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Kinetics of the oxidation of aliphatic aldehydes by Os(VIII) in alkaline solution
Author(s) -
Sharma Vinita,
Chowdhury Kakuli,
Banerji Kalyan K.
Publication year - 1990
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/kin.550221004
Subject(s) - chemistry , aldehyde , hydrate , reaction rate constant , kinetics , ionic strength , inorganic chemistry , rate determining step , kinetic isotope effect , reaction rate , ion , hydride , medicinal chemistry , photochemistry , aqueous solution , catalysis , organic chemistry , metal , physics , deuterium , quantum mechanics
Kinetics of oxidation of six aliphatic aldehydes by Os(VIII) in alkaline solutions have been studied. The reaction is of first order with respect to each of the aldehyde and Os(VIII). The pseudo‐first order rate constants decreased with an increase in the concentration of hydroxyl ions. The oxidation of deuterioacetaldehyde (MeCDO) exhibited a substantial primary kinetic isotope effect. Separate rate constants for the oxidation of hydrate and free aldehyde forms have been evaluated. The aldehyde hydrate is postulated as the active reductant. Ionic strength has no noticable effect on the rate. The rate‐determining step is, therefore, postulated to be a bimolecular reaction between the aldehyde hydrate and [OsO 4 (OH) 2 ] −2 . The value of the limiting rate constant exhibited an excellent correlation with Taft σ* values; reaction constant being negative. A mechanism involving transfer of a hydride ion from the aldehyde hydrate to Os(VIII) has been proposed.