LIQUID-PHASE DIACETOXYLATION OF 1,3-BUTADIENE WITH PD-TE-C CATALYST

The catalytic properties of PdTe bimetallic system supported on charcoal (PdTeC) for liquid-phase diacetoxylation of butadiene was studied in comparison with other heterogeneous (PdC, PdAsC, PdBiC, PdSbC, PdSeC, Pd-TeAl2O3, or PdTeSiO2) or homogeneous [Pd(OAc)2Cu(OAc)2KOAc or PdCl2CuCl2KOAc] palladium-based catalysts. The highest activity for 1,4-diacetoxylation was obtained with the PdTeC catalyst prepared from Pd(NO3)3 and TeO2 dissolved in aqueous nitric acid solution, for all the catalysts studied. The reaction seems to proceed catalytically on the surface of this supported bimetallic system, and its active species is suggested to be some palladium tellurides, in which Pd serves by a redox mechanism, being coupled with Te. The PdTeC system catalyzed the direct diacetoxylation of butadiene, which is considered to proceed via π-allyl-type intermediate. The use of the ratio of Pd:Te ∼- 10:1 on charcoal is the most effective; a higher content in Te results in a lowering of the activity, possibly brought on by the unfavorable deposition of tellurium oxides on the catalyst surface. With the PdTeC system, the following values of selectivities of diacetoxybutenes were obtained: trans-1,4-diacetoxy-2-butene, 75%; cis-1,4-diacetoxy-2-butene, 14%; and 3,4-diacetoxy-1-butene, 10%. © 1979.