Acid hydrolysis kinetics complexes

The redox potential and the reactivity of this oxidation state depend strongly upon the anion (Table 11). Strong complexes are formed with SO ". Even in perchloric acid, hydrolysis and polymerisation greatly complicate kinetics. The co-ordination number of Ce(lV) in solution is not established . 

In order to elucidate the causes of the increased stability of the hydrolyzed cluster ions compared with the unhydrolyzed ions, further studies were made of the behaviour of [Te2X8]3 (where X = Cl,Br, or I) in solutions of hydrogen halides [43,52,80,87]. The studies were performed mainly in relation to the most stable and most readily synthesized [Tc2C18]3- ion (Fig. la) kinetic methods with optical recording were employed. The identity of the reaction products was in most cases confirmed by their isolation in the solid phase. The studies showed that the stability of the [Tc2X8]3 ions (where X = Cl, Br, or I) in aqueous solutions is determined by the sum of competing processes acid hydrolysis complex formation with subsequent disproportionation and dissociation of the M-M bonds, and oxidative addition of atmospheric oxygen to the Tc-Tc multiple bond. 

Much work has been done since, and it is quite evident that this seemingly simple hydrolysis to acetic and salicylic acids is both complex and controversial. I am fortunate that I can refer the reader to the excellent and detailed review by Clark A. Kelly151 already mentioned in Section 5.61. The most complete and thorough kinetic studies of the factors involved in the hydrolysis of aspirin are undoubtedly those by Edwards17 3, which were further elaborated by Garrett.174... 

The whole series of pyrrol-l-ylborates, M[BH (NC4H4)4 ], has been synthesized (Tables 9 and 12). The mechanism of their formation and their hydrolysis kinetics have been studied in detail.100 The hydropyrazol-l-ylborates are very stable compounds and can be prepared in acid form.101 The di- and tri-pyrazol-l-ylborates are extensively used as complexing ligands (see Chapter 13.6). The photoelectron spectra of the sodium and thalliumfl) hydrotris(pyrazol-l-yl)borates and the electronic structure of the anion itself are reported.11 ... 

The kinetics of the acid hydrolysis of dihydroxo-bridged cobalt(III) complexes have been studied for both cationic and anionic species. The stoichiometry of the hydrolysis reaction for cationic complexes can be expressed by Eq. (56). The equilibrium lies completely to the right at low pH (typically less than 3) and the reverse process in Eq. (56) can normally be disregarded. For all the systems studied to date the observed rate laws can be interpreted in terms of Scheme 4. 

Both alkaline proteases form an intermediate, the acyl-enzyme complex, on the reaction coordinate from the amino acid component to the dipeptide, which is formed by the triad Ser-(or Cys-)-His-Asp (or -Glu) (see Chapter 9, Section 9.5). The acyl-enzyme complex can be formed with the help of an activated amino acid component such as an amino acid ester. The complex can react either with water to the undesired hydrolysis product, the free amino acid, or with the amine of the nucleophile, such as an amino acid ester or amide, to the desired dipeptide. The particular advantage of enzyme-catalyzed peptide synthesis rests in the biocatalyst specificity with respect to particular amino acids in electrophile and nucleophile positions. Figure 7.26 illustrates the principle of kinetically and thermodynamically controlled peptide synthesis while Table 7.3 elucidates the specificity of some common proteases. 

The kinetics of substitution of bipy or phen into Co (467, 574), Ni (144), and Pt (697) complexes have been reported. Several studies of the hydrolysis of complexes of form [Co(III)(bipy)2XY] may be found. For both cis and trans isomers where X = Y = CY, hydrolysis is instantaneous (581), whereas for the cis isomer with X = acetate and Y = acetate or OH , reaction is very slow as a conjugate base mechanism cannot operate and the first-order reaction is therefore independent of [OH ] (124). One NO2 group in acid dependent and under acidic conditions is thought to proceed via protonation of one nitro group (289, 472). The interconversion of the cis and trans isomers, where X = N02 and Y = H2O, has an overall rate constant equal to + A [H+], implying reactions for both OH and... 

Anaerobic treatment, a multistep complex process, can be described from a kinetic viewpoint as a three-step process involving (1) hydrolysis of complex organic material (2) organic acid production (3) methane fermentation (2). In the first step complex organics are converted to less complex soluble organic compounds by enzymatic hydrolysis. In the... 

The acid hydrolysis of CD was investigated based on the measurement of reducing power with an alkaline copper reagent [62]. The kinetics was found to be complex (Table 16.3). 

From the study of acid hydrolysis of the complex K[PtCl3(DMSO)], formed readily by the reaction of one equivalent of DMSO with K2PtCli in water. Elding (19) concluded that the cis and trans influences were of the magnitude of C2H, a point made by Kukushkin in comparison of the DMSO complex with Zeise s salt, K[Pt(C2Hi )Cl3] (20). These influences are small compared to the kinetic effects which are in the order ... 

This last reaction, the hydrolysis of coordinated nitriles, has been extensively studied by Ford and co-workers acidic hydrolysis of [Rh(NH3)5NCO] has been used as an alternate route to the hexaammine (equation 113). The reaction was shown to go through a carbamic acid intermediate, which was isolated and characterized. The kinetic study of the hexaammine formation was complicated by the presence of these two consecutive reactions, and by two different reaction paths. The mechanism proposed for the hydrolysis of the coordinated cyanate is shown in Scheme 14 at low acid concentrations (0.005 to 0.025 M) the rate determining step is HjO attack of the protonated species leading to a rate expression which is first-order in [H ] rate = ky [RhlfH" ]. At higher acid concentrations (0.2 to 1.0 M), decomposition of the carbamic acid complex is rate determining, and... 

The Cr —N bond is much more susceptible to acid hydrolysis than is the Co "—N bond, and Garner and his coworkers have carefully investigated the stepwise dechelation kinetics of Cr(dien)-(0H2)] and other Cr" poly amine complexes" in acid solution. Thus, Cr(dien-H)(OH2)J" and Cr(dien-H2)(OH2)5 have been isolated chromatographically and characterized in solution. ... 

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