Hydrogen peroxide conversion

A calorimetric study of the alkaline hydrogen peroxide conversion of organic nitriles to amides was undertaken. The reaction showed potential for runaway if carelessly scaled up. 

Determination of the level of total sulfur in a rubber can give information on the type of cure system used, for example, elemental sulfur plus accelerator or sulfur donor system, etc. The ISO 6528-1 1992 method — Rubber — Determination of total sulfur content — Part 1 Oxygen combustion flask method is often employed. The principle of the method is oxidation by ignition in an atmosphere of oxygen in the presence of hydrogen peroxide, conversion of sulfur to sulfuric acid and determination of the sulfate by titration with barium perchlorate. The method is... 

Properties.—The blue solution is unstable and decomposes slowly, with formation of sulphuric acid, sulphur dioxide and nitrogen dioxide. When shaken with air or submitted to oxidation by chlorine, nitric acid or hydrogen peroxide, conversion into nitrosulphonic acid is effected, brown fumes being liberated. Dilution -with water also destroys the coloured substance. If strongly cooled, the solution changes to an intense red, so that if a solution is too weak to possess a marked colour at the ordinary temperature, the presence of the purple acid can easily be detected by cooling in a mixture of acetone and solid carbon dioxide. 

Wakakura, M. et al., Netsu Sokutsei, 1994, 21(2), 68 Client. Abs., 1994,121, 5741 If A calorimetric study of the alkaline hydrogen peroxide conversion of organic nitriles to amides was undertaken. The reaction showed potential for runaway if carelessly scaled up. 

Olefin Temperature (°C) Time (min) Hydrogen peroxide (% conversion) Epoxide yield (%)... 

Using FeS04 (1.67 x 10 M) in conjunction with equimolar amounts of methyl-pyrazine-5-carboxylic acid N-oxide and trifluoroacetic acid, in a water-acetonitrile-benzene (5 5 1 v/v/v) biphasic system, with benzene-H202-FeS04 = 620 60 1, a benzene conversion of 8.6% is achieved (35 °C 4h). Hydrogen peroxide conversion is almost complete (95%) and selectivities to phenol are 97% (based on benzene) and 88% (based on H2O2) [13]. These values are definitely higher than those described in the literature for the classical Fenton system [14], whereas iron complexes with pyridine-2-carboxylic acid derivatives are reported to be completely ineffective in the oxidation of benzene under the well-knovm Gif reaction conditions [15]. 

Hydrocarbons used in catalytic experiments were obtained by Fluka - ethylbenzene and 1-propylbenzene, and Merck - toluene and 2-propylbenzene. Catalytic experiments were performed in a 50-ml round-bottomed flask equipped with magnetic stirrer and condenser. The initial mixture containing 0.1 g catalyst, 5.0 ml solvent and 2.0 ml substrate was stirred and heated up to the reaction temperature. Then 1.0 ml 30% aqueous solution of hydrogen peroxide (Merck) was added. Small samples (0.1 ml) of the reaction mixture were taken after 1, 2 and 4 h, diluted in 4.0 ml methanol, dried and analysed by GC-MS (Hewlett-Packard). Veratrole was used as internal standard. Hydrogen peroxide conversion was followed by standard iodometric titration. 

Chan, R.J., Y.O. Su, and T. Kuwana (1985). Electrocatalysis of oxygen reduction. 5. Oxygen to Hydrogen peroxide conversion by cobalt (It) tetrakis (V-methyl-4p5ridyl) porphyrin. Inorg. Chem. 24, 3777-3784. 

O is an oxidized form of rifamycin B, which was obtained by oxidizing rifamycin B with hydrogen peroxide. Conversely, rifamycin O can be transformed into rifamycin B by treating rifamycin O with ascorbic acid. 

Catalase (EC 1.11.1.6) rapidly formed a reversible complex stoichiometrically with nitric oxide with the Soret band shifting from 406 to 426 nm and two new peaks appeared at 540 and at 575 nm, consistent with the formation of a ferrous-nitrosyl complex (Brunelli et al. 2001). Catalase consumed more nitric oxide upon the addition of hydrogen peroxide. Conversely, micromolar concentrations of nitric oxide slowed the catalase-mediated decomposition of hydrogen peroxide. Catalase pre-treated with nitric oxide and hydrogen peroxide regained full activity after dialysis. 

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