ASIAN JOURNAL OF PHYSICS

 

Asian Journal of Physics                                                                                                                Vol. 3 No 2, 1994, 71-75

Vibrational and NMR studies on o-, m- and p- chlorobenzoic acids

 

P KOCZON¹ , H. BARANSKA² and W LEWANDOWSKI¹

¹Institute of General Chemistry, Warsaw Agricultural University, SGGW,
Rakowiecka 26/30, 02-528 Warsaw, Poland.

²Department of Technology Fundamentals, Industrial Chemistry Research Institute,
Rydygiera 8, 01-793 Warsaw, Poland.

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The ¹H NMR, IR, and Raman spectra of o-, m- and p- chlorobenzoic acids were recorded and studied. The effect of position of substituents on the electronic properties (mainly π-electron system) of the molecules have been investigated. Three independent criteria: frequency and intensity of bands in vibrational spectra, chemical shifts of protons in ¹H NMR spectra, and calculated values of delocalization energy, were applied to estimate perturbation of the aromatic system of benzoic acid in compounds under study. Comparing spectral and semi-empirical data we have found correlations between the degree of perturbation of the aromatic system of benzoic acid and positions of substituents in the ring. Dependence between chemical shifts in NMR spectra and electronic charge density are also reported.

Total Refs:9