Kinetic and Theoretical Investigation of the Gas-Phase Ozonolysis of Isoprene: Carbonyl Oxides as an Important Source for OH Radicals in the Atmosphere

Autor:	Roland Gutbrod, Elfi Kraka, Dieter Cremer, Ralph N. Schindler
Rok vydání:	1997
Předmět:	chemistry.chemical_classification Ozonolysis Alkene Radical General Chemistry Alkylation Photochemistry Biochemistry Catalysis Propene chemistry.chemical_compound Colloid and Surface Chemistry chemistry Isoprene Bond cleavage Alkyl
Zdroj:	Journal of the American Chemical Society. 119:7330-7342
ISSN:	1520-5126 0002-7863
Popis:	Kinetic measurements as well as B3LYP/ and MP2/6-31G(d,p) calculations provide evidence that carbonyl oxides formed in the gas-phase ozonolysis of alkylated alkenes are an important source of OH radicals. In the gas-phase ozonolysis of propene, cis-2-butene, trans-2-butene, tetramethylethene, and isoprene, 18, 17, 24, 36, and 19% OH radicals (relative to reacted ozone, error margin ≤4%) are measured using CO as a scavenger for OH. The quantum chemical calculations show that OH radical production depends on syn positioned methyl (alkyl) groups and their interaction with the terminal O atom of a carbonyl oxide. For example, in the gas-phase ozonolysis of ethene only 5% OH radicals are measured while for a carbonyl oxide with syn-positioned methyl (alkyl) group, a much larger amount of OH radicals is formed. This is due to the fact that 1,4 H migration and the formation of an intermediate hydroperoxy alkene, that is prone to undergo OO bond cleavage, is energetically more favorable than isomerization to diox...
Databáze:	OpenAIRE
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