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Theoretical Study on the Reaction Mechanism of Ketene CH 2 CO with Isocyanate NCO Radical
Author(s) -
Zhao LiWei,
Kan Wei,
Yu HaiTao,
Fu HongGang,
Sun JiaZhong
Publication year - 2007
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.200790206
Subject(s) - chemistry , ketene , isocyanate , hydrogen atom abstraction , methylene , photochemistry , molecule , hydrogen atom , reaction mechanism , hydrogen , computational chemistry , medicinal chemistry , organic chemistry , catalysis , alkyl , polyurethane
The bimolecular single collision reaction potential energy surface of an isocyanate NCO radical with a ketene CH 2 CO molecule was investigated by means of B3LYP and QCISD(T) methods. The computed results indicate that two possible reaction channels exist on the surface. One is an addition‐elimination reaction process, in which the CH 2 CO molecule is attacked by the nitrogen atom at its methylene carbon atom to lead to the formation of the intermediate OCNCH 2 CO followed by a C–C rupture channel to the products CH 2 NCO+CO. The other is a direct hydrogen abstraction channel from CH 2 CO by the NCO radical to afford the products HCCO+HNCO. Because of a higher barrier in the hydrogen abstraction reaction than in the addition‐elimination reaction, the direct hydrogen abstraction pathway can only be considered as a secondary reaction channel in the reaction kinetics of NCO+CH 2 CO. The predicted results are in good agreement with previous experimental and theoretical investigations.