共查询到20条相似文献,搜索用时 15 毫秒
1.
Ahmed A. Abdel-Khalek Alaa E. -D. M. Abdel-Hady Mohamed F. El-Shahat 《Transition Metal Chemistry》1994,19(2):169-172
Summary A kinetic study of the oxidation of chromium(III) by N-bromosuccinimide (NBS) in aqueous solutions and H2O-MeOH solvent mixtures were performed. The kinetics in aqueous solutions obeyed the rate law: d[CrVI]/dt = {k
4
K
h
K
2[NBS][CrIII]T}/[+]{1 + K
h/[H+] + (K
1 + K
h
K
2/[H+][NBS])} where K
h, K
1 and K
2 are the hydrolysis constant of [CrIII(H2O)6]3+, and pre-equilibrium formation constants for the protonated and deprotonated precursor complexes, respectively. An innersphere
mechanism is proposed. An argument based on isokinetic correlations among activation parameters for the oxidation of a series
of cobalt(II) and chromium(III) complexes including [Cr(H2O)6]3+ is presented in support of a common mechanism for these reactions.
Abstracted from the Ph.D. Thesis (Ain Shams University) of A. E.-D. M. Abdel-Hady. 相似文献
2.
Ahmed A. Abdel-Khalek 《Transition Metal Chemistry》1991,16(2):173-175
The kinetics of the oxidation of [CrIII(H2O)(XOH)], (XOH=N-(2-hydroxycyclohexyl)ethylenediaminetriacetate) to CrVI by periodate have been investigated in aqueous solution at various pH values (6.00–7.20) and temperatures (15.0–35.0°C). The reaction follows the rate law:
相似文献
3.
4.
Summary The kinetics of chromium(III) oxidation by periodate were studied in various EtOH–H2O solvent mixtures covering the 0.0 to 58.0 wt% EtOH range, at five different temperatures in the 15–35°C range. The rate of reaction increases with increasing EtOH content. Thermodynamic activation parameters have been calculated and an appropriate mechanism is suggested. 相似文献
5.
The kinetics of oxidation of nitrilotris(methylenephosphonato)chromium(III), CrIIINTMP, by periodate to yield CrVI have been studied spectrophotometrically over the 5.80–6.85 pH range at 22–33 °C. The reaction rate, which is first-order with respect to [CrIIINTMP] and [IO–
4] and inversely dependent on [H+], obeys the rate law:-d[CrIIINTMP/dt=kKKh[IO-
4] [CrIII]T/Kh+ [H+] +KKh[IO-
4] The values of the intramolecular electron transfer, k, and the formation constant of the intermediate complex, K, were determined at various temperatures. The hydrolysis constant for CrIIINTMP, K
h
, was determined spectrophotometrically and is in agreement with the value estimated from the kinetic data. The activation parameters were calculated from the temperature dependence of the specific rate constants. A mechanism is proposed in which the hydroxo complex, [CrHNTMP(OH)]3–, is the reactive species. The results support a mechanism where intramolecular electron transfer is the rate-determining step. 相似文献
6.
7.
Ahmed A. Abdel-Khalek Said M. Sayyah Fadia F. Abdel-Hameed 《Transition Metal Chemistry》1994,19(1):108-110
A novel chromium(III) complex of tetraoxalylurea was prepared. In aqueous solutions, [CrIII(H2L)(H2O)]+ (H2L = diprotonated tetraoxalylurea) is oxidized by IO
4
–
according to the rate law
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