Articles written in Proceedings – Section A
Volume 50 Issue 2 August 1959 pp 156-165
Studies in oxidation: Oxidation of some aliphatic secondary alcohols with chromium (VI) oxide—Part I
The oxidation of isopropyl alcohol, butanol-2, pentanol-2 and octanol-2 by chromium (VI) oxide, has been studied in acetic acid-water mixtures under conditions of constant ionic strength and hydrogen-ion concentrations, between 35° C. and 50° C. The reaction is of the second order and the rate increases with increasing proportions of acetic acid. The results of the present study are not easily explicable on the basis of the hitherto generally accepted mechanism of Westheimer.
Volume 51 Issue 6 June 1960 pp 310-318
Kinetics of oxidation of alcohols by chromic acid—the mechanism of the reaction
S V Anantakrishnan N Venkatasubramanian
An analysis of the various factors affecting the oxidation of secondary alcohols by chromic acid in aqueous acetic acid systems shows the following features. The formation of an ester of chromic acid is not essential to oxidation. Both structural and solvent influences from the study of a series of secondary alcohols, aliphatic as well as aromatic, suggest that in the rate-determining step of the reaction the C-H hydrogen is removed as a hydride ion. The rate-determining step involves a two-electron transfer and the reacting species can be hexavalent and pentavalent chromium. A tentative mechanism of the reaction has been suggested incorporating these features.
Volume 53 Issue 2 February 1961 pp 80-88
Studies in oxidation: Oxidation of some aromatic secondary alcohols with chromium (VI) oxide—Part II
The oxidation of
Volume 57 Issue 5 May 1963 pp 305-310
Studies in oxidation: Salt effects in the oxidation of secondary alcohols with chromium (VI) oxide-possible intermediate species of chromium—Part VI
The effect of added salts and oxidisable cations on the chromic acid oxidation of secondary alcohols in acetic acid-water mixtures is discussed and a tentative scheme for the intermediate stages of reduction of the chromium species is presented.
Volume 65 Issue 1 January 1967 pp 30-37
Conformational aspects in chromic acid oxidations—Oxidation of some cyclanols by chromium (VI) oxide
Volume 67 Issue 1 January 1968 pp 37-41
Mechanism of oxidation of secondary alcohols by bromine—oxidation of bicyclic secondary alcohols
V Thiagarajan N Venkatasubramanian
The kinetics of the bromine oxidation of borneol, isoborneol,
Volume 69 Issue 3 March 1969 pp 162-167
The chromic acid oxidation of hydroxy acids—Catalysis by manganous ions
S Sundaram N Venkatasubramanian
Kinetic data for the catalysis by manganese (II) of the chromic acid oxidation of α-hydroxy and α-keto acids over a range of Mn (II) concentrations are reported. A first order dependence on Mn(II) in the lower concentration regions with an upper limit is noticed. The results are explained on the basis of a slow rate determining decomposition of an Mn (III)—substrate complex which is formed by the oxidation of an Mn (II)—substrate species formed initially. The enhanced positive catalysis by Mn (II) in the case of Cr (VI) oxidation of pyruvic acid over that of lactic acid is attributed to an independent mechanistic path.
Volume 70 Issue 4 October 1969 pp 157-164
S Sundaram N Venkatasubramanian
The kinetics of the chromic acid oxidation of
Volume 71 Issue 1 January 1970 pp 1-8
The chromic acid oxidation of aliphatic secondary alcohols—substituent effects and the mechanism
N Venkatasubramanian G Srinivasan
The mechanism of the chromic acid oxidation of a number of substituted propan-2-ols has been studied in aqueous acetic acid medium. Electron withdrawing substituents retard the reaction considerably while electron-releasing substituents accelerate the reaction. A good correlation exists between the rate and σ* values. The ρ* value is −1.60. The results are interpreted in terms of a rate-determining abstraction of the secondary hydrogen as a hydride anion.
Volume 72 Issue 6 December 1970 pp 261-265
The transition state in the chromic acid oxidation of some naphthalene derivatives
V S Srinivasan S Sundaram N Venkatasubramanian
The kinetics of the chromic acid oxidation of 1-naphthyl and 2-naphthyl methyl carbinols have been investigated. 2-Naphthyl methyl carbinol reacts at a faster rate than the 1-naphthyl isomer. This is attributed to a peri-interaction in the transition state of the latter compound. The thermodynamic parameters have also been evaluated for the reactions.
Volume 75 Issue 1 January 1972 pp 8-12
Salt effects in the alkaline hydrolysis of dicarboxylic esters in aqueous DMSO—The mechanism of half-ester hydrolysis
G Venkoba Rao N Venkatasubramanian
The effect of addition of several salts on the rate of hydrolysis of dicyclohexyl phthalate and sodium monobenzyl phthalate in aqueous DMSO has been studied. It is found that the rate of the second step of the hydrolysis is dependent on the character and the concentration of the cation of the electrolyte added while the rate of the first step is not much affected. The results are taken to point to the operation of an iondipole mechanism in the half-ester hydrolysis rather than an ion-ion mechanism.
Volume 80 Issue 1 July 1974 pp 50-56
Solvent influences in the alkaline hydrolysis of esters in aqueous ethanol
M Balakrishnan G Venkoba Rao N Venkatasubramanian
The rate data for the alkaline hydrolysis of a number of monoesters, diesters and lactones have been obtained in varying compositions of aqueous ethanol. The application of the Amis and Laidler-Landskroener equations to the data yields reasonable values for the parameters representing the radius of the transition state for the hydrolysis confirming the ion-dipole nature of the reaction. An attempt to explain the rate data on the basis of the solvation requirements of the transition state has been made.