Heterogenized Homogeneous Catalysts. Hydrogenation of Methyl Sorbate by Polystyrene-Anchored Tricarbonylchromium.

The reaction of a swollen 1 divinylbenzene-crosslinked polystyrene with hexacarbonylchromium gave polymer-anchored tricarbonylchromium moieties eta6-bonded to the polymers phenyl rings. Using this heterogenized catalyst, methyl sorbate was converted selectively 96-97 to Z-methyl 3-hexenoate with small amounts of methyl hexanoate and E-methyl 2-hexenoate in cyclohexane at 160C and 500psi of hydrogen. The product distribution was sensitive to solvent and reaction temperature. No significant hydrogenation of cyclohexene or E,E,E-1,5,9-cyclododecatriene occurred at 150C and 500psi of hydrogen in 24 hrs. This heterogenized homogeneous catalyst system is discussed in relation to known homogeneous hydrogenation catalysts for methyl sorbate.