Peroxyacids center

The epoxide formed by top-side attack of a peroxyacid on trans-4-octene has two chirality centers of R configuration. The epoxide formed by bottom-side attack has (S,S) configuration. The two epoxide enantiomers are formed in equal amounts and constitute a racemic mixture. 

The last two steps are rather well understood. There exist some uneertainties encountering initiation steps due to the character and distribution of initiation centers in the polymer mass such as sensitizing impurities, charge transfer complexes (CTC) and/or participation of active environmental pollutants [3-5]. Generally this does not affeet however the structure of the oxidation products having oxidation properties formed in the eonsecutive steps to initiation [alkylhydroperoxides POOH, peroxyacids PC(0)00H] and their oxygen-centered free radieal precursors [POO, PC(0)00 ] that play an important role in the fate of polymer additives, stabilizers in particular. 

Detailed review of studies on the auto- and catalytic-oxidation of unsaturated aldehydes in the liquid phase may be found in [2,9], Here we just note the main specific feature of the unsaturated aldehydes oxidation, briefly cited in Section 5.2. It implies that the free-radical chain process of the aldehyde group oxidation stimulates undesirable reactions, including the copolymerization of aldehyde with oxygen through the aldehyde s double bond, and in some cases also the copolymerization of the reaction products, the unsaturated acids and peroxyacids with oxygen. The oxidation reactions of unsaturated aldehydes are defined as the multicentered chain processes with two types of reaction centers acyl monomeric and polyperoxide free radicals. 

Addition of a peroxyacid to cw-2-butene forms a meso compound since both asymmetric centers are attached to the same four groups (Section 4.13). 

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