Dicumyl peroxide radical yield

Evidence suggesting a change in the mode of peroxide decomposition under conditions of rapid thermolysis is provided by the decomposition of dicumyl peroxide in mineral oil ). Thus, although the yield of cumyl alcohol is the same whether the decomposition occurs at 135 or 180 C, the yield of acetophenone and methane, the products of ketonic scission of the cumyloxy radical, essentially doubles at the higher temperature. 

Acrylic esters and unsaturated polyesters are commercially cured with peroxides or peresters. The choice of per compound is determined on the basis of price, the achievable polymerization rate, and the side products formed. The polymerization rate is determined by the decomposition rate of the initiator, when mixed with the material to be cured, as well as on the free radical yield. In addition, attention should be paid to the fact that many per compounds decompose slowly during storage, thus reducing the polymerization activity per unit initiator mass. For this reason, crystalline per compounds are more stable because of the lower diffusion than amorphous or dissolved per compounds. Side products of initiator compounds can have an unfavorable effect on the long-term thermoset properties dibenzoyl peroxide, for example, forms acids dicumyl peroxide forms ketones. Acids can hydrolyze the ester bonds of polyester chains, causing scission, and ketones can... 

Many organic peroxides can be employed, one of the more widely used ones being dicumyl peroxide. Dicumyl peroxide decomposes either thermally to yield free radicals or in acid media by an ionic cleavage mechanism without the production of free radicals. Since the free-radical mechanism is required for the polymer vulcanization reaction, the ionic cleavage decomposition has to be suppressed by the use of a non-acidic medium. The factor determines what type of filler can be used. 

Peroxide treatment The functional group of peroxide can be represented as -ROOR-. Most commonly used peroxides for this treatment are benzoyl peroxide and dicumyl peroxide. The main advantage of peroxide treatment is the quick decomposition of a peroxide yielding free radical that can react with the hydrogen group of the matrix and fiber. Like some of the other treatment methods, fibers are pretreated with alkali before treating with peroxides [2], The reactions that take place during peroxide treatment are represented in the Equations 9.7a, 9.7b, 9.7c, and 9.7d. The matrix used in these equations is polyethylene (PE). 

In 2008, Zhang et al. [97] showed the smooth arylation of dicumyl peroxide in the presence of 10% Pd(OAc)j (Scheme 4.16). The TBP (fert-butylpyridine) served as the electrophilic reagent and the oxidant. Thirteen examples were shown and the yields ranged from 33% to 95%. A radical mechanism was suggested and this work led to the intermolecular CDC of arenes with nonactivated alkanes [98]. 

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