Abstract
The rate of peroxidation of methyllinoleate in methanol was measured by monitoring oxygen consumption in the presence and absence of ferric chloride and L-histidine. Histidine enhanced the ferric-inducing peroxidation of methyllinoleate in a non-aqueous system, which was likewise reported in an aqueous solvent. The rate depended on the ratio of the relative concentration of iron to histidine. The ratio of 1 : 6 in a molar concentration gave the maximum rate. Spectroscopic observation for the first time strongly suggested the formation of two ferric-histidine chelates of the composition of 1 : 1 and 1 : 2 in methanol. The apparent formation constants of the 1 : 1 and 1 : 2 complexes, logβ1 and logβ2, were calculated to be 4.6 and 8.3, respectively. Correlation of the peroxidation rates to the spectroscopically observed species led to the conclusion that the 1 : 2 chelate was responsible for the maximum peroxidation rate of methyllinoleate under the conditions of this investigation.
