Reaction between isopropyl alcohol and chromium VI

Oxidation of isopropyl alcohol (H2R) by chromic acid has been studied in det ai by Westheimer and Novick , and it was found that acetone (R) is formed nearly quantitatively. The reaction proved to be first order with respect to hydrogen chromate and second order with respect to hydrogen ions. Measurements using 2-deutero-2-propanol under identical conditions as those for the oxidation of ordinary isopropyl alcohol showed the rate of reaction to be of that with the hydrogen compound. This fact is considered to prove that the secondary hydrogen atom is removed in the rate-controlling step and that the assumption of hydride-ion abstraction can be excluded. The data are consistent with the following mechanism 

A recent study by Lee and Stewart confirms the previous observations that with rather low acid concentrations the oxidation rate of H2R depends only on the acidity of the medium and not on the nature of the proton-supplying mineral acid. On the contrary, at rather high acid concentrations the rate of oxidation depends not only on the acidity but also on the nature of the acids. This can be explained by the fact that the hydrogen chromate and the acid present interact with each other 

APPARENT pA VALUES OF CHROMIC ACID IN AQUEOUS SOLUTIONS OF VARIOUS MINERAL ACIDS, ACCORDING TO LEE AND STEWART  

The first step in the oxidation of the alcohol is the formation of a chromate ester which probably decomposes unimolecularly to products, viz. 

At higher acid concentrations, when formation of HCrOsB is also to be considered, because of the incorporation of the conjugate base the rate of oxidation will depend also on the nature of the acid radical present, viz. 

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