Correlation of substituent – inducted chemical shifts of aromatic protons: Substituted benzonitriles and methyl benzoates

[img]PDF - Authorized users only
Language: English
658Kb
Title:Correlation of substituent – inducted chemical shifts of aromatic protons: Substituted benzonitriles and methyl benzoates
Creators:
Exner, Otto
Buděšínský, Miloš
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 56, 11, pp. 2234-2250

Abstract

Proton NMR spectra in deuteriochloroform are reported for 53 <i>meta</i>- and <i>para</i>-substituted benzonitriles and 61 methyl benzoates. The substituent-induced chemical shifts (SCS) were correlated with dual substituent parameters (DSP), with <sup>13</sup>C SCS of the adjoining carbon, and with the other <sup>1</sup>H SCS using the principal component analysis (PCA). They are controlled by different factors in each position to the variable substituent. In the position 4 the long-range polar effects, as expressed by DSP, are decisive, the conjugative component being more important. Remarkable is also very close correlation of <sup>13</sup>C and <sup>1</sup>H SCS in this position which has no analogy in the other position. In the position 3 there is an additional specific effect of heavier halogens. In the position 2 the short-range effect can be quantified by special constants, only for a subgroup of simple donor substituents it is proportional to DSP. In all positions SCS are practically independent of the second substituent, so that the total chemical shifts can be calculated by an additive scheme. The coupling constants <i>J</i>(2,3), <i>J</i>(5,6), and <i>J</i>(2,6) depend on substitution in the same manner, probably are controlled mainly by substituent electronegativity.

Title:Correlation of substituent – inducted chemical shifts of aromatic protons: Substituted benzonitriles and methyl benzoates
Creators:
Exner, Otto
Buděšínský, Miloš
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:56
Number:11
Page Range:pp. 2234-2250
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19912234UNSPECIFIED
ID Code:5153
Item Type:Article
Deposited On:22 Feb 2010 11:32
Last Modified:22 Feb 2010 10:32

Citation

Exner, Otto; Buděšínský, Miloš (1991) Correlation of substituent – inducted chemical shifts of aromatic protons: Substituted benzonitriles and methyl benzoates. Collection of Czechoslovak Chemical Communications, 56 (11). pp. 2234-2250. ISSN 0010-0765

Repository Staff Only: item control page