Hydrogen peroxide complexes, with

Some recent advances have been reported in oxime oxidation, including the in situ generation of peroxytrifluoroacetic acid from the reaction of urea hydrogen peroxide complex with TFAA in acetonitrile at 0 °C This method gives good yields of nitroalkanes from aldoximes but fails with ketoximes. 

The reactions of the lactoperoxidase-hydrogen peroxide complexes with ascorbic acid and with p3rrogallol were investigated by Chance (95) and allow us to compare the h values of two different peroxidases with the same donor. Some of the rate constants of the peroxidase-HtOt S3rstems are listed in Table IX. 

Pairing properties of 2-hydroxyadenine and 8-oxoadenine with four standard DNA bases were studied at the Hartree-Fock level [99JST59] and adenine-hydrogen peroxide complexes at the MP2 and DFT levels [99JPC(A)4755]. 

Anhydrous peroxytrifluoroacetic acid is not easy to handle, but the procedure has recently been revised.121 Namely, reaction of urea-hydrogen peroxide complex (UHP) with tri-fluoroacetic anhydride in acetonitrile at 0 °C gives solutions of peroxytrifluoroacetic acid, which oxidize aldoximes to nitroalkanes in good yields (Eqs. 2.58 and 2.59). Ketoximes fail to react under these conditions, the parent ketone being recovered. 

The oxidation of picolinaldehydes to the corresponding Af-oxides with dimethyldioxirane proceeds in good yield without the need to protect the aldehyde function <99T12557>. The urea-hydrogen peroxide complex oxidizes pyridines to pyridine Af-oxides <990L189>. 

Chromium peroxide (CrOs), obtained by the oxidation of chromium trioxide with hydrogen peroxide, reacts with amines forming complexes, like 2,2 -bipyridylchromium (BPCP) and pyridinechromium (PCP) peroxides, that oxidize efficiently alcohols to aldehydes and ketones 426b... 

The workers proposed that alkyl hydroperoxides and aqueous hydrogen peroxide interact with TS-1 in a similar manner, forming titanium alkyl peroxo complexes and titanium peroxo complexes, respectively. However, the titanium alkyl peroxo complexes were not active because the substrate could not enter the void due to steric effects. Consequently, no activity was possible for either alkane hydroxylation or alkene epoxidation. Comparison with Ti02-Si02/alkyl hydroperoxide for alkane and alkene oxidation indicated that this material was active because the oxidation took place on the surface and not in the pores. Figures 4.4 and 4.5 show the possible mechanisms in operation for the oxidation of alkenes and alkanes with a TS-1/hydrogen peroxide system. 

The bromide ion does not appear to react with one form of the enzyme-hydrogen peroxide complex. It is clear that at least two pH-dependent intermediates are present, which react with bromide to yield the oxidized bromine species. The second-order rate constant for the reaction between bromide and these peroxo-intermediates w is estimated to be 1.7 X 10 s" Bromide also acts as an inhibitor of the enzyme in a... 

As is seen from the data in Table 4, upon treatment of the carbon surface with hydrogen, the value of its free surface energy sharply decreases. This agrees with the notion that such a treatment results in a decrease in the surface concentration of oxidized carbon atoms that form hydrogen-bonded complexes with water molecules. Besides, a sharp decrease in the concentration of water in the adsorbent micropores is also observed. This effect can be explained by lower accessibility of micropores for water molecules caused by deteriorating hydrophilic properties of the adsorbent surface. When a carbon surface is treated with hydrogen peroxide, we observe an increase in the bound water concentration at the expense of the creation of new oxidized sites that would form hydrogen-bonded complexes with water molecules. 

The decomposition of 1, 2, and 3 in solution was also examined [3, 7], The full kinetic pH profile for the base-promoted decomposition of complex 1 to CH4 and [Re04] has been examined. In the presence of hydrogen peroxide, complexes 2 and 3 decompose to methanol and perrhenate with a rate that is dependent on [H2O2] and [3]. 

The reagent is prepared by slow addition of 34 g. (0.5 mole) of 50% hydrogen peroxide to 26 g. (0.25 mole) of N-methylmorpholine in 100 ml. of t-butanol while maintaining the temperature at 30-35° with a water bath. The mixture is diluted with 170 ml. of t-butanol and allowed to stand for 48 hrs. to complete the oxidation of N-methylmorpholine. The solution may be titrated for peroxide content and used as such for the oxidation of olefins, or dried with magnesium sulfate and the volatile materials distilled in vacuo to leave the crystalline N-methylmorpholine oxide —hydrogen peroxide complex, which is triturated with acetone and collected. 

Catalase was found to form an intermediate compound in the presence of hydrogen peroxide (Chance, 69). The spectrum was measured from 380-430 nqi and is slightly shifted toward the visible as compared with free catalase. The complex shows no similarities to cyan-catalase or the compound formed when peroxide is added to azide catalase. Its formation is very rapid, the bimolecular velocity constant having a value of about 3 X 107 M.-1 sec.-1. In the absence of added hydrogen donors, the complex decomposes slowly according to a first order reaction with a velocity constant of about 0.02 sec.-1. This catalase complex thus resembles the green primary hydrogen peroxide complex of peroxidase. 

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