Chemometric Analysis of Substituent Effects. XII. Application of Relationship Between 2- and 4-Substitution of Benzene Ring to Study ortho Effect in Selected Compounds with Different Reaction Centres

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Title:Chemometric Analysis of Substituent Effects. XII. Application of Relationship Between 2- and 4-Substitution of Benzene Ring to Study ortho Effect in Selected Compounds with Different Reaction Centres
Creators:
Pytela, Oldřich
Prusek, Ondřej
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 64, 10, pp. 1617-1628
Uncontrolled Keywords:Benzoic acid, PCA, Chemometric, Phenol, <i>ortho</i> Effect, Dissociation constants, Aniline, PLS, Substituent effects

Abstract

Three model compounds have been selected to study the relationship between <i>ortho</i> and <i>para</i> substitution: benzoic acid, phenol, and aniline. Sixteen substituents have been chosen involving also those capable of potential interaction between <i>ortho</i> substituent and the reaction centre. For the combinations given, literature presents 25 pairs of data obtained by measuring a particular process for both the <i>ortho</i> and <i>para</i> substituted derivatives. The missing dissociation constants of 16 <i>ortho</i> substituted benzoic acids in water and ethanol and 16 <i>para</i> substituted benzoic acids in dimethyl sulfoxide and pyridine have been measured by potentiometric titration. The data matrices were submitted to analysis by the methods of projection of latent structures (PLS) and principal component analysis (PCA). It has been found that the substituent effects from <i>ortho</i> and <i>para</i> positions have the same character unless the <i>ortho</i> substituents interact with the reaction centre. Such interactions can change the experimentally found value by as much as 20% of its magnitude. The most significant interaction is a hydrogen bond formation. Out of the three models studied the most extensive interactions are present in benzoic acid, whereas almost none were observed in aniline. The capability of donation of electron pair to a hydrogen bond decreases in the substituent series COCH<sub>3</sub> &gt; SO<sub>2</sub>CH<sub>3</sub> &gt; NO<sub>2</sub>. The capability of donation of proton to a hydrogen bond with electron-pair donor decreases in the substituent series OH &gt; NHCOCH<sub>3</sub> ≈ SH &gt; NH<sub>2</sub> &gt; SO<sub>2</sub>NH<sub>2</sub>. <p>

Title:Chemometric Analysis of Substituent Effects. XII. Application of Relationship Between 2- and 4-Substitution of Benzene Ring to Study ortho Effect in Selected Compounds with Different Reaction Centres
Creators:
Pytela, Oldřich
Prusek, Ondřej
Uncontrolled Keywords:Benzoic acid, PCA, Chemometric, Phenol, <i>ortho</i> Effect, Dissociation constants, Aniline, PLS, 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:64
Number:10
Page Range:pp. 1617-1628
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19991617UNSPECIFIED
ID Code:1584
Item Type:Article
Deposited On:06 Feb 2009 17:10
Last Modified:06 Feb 2009 16:10

Citation

Pytela, Oldřich; Prusek, Ondřej (1999) Chemometric Analysis of Substituent Effects. XII. Application of Relationship Between 2- and 4-Substitution of Benzene Ring to Study ortho Effect in Selected Compounds with Different Reaction Centres. Collection of Czechoslovak Chemical Communications, 64 (10). pp. 1617-1628. ISSN 0010-0765

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