Hexacyanoferrate(III) oxidation of n-valeric and iso-valeric acid hydrazides in perchloric acid

Abstract

The kinetics of the title reaction were determined spectrophotometrically. The oxidation was second order; but first order with respect to both [hexacyanoferrate(III)]o and [hydrazide]0. The effect of [HCIO4] on the reaction rate was curious; as the HC10 4 concentration increased the rate decreased and, reaching a minimum. The rate was slightly enhanced by an increase in ionic strength, but was insensitive to added salts, such as NaC10~, NaNO3, NaC1, KC1, LiC1 and K4Fe(CN)6 at constant ionic strength. Addition of MeOH retarded the oxidation rate and the entropy of activation was negative. Carboxylic acids and N z were identified as the oxidation products. A radical mechanism and a rate law consistent with the experimental results is proposed.

A mechanistic study on the oxidation of hydrazides: application to the tuberculosis drug isoniazid

“…When we first began this work little was known about the mechanism for the oxidation of hydrazides although it was well established that an electrophilic species is generated that has been exploited for acyl nucleophilic substitution reactions. 6,7 Only recently, when Braslau oxidized aryl and aliphatic hydrazides with PbO 2 in the presence of the radical trap 2,2,6,6,tetramethylpiperidine-1-oxyl (TEMPO, 3, Fig. 1), was it shown that the oxidation of hydrazides with transition metal oxidants involves the formation of an acyl radical intermediate.…”