Improvement of catalyst activity in the Ru-catalyzed dimerization of acrylonitrile by using diphenyl ether as a solvent
For the catalyst system of ruthenium and carboxylic acid, which is useful for the efficient tail-to-tail dimerization of acrylonitrile, the TON increases as the ruthenium catalyst concentration is decreased. Furthermore, the addition of aromatic solvents of equal volume to that of acrylonitrile improves the catalyst activity. Especially, the use of diphenyl ether leads to a 1.7 time improvement of the TON. Copyright
Linear relationship between activity of a new Ru-catalyst and acidity of substituted benzoic acids in the dimerization of acrylonitrile
A new type of catalyst system using ruthenium and carboxylic acid is useful for the tail-to-tail dimerization of acrylonitrile, proceeding without the formation of undesired by-product propionitrile. Carboxylic acids having pK a 3.5-5 are suitable as co-catalysts for the dimerization of acrylonitrile. The relationship between the logarithm of the relative rate in the dimer formation and the pKa of m- and p-substituted benzoic acids (Bronsted plot) was linear (R2 = 0.946) with a slope of -0.199. The role of the carboxylic acids can be considered to be effective protonation in the protonolysis of the carbon-ruthenium bond of an intermediate Ru complex. Copyright
The kinetics and mechanism of the phosphorus-catalysed dimerisation of acrylonitrile
The kinetics and mechanism of the phosphinite-catalysed dimerisation of acrylonitrile to 1,4-dicyanobut-1-ene and 2,4-dicyanobut-1-ene are presented and discussed.
Hall, C. Dennis,Lowther, Nicholas,Tweedy, Bruce R.,Kayhanian, Robert,Piffl, Michaela,Shaw, Gordon
p. 521 - 524
(2007/10/03)
On the Knowledge of the Catalytic Dimerization of Acrylic Acid Derivatives by Palladium Complexes. III. Reactions of β-Palladio Acrylates and Their Relation to the Catalytic Reaction
Complexes of the type L2PdCl(CH=CHCOOCH3) (L2 = 2PPh3 or Ph2PCH2CH2PPh2) were decomposed to dimethyl muconate by pyrolysis or by substraction of the phosphine ligands with (CH3CN)2PdCl2 in acetonitrile.The last mentioned reaction gave Δ3-dimethyl dihydromuconate in the presence of hydrochloric acid. Δ3-Dimethyl dihydromuconate was also formed by decomposition of (Ph2PCH2CH2PPh2)PdCl(CH=CHCOOCH3) with HBF4 in acetonitrile, but the analogous reaction in methyl acrylate as solvent gave Δ2-dimetyl dihydromuconate.Thus, we have simulated the formation of the two m ain products of the catalytic dimerization of methyl acrylate with palladium(II)chloride in a stoichiometric manner.Mechanisms with hydride and carbene intermediates are discussed.
Oehme, G.,Pracejus, H.
p. 798 - 808
(2007/10/02)
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