Hydrogen peroxide complex

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. 

Bentley et al.m recently improved upon Julia s epoxidation reaction. By using urea-hydrogen peroxide complex as the oxidant, l,8-diazabicyclo[5,4,0]undec-7-ene (DBU) as the base and the Itsuno s immobilized poly-D-leucine (Figure 4.2) as the catalyst, the epoxidation of a, (3-unsaturated ketones was carried out in tetrahydrofuran solution. This process greatly reduces the time required when compared to the original reaction using the triphasic conditions. 

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. 

Varma and Naicker published a solid-state oxidative protocol for the transformation of nitriles to amides and of A-heterocycles to A-oxides employing the urea hydrogen peroxide complex (Scheme 156) . The A-oxides depicted in Scheme 156 were synthesized... 

On the other hand, the commonly available urea-hydrogen peroxide complex offers considerable advantage over DABC0 2H202 for the preparation of BTSP from N,N -bis(trimethylsilyl)urea (equation 8) . 

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>. 

Keywords 2-hydroxybenzaldehyde, sulfide, nitrile, pyridine, urea-hydrogen peroxide complex, catechol, sulfoxide, sulfuric ester, amide, pyridine-/V-oxidc... 

Use of the urea-hydrogen peroxide complex and /V,/V -bis(TMS) urea provides an improved method126 for the preparation of bis(TMS) peroxide, TMSOOTMS. In the presence of Fe(m)(picolinic acid)3, bis(TMS) peroxide carries out selective oxidation of alkanes to ketones by a non-radical mechanism. The Fe(III)-Fe(IV) manifold is believed to be responsible127. On the other hand, using FeCU in pyridine, alkyl chlorides are formed through a radical mechanism. Here, the Fe(n)-Fe(IV) manifold has been proposed128. 

The cytochrome-c peroxidase test offers the advantages of stability of the peroxidase-hydrogen peroxide complex and high specificity for its hydrogen donor, cytochrome c. 

Secondary amines 65 were easily oxidized [27] to the corresponding nitrones 66 by hydrogen peroxide or urea hydrogen peroxide complex in the presence of Se02 as a catalyst (Eq. 11). 

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... 

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]. 

Varma, R. S., Naicker, K. P. The Urea-Hydrogen Peroxide Complex Solid-State Oxidative Protocols for Hydroxylated Aldehydes and Ketones (Dakin Reaction), Nitriles, Sulfides, and Nitrogen Heterocycles. Org. Lett. 1999,1, 189-191. 

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. 

Fig. 53.1. Absorption spectra of the hydrogen peroxide complexes of titanium (1), vanadium (2) and molybdenum (3)...

The yields of epoxides are 35-70% the yields of 1,3-diphenylurea are 92-98%. Yields of epoxides are improved by use of nonpolar solvents such as n-pentane or benzene. p-Chlorophenyl isocyanate gives somewhat higher yields than phenyl isocyanate. The active intermediate is probably an isocyanate-hydrogen peroxide complex rather than a peroxycarbamic acid (CgHsNHCOgH).1 N. Matsumura, N. Sonoda, and S. Tsutsumi, Tetrahedron Letters, 2029 (1970)... 

Aluminium, titrimetric EDTA. Titanium, EDTA titration of titanium-hydrogen peroxide complex. 

Urea-Hydrogen peroxide complex, H2NCONH2 H2O2. 

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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