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Selective formation of trans-2-butene-1,4-d/sub 2/ and (E)-2-methyl-2-butene-1,4-d/sub 2/ in deuteration of 1,3-butadiene derivatives over thorium oxide catalyst

Journal Article · · J. Catal.; (United States)
OSTI ID:6337644

Stereoselective hydrogenations of 1,3-butadiene and 2-methyl-1,3-butadiene over thorium oxide catalyst were investigated to elucidate the intermediates of the reactions. Hydrogenation of 1,3-butadiene produced predominantly trans-2-butene. Deuterium tracer studies provided direct evidence that 1,4-addition was a dominant mechanism. Deuteration of 1,3-butadiene yielded exclusively monoenes-d/sub 2/, while no deuterium was exchanged with hydrogen in 1,3-butadiene. Deuteration of 2-methyl-2-butene gave mainly (E)-2-methyl-2-butene-1,4-d/sub 2/. For both reactants, most stable conformations of starting diens (s-trans form) were reflected on the structure of the products. The geometrical structures as well as molecular identity of a hydrogen molecule were maintained during hydrogenation. Reaction of a mixture containing 1-butene and 1,3-butadiene-d/sub 6/ in the presence of hydrogen revealed that 1-butene and 1,3-butadiene independently underwent isomerization and hydrogenation, respectively. The nature of their active sites is discussed. Key intermediate of the hydrogenation of conjugated diene is postulated to be the syn form of methyl- or dimethyl-..pi..-allyl carbanion which is hydrogenated before interconverting to their isomeric anti form of the ..pi..-allyl carbanion. 5 figures, 6 tables.

Research Organization:
Hokkaido Univ., Sapporo, Japan
OSTI ID:
6337644
Journal Information:
J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 56:3; ISSN JCTLA
Country of Publication:
United States
Language:
English

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