Organic solvents, peroxide value

Zinc peroxide is not hygroscopic and insoluble in water and organic solvents. The compound results from reaction of an ammoniacal zinc sulfate solution wit 30% hydrogen peroxide at 80°-95 °C. The bulk density and oxygen value can ba varied over a relatively wide range if certain temperature and concentration conditions are maintained. 

Concentrated organic peroxides, such as f-butyl peroxybenzoate (TBPB), have an F value of about 100 to 150 kj/kg. These compounds can produce a runaway ending in a deflagration. Dilution of the peroxide with the proper solvent will result in a considerable decrease of the F value because of the decrease in concentration of the active component and the decrease in the maximum temperature due to heating and evaporation of the solvent. 

The exact nature of the beginning and end of such a polymer chain is not certain. In general, the polymer can be characterized by its average degree of polymerization, i.e., the value of n, or more precisely by the distribution of n values. The heat of polymerization is 17.4 0.2 kcal/mole at 26.19°C. The reaction may be initiated by heat or by means of catalysts. Organic peroxides are typical initiators. Styrene also will polymerize in the presence of various inert materials, such as solvents, fillers, dyes, pigments, plasticizers, rubbers, and resins. Moreover, it forms a variety of copolymers with other mono- and polyvinyl monomers. 

The catalytic activity of MePc depends on the nature of the ligand in the apical position and should therefore be solvent dependent.[56] From the chromatographic determination of the respective adsorption coefficients of the reaction partners in pre-catalytic conditions, a very pronounced activity difference is found depending on the nature of the solvent used.[64] However, the sequence of the adsorption coefficients is of zeolitic origin and reflects a sorption effect rather than a coordination effect. The respective values of the adsorption coefficients indicate that for the oxidation of alkanes, cyclohexane, with organic peroxide for example, in acetone the oxidant is enriched in the intracrystalline voids, resulting preferentially in peroxide decomposition. In excess cyclohexane, the substrate is enriched in the pores, so that every adsorbed peroxide molecule results in an efficient oxygenation. 

With alkenes and peroxides room temperature epoxidation can be performed, the selectivity with respect to ring-openend products being dependent on solvent and hydroperoxide nature.[96] With organic peroxides the epoxide selectivity is high, while with HOOH in acetone high diol selectivity is evident with the cis/trans diol isomer ratio at its equilibrium value. 

TS-1 catalyzes the hydroxylation of alkanes with dilute solutions of hydrogen peroxide in water, in a biphasic system of alkane and aqueous H2O2, or in aqueous-organic solution. The rate of reaction decreases in the solvent order butanol > butanol/water > methanol = acetonitrile = water [24, 25]. The temperature is generally lower than 55 °C in methanol, close to 100°C in water and of intermediate values in other solvents. Hydroxylation occurs at secondary and tertiary C—H bonds, while primary ones are completely inert (Equations 18.3 and 18.4). 

Polyaromatics (anthracene and phenanthrene) have also been oxidized by FePcS/H202. This catalytic system is highly influenced by the presence of an organic co-solvent and phosphate ions. Iron tetra-amide complexes are also able to efficiently catalyze the oxidative cleavage of TCP with hydrogen peroxide at basic pH values. ... 

The decomposition of most organic free radical initiators follows first order kinetics. With certain peroxides, however, higher order deeompositions are observed. Generally, the higher order reaetion is caused by a reaction of radicals with the initiator (indueed decomposition). The value of the rate for unimoleeular decomposition m be determined either by extrapolation of the rate back to zero initiator concentration or by use of a monomer or other radical trap . Some of the peroxides may also decompose by non-radical routes. Acids, bases, and polar solvents favor ionic intermediates. Koenig (296) presents an excellent discussion of dw and peroxide decomposition pathways. 

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