Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous Bu4NBr

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Title:Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous Bu4NBr
Creators:
Nummert, Vilve
Piirsalu, Mare
Vahur, Signe
Travnikova, Oksana
Koppel, Ilmar A.
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 74, 1, pp. 29-42
Uncontrolled Keywords:IR stretching frequencies of carbonyl group, <i>ortho</i>-Effect, Kinetics, Esters, Alkaline hydrolysis, Phenyl benzoates, Substituent effects, Hammett equation

Abstract

The second-order rate constants <i>k</i> (in dm<sup>3</sup> mol<sup>–1</sup> s<sup>–1</sup>) for alkaline hydrolysis of phenyl esters of <i>meta</i>-, <i>para</i>- and <i>ortho</i>-substituted benzoic acids, X-C6H<sub>4</sub>CO<sub>2</sub>C<sub>6</sub>H<sub>5,</sub> have been measured spectrophotometrically in aqueous 0.5 and 2.25 <span class="small_cap">M</span> Bu<sub>4</sub>NBr at 25 °C. The substituent effects for <i>para</i> and <i>meta</i> derivatives were described using the Hammett relationship. For the <i>ortho</i> derivatives the Charton equation was used. For <i>ortho</i>-substituted esters two steric scales were involved: the <i>E</i><sub>s</sub>B and the Charton steric (υ) constants. When going from pure water to aqueous 0.5 and 2.25 <span class="small_cap">M</span> Bu<sub>4</sub>NBr, the <i>meta</i> and <i>para</i> polar effects, the <i>ortho</i> inductive and resonance effects in alkaline hydrolysis of phenyl esters of substituted benzoic acids, became stronger nearly to the same extent as found for alkaline hydrolysis of C<sub>6</sub>H<sub>5</sub>CO<sub>2</sub>C<sub>6</sub>H<sub>4</sub>-X. The steric term of <i>ortho</i>-substituted esters was almost independent of the media considered. The rate constants of alkaline hydrolysis of <i>ortho</i>-, <i>meta</i>- and <i>para</i>-substituted phenyl benzoates (X-C<sub>6</sub>H<sub>4</sub>CO<sub>2</sub>C<sub>6</sub>H<sub>5</sub>, C<sub>6</sub>H<sub>5</sub>CO<sub>2</sub>C<sub>6</sub>H<sub>4</sub>-X) and alkyl benzoates, C<sub>6</sub>H<sub>5</sub>CO<sub>2</sub>R, in water, 0.5 and 2.25 <span class="small_cap">M</span> Bu<sub>4</sub>NBr were correlated with the corresponding IR stretching frequencies of carbonyl group, (Δν<sub>CO</sub>)<sub>X</sub>.

Title:Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous Bu4NBr
Creators:
Nummert, Vilve
Piirsalu, Mare
Vahur, Signe
Travnikova, Oksana
Koppel, Ilmar A.
Uncontrolled Keywords:IR stretching frequencies of carbonyl group, <i>ortho</i>-Effect, Kinetics, Esters, Alkaline hydrolysis, Phenyl benzoates, Substituent effects, Hammett equation
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:74
Number:1
Page Range:pp. 29-42
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc2008019UNSPECIFIED
ID Code:4084
Item Type:Article
Deposited On:02 Mar 2009 10:29
Last Modified:02 Mar 2009 09:29

Citation

Nummert, Vilve; Piirsalu, Mare; Vahur, Signe; Travnikova, Oksana; Koppel, Ilmar A. (2009) Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous Bu4NBr. Collection of Czechoslovak Chemical Communications, 74 (1). pp. 29-42. ISSN 0010-0765

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