Kinetic study of the iron-catalyzed reaction of the oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone with N,N-dimethylaniline

The iron(III)-catalyzed reaction of the oxidative coupling reaction of 3-me thyl-2-benzothiazolinone hydrazone (MBTH) with N,N-dimethylaniline (DMA) wa s studied kinetically by an initial-rate method. All reactions were run at constant ionic strength 0.3 M and 40 degreesC and followed by measuring the absorbance at 590 nm of the violet compound formed. According to results o f a kinetic study of the iron(III)-catalyzed reaction, a mechanism is propo sed which leads to the following rate equation: R-0cat = {[DMA][MBTH]/P'[H+]+Q'[H+]DMA]+S'[DMA] + [DMA][MBTH]/T'[H+]+U'[H+] [MBTH]+V'[H+][MBTH][DMA]+[W'[MBTH][DMA]} [Fe](0) The equation describes in detail the quantitative behavior of the reaction throughout the range of conditions studied. The optimum conditions for iron determination by initial rate procedure were estimated using this rate equ ation and analytical implications of the mechanistic study are discussed. ( C) 2000 Elsevier Science B.V. All rights reserved.