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Alkoxy homolysis/decomposition

Oxygen-centered radicals are arguably the most common of initiator-derived species generated during initiation of polymerization and many studies have dealt with these species. The class includes alkoxy, hydroxy and aeyloxy radicals and tire sulfate radical anion (formed as primary radicals by homolysis of peroxides or hyponitrites) and alkylperoxy radicals (produced by the interaction of carbon-centered radicals with molecular oxygen or by the induced decomposition of hydroperoxides). [Pg.118]

Chemical Properties. Acyclic di-ferf-alkyl peroxides efficiently generate alkoxy free radicals by thermal or photolytic homolysis. Primary and secondary dialkyl peroxides undergo thermal decompositions more rapidly than expected owing to radical-induced decompositions. Such radical-induced peroxide decompositions result in inefficient generation of free radicals. [Pg.1230]

The first isolable product of oxidation of the triglyceride is a tasteless and odourless hydroperoxide. The hydroperoxide can undergo homolysis, usually catalysed by a metal ion, to form an alkoxy radical whose decomposition may follow either ( > or T scission, ( > Scission gives a free aldehyde with flavour and/or odour along with an intermediate free triglyceride radical that can react further. Alternatively the alkoxy radical decomposes according to () scission, leading to a bound, odourless aldehyde and an R° radical that can react with other neutral molecules, or with itself, to form R-R. [Pg.43]

The thermal or photochemical homolysis of the hydroperoxide leads to the formation of an alkoxy radical. The alkoxy radical is the precursor of unsaturated alcohols, acids and ketones. The decrease in intensity of the band at 807 cm-1 indicated saturation of the double bond, which could result from a radical addition to the double bond (for example, by reaction with the hydroxyl radicals resulting from the decomposition of hydroperoxides). Saturation reactions result in the formation of saturated alcohols, acids and ketones. [Pg.719]

Mechanisms for the decomposition of hydroperoxides under a variety of conditions have been recently reviewed . Kinetics of the thermal decomposition of hydroperoxides are difficult to interpret in most instances due to the extreme suc-ceptibility of these peroxides to induced decomposition. It appears that simple homolysis to alkoxy and hydroxy radicals without induced decomposition has been approached but not attained " . [Pg.539]

The decomposition of the peroxyketals (53) follows a stepwise, rather than a concerted mechanism. Initial homolysis of one of the 0-0 bonds gives an alkoxy radical and an a-peroxyalkoxy radical (Scheme 3.36). " This latter species decomposes by 3-scission with loss of either a peroxy radical to form a ketone as byproduct or an alkyl radical to form a peroxyester intermediate. The peroxyester fonned may also decompose to radicals under the reaction conditions. Thus, four radicals may be derived from the one initiator molecule. [Pg.91]

In the absence of phosphite ligand, benzaldehyde was detected upon thermal decomposition of complex 17 at 90°C. With a-alkoxy radicals known to undergo fragmentation to carbonyl compounds [22], the formation of benzaldehyde could readily be explained by homolysis of the rhodium-alkyl bond. In the presence of CCI4 the putative methyl radical was trapped as the methyl chloride under the thermolysis conditions. [Pg.91]


See other pages where Alkoxy homolysis/decomposition is mentioned: [Pg.90]    [Pg.182]    [Pg.33]    [Pg.424]    [Pg.90]    [Pg.6900]    [Pg.2087]   
See also in sourсe #XX -- [ Pg.37 , Pg.40 , Pg.48 , Pg.64 , Pg.64 ]




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Homolysis

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