Platinum Metals Rev., 1963, 7, (4), 131
The Isomerisation of Olefins
Catalysis by Palladium Compounds
During an experimental study of the Wacker process carried out by Dr M. B. Sparke and his associates at B.P. Chemical Co. Ltd, Sunbury-on-Thames (M. B. Sparke, L. Turner and A. J. M. Wenham, paper AB4-30, presented at the I.U.P.A.C. conference, London, July 1963), it was observed that if the reaction was arrested before completion the original olefin used had isomerised. The isomerisation process was further investigated and was found to proceed rapidly under mild conditions: thus in the case of methyl pentenes and n-hexenes, the thermodynamic equilibrium mixture of isomers was formed when the olefin was refluxed with catalytic quantities of palladous chloride for ½ to 2 hours. No side reactions were observed.
The induction period which was observed when palladous chloride was used disappeared when ethylene palladous chloride or bis-benzonitrile palladous chloride was used instead. The mechanism of the reaction was not definitely established, but the migration of the double bond in the olefin molecule was shown to proceed stepwise along the carbon chain. Palladium bromide complexes and π alkenyl-palladium complexes were virtually inactive, but ethylene platinous chloride had a definite but low isomerisation activity.