Kinetics and mechanism of oxidation of benzoic acid hydrazide by bromate catalyzed by octamolybdomanganate(II)

Abstract

Oxidation of benzoic acid hydrazide by bromate in the presence of octamolybdomanganate(II), [Mn II Mo 8 O 27 ] 4-, was studied in hydrochloric acid medium. The mechanism of the reaction involves oxidation of the catalyst to [Mn IV Mo 8 O 27 ] 2-by bromate which then forms a complex with the unoxidized catalyst. Both the complex and [Mn IV Mo 8 O 27 ] 2-react with the substrate in rate-determining steps to generate an intermediate acyl diimide, RCONNH.The reaction of water with the diimide then leads to the formation of benzoic acid and nitrogen as products through an NH-NH intermediate. There was no formation of free radical, indicating the involvement of only two-electron transfer steps in the mechanism. The order of more than unity in catalyst concentration is due to the formation of complex between the catalyst and the oxidized form of the catalyst. A rate law explaining all the kinetic results has been derived and verified. The effects of ionic strength and solvent polarity have also been studied, and the thermodynamic parameters were determined. A less solvated transition state as a result of interaction between the complex and oxidized form of the catalyst satisfactorily explains all the effects observed.

Oxidations of Benzhydrazide and Phenylacetic Hydrazide by Hexachloroiridate(IV): Reaction Mechanism and Structure–Reactivity Relationship

“…Indeed, BH and its derivatives have been investigated extensively towards discovery of new drugs [9,10,21,22] and catalysts [23]. The oxidation kinetics of BH by bromate in acidic media catalyzed by V(IV) and Mn(II) [24,25] and by enzymes [26,27] were reported; but in these studies, the enol/enolate form of BH was not considered.…”

Kinetics and Mechanism of 13-Vanadomanganate(IV) Catalyzed Oxidation of Benzoic Acid Hydrazide by Bromatein Buffer Solution of pH 4.0

“…In comparison with Keggin and Dawson type of salts, less attention is given to other type of POM anions. In continuation of our interest [8][9][10] in the electron transfer reactions involving POMs, the present study, oxidation of benzoic acid hydrazide (BAH), by bromate catalyzed by 13-vanadomanganate(IV), was carried out in acetic acidsodium acetate buffer solution of pH 4.0.…”

“…Hydrazides are pharmaceutically important compounds as anti-tubercular 11 and antibacterial 12 agent. Hydrazides on oxidation generally give corresponding acids 9 and in some cases 13 esters or amides. Hydrazides have also been converted into N-N-diacylhydrazines with various oxidants 14 .…”

Kinetics and mechanism of oxidation of pyridoxine by enneamolybdomanganate(IV)

“…The modification of the redox properties of the central metal ion by changing the oxometalate moiety leads to the stability of otherwise unstable metal ions while their acidic properties can be altered by changing the hetero atom at the center. Therefore, because of such variation in almost all physical properties of PMO's it makes them very good acid [2][3][4][5] as well as redox [6][7][8] catalysts. They are also used as analytical reagents, staining agents, precipitating reagent, electron acceptors, antiviral and antitumoral reagents [1] in biochemical applications.…”

“…Molybdenum, the major content of the oxidant used, is found in several tissues of the human body and is required for the activity of xanthine oxidase which is involved in the catabolism of purines [15]. In continuation of our earlier studies [6,7,16,17], oxidation of vitamin B6 by enneamolybdomanganate(IV) was carried All chemicals were of reagent grade and double-distilled water was used throughout the work. A solution of pyridoxine hydrochloride (vitamin B6)(Hi Media) was freshly prepared by dissolving an appropriate amount of sample in double-distilled water.…”