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Kinetics and mechanism of the reaction between dimethylformamide and chromium(VI)
Author(s) -
Khan Zaheer
Publication year - 1999
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1999)31:6<409::aid-kin2>3.0.co;2-8
Subject(s) - chemistry , chromium , dimethylamine , reaction rate constant , perchloric acid , kinetics , dimethylformamide , aqueous solution , ionic strength , inorganic chemistry , reaction mechanism , medicinal chemistry , rate determining step , organic chemistry , solvent , catalysis , physics , quantum mechanics
The kinetics of oxidation of N,N‐dimethylformamide by chromium(VI) has been studied spectrophotometrically in aqueous perchloric acid media at 20°C. The rate showed a first‐order dependence on both [Cr(VI)] and [DMF], and increased markedly with increasing [H + ]. The order with respect to [HClO 4 ] was found to lie between 1 and 2. The rate was found to be independent of ionic strength as well as of any inhibition effect of Mn(II). The formation of superoxochromium(III) ion was detected in an aerated solution of chromium(VI), DMF and HClO 4 . The proposed mechanism, involving two reaction pathways, leads to the rate law, rate = K a1 [HCrO 4 − ] [DMF] (k I K a2 [H + ]²+k II [H + ]). The first pathway, with rate constant k I , involves the formation of chromium(V) and a free radical. The second pathway, with rate constant k II , involves the formation of Cr(IV), CO 2 and dimethylamine. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 409–415, 1999