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.

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.

The oxidation ofdl-α-phenyl ethyl alcohol, benzhydrol and fluorenol by chromium (VI) oxide has been studied in acetic acid-water mixtures under conditions of constant ionic strength and hydrogen-ion concentrations between 35° and 50°. The reaction is of the second order and the rate increases with increasing proportions of acetic acid. The reaction is not a base catalysed one and the results are not explicable on the basis of the hitherto generally accepted mechanism of Westheimer.

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.

The kinetics of the bromine oxidation of borneol, isoborneol,α-norborneol andβ-norborneol have been investigated in order to find out whether the oxidation is sensitive to the configuration of the alcohol. There is a definite and considerable variation in rate which is shown to arise from stereochemical consequences. The Arrhenius parameters of the reaction have also been calculated.

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.

The kinetics of the chromic acid oxidation ofα-hydroxy acids, their salts and esters has been investigated in binary solvent mixtures of acetic acid and water. The results indicate that the Westheimer hypothesis of a rate-determining proton-abstraction from a preformed chromate ester is unlikely. Substituent and salt effects indicate the likelihood of a mechanism involving a rate-determining hydride ion abstraction assisted by a proximate substituent.

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.

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.

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.

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.