US EPA

1198632 

Journal Article 

KINETICS AND MECHANISM OF OXIDATION OF FREE AND METAL-BOUND THIOCARBOHYDRAZIDE BY N-BROMOACETAMIDE AND N-CHLORO-BENZAMIDES AND N-BROMO-BENZAMIDES IN AQUO-ACIDIC AND AQUO-ORGANIC MEDIA 

Gowda, BT; Rao, PJM 

1991 

1 

Indian Journal of Chemistry. Section A
ISSN: 0376-4710
EISSN: 0975-0975 

30 

2 

148-153 

WOS:A1991EV62100011 

http://://WOS:A1991EV62100011
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Kinetics of oxidation of free and Zn(II)-bound thiocarbohydrazide (TCH) by N-bromoacetamide (NBA), N-chlorobenzamide (NCB) and N-bromobenzamide (NBB) have been studied in aqueous, water-methanol and water-acetic acid (1:1, v/v) media in the presence of perchloric acid or buffer. The reactions show first order kinetics in [oxidant] and fractional order each in [substrate] and [H+]. Addition of the reduced product of the oxidant decreases the rate of NBB oxidation, while it has no effect in NCB and NBA oxidations. Increase in either ionic strength or dielectric constant of the medium increases the rates of oxidation in all the cases. Both Michaelis-Menton type and two-pathway mechanisms have been considered to explain the results. The rate constants are also predicted from the deduced rate laws and the predicted values are in good agreement with the experimental constants providing support to the proposed mechanism. The metal complexation of thiocarbohydrazide has little effect either on the rate of oxidation or kinetic orders.