Kinetic studies of the reduction

While ether is the common solvent for LiAlH4, in which it is soluble, hydroxylic solvents like water, methanol and ethanol are preferred for NaBH4, It is more soluble in methanol than in ethanol, but since it reacts with the former at an appreciable rate than the latter, hence ethanol is the preferred solvent. Isopropanol, in which NaBH4 is stable, is used for kinetic studies of the reduction of aldehydes and ketones. 

Weber EJ, Wolfe NL. 1987. Kinetic studies of the reduction of aromatic azo compounds in anaerobic sediment/water systems. Environ Toxicol Chem 6 911-919. 

The chromium(II) complex of 1,4,8,12-tetraazacyclopentadecane ([15]aneN4 81) has been prepared in aqueous solution and used as an intermediate in the production of chromium(III) complexes (Scheme 25), including some which contain Cr—C o bonds.297 Its powerful reducing ability and the chemical inertness of the Cr111 products (it is preferable to Cr2+aq) have been exploited298 in kinetic studies of the reduction of ferredoxins. 

Heterogeneous charge transfer kinetic study of the reduction of benzonitrile (BN) in N, JV-dimethylformamide using NPSVa... 

The results of kinetic studies of the reduction of stellacyanin, plastocyanin, and azurin by Fe(EDTA)2" are summarized in Table III (20, 21). The order of cross reaction rate constants (ki2 values) is stellacyanin > plastocyanin > azurin, which is surprising, as considerations based on driving force alone would predict stellacyanin to be the least reactive of... 

Vurzel and Polak (55) carried out extensive kinetic studies of the reduction of silicon tetrachloride to silicon in plasma devices. They first decomposed SiCl4 to SiCls in an adiabatic compression-expansion device and then completed the reduction in an RF plasma. They claimed that the decomposition of SiCl4 to silicon proceeded by a two-stage mechanism of chlorine atom removal ... 

Another system for which thermodynamic data have been obtained in some detail is the Tp Rh(CNneopentyl)(R)H system studied by Jones. Here, the relative thermodynamic stabilities of a number of adducts were obtained by measuring both the competitive kinetic selectivity for two types of C-H bond (AAGt in Fig. 2) as well as the barrier for reductive elimination of free alkane from each adduct (AG and AG in Fig. 2). The free energies for the latter were obtained from kinetic studies of the reductive elimination of hydrocarbon in benzene. A summary of the AG° values, calculated equilibrium constants, and relative metal-carbon bond strengths are given in Table 4 [26]. For DC H for benzene, see ref. 

Both reduction and oxidation processes have been found to be biphasic. Thus, in kinetic studies of the reduction of synthetic oxidation with Fe , respectively, a fast first electron-exchange step was followed by a slow second step (210). Whereas the quinone-quinol relationship involves an exchange of two electrons, only 0.5 electrons were accounted for the fast reaction step between d,/-dopa melanin and Tp similarly, only 0.02 electrons per indole unit was exchanged with Fe (210). From the 25 I ratio for the fast reduction versus oxidation steps, it was concluded that melanin in an air atmosphere exists predominantly in the quinonoid form. This finding was further supported by an experiment in which reduced d,/-dopa melanin was partially reoxidized by air. 

Weber, E. J., and N. L. Wolfe (1987), Kinetic Studies of the Reduction of Aromatic Azo Compounds in Anaerobic Sediment/Water Systems, Environ. Toxicol. Chem. 6, 911 919. 

The kinetic studies of the reduction of benzylideneaniline with the catalyst RuCL (2-mebzlH)2 were carried out in DMF in presence of NaBR. All the reaction parameters except the varied one were kept constant during any catalytic run. Kinetic reactions with Schiff bases were repeated at different initial [catalyst] and [substrate] concentrations. The kinetic experiments were conducted at hydrogen pressure equivalent to atmospheric pressure. The kinetic data in each case could be fitted in to a first order plot of log (a-x) versus t where... 

In a transient kinetic study of the reduction of chromophoric aldehydes, Bernhard and co-workers (354) observed a biphasic optical change... 

An initiation time for the reduction reaction was found by Weigmann [22] in his kinetic study of the reduction of wool fiber. Weigmann attributed the initiation time to the epicuticle, this initial barrier to reduction is eliminated after only a short reduction time. Weigmann suggested that the epicuticle is substantially altered during permanent-waving. As a consequence, hair that has been permanent-waved or has undergone alterations to the epicuticle should provide no initiation time in subsequent reductions or reactions. 

A kinetic study of the reductive opening of the diphenylmethylene acetal in methyl 2,3-0-diphenylmethylene-o -L-rhamnopyranoside has been compared to earlier quantum calculations. ... 

Abstract The activation of C-H bonds by oxidative addition in about 30 different substrates has been examined with three closely related metal species, [Tp RhL], where L = CNneopentyl, PMes, and P(OMe)3. Kinetic studies of the reductive elimination of R-H provided data to ascertain the relative metal-carbon bond strengths for a wide range of compounds. Trends in these bond strengths reveal that there are two classes of C-H substrates parent hydrocarbons and substituted methanes. DPT calculations are used to support the observed trends, and some generalizations are made by comparison to other metal systems. 

A kinetic study of the reduction of 4-substituted camphors with Na[BH4] indicated that the major product is the exo-alcohol. The reaction rates are greater for electron-withdrawing substituents and the results are ascribed to increasing the ground state double bond character and stabilization of the transition state [10]. 

Overman, L. E. and O Connor, E. M., 1976. Nucleophilic cleavage of the sulfur-sulfur bond by phosphorus nucleophiles. IV. Kinetic study of the reduction of alkyl disulfides with triphenylphosphine and water. J. Am. Chem. Soc. 98, 771-775. 

Annibale and coworkers have reported a kinetic study of the reduction of Au(III) to Au(I) by various dialkyl sulfides. In their evaluation of the reactions, the authors concluded (0 The first step of the interaction establishes the substitution equilibria (h) The second step involves transfer of a chlorine atom from Au(III) to free sulfide. This leads to a digonal gold(l) complex and a halosulfonium salt, [R2SC1]C1, as the primary reaction products. Scheme 9.5 ... 

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