Steric Effects and Steric Inhibition of Resonance in Benzene Derivatives: 2,3-Dimethylbenzoic Acid

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Title:Steric Effects and Steric Inhibition of Resonance in Benzene Derivatives: 2,3-Dimethylbenzoic Acid
Creators:
Císařová, Ivana
Podlaha, Jaroslav
Böhm, Stanislav
Exner, Otto
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 65, 2, pp. 216-226
Uncontrolled Keywords:Conformation, Carboxylic acids, X-Ray diffraction, Crystal structure, Inhibition of resonance, Steric effects, Substituent effects

Abstract

Structure of 2,3-dimethylbenzoic acid was determined both by single-crystal X-ray diffraction and by <i>ab initio</i> calculation at an RHF/6-31+G** level. Comparing with a previous X-ray analysis of another crystal modification of the same compound, it was possible to estimate the effect of crystal forces on the conformation. The isolated molecule is not planar as deduced previously, mainly from IR spectra, but the carboxyl group is twisted out of the ring plane by a torsion angle ϕ = 12°. In the crystal, the molecule is more flat and ϕ is reduced to 7 and 1° in the two modifications, respectively. Further significant differences between the modifications were not detected. The flattening in the crystal structure is accompanied by additional small changes in the geometry, connected with greater steric crowding in the less twisted molecule: the example shows well the limits in which molecular structure can be deduced from the solid-state structure. Previous division of methylated benzoic acids into two subgroups, planar and nonplanar, is to be formulated with more precision: the former group includes even acids with nearly planar conformation (ϕ up to 15°). <p>

Title:Steric Effects and Steric Inhibition of Resonance in Benzene Derivatives: 2,3-Dimethylbenzoic Acid
Creators:
Císařová, Ivana
Podlaha, Jaroslav
Böhm, Stanislav
Exner, Otto
Uncontrolled Keywords:Conformation, Carboxylic acids, X-Ray diffraction, Crystal structure, Inhibition of resonance, Steric effects, Substituent effects
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:65
Number:2
Page Range:pp. 216-226
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20000216UNSPECIFIED
ID Code:1637
Item Type:Article
Deposited On:06 Feb 2009 17:11
Last Modified:06 Feb 2009 16:11

Citation

Císařová, Ivana; Podlaha, Jaroslav; Böhm, Stanislav; Exner, Otto (2000) Steric Effects and Steric Inhibition of Resonance in Benzene Derivatives: 2,3-Dimethylbenzoic Acid. Collection of Czechoslovak Chemical Communications, 65 (2). pp. 216-226. ISSN 0010-0765

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