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Atmospheric photooxidation of isoprene part I: The hydroxyl radical and ground state atomic oxygen reactions
Author(s) -
Paulson Suzanne E.,
Flagan Richard C.,
Seinfeld John H.
Publication year - 1992
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550240109
Subject(s) - isoprene , chemistry , methacrolein , methyl vinyl ketone , furan , product distribution , photochemistry , organic chemistry , catalysis , monomer , copolymer , methacrylic acid , polymer
The OH reaction with isoprene is studied. Methyl nitrite photolysis experiments were carried out in an outdoor smog chamber in an attempt to identify as completely as possible OH‐isoprene product distribution. Emphasis was placed on identification and quantification of oxygenated products. A Tenax‐based cryo‐trap thermal desorber used to trap, concentrate, and dry chamber samples for identification on a GC/MS is described. Analysis of the products revealed that O( 3 P) can form in reaction systems designed to study OH reactions that include high concentrations of NO, and consequently NO 2 , hence, this reaction is also examined. The yields of methacrolein and methyl vinyl ketone are determined as 25 ± 3 and 35.5 ± 4%, respectively, with an additional 4 ± 2% as 3‐methyl furan, totaling 65 ± 4%. These results, combined with those of previous studies allow 80% of isoprene's products to be explicitly identified, and the general structure of the remaining products to be ascertained. The O( 3 P) reaction produces 84 ± 8% epoxides, and 8 ± 3% species which result in production of HO 2 , and subsequently, OH. A heretofore unidentified product of the O( 3 P) reaction, 2‐methyl 2‐butenal, is identified. The rate constant of the NO 2 ‐isoprene reaction is measured.