title: Gas-Phase Reaction of Hydroxyl Radical with p-Cymene over an Extended Temperature Range.
abstract: The kinetics of the reaction of OH radicals with p-cymene has been studied in the temperature range of 243-898 K using a flow reactor combined with a quadrupole mass spectrometer: OH + p-cymene → products. The reaction rate constant was determined as a result of absolute measurements, from OH decay kinetics in excess of p-cymene and employing the relative rate method with OH reactions with n-pentane, n-heptane,1,3-dioxane, HBr, and Br2 as the reference ones. For the rate coefficient of the H atom abstraction channel, the expression k1b = (3.70 ± 0.42) × 10(-11) exp[-(772 ± 72)/T] was obtained over the temperature range of 381-898 K. The total rate constant (addition + abstraction) determined at T = 243-320 K was k1 = (1.82 ± 0.48) × 10(-12) exp[(607 ± 70)/T] or, in a biexponential form, k1 = k1a + k1b = 3.7 × 10(-11) exp(-772/T) + 6.3 × 10(-13) exp(856/T), independent of the pressure between 1 and 5 Torr of helium. In addition, our results indicate that the reaction pathway involving alkyl radical elimination upon initial addition of OH to p-cymene is most probably unimportant.
authors.affiliation: Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS and Université d'Orléans , 45071 Cedex 2, Orléans, France.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Bedjanian
authors.affiliation: Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS and Université d'Orléans , 45071 Cedex 2, Orléans, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Morin
authors.affiliation: Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS and Université d'Orléans , 45071 Cedex 2, Orléans, France.
authors.forename: Manolis N
authors.initials: MN
authors.lastname: Romanias
mesh_terms: D000148:Acids, Noncarboxylic / Q000737:chemistry; D001888:Boric Acids / Q000737:chemistry; D000081007:Cymenes; D005740:Gases / Q000737:chemistry*; D006371:Helium / Q000737:chemistry; D006536:Heptanes / Q000737:chemistry; D018054:Hydrobromic Acid / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D013058:Mass Spectrometry; D039821:Monoterpenes / Q000737:chemistry*; D010420:Pentanes / Q000737:chemistry; D011312:Pressure; D013696:Temperature
chemical_list: D000148:Acids, Noncarboxylic; D001888:Boric Acids; D000081007:Cymenes; D005740:Gases; D006536:Heptanes; D039821:Monoterpenes; D010420:Pentanes; C007210:4-cymene; D006371:Helium; D017665:Hydroxyl Radical; D018054:Hydrobromic Acid; C028618:n-heptane; C033353:pentane; D006859:Hydrogen; C531577:bromic acid; C032688:boric acid