Hydroxyalkyl peroxides, decomposition

The di(hydroxyaLkyl) peroxide (2) from cyclohexanone is a soHd which is produced commercially. The di(hydroxyaLkyl) peroxide (2) from 2,4-pentanedione (11, n = 1 X = OH) is a water-soluble soHd which is also produced commercially (see Table 5). Both these peroxides are used for curing cobalt-promoted unsaturated polyester resins. Because these peroxides are susceptible to promoted decomposition with cobalt, they must exist in solution as equihbrium mixtures with hydroperoxide stmctures (122,149). 

Rate Constants of the Decomposition of ROOH (k-,) and R1C(OH)(OOR)R2 (k2) and Equilibrium Constants K of Hydroxyalkyl Peroxide Formation from ROOH and Ketone... 

Some attention has been given to the effect of substituents upon the kinetics of dialkyl peroxide decomposition. The data are presented in Table 67. A linear enthalpy-entropy of activation correlation was made for the decomposition of alkyl peroxides (exclusive of the hydroxyalkyl peroxides) using data in solution and in the gas phase. The isokinetic temperature was found to be 483 °K (210 °C) . No rational explanation was advanced for the substituent effects in solution or the gas phase . However, the discussion of the effect of a chain reaction upon the activation parameters, given in the section on gas phase reactions, should be consulted. The large differences in and log A between the alkyl and the hydroxyalkyl peroxides suggests a change in mechanism. This is supported by the products from the hydroxyalkyl peroxides. A cyclic activated complex was suggested , viz. 

Thermal decomposition of hydroxyalkyl hydroperoxyalkyl peroxides produces mixtures of starting carbonyl compounds, mono- and dicarboxyHc acids, cycHc diperoxides, carbon dioxide, and water. One specific hydroxyalkyl hydroperoxyalkyl peroxide from cyclohexanone (2, X = OH, Y = OOH) is a soHd that is produced commercially as a free-radical initiator and bleaching agent (see Table 5). On controlled decomposition, it forms 1,12-dodecanedioic acid (150). 

Polymeric a-Oxygen-Suhstituted Peroxides. Polymeric peroxides (3) are formed from the following reactions ketone and aldehydes with hydrogen peroxide, ozonization of unsaturated compounds, and dehydration of ur-hydroxyalkyl hydroperoxides consequently, a variety of polymeric peroxides of this type exist. Polymeric peroxides are generally viscous liquids or amorphous solids, are difficult to characterize, and are prone to explosive decomposition. 

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