Catalytic features of the reaction of oxidative cross-coupling of styrene and hexene-1

Abstract

The reaction of oxidative cross-coupling of styrene and hexene-1 in the medium of ice acetic acid was studied in the presence of various active phases based on palladium deposited on carbon-containing carrying agents, activated carbon, fullerenes, astralenes, and nanotubes. Earlier [1] it has been shown that in the case of oxidative cross-coupling of styrene and hexene-1 in the medium of ice acetic acid at 110°С and pressure 3 MPa in the presence of the Pd 3 Sb/C catalyst the full conversion of reagents with the 80% selectivity of 1-phenyl-1,3-octadiene formation can be reached. The choice of the catalyst nature in this case was dictated by a known and exclusive feature of palladium complexes to catalyze cross-coupling reactions [2]. At the same time the application of the catalyst containing the active intermetallic phase Pd 3 Sb was caused by suffi cient stability and effectiveness of this system in oxidative acetoxylation reactions, which are extremely close in realization conditions to the cross-coupling reactions [3].Positive results obtained for the cross-coupling reactions on heterogeneous catalysts for the fi rst time have allowed expanding a search for active components of contacts based on palladium. Furthermore, the aim of the work included the study of the effect of the carrying agent nature on the fi nal product yield, as the restriction imposed earlier [4] is caused by the exclusive feature of activated carbon not to inhibit a simultaneously passing acetoxylation reaction. The inhibiting action of other carrying agents was attributed to the capability of contact components to react with Al 2 O 3 , SiO 2 , etc., which resulted in destruction of redox pairs like Pd-Sb, Pd-Te, Pd-Sn, RhBi, Rh-Ga, and others, and thus catalysts became inactive.In view of the fact that the work was aimed at the one-reactor performing of two reactions, cross-coupling and acetoxylation, we have also selected various carbon derivatives, supramolecular structures: fullerenes, astralenes, and nanotubes. In this case it was possible to expect a certain modifi cation of properties of contacts, at least due to a more diffusive distribution of an active phase or to the formation of more active endohedral structures [5].Theoretically interest to modifi cators of palladium is limited by p-elements of the IIIA-VIA groups. The fact of a high activity of palladium-tellurium-tungsten and analogous rhenium compositions for 1,3-butadiene acetoxylation [3] is practically known, therefore in application to the cross-coupling reaction an expanded experimental study is required. To reduce labor-consuming practical work and to choose faster a set of effective catalysts, and also to detect predominant physical factors responsible for successful operation of contacts, we have applied the extrapolation forecasting method [6,7].The essence of the method (algorithm of the binary linear qualifi er with a zero threshold) consists in searching hyperplanes separating good objects from poor objects in the space of recognition criteria (they can be var...