SELECTIVE, HOMOGENEOUS HYDROGENATION OF CYCLOHEPTATRIENE TO CYCLOHEPTENE CATALYZED BY (η4-CYCLOOCTA-1,5-DIENE)(η6-CYCLOHEPTA-1,3,5-TRIENE)RUTHENIUM(0)

Article abstract of DOI:10.1016/S0022-328X(00)93432-6

In the presence of small amounts of 4-COD)(η⁶-C8H10)> (1), cycloheptatriene is hydrogenated to cycloheptene, under one atmosphere of hydrogen at room temperature in homogeneous phase.The formation of a small amount of cyclooctene and the existence of an induction period, which do not occur when 4-COD)(η⁶-C7H8)> (2) is used as the catalyst, suggest that 2 is the real catalyst.The selectivity of this hydrogenation is 100percent in n-hexane as solvent, 99.5percent in THF, and low in ethanol.Conversion is quantitative in THF and ethanol, but not more than 65percent in n-hexane.In the presence of 1 or 2, cycloheptene is rapidly hydrogenated to cycloheptane in THF and ethanol, but not in n-hexane.A mechanism for these catalytic hydrogenations is proposed, and discussed on the basis of the dominant role of the solvents.Increase of temperature and/or pressure of hydrogen increases the rate of hydrogenation.