The autoxidation of aliphatic esters. Part 2. The autoxidation of neopentyl esters

Abstract

The autoxidation of six esters, neopentyl butanoate, 2,2-dimethylpropanoate, 3,3-dimethylbutanoate, 2,2-dimethylbutanoate, 2-methylbutanoate and 1,1-[²H₂]-neopentyl butanoate, has been studied at 438 K. The reaction products were determined for each system and key reactions leading to the formation and further reactions of the primary products have been identified.

Primary products include a range of hydroperoxides which lead to the formation of keto- and hydroxy-esters. Large amounts of neopentanol and the parent carboxylic acid are formed from each ester. It is shown that these are principally oxidation, and not hydrolysis, products.

The relative rates of autoxidation of the first five esters mirror the relative rates of attack that occur on reaction with alkoxyl radicals; the sites of attack are on both the alkyl and acyl groups, with the α-alkyl hydrogen atoms on the ester showing particular vulnerability compared to the acyl hydrogen atoms. The analysis of products from the deuterated ester supports this conclusion.

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