- Alkyl nitrite photolysis in the gas phase was utilized in this research for the generation of alkoxy radicals. The goal of this work was to determine rate coefficients for alkoxy radical oxidation reactions, which are important in photochemical smog and combustion. Three alkyl nitrites, C(,2)H(,5)ONO, n-C(,3)H(,7)ONO, and i-C(,4)H(,9)ONO, were studied., Each alkyl nitrite was photolyzed with 366 nm radiation in a static system in the presence of NO, O(,2), and N(,2). Products were measured by gas chromatography. Quantum yields of the products were measured as a function of reaction conditions., The primary photochemical act results in the formation of an alkoxy radical and a molecule of NO. Primary quantum yields were determined for each nitrite; they are 0.29 (+OR-) 0.03, 0.38 (+OR-) 0.04, and 0.24 (+OR-) 0.02 for C(,2)H(,5)ONO, n-C(,3)H(,7)ONO, and i-C(,4)H(,9)ONO, respectively, independent of temperature., Alkoxy radical oxidation rate coefficients (k(,ox)) were determined relative to the RO + NO rate coefficient (k(,NO)). They fit the Arrhenius expressions: log (k(,ox)/k(,NO)) = -2.17 (+OR-) 0.14 - (924 (+OR-) 94)/2.303T for C(,2)H(,5)O, log (k(,ox)/k(,NO)) = -2.17 (+OR-) 0.20 - (879 (+OR-) 117)/2.303T for n-C(,3)H(,7)O, log (k(,ox)/k(,NO)) = -2.15 (+OR-) 0.22 - (836 (+OR-) 159)/2.303T for i-C(,4)H(,9)O. The experiments were performed over the following temperature ranges: -48 to 120(DEGREES)C for C(,2)H(,5)O, -26 to 120(DEGREES)C for n-C(,3)H(,7)O, and -8 to 120(DEGREES)C for i-C(,4)H(,9)O., and RO decomposition rate constants were determined for n-C(,3)H(,7)O and i-C(,4)H(,9)O at some of the higher temperatures. Activated complex theory calculations were performed for the oxidation reactions to test the validity of the experimental method. The reaction of HO radicals with alkyl nitrites was determined to occur by two pathways. The HO radical can abstract a hydrogen atom or an NO molecule. Each path occurs approximately 50 percent of the time, independent of temperature.
- Dissertation Note:
- Ph.D. The Pennsylvania State University 1984.
- Source: Dissertation Abstracts International, Volume: 46-01, Section: B, page: 1840.
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