Affiliation:
1. Faculty of Science, Department of Chemistry, University of Khartoum, P.O. Box 321, Khartoum, Sudan
2. Department of Chemical and Process Engineering Technology, Jubail Industrial College, P.O. Box 10099, Jubail Industrial City – 31961, Saudi Arabia
Abstract
Abstract
The conformation and vibration analysis of 2-, 3- and
4-pyridinecarbonyl chlorides have been computed using B3LYP hybrid
density functional with 6-311++G** basis set. All structures have
been fully optimized, and the optimized geometries, dipole moments,
infrared vibrational frequencies and relative energies are
reported. From the computations, 2-pyridinecarbonyl chloride is
predicted to exist predominantly in trans conformation, while
the 3-pyridinecarbonyl chloride is predicted to exist predominantly
in cis conformation with the trans-cis rotational
barrier of 4.63 and 5.48 kcal/mol respectively. The two
equivalent planar structures of 4-pyridinecarbonyl chloride are
separated by an energy barrier of 4.55 kcal/mol. The effect
of solvents on the conformational stability have been examined for
nine different solvents (heptane, chloroform, THF, dichloroethane,
acetone, ethanol, methanol, DSMO and water). The Integral Equation
Formalism version of Polarized Continuum model (IEF-PCM) used for all
solution phase computations. The trans conformer of
2-pyridinecarbonyl chloride and the cis conformer of
3-pyridinecarbonyl chloride which are more stable in gas phase
remain the stable confomers in solution, but the stability decreases
as the dielectric constant of the solvent increases. The variation of
relative energies, dipole moments, solvation energies as function of
the dielectric constant of solvents has been investigated.
Subject
Physical and Theoretical Chemistry
Cited by
15 articles.
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