Intermediates in catalytic hydrogenation of 1,3-butadiene, propadiene and methylacetylene on MoS2 catalyst
- 1 January 1979
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 75, 1403-1416
- https://doi.org/10.1039/f19797501403
Abstract
Hydrogenation of 1,3-butadiene with a mixture of H2 and D2 on a MoS2 catalyst gave [2H0]but-1-ene and [2H2]but-1-ene in proportion to the partial pressures of H2 and D2, but little [2H1]but-1-ene was formed. If hydrogenation of butadiene was performed with HD, 3-[2H1]but-1-ene and 4-[2H1]-but-1-ene were mainly formed. The ratio of 3-[2H1] to 4-[2H1] isomers was found to be in good agreement with the isotope effect for the reaction with H2 and D2. On the basis of these results, a s-butenyl intermediate (σ-allylic complex, CH3—CH—CHCH2) was derived for the hydro-genation of butadiene. The intermediates in the hydrogenation of propadiene as well as the conversion of methylacetylene to propene were deduced by the same procedures as was σ-allyl (CH2—CHCH2) for propadiene and n-propenyl (CHCH—CH3) for methylacetylene. These-results indicate that the σ-allylic complexes formed on the active sites for the hydrogenation reaction do not undergo reversible interconversion to the corresponding π-allylic complexes. The selective 1,2-addition of a hydrogen molecule to the dienes and the other catalytic features of MoS2 are explained well by the isolated active site having three degrees of coordinative unsaturation described by the 3M-site.Keywords
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