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Theoretical study on the mechanism of the CH 2 F + NO 2 reaction
Author(s) -
Zhang JiaXu,
Li ZeSheng,
Liu JingYao,
Sun ChiaChung
Publication year - 2006
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20397
Subject(s) - isomerization , chemistry , radical , adduct , bond cleavage , reaction mechanism , stereochemistry , molecule , computational chemistry , medicinal chemistry , catalysis , organic chemistry
Despite the importance of the Fluoromethyl radicals in combustion chemistry, very little experimental information on their reactions toward stable molecules is available in the literature. Motivated by recent laboratory characterization about the reaction kinetics of Chloromethyl radicals with NO 2 , we carried out a detailed potential energy survey on the CH 2 F + NO 2 reaction at the B3LYP/6‐311G(d,p) and MC‐QCISD (single‐point) levels as an attempt toward understanding the CH 2 F + NO 2 reaction mechanism. It is shown that the CH 2 F radical can react with NO 2 to barrierlessly generate adduct a (H 2 FCNO 2 ), followed by isomerization to b 1 (H 2 FCONO‐ trans ) which can easily interconvert to b 2 (H 2 FCONO‐ cis ). Subsequently, Starting from b (b 1 , b 2 ), the most feasible pathway is the CF and NO1 bonds cleavage along with NF bond formation of b (b 1 , b 2 ) leading to P 1 (CH 2 O + FNO), or the direct NO1 weak‐bond fission of b (b 1 , b 2 ) to give P 2 (CH 2 FO + NO), or the 1,3‐H‐shift associated with NO1 bond rupture of b 1 to form P 3 (CHFO + HNO), all of which may have comparable contribution to the reaction CH 2 F + NO 2 . Much less competitively, b 2 either take the 1,4‐H‐shift and O1N bond cleavage to form product P 4 (CHFO + HON) or undergo a concerted H‐shift to isomer c 2 (HFCONOH), followed by dissociation to P 4 . Because the rate‐determining transition state (TSab 1 ) in the most competitive channels is only 0.3 kcal/mol higher than the reactants in energy, the CH 2 F + NO 2 reaction is expected to be rapid, and may thus be expected to significantly contribute to elimination of nitrogen dioxide pollutants. The similarities and discrepancies among the CH 2 X + NO 2 (X = H, F, and Cl) reactions are discussed in terms of the electronegativity of halogen atom. The present article may assist in future experimental identification of the product distributions for the title reaction, and may be helpful for understanding the halogenated methyl chemistry. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 894–905, 2006