The Effect of Aromatic Hydrocarbons on the Oxidation Stability of Squalane (Part 1)

Abstract

This paper describes the kinetic treatment of oxidation of squalane at 60∼120°C.Di-tert-butyl peroxide (DTBP) and 2, 2'-azobisisobutyronitrile (AIBN) were used as initiators and chlorobenzene was used as an inert solvent.The values of kp/(2kt)1/2 in the neat phase are slightly less than those in chlorobenzene solution for a given initiator concentration and temperature. This retardation can be attributed to the solvent effect of chlorobenzene on the decomposition rate of DTBP, since the correction of the solvent effect eliminates the decrease in kp/(2kt)1/2. The values of first-order term "aRi" were calculated from the data, and the values of "a" were found to be 0.77 and 0.65 at 60 and 95°C, respectively, instead of 0.50, which was predicted by simple oxidation scheme.The kinetic order with respect to the initiation rate is 0.57 at 95°C instead of the theoretical value of 0.50 both in the neat phase and in chlorobenzene solution.The values of activation energy (Ep-Et/2) are obtained as 11.6kcal/mole and 14.3kcal/mole in chlorobenzene solution and in the neat phase, respectively, on the assumption that the decomposition rate of DTBP in the neat phase is the same as that in chlorobenzene solution. The correction of the solvent effect also eliminates the difference in both values.The solvent effect on the decomposition rate of DTBP plays an important role especially in the initiated oxidation of aliphatic hydrocarbons.