6533b82efe1ef96bd1293b9c

RESEARCH PRODUCT

Die dimerisierung von endständigen α-hydroxyacetylenen mit rhodiumkomplexkatalysatoren

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Abstract The dimerisation of monosubstituted α-hydroxyacetylenes, which is catalysed by rhodium complexes, yields 1,4-disubstituted vinylacetylenes. The catalyst has been optimized for 3-methylbut-1-yn-3-ol as the substrate by using different ligands. Kinetic measurements were carried out with the monomers 3-methylbut-1-yn-3-ol, 3-methylpent-1-yn-3-ol and 1-ethynylcyclohexan-1-ol. In addition the rates of the dimerisation have been compared with those for a further series of α-hydroxyacetylenes. The by-products from the reaction of 3-methylbut-1-yn-3-ol with [(C 6 H 5 ) 3 P] 3 RhCl as catalyst were determined and the yields of the products compared with those of but-1-yn-3-ol and prop-1-yn-3-ol. Codimerisations of 3-methylbut-1-yn-3-ol with some other terminal tertiary hydroxyacetylenes show that the less bulky acetylene is preferentially fixed in a π-complex and the second hydroxyacetylene is added to the π-bonded acetylene in the rate-determining step.