Metathesis of α,ω-dienes over a CsNO 3-Re 2O 7-Al 2O 3 catalyst in liquid phase

Abstract

The metathesis of five kinds of α,ω-dienes containing from six to ten carbon atoms were investigated over CsNO 3-Re 2O 7-Al 2O 3 catalyst. The reactions were carried out in a continuous-flow system with a fixed catalyst bed at atmospheric pressure in the liquid phase. The α,ω-dienes were easily metathesized and all the reaction products were metathesis products. By-products resulting from double-bond isomerization of α,ω-diene were not found in the reaction products. Thus, the catalyst appeared to be a very active and selective catalyst for the metathesis of α,ω-dienes. 1,7-Octadiene underwent only intramolecular metathesis with quantitative yield of cyclohexene. On the contrary, 1,5-hexadiene and 1,9-decadiene underwent only intermolecular metathesis and both intra- and intermolecular metathesis took place for 1,6-heptadiene and 1,8-nonadiene. The relative reactivities of the α,ω-dienes were measured by both conventional and competitive reaction and the reactivity was obtained in decreasing order: 1,7-octadiene > 1,6-heptadiene > 1,8-nonadiene > 1,5-hexadiene > 1,9-decadiene. The reaction behavior and the relative reactivity were discussed and explained on the basis of the metal carbene mechanism.