Cupric salts kinetics

Equation (8) also describes the kinetics of the reduction of the cupric salt, ultimately to metallic copper, which is observed in the absence of an added substrate (Macgregor and Halpern, 16). This reaction proceeds by a mechanism in which step (11) is replaced by the rapid disproportionation of Cu+ to give metallic copper ... 

The accelerating effect of cupric ions on the ferric ion catalysis which was observed by Bohnson and Robertson is considered by Barb el al. to be due to reaction (5 ), as was the analogous effect of cupric salts on the ferrous ion catalysis. For conditions in which Scheme A applies reaction (4 ) is in effect catalyzed by (5 ). At high cupric ion concentrations (5 ) will eliminate (3), since effectively all the radical HO2 will react in (5 ). In these conditions the enhancement reaches a limit as was observed by Bohnson and Robertson. However (1) now becomes the operative chain-terminating step, and hence the kinetics of Scheme B should apply (Eq. g). Unfortunately no data on the peroxide dependence is available, but analysis of the data (43,66) shows the rate to be proportional to [Fe+++]w as required by (g). There is the same discrepancy in hydrogen ion dependence as was found in the simple ferric reaction. 

Chlorpyrifos is stable to hydrolysis in the pH range of 5-6 (Mortland and Raman, 1967). However, in the presence of a Cu(lf) salt (i.e., cupric chloride) or when present as the exchangeable Cu(II) cation in montmorillonite clays, chlorpyrifos is completely hydrolyzed via first-order kinetics in <24 h at 20 °C. It was suggested that chlorpyrifos decomposition in the presence of Cu(II) was a result of coordination of molecules to the copper atom with subsequent cleavage of the side chain containing the phosphorus atom forming 3,5,6-trichloro-2-pyridinol and 0,0-ethyl-0-phosphorothioate (Mortland and Raman, 1967). 

The complex then reacts with the alcohol in a manner similar to that postulated by the Baker mechanism for the base-catalyzed reaction. The kinetics involving this square root law is not valid for the cupric acetate-or zinc naphthenate-catalyzed reaction of these tertiary isocyanates. It seems that metal salts of strong acids and of weak acids conform to different mechanisms. 

Olefin oxidation with an aqueous palladium chloride solution according to eqs. (2)-(4) occurs stoichiometrically. A catalytic reaction is only possible if the metallic palladium can be reoxidized immediately. With gaseous oxygen, conditions to oxidize even finely divided palladium black are not optimal. However, metal salts such as cupric and ferric chlorides, chromates, heteropoly acids of phosphoric acid with molybdic and vanadic acids, or other oxidants - e. g., ben-zoquinone is used in kinetic investigations [10] - are suitable for reoxidation of the palladium metal. This fact explains the increase of the yield of acetaldehyde in the first experiments of the Consortium carried out in the presence of cupric and ferric chlorides, as mentioned above. 

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