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Indian Journal of Chemistry -Section A (IJC-A) >
IJC-A Vol.51A [2012] >
IJC-A Vol.51A(05) [May 2012] >
| Title: | Kinetic and mechanistic studies of oxidation of glycine and valine by N-bromosuccinimide using chloro complex of Rh(III) in its nano-concentration range as homogeneous catalyst |
| Authors: | Singh, Ashok Kumar
Singh, Rajesh Kumar
Srivastava, Jaya
Rahmani, Shahla
Yadav, Sarita |
| Keywords: | Kinetics
Reaction mechanisms
Rhodium
Oxidation
Amino acids |
| Issue Date: | May-2012 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | Kinetics
of oxidation of glycine (gly) and valine (val) by N-bromosuccinimide (NBS)
using chloro complex of Rh(III) in its nano-concentration range as homogeneous
catalyst have been investigated at 35 oC . The reaction shows first order kinetics with
respect to NBS and Rh(III) in the oxidation of both the amino acids. The first
order kinetics with respect to amino acid obtained at its lower concentration
changes to zero order at its higher concentration. Inverse fractional order
with respect to [H+] was obtained in Rh(III)-catalysed oxidation of
gly and val. Variation in [Hg(II)], [NHS], [Cl-], ionic strength and dielectric constant of the
medium has no effect on the rate of oxidation of both the amino acids. NBS itself and [RhCl5(H2O)]2-
have been postulated as the reactive species of NBS and Rh(III) chloride
in acidic medium, respectively. Various activation parameters have been
calculated with the pseudo-first-order rate constant values observed at four
different temperatures. The main oxidation products of the reactions have been
identified as formaldehyde and ammonia in the case of gly and isobutaldehyde
and ammonia in the case of val. The proposed reaction mechanism is well
supported by kinetic data, spectrophotometric evidence and positive entropy of
activation. |
| Page(s): | 681-689 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-0975(Online); 0376-4710(Print) |
| Source: | IJC-A Vol.51A(05) [May 2012]
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