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Asian Journal of Research in Chemistry
Year : 2017, Volume : 10, Issue : 6
First page : ( 803) Last page : ( 809)
Print ISSN : 0974-4169. Online ISSN : 0974-4150.
Article DOI : 10.5958/0974-4150.2017.00134.1

Structure-reactivity correlation in the oxidation of meta and para-substituted benzaldehydes by Tetrakis (Pyridine) Silver Dichromate

Kharche Amol P.**, Dr. Shastri Indu M.*

Department of Chemistry, R.D. and S.H. National College and S.W.A. Science College, Bandra(W), Mumbai, 400050, India

*Corresponding Author E-mail: indushastri@rediffmail.com

** amol.kharche85@gmail.com

Online published on 26 March, 2018.

Abstract

Oxidation of twenty-three monosubstituted benzaldehydes by tetrakis pyridine silver dichromate in dimethyl sulphoxide, leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to tetrakis pyridine silver dichromate and aldehydes. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs= a + b [H+]. The oxidation of duteriated benzaldehyde exhibits substantial primary kinetic isotope effect. The reaction was studied in nineteen different organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para and ameta-substituted benzaldehydes showed excellent correlation in terms of Charton'striparametric LDR equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. A suitable mechanism has been proposed.

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Keywords

Benzaldehydes, Dichromate, Correlation analysis, Kinetics, Mechanism.

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