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Trans‐cis isomerization of 4‐(2‐(9‐anthryl)vinyl)pyridine. Molecular structures and 1 H NMR kinetic studies
Author(s) -
Choi YaYin,
Wong WaiYeung,
Wong WingTak
Publication year - 1999
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.19990170202
Subject(s) - chemistry , isomerization , pyridine , cis–trans isomerism , arrhenius equation , kinetic energy , nuclear magnetic resonance spectroscopy , reaction rate constant , crystallography , toluene , stereochemistry , kinetics , activation energy , medicinal chemistry , organic chemistry , catalysis , physics , quantum mechanics
Both cis‐ and trans ‐isomers of 4‐(2‐(9‐anthryl) vinyl) pyridine were isolated and their molecular structures established by X‐ray crystallographic method. Variable temperature 1 H NMR spectroscopy was used to study the trans to cis isomerization of the title compound. The kinetic study of the reaction was based on the ratio of the NMR integration heights in toluene‐ d 8 of the double doublet due to the cis ‐isomer at δ 8.51 to that of the multiplet at δ 8. 15 which was kept constant during the whole experiment. The isomerization process was found to be first order and the Arrhenius activation parameters E 8 , ln A , Δ H ≠ and ΔS ≠ were calculated as 27.84 kJ/mol, 6.71, 25.23 kJ/mol and −197.89 J/(K·mol), respectively. Besides, conformational analyses of both compounds based on molecular modeling were carried out and the results were used to compare with the experimental data.