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 eta(6)-bonded to the polymer's 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.