定性; 空间转换; molecular structure; thermal stability; steric hinderance; benzocarbazole; maturity
• DOI: 10.1007/s11631-008-0135-x
• ISSN: 1000-9426; 2096-0956

The distance between 4-H and adjacent H on the substitutional benzene ring in benzo[c]carbazole was calculated in terms of molecular structure parameters. The result showed that the distance is shorter than the sum of van der Vaals＇ radii of two hydrogen atoms. This means that there is a steric hinderance between them. This effect will make the bond angle stretch and the bond length extend, or cause the molecule to distort, thus making benzo[c]carbazoles become unstable in thermodynamics. On the contrary there is no such effect for benzo[a]carbazoles. This conclusion has been confirmed by the result of calculation of the distance between the same two atoms with software GaussView. So the skeleton of benzo[c]carbazoles in sediments may be breached or isomerized with increasing maturity. It is consistent with the decrease of the ratio of benzo[c]carbazole to benzo[a]carbazole in hydrocarbon migration, suggesting that [c]/[a] not only changes with the distance of migration, but also may be influenced by maturity.