H2O2, oxidation

Acetate, (reduction with) ascorbic acid + KI, citrate, V,V-dihydroxyethylglycine, EDTA, F , formate, NaOH + H2O2, oxidation to CrOJ , NagP30io, sulfosalicylate, tartrate, triethylam-ine, tiron... 

The concentration of SO2 in atmospheric samples can be determined by bubbling a sample of air through a trap containing H2O2. Oxidation of SO2 by H2O2 results in the... 

Treatment with alkaline H2O2 oxidizes trialkylboranes to esters of boric acid. This reaction does not affect double or triple bonds, aldehydes, ketones, halides, or nitriles. The R group does not rearrange, and this reaction is a step in the hydro-boration method of converting alkenes to alcohols (15-16). The mechanism has been formulated as involving a rearrangement from boron to oxygenr ... 

Tertiary amines can be converted to amine oxides by oxidation. Hydrogen peroxide is often used, but peroxyacids are also important reagents for this purpose. Pyridine and its derivatives are oxidized only by peroxyacids. In the attack by hydrogen peroxide there is first formed a trialkylammonium peroxide, a hydrogen-bonded complex represented as R3N-H202, which can be isolated. The decomposition of this complex probably involves an attack by the OH moiety of the H2O2. Oxidation with Caro s acid has been shown to proceed in this manner ... 

Jacob s group reported a protocol that used mild H2O2 oxidations and MPTMS for three approaches, namely, grafted, coated, and co-condensed MCM-41 and HMS materials [58] (Figure 6.1a). The propyl spacer was stable to the oxidation conditions while sulfonic groups were generated as evidenced by NMR spectra. These materials... 

It may be that (40) has some cyclic character as the overall addition of BHj is found, in suitable cases, to be stereoselectively SYN. The first-formed RBH2 then reacts further with the alkene to yield the trialkylboron, RjB (38). H2O2 oxidation results in fission of the C—B bond to yield the alcohol (39), the net result being overall anti-Markownikov hydration that is often stereoselectively SYN yields are usually very good. 

From the data presented in Table 4 it may be concluded that the porous nature of the chemically modified silica remains more or less the same after immobilization of the cobalt(lll) complexes. In addition, there is a decrease in the surface area of the support following the incorporation of the metal complexes. The AAS data on Co(III)-CMS2 and Co(lll)-CMS3 appear to suggest that the extent of cobalt loading is dependent upon the initial amount of cobalt used. The cobalt loadings obtained for the catalysts prepared by H2O2 oxidation of CMS suspensions in 1 and 2 mmol cobalt(ll) solutions (in presence of 1 and 2... 

Me3)(NC0)]C104, has been prepared by H2O2 oxidation of [Ru i presence of NaNCO. The X-ray structure revealed a Ru=0 distance... 

The catalyst remains in the fluorous phase, whilst the product is completely extracted, and secondary alcohol can be prepared by H2O2 oxidation. The catalyst solution can be recycled several time without loss of activity. 

The full account of the use of sulphenylation-dehydrosulphenylation for the introduction of a -unsaturation into carbonyl compounds includes some steroidal examples. The similar selenylation-dehydroselenylation of 17-oxo-steroids resulted in the formation of the unsaturated lactones (118) owing to Baeyer-Villiger oxidation during the H2O2 oxidation of the a-phenyl selenyl intermediate (see also ref. 210). 

Catalytic H2O2 Oxidations. The reactions were carried out in 10-mL tubes equipped with serum cap and a stirring bar. The catalyst, hydrogen peroxide, and substrate were dissolved in of CH3CN. Trimethylacetonitrile was added to the reaction as an internal standard. All reactions were done under argon, each was purged by three freeze-thaw cycles and GC analysis was performed on aliquots withdrawn directly from the reaction mixture. Typically, alkene (1 mmol) was added... 

A major concern in H2O2 oxidation is the alcohol/olefin chemoselectivity (Rao, 1991). This biphasic oxidation was initially developed for olefin epoxidations but with an (aminomethyl)phosphonic acid additive for high selectivity (Rudolph et al., 1997). Now, the removal of this additive has been found to significantly increase the rate and selectivity of alcohol oxidation. 

Fig. 21. H2O2 oxidation of 2-octanoI catalyzed by TS-I first-order kinetics x represents conversion. (From van der Pol et al 1993b.)...

The discovery of the new titanium silicates and of their catalytic properties in H2O2 oxidation reactions has had a major impact in catalytic science and its industrial applications. One 10,000 ton/year plant for the production of catechol and hydroquinone has been operating since 1986 with excellent results. Moreover, successful tests conducted on a 12,000-ton/year pilot plant for cyclohexanone ammoximation (Notari, 1993b) could be followed soon by an industrial-size plant that would greatly simplify the synthesis of caprolactam. Both these examples are clear indications of the potentials of the new oxidation chemistry made possible by the new materials. 

The catalytic epoxidation proceeds via the formation of peroxytungstic acid. Similarly, other metal catalysts are effective in the H2O2 oxidation. Aqueous conditions are not appropriate for epoxidations since epoxides are prone to undergo acid-catalyzed hydrolysis36. Polymer-anchored catalysts are conveniently separated from the reaction mixture after catalyzed H2O2 epoxidations (equation 8)9. 

Monocyclic Phosphoranide Anion. The intramolecular oxidative addition of hydroxyalkyl phosphites, which gives P-H phosphoranes, is well known (10). Some P-H phosphoranes are so stable that the open-chain P(III) tautomers cannot be detected spectroscopically or even by attempted H2O2 oxidation (8). Thus, it is surprising to find no evidence for an equilibrium between phosphine alcohol 1 and its closed-ring tautomer phosphorane 2. Phosphine 1 is quaternized by alkyl halides giving phosphonium halides such as 3. These in turn are converted to alkoxyphosphor-anes, such as 4 by NaH (Scheme I). 

Several of the decatungsto anions have been investigated as catalysts for H2O2 oxidations, e.g., alkene epoxidations and oxidation of primary and secondary alco-... 

Figure 2. Isotopic influence of the H2O2 oxidant on the SO product.

---