Regular Kinetic Features of the Chain Oxidation of Organic Compounds

Reaction pathways in lubricant degradation. 3. Reaction model for n-hexadecane autoxidation

“…a -Hexadecane. During the initial stages of hydrocarbon autoxidation, under conditions of high oxygen concentration, the disappearance of hydrocarbon can be described using the rate law shown in eq 1 (Van Sickle et al, 1973; Denisov et al, 1977;Boss and Hazlett, 1975).…”

“…One potential mechanism for hydroperoxide disappearance in the presence of paraffin autoxidation products is decomposition to ketones assisted by some other product of the oxidation, as in reaction 8 (Jensen et al, 1990;Boss and Hazlett, 1975) RCH(OOH)R' + M -R(C=0)R' + H20 +M (8) where M denotes a molecular species (e.g., carboxylic acids). One final route for hydroperoxide decomposition is the bimolecular reaction shown in reaction 9 (Denisov et al, 1977;Hiatt, 1980). The importance of this reaction will increase as the hydroperoxide concentration increases.…”

“…Hydroperoxide Formation. During the initial stages of hydrocarbon autoxidation, where hydroperoxide concentrations and hydrocarbon conversions are low, the rate of hydroperoxide formation follows a rate law that is half-order with respect to the hydroperoxide concentration (Benson, 1981; Denisov et al, 1977). We can use this fact to calculate rate constants that are useful for making comparisons.…”

“…Much of this work, 0888-5885/92/2631-0069103.00/0 however, was limited to the initial stages of the oxidation, where the hydrocarbon concentration remains essentially constant and hydroperoxides are the major oxidation product. These studies of the initial stages of hydrocarbon oxidation have led to the detailed resolution of reaction fundamentals for the formation of primary (Jensen et al, 1979;Emanuel, 1965; Brown and Fish, 1969;Benson, 1981; Denisov et al, 1977;Van Sickle et al, 1973;Mill et al, 1972; Boss and Hazlett, 1975; Garcia-Ochoa et al, 1989) and some secondary (Jensen et al, 1981; Brown and Fish, 1969;Boss and Hazlett, 1975; Garcia-Ochoa et al, 1989) oxidation products. Under more severe reaction conditions (i.e., longer reaction times and higher temperatures), however, the oxidation chemistry becomes more complex, as evidenced by the formation of a broader spectrum of oxidation products (Brown and Fish, 1969).…”

Reaction pathways in lubricant degradation. 2. n-Hexadecane autoxidation

“…This complexity has motivated much experimental work with model reactants such as paraffins because they provide simpler systems to study. These studies of paraffin oxidation (e.g., Emanuel, 1965;Brown and Fish, 1969;Boss and Hazlett, 1969;Benson, 1981;Jensen et al, 1979;Denisov et al, 1977; Van Sickle et al, 1973;Mill et al, 1972; Van Sickle, 1972 reaction fundamentals, but typically this insight was limited to the initial stages of the autoxidation reaction. This limitation was the result of the number of individual reaction products and the complexity of the product spectrum increasing with conversion.…”