Abstract: A process for the polymerization of ethylene and/or one or more alpha-olefins comprising contacting ethylene, and/or the alpha-olefin(s) with a catalyst comprising a first component which is a bis(cyclopentadienyl) Group IVA metal compound containing a substituent capable of reacting with a cation, and a second component which is a compound having a bulky anion containing one or more boron atoms and which is substantially non-coordinating under the reaction conditions and a cation, in which process additional first component is added.

Abstract: A process for the preparation of a compound of general formula ##STR1## in which R.sup.1 represents a hydrogen atom or a methyl group, one of R.sup.2 and R.sup.3 represents a hydrogen atom and the other of R.sup.2 and R.sup.3 is the same as R.sup.1, which comprises reacting a compound of the general formulaR.sup.1 CH.dbd.C.dbd.CH.sub.2 (II)with a salt of formic acid in the presence of a catalyst system comprising a palladium salt and a phosphorus compound of general formulaP(OX).sub.n (X).sub.3-n (III)in which n is 0,1,2 or 3 and each X independently represents an alkyl, alkenyl, aryl, aralkyl, alkaryl or cycloalkyl group, and recovering the desired compound of formula (I).

Abstract: Process for the preparation of dienes and/or trienes comprising reacting a polyolefinically unsaturated compound in the presence of a heterogeneous disproportionation catalyst with a compound according to the general formula ##STR1## wherein R.sup.1 and R.sup.2, which may be the same or different, each represents an alkyl, aryl, alkaryl or aralkyl group which may or may not contain one or more inert substituents or R.sup.1 and R.sup.2 form part of a cyclic structure together with the carbon atom to which they are attached. Isononadiene (2,6-dimethyl-1,5-heptadiene) and/or 2,6,10-trimethyl-1,5,9-undecatriene can be obtained by reacting cis-1,4-polyisoprene with isobutene in the presence of a heterogeneous disproportionation catalyst.