The products of ester oxidation

The main oxidation products of the methyl esters of aliphatic acids containing n C atoms are methyl esters of dicarboxylic acids C4—C 3, aliphatic acids Ci— Cn-i, and keto- and hydroxy compounds [301—307]. Oxidation of acetates (140—160° C) yield acids, carbon dioxide, hydroxy, and keto compounds (see Table 17). Hydroperoxide is the primary product of oxidation. Oxidation of dimethyl esters of dicarboxylic acids gives monoesters with a lower number of C atoms in the acidic group (see Table 17). Carbon dioxide is formed in parallel with acids and monoesters [308]. All monoesters C 1 Cn 2 etc. are also formed in parallel. This suggests several mechanisms of C—C bond scission in the oxidation, an a-mechanism with only one C—C bond broken to form Cm and C — products, a /3-mechanism with two C—C bonds broken in the /3-position to form Cm, C —m— and C02, etc. The a, /3, and 7-mechanisms of C—C bond scission may be regarded as a result of peroxy radical isomerization to form labile dihydroperoxides, e.g. 

The probabilities of C—C bond rupture by different mechanisms (Pa, Pp ) calculated by the analysis of the products formed in the oxidation of dimethyl esters (170° C) are [309] 

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