Catalytic with hydrogen peroxide

Oxidation. Maleic and fumaric acids are oxidized in aqueous solution by ozone [10028-15-6] (qv) (85). Products of the reaction include glyoxyhc acid [298-12-4], oxalic acid [144-62-7], and formic acid [64-18-6], Catalytic oxidation of aqueous maleic acid occurs with hydrogen peroxide [7722-84-1] in the presence of sodium tungstate(VI) [13472-45-2] (86) and sodium molybdate(VI) [7631-95-0] (87). Both catalyst systems avoid formation of tartaric acid [133-37-9] and produce i j -epoxysuccinic acid [16533-72-5] at pH values above 5. The reaction of maleic anhydride and hydrogen peroxide in an inert solvent (methylene chloride [75-09-2]) gives permaleic acid [4565-24-6], HOOC—CH=CH—CO H (88) which is useful in Baeyer-ViUiger reactions. Both maleate and fumarate [142-42-7] are hydroxylated to tartaric acid using an osmium tetroxide [20816-12-0]/io 2LX.e [15454-31 -6] catalyst system (89). 

Peroxosilicates. No sohd peroxosiUcates are known. There is some indirect evidence based on catalytic studies for the existence of peroxosihcates in solution (32,33), but nmr spectra of aqueous solutions of siUcates mixed with hydrogen peroxide give no evidence for peroxo species (34). A peroxohydrate of sodium siUcate, Na SiO 3H202, is well estabhshed (35—37) but has found no appHcation. 

G. Stmkul, ki G. Stmkul, ed.. Catalytic Oxidations with Hydrogen Peroxide as Oxidant, Kluwer Academic Pubhshers, Dordrecht, 1993, Chapt. 6. 

Titanium Silicates. A number of titanium siUcate minerals are known (160) examples are Hsted in Table 19. In most cases, it is convenient to classify these on the basis of the connectivity of the SiO building blocks, eg, isolated tetrahedra, chains, and rings, that are typical of siUcates in general. In some cases, the SiO units may be replaced, even if only to a limited extent by TiO. For example, up to 6% of the SiO in the garnet schorlomite can be replaced by TiO. In general, replacement of SiO by TiO bull ding blocks increases the refractive indices of these minerals. Ti has also replaced Si in the framework of various zeofltes. In addition, the catalytic activity of both titanium-substituted ZSM-5 (TS-1) and ZSM-11 (TS-2) has received attention (161), eg, the selective oxidation of phenol, with hydrogen peroxide, to hydroquinone and catechol over TS-1 has been operated at the 10,000 t/yr scale in Italy (162). 

Because osmium tetroxide is expensive, and its vapors are toxic, alternate methods have been explored for effecting vic-glycol formation. In the aliphatic series, olefins can be hydroxylated with hydrogen peroxide with the use of only a catalytic amount of osmium tetroxide. Anhydrous conditions are not necessary 30% hydrogen peroxide in acetone or acetone-ether is satisfactory. The intermediate osmate ester is presumably cleaved by peroxide to the glycol with regeneration of osmium tetroxide. When this reaction was tried on a A -steroid, the product isolated was the 20-ketone ... 

Oxidative rearrangement of 5a-cholestan-3-one (62) with hydrogen peroxide and a catalytic amount of selenic acid affords 2a-carboxy-A-nor-5a-cholestane, isolated in about 35 % yield as the methyl ester (63)." However, the reaction gives a complex mixture of A-nor- and seco-acids, and under... 

As in the case of the steroids, introduction of additional nuclear substituents yields morphine analogs of increased potency. The more important of these are derived from one of the minor alkaloids that occur in opium. Thebaine (14), present in crude opium in about one-tenth the amount of morphine, exhibits a reactive internal diene system that is well known to undergo various addition reactions in a 1,4 manner (e.g., bromination). Thus, reaction with hydrogen peroxide in acid may be visualized to afford first the 14-hydroxy-6-hemiketal (15). Hydrolysis yields the isolated unsaturated ketone (16). Catalytic reduction... 

The use of molybdenum catalysts in combination with hydrogen peroxide is not so common. Nevertheless, there are a number of systems in which molybdates have been employed for the activation of hydrogen peroxide. A catalytic amount of sodium molybdate in combination with monodentate ligands (e.g., hexaalkyl phosphorus triamides or pyridine-N-oxides), and sulfuric acid allowed the epoxidation of simple linear or cyclic olefins [46]. The selectivity obtained by this method was quite low, and significant amounts of diol were formed, even though highly concentrated hydrogen peroxide (>70%) was employed. 

The most widely employed methods for the synthesis of nitrones are the condensation of carbonyl compounds with A-hydroxylamines5 and the oxidation of A+V-di substituted hydroxylamines.5 9 Practical and reliable methods for the oxidation of more easily available secondary amines have become available only recently.10 11 12 13. These include reactions with stoichiometric oxidants not readily available, such as dimethyldioxirane10 or A-phenylsulfonyl-C-phenyloxaziridine,11 and oxidations with hydrogen peroxide catalyzed by Na2W044 12 or Se02.13 All these methods suffer from limitations in scope and substrate tolerance. For example, oxidations with dimethyldioxirane seem to be limited to arylmethanamines and the above mentioned catalytic oxidations have been reported (and we have experienced as well) to give... 

In this work, catalysts containing iron supported on activated carbon were prepared and investigated for their catalytic performance in the direct production of phenol fiom benzene with hydrogen peroxide and the effect of Sn addition to iron loaded on activated carbon catalyst were also studied. 

The preparation of iron impregnated activated carbon as catalysts and the catalytic performance of these catalysts were studied in benzene hydroxylation with hydrogen peroxide as oxidant. 5.0Fe/AC catalyst containing 5.0 wt% iron on activated carbon yielded about 16% phenol. The addition of Sn on 5.0Fe/AC catalyst led to the enhancement of selectivity towards phenol. 

In the M. capsulatus (Bath) system, all three components are necessary to obtain turnover with NADH as the reductant (57). With the M. trichosporium OB3b system, protein B is apparently not required (27). Instead, in this latter system, protein B increases the initial rates of the catalytic hydroxylation reaction (27). Catalysis can be achieved by means of a shunt pathway with hydrogen peroxide and Hox alone from both organisms (58-60). The efficiency of the shunt pathway, however, varies significantly. With M. trichosporium OB3b, alcohol yields greater than those obtained with the completely reconstituted system have been observed (58). Furthermore, upon addition of protein... 

Gallot et al. (1998) studied the catalytic oxidation of 3-hexanol with hydrogen peroxide. The data on the effect of the solvent (CH3OH) on the partial conversion, y, of hydrogen peroxide are given in Table 4.1. The proposed model is ... 

Other cationic surfactants such as TTAB, DTAB, DODAB, STAC, CEDAB, and DDDAB have been used in CL reactions with less frequency. Thus, tetradecyltrimethylammonium bromide [TTAB] has been used to increase the sensitivity of the method to determine Fe(II) and total Fe based on the catalytic action of Fe(II) in the oxidation of luminol with hydrogen peroxide in an alkaline medium [47], While other surfactants such as HTAB, hexadecylpiridinium bromide (HPB), Brij-35, and SDS do not enhance the CL intensity, TTAB shows a maximum enhancement at a concentration of 2.7 X 10 2 M (Fig. 11). At the same time it was found that the catalytic effect of Fe(II) is extremely efficient in the presence of citric acid. With regard to the mechanism of the reaction, it is thought that Fe(II) forms an anionic complex with citric acid, being later concentrated on the surface of the TTAB cationic micelle. The complex reacts with the hydrogen peroxide to form hydroxy radical or superoxide ion on the... 

Urea complex with hydrogen peroxide (UHP) seems to be a very useful and convenient oxidation system in nonaqueous medium. The UHP reaction proceeds in methanol and is catalyzed by Mo (VI), W (VI) salts, or SeC>2 (83). Catalytic oxidation in a water-free medium can be carried out with alkylhydroxyperoxides, the catalysts being titanium alkoxides (84) or selenium compounds (85). The reaction appears to proceed quickly and with good selectivity. 

Bertsch-Frank, B., Dorfer, A., Goor, G., and Suss, H. U., in Industrial Inorganic Chemicals Production and Use, Thompson, R., Ed., Royal Society of Chemistry, Cambridge, 1995, 176. Goor, G., in Catalytic Oxidations with Hydrogen Peroxide as Oxidant, Stmkul, G., Ed., Kluwer Academic Publishers, Dordrecht, England, 1993, 13. 

DeDiox A process for destroying polychlorinated dioxins and furans in flue-gases by catalytic oxidation with hydrogen peroxide. The catalyst is based on silica and the process is operated at 80 to 100°C. Developed by Degussa from 1994. The business was offered for sale in 1998. 

Stirbar stirred vials Catalytic oxidation with hydrogen peroxide selective oxidation of methylcyclohexene6... 

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