Reactions of fatty materials with oxygen. XVI. Relation of hydroperoxide and chemical peroxide content to total oxygen absorbed in autoxidation of methyl oleate

Abstract

Summary Methyl oleate has been autoxidized at 100°, 80°, and 60° in the Barcroft‐Warburg apparatus. Samples have been analyzed for total peroxide by the iodometric method and for hydroperoxide by the polarographic method. These peroxide values have been compared with each other and with total oxygen absorbed. The relation of chemical peroxide (y c ) to oxygen uptake (x) is expressed by y c =1.09x 0.936 . This equation is equally valid at the three temperatures for the first 150 millimoles (15%) of oxygen absorbed per mole of methyl oleate. Similarly, the hydroperoxide content (y h ) for the first 150 millimoles of oxygen absorbed at 80° and 100° is given by the equation y h =1.02x 0.936 . The ratio of hydroperoxide to chemically determined peroxide was, on the whole, constant throughout the entire range of oxidation (15–300 millimoles of oxygen absorbed per mole), and averaged about 95%. It has been shown unequivocally that the major portion of the peroxides formed in the autoxidation of methyl oleate are hydroperoxides, confirming conclusions of recent investigators. A small but significant amount of non‐hydroperoxidic peroxide appears to be formed concurrently.