Hydrogen peroxide, decomposition experiments

The effects mentioned above have been attributed by others to hydrogen peroxide, but experiments lead to the conclusion that the hydrogen peroxide produced from combustion in heated tubes or in the engine during compression is a decomposition product arising from much more active and unstable peroxides previously formed. 

The peroxomonosulphuric acid so formed is supposed to decompose rapidly to form oxygen at acid concentrations less than or equal to 0.5 M under the experimental conditions used. The result of the oxygen-tracer experiment (O2 from S20 ) resembles observations of hydrogen peroxide decompositions. The reaction does not show inhibition related to the concentration product [H ]... 

When dissolved ia water, the solution is identical with that obtained by dissolving sodium carbonate ia aqueous hydrogen peroxide. There is some evidence for the presence of the traces of tme peroxocarbonate anion, HCO , ia these solutions (95). If the peroxohydrate is heated for about an hour at 100°C and then allowed to cool to room temperature, some decomposition occurs and the product effervesces when placed ia water. Electron spia resonance experiments (64) iadicate that free radicals are present ia this partially decomposed material, but the nature of these radicals is obscure. 

The effect of jumping of the maximal hydroperoxide concentration after the introduction of hydrogen peroxide is caused by the following processes. The cumyl hydroperoxide formed during the cumene oxidation is hydrolyzed slowly to produce phenol. The concentration of phenol increases in time and phenol retards the oxidation. The concentration of hydroperoxide achieves its maximum when the rate of cumene oxidation inhibited by phenol becomes equal to the rate of hydroperoxide decomposition. The lower the rate of oxidation the higher the phenol concentration. Hydrogen peroxide efficiently oxidizes phenol, which was shown in special experiments [8]. Therefore, the introduction of hydrogen peroxide accelerates cumene oxidation and increases the yield of hydroperoxide. 

Frimer, A. A., J. Org. Chem., 1977, 42, 3194-3196, footnote 7 A new method of preparation involves interaction of ally lie halides in solvents with 98% hydrogen peroxide in presence of silver ion and base at ambient temperature under argon. The reactions must be run in the dark to prevent precipitation of metallic silver, which will catalyse decomposition of the hydroperoxide or excess hydrogen peroxide. In an experiment not run in the dark, the hydroperoxide from 3-chlorocyclohexene ignited spontaneously after isolation and concentration. 

Decomposition of Hydrogen Peroxide in the Presence of Potassium Dichromate (the experiment is performed by two students). Assemble the apparatus shown in Fig. 45. Fill the burette with water up to its zero graduation. Close the burette opening with your thumb, invert the burette, and immerse it in a bath with water. Fasten the burette in the stand and note the level of the water in it. Maintain a constant temperature of the water in the bath (25 °C), for which purpose add hot water to it from time to time. 

A student performed two experiments to establish how effective manganese(iv) oxide was as a catalyst for the decomposition of hydrogen peroxide. 

Early experiments in liquids were quite variable for many reasons. The conductivity technique, which was used in the gas phase to measure dose, was not applicable to the liquid phase. Reactions were measured using dissolved radium salts or radon gas as the ionization source. Some thought the chemistry was due to the reactions with radium however, it was soon recognized that it was the emitted rays that caused the decomposition. Both radium and radon could cause radiation damage. Because the radon would be partitioned between the gas and liquid phase, the amount of energy that was deposited in the liquid depended critically on the experimental conditions such as the pressure and amount of headspace above the liquid. In addition, because the sources were weak, long irradiation times were necessary and products, such as hydrogen peroxide, could decompose. 

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