Separation of ortho Inductive, Resonance and Steric Terms in Alkaline Hydrolysis of Substituted Phenyl Benzoates and Phenyl Tosylates

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Title:Separation of ortho Inductive, Resonance and Steric Terms in Alkaline Hydrolysis of Substituted Phenyl Benzoates and Phenyl Tosylates
Creators:
Nummert, Vilve
Piirsalu, Mare
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 67, 12, pp. 1833-1857
Uncontrolled Keywords:Chemometrics, Steric effect, Phenyl tosylates, Kinetics, Esters, Alkaline hydrolysis, <i>ortho</i> Effects, Phenyl benzoates, Substituent effects

Abstract

The second-order rate constants <i>k</i><sub>2</sub> (l mol<sup>-1</sup> s<sup>-1</sup>) for the alkaline hydrolysis of <i>meta</i>-, <i>para</i>- and <i>ortho</i>-substituted phenyl benzoates C<sub>6</sub>H<sub>5</sub>CO<sub>2</sub>C<sub>6</sub>H<sub>4</sub>-X and phenyl tosylates 4-CH<sub>3</sub>-C<sub>6</sub>H<sub>4</sub>SO<sub>2</sub>OC<sub>6</sub>H<sub>4</sub>-X in aqueous 5.3 M NaClO<sub>4</sub> have been measured spectrophotometrically at various temperatures. The log <i>k</i> values at a single temperature were analysed according to the equations log <i>k</i><sub>m,p</sub> = log <i>k</i><sub>0</sub> + (ρ)°<sub>m,p</sub>σ°, log <i>k</i><sub>ortho</sub> = log <i>k</i><sub>0</sub>+ (ρ<sub>I</sub>)<sub>ortho</sub>σ<sub>I</sub> + (ρ<sub>R</sub>)<sub>ortho</sub>σ<sub>R</sub>° + δ<sub>ortho</sub>υ and log <i>k</i><sub>m,p,ortho</sub> = log <i>k</i><sub>0</sub>+ (ρ<sub>I</sub>)<sub>ortho</sub>σ<sub>I</sub> + (ρ<sub>I</sub>)<sub>meta</sub>σ<sub>I</sub> + (ρ<sub>I</sub>)<sub>para</sub>σ<sub>I</sub> + (ρ<sub>R</sub>)<sub>ortho</sub>σ<sub>R</sub>° + (ρ<sub>R</sub>)<sub>meta</sub>σ<sub>R</sub>° + (ρ<sub>R</sub>)<sub>para</sub>σ<sub>R</sub>° + δ<sub>ortho</sub>υ. In the case of various temperatures, the equation for data processing involved the additional c<sub>1</sub>(1/<i>T</i>) term and the cross term c<sub>m,p</sub>(1/<i>T</i>)σ° or c<sub>2</sub>(1/<i>T</i>)σ<sub>I</sub> and c<sub>3</sub>(1/<i>T</i>)σ<sub>R</sub>° different for <i>ortho</i>-, <i>meta</i>- and <i>para</i>-substituted derivatives. As the measure of the steric influence from <i>ortho</i> position, the Charton υ values were used. In the case of a single temperature, the sensitivity to the inductive effect of <i>ortho</i> substituents was found to be about 1.7 times (in water 1.5 times) stronger than that of <i>para</i> and <i>meta</i> substituents in both reaction series studied. The variation of the <i>ortho</i> inductive influence with temperature appeared to be more than twice larger than that for <i>para</i> substituents. Compared to water, in aqueous 5.3 M NaClO<sub>4</sub> the inductive effect from <i>ortho</i> position was nearly unchanged while the <i>para</i> inductive effect was found to be about 0.13 units of ρ<sub>I</sub> smaller in the case of both reaction series studied, though the polar effects in these reaction series differ about two-fold. Due to different variation of the <i>ortho</i> and <i>para</i> inductive effects with solvent and temperature, the relative increase in the <i>ortho</i> effect was observed when going from water to aqueous 5.3 M NaClO<sub>4</sub>. <p>

Title:Separation of ortho Inductive, Resonance and Steric Terms in Alkaline Hydrolysis of Substituted Phenyl Benzoates and Phenyl Tosylates
Creators:
Nummert, Vilve
Piirsalu, Mare
Uncontrolled Keywords:Chemometrics, Steric effect, Phenyl tosylates, Kinetics, Esters, Alkaline hydrolysis, <i>ortho</i> Effects, Phenyl benzoates, 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:67
Number:12
Page Range:pp. 1833-1857
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20021833UNSPECIFIED
ID Code:2037
Item Type:Article
Deposited On:06 Feb 2009 17:15
Last Modified:06 Feb 2009 16:15

Citation

Nummert, Vilve; Piirsalu, Mare (2002) Separation of ortho Inductive, Resonance and Steric Terms in Alkaline Hydrolysis of Substituted Phenyl Benzoates and Phenyl Tosylates. Collection of Czechoslovak Chemical Communications, 67 (12). pp. 1833-1857. ISSN 0010-0765

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