Spontaneous decomposition, peroxidic

Because the electrolyte contains excess alkaH which could cause spontaneous decomposition of the hydrogen peroxide, the H2O2 in the product... 

Organic peroxides and hydroperoxides decompose in part by a self-induced radical chain mechanism whereby radicals released in spontaneous decomposition attack other molecules of the peroxide.The attacking radical combines with one part of the peroxide molecule and simultaneously releases another radical. The net result is the wastage of a molecule of peroxide since the number of primary radicals available for initiation is unchanged. The velocity constant ka we require refers to the spontaneous decomposition only and not to the total decomposition rate which includes the contribution of the chain, or induced, decomposition. Induced decomposition usually is indicated by deviation of the decomposition process from first-order kinetics and by a dependence of the rate on the solvent, especially when it consists of a polymerizable monomer. The constant kd may be separately evaluated through kinetic measurements carried out in the presence of inhibitors which destroy the radical chain carriers. The aliphatic azo-bis-nitriles offer a real advantage over benzoyl peroxide in that they are not susceptible to induced decomposition. 

The activation energy for the spontaneous decomposition of benzoyl peroxide is 30 ( 1) kcal. per mole, and the same value applies also within experimental error to the azo nitrile.The apparent activation energy for the polymerization of styrene initiated by either is about 23 kcal. per mole, therefore. 

If the rate constant kd for spontaneous decomposition of the initiator is known, the efficiency / of initiation may be determined. (This is a refinement of the molecular weight method set forth in Sec. Ic) The spontaneous decomposition rate of benzoyl peroxide in styrene, according to the work of Swain, Stockmayer, and Clarke is 3.2X10- sec. at 60°C. Hence the efficiency of initiation of the polymerization of styrene by benzoyl peroxide at 60°C is indicated to be about 0.60. 

An exactly similar reaction of phenylhydrazine will be discussed later (p. 296). A simple example of this type is provided by the spontaneous decomposition, of hydrogen peroxide into oxygen and water ... 

The spontaneous decomposition of hydrazobenzene, like that of hydrogen peroxide, is catalyticaUy accelerated by metallic platinum. 

By double distillation and fractional condensation of peroxide which contains 30 to 35 per cent b. w. H202,a product is obtained containing 80 to 85 per cent b. w. H202. If peroxide is manufactured which contains more than 87 per cent H202 spontaneous decomposition sets in during distillation so that 85 per cent should be considered the limit concentration for the technical product, which possibly cannot be exceeded on an industrial scale. 

One of the protons is highly acidic, but the other (attached to the peroxide group) is weakly acidic, and the second p/f is 9.4 (Ball and Edwards ). At room temperature in aqueous solutions of about pH 9 the spontaneous decomposition of the acid... 

The shift in the redox potentials for O2 within aprotic solvents [-0.65 V in dimethylformamide (DMF) versus -0.16 V in H2O] is the result of a much weaker solvation of anions by such media relative to water (for O2 -, about 88 kcal mol in DMF versus 100 kcal mol l in H2O). Likewise, the addition of base to hydrogen peroxide results in its spontaneous decomposition. 

E Koubek, ML Haggett, CJ Battalgia, Ml-r Kairat, HY Pyun, and JO Edwards. Kinetics and mechanism of the spontaneous decomposition of some peroxoacids, hydrogen peroxide and t-butyl hydroperoxide. J. Am. Chem. Soc. 85 2263-2268, 1963. 

If the spontaneous decomposition rate of benzoyl peroxide is 3.2 x mVmol-s , calculate the initial rate of polymerization. 

Perhaps the most versatile of the copper etchants is the hydrogen per-oxide/sulphuric acid mixture, although these solutions require stabilizers to retard the spontaneous decomposition of peroxide to water and oxygen. The reactions occuring during etching are ... 

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