Patent ID: 7381857

Claim:
A process for the trimerization and tetramerization of olefinic monomers wherein the process comprises contacting at least one olefinic monomer under trimerization and tetramerization reaction conditions with a catalyst system comprising: a) a source of chromium, molybdenum or tungsten; b) a first ligand having the general formula (I); (R 1 )(R 2 )P-X-P(R 3 )(R 4 ) (I) wherein: X is a bivalent alkylene bridging group; R 1 and R 3 are independently selected from aromatic groups which do not contain a polar substituent at any of the ortho-positions; R 2 and R 4 are independently selected from substituted aromatic groups, each R 2 and R 4 bearing a polar substituent on at least one of the ortho-positions; c) a second ligand having the general formula (II); (R 1′ )(R 2′ )P-X′-P(R 3′ )(R 4′ ) (II) wherein: X′ is a bridging group of the formula —N(R 5′ )—, wherein R 5′ is selected from hydrogen, a hydrocarbyl group, a substituted hydrocarbyl group, a heterohydrocarbyl group, a substituted heterohydrocarbyl group, a silyl group or derivative thereof; and R 1′ , R 2′ , R 3′ and R 4′ are independently selected from aromatic and substituted aromatic groups, including heteroaromatic and substituted heteroaromatic groups, of which at least one of R 1′ , R 2′ , R 3′ and R 4′ contains a polar substituent, or R 1′ , R 2′ , R 3′ and R 4′ are independently selected from aromatic and substituted aromatic groups, including heteroaromatic and substituted heteroaromatic groups, wherein any substituents in one or more of R 1′ , R 2′ , R 3′ and R 4′ are non-polar; and d) a cocatalyst.