Hydrogenation of methyl sorbate and soybean esters with polymer-bound metal catalysts |
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Authors: | E N Frankel J P Friedrich T R Bessler W F Kwolek N L Holy |
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Affiliation: | (1) Northern Regional Research Center, Agricultural Research, Science and Education Administration, USDA, 61604 Peoria, IL;(2) Department of Chemistry, Western Kentucky University, 42101 Bowling Green, KY |
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Abstract: | New polymer-bound hydrogenation catalysts were made by complexing PdCl2, RhCl3·3H2O, or NiCl2 with anthranilic acid anchored to chloromethylated polystyrene. The Pd(II) and Ni(II) polymers were reduced to the corresponding
Pd(O) and Ni(O) catalysts with NaBH4. In the hydrogenation of methyl sorbate, these polymer catalysts were highly selective for the formation of methyl 2-hexenoate.
The diene to monoene selectivity decreased in the order: Pd(II), Pd(O), Rh(I), Ni(II), Ni(O). Kinetic studies support 1,2-reduction
of the Δ4 double bond of sorbate as the main path of hydrogenation. In the hydrogenation of soybean esters, the Pd(II) polymer
catalysts proved superior because they were more active than the Ni(II) polymers and produced lesstrans unsaturation than the Rh(I) polymers. Hydrogenation with Pd(II) polymers at 50~100 C and 50 to 100 psi H2 decreased the linolenate content below 3% and increasedtrans unsaturation to 10~26%. The linolenate to linoleate selectivity ranged from 1.6 to 3.2. Reaction parameters were analyzed
statistically to optimize hydrogenation. Recycling through 2 or 3 hydrogenations of soybean esters was demonstrated with the
Pd(II) polymers. In comparison with commercial Pd-on-alumina, the Pd(II) polymers were less active and as selective in the
hydrogenation of soybean esters but more selective in the hydrogenation of methyl sorbate.
Presented at ISF-AOCS Meeting, New York, April 1980. |
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