Preparation of unsymmetrical polyenes

#This invention is directed to the preparation of acyclic polyenes by the reaction of acyclic .alpha.-olefins with monocycloolefins. More specifically this invention is directed to the preparation of unsymmetrical acyclic polyenes prepared by the reaction of 1-pentene with cyclopentene.

#The reaction of 1-pentene with cyclopentene in the presence of cross metathesis catalysts give a product which is a mixture of polyenes which are predominately unsymmetrical. The prior art heretofore, by the use of cross metathesis catalysts results in the reaction of acyclic .alpha.-olefins with monocycloolefins, has produced a rather predictable mixture of symmetrical to unsymmetrical acyclic polyenes. Usually the ratio of symmetrical/unsymmetrical/symmetrical acyclic polyene mixture is in the range of 1/2/1. The present invention produces an unexpected mixture of symmetrical to unsymmetrical acyclic polyenes. Said unsymmetrical acyclic polyenes can be used in the preparation of EPDM polymers wherein an acyclic polyene is needed with a terminal double bond.

#The reaction of 1-pentene with cyclopentene can form a mixture of cross metathesis products which are acyclic polyenes and can generally be described by the following series of formulas: ##STR1##

#Further practice of this invention is illustrated by reference to the following examples which are intended to be illustrative and in no way limiting the scope of this invention.

#Cyclopentene and 1-pentene monomer were purified by distillation and treated by passing over activated silica gel prior to use. The monomers were then syringed under a nitrogen atmosphere into 2-ounce polymerization bottles equipped with self-sealing gaskets and teflon liners. A known quality of n-nonane was added to each bottle to serve as an internal standard for analytical purposes and the mixture was sparged with nitrogen. This mixture was analyzed on a gas chromatograph for quantitative composition. Thus, to 3.8 g. (0.056 mole) cyclopentene and 9.5 g. (0.135 mole) 1-pentene, maintained at either 0.degree. or 25.degree. C. were added by hypodermic syringe 1.0 ml. of 0.05 molar tungsten hexachloride (WCl.sub.6)-trichloroethanol (Cl.sub.3 CCH.sub.2 OH) solution, followed by 0.75 ml. of 0.2 molar ethyl aluminum dichloride (C.sub.2 H.sub.5 AlCl.sub.2) solution. The reactions were shortstopped at the appropriate time by the addition of 0.1 ml. methanol and the product composition of the mixture was determined.

#Column 1 is the Experiment number; column 2 is temperature in .degree.C.; column 3 is the amount of unreacted cyclopentene after the metathesis reaction; column 4 is the amount of cyclopentene which was converted to unsymmetrical polyenes; column 5 is the amount of unsymmetrical polyene which was determined as a weight percent by the gas chromatograph of the product mixture up to 28 carbon atoms; column 6 is the amount of cyclopentene which was undetectable under the limitations of direct observation up to C.sub.28, however, with the knowledge of the observed product distribution one can extrapolate to higher molecular weight members of the series which are beyond direct observation but should follow the same product distribution in order to account for the remaining cyclopentene; and column 7 is the total amount of selectivity based on the amounts of cyclopentene which was initially charged.