Catalytic Ethylene Oligomerization Research Articles

Synthesis and catalytic activity of allyl, methallyl and methyl complexes of nickel(II) and palladium(II) with biphosphine monoxide ligands: oligomerization of ethylene and copolymerization of ethylene and carbon monoxide

The syntheses of new cationic nickel complexes {[η 3-methallyl]Ni[κ 2P,O-Ph 2P(X)P(O)Ph 2]}SbF 6, ( 1)–( 2) [X=( o-C 6H 4) ( 1), (NH), ( 2)] have been accomplished. The complexes oligomerize ethylene to linear α-olefins with selectivities as high as 89%. A dependence of oligomerization grade and activity on backbone geometry was shown. New cationic allyl and methyl complexes of palladium(II) [(CH 3CN)(Me)Pd(κ 2P,O–Ar 2P(CH 2) n P(O)Ar 2)]X [ n=1–3, X=BF 4, Ar=C 6H 5 ( 18– 20)] [ n=1, X=SbF 6, Ar= p-tolyl ( 23); n=1 or 2, X=SbF 6, Ar=C 6H 5 ( 21) or ( 22)]; [(η 3-C 3H 5)Pd(κ 2P,O-Ph 2P(CH 2) n P(O)Ph 2)]X, [ n=2, X=triflate ( 10), tosylate ( 13); n=3, X=triflate ( 11), tosylate ( 14)], [(η 3-C 3H 5)]Pd(κ 2P,O-Ar 2P(CH 2) n P(O)Ar 2)]X, [ n=1, X=SbF 6, Ar= p-tolyl ( 17); n=2, X=SbF 6 Ar=C 6H 5( 16)] have been synthesized in good yields. These complexes have been used in the catalytic oligomerization of ethylene, and in the catalytic alternating copolymerization of ethylene and carbon monoxide, to yield polyketones.

Catalytic oligomerization of ethylene to lower α-olefins by the catalyst system DPA(Na)/NiCl 2·6H 2O/Zn

The catalyst system DPA(Na)/NiCl 2·6H 2O/Zn (DPA(Na), sodium salt of diphenylphosphinoacetic acid has high activity and selectivity to form lower α-olefins in the oligomerization of ethylene. The amount of zinc highly affects the activity, and the Zn 2+ which came from the oxidation of zinc is likely to enhance the selectivity to lower α-olefins. The solvent used in this system offers the hydrogen of the nickel hydride.

Catalytic Oligomerization of Ethylene to Lower α-Olefins by Nickel Chelate

Catalytic Oligomerization of Ethylene to Lower α-Olefins by Nickel Chelate

Nickel complexes with heterofunctionalized phosphine ligands. Catalytic oligomerization of ethylene with [Ni(C5Ph5){Ph2PCHC(O)Ph}

Reaction of [Ni(C5Ph5)Br(CO)] with Ph2PCH2C(O)Ph in the presence of 1,8-bis(dimethylamino)naphthalene (proton sponge) gives the chelate complex [Ni(C5Ph5){Ph2PCHC(O)Ph}]1. The complexes [Ni(C5Ph5){Ph2PCHC(O)(C5H4)Fe(C5H5)}]2, [Ni(C5Ph5){Ph2PCHC(O)(1,3-C6H4)C(O)HCPPh2}Ni(C5Ph5)]3, [Ni(C5H5){Ph2PCHC(O)Ph}]4 and [Ni(C5H5){Ph2PCHC(O)(C5H4)Fe(C5H5)}]5 have been synthesised using the appropriate phosphine ligand and applying a procedure similar to that for 1. Complex 1, activated with NaBH4, exhibits catalytic activity in the low-pressure oligomerization of ethylene. At 130 °C, under 38 bar of ethylene, selectivities of up to 98% towards linear α-olefins were achieved. Protonation of the bimetallic complex 2 with HBF4 gave the cationic complex [Ni(C5Ph5){Ph2PCH2C(O)(C5H4)Fe(C5H5)}]BF46. Crystais of 6 belong to the orthorhombic space group Pbca with a= 19.427(6), b= 38.595(11), c= 13.001(4)A and Z= 8. The structure was refined to R= 0.049 (R′= 0.067). The bonding of C5Ph5 contrasts with the bonding modes usually found for cyclopentadienyl ligands. The ring contains two short [1.384(8) and 1.389(8)], two medium [1.444(8) and 1.443(8)], and one long [1.474(8)A] C–C bonds so that the C5Ph5 may be viewed as an (alkyl, diene) ligand. This unusual bonding is likely to result from the ‘chemical’ dissymmetry of the P,O ligand and the low trans influence of the oxygen atom. The extremely low ν, (CO) frequency of the co-ordinated ketone (1525 cm–1) reflects the strong electron-withdrawing effect of the Ni(C5Ph5)+ moiety.

Linear Alpha-Olefins by Catalytic Oligomerization of Ethylene

Abstract This paper describes a new catalytic process for linear alpha-olefins by oligomerization of ethylene using a soluble alkyl aluminum chloride-titanium tetrachloride catalyst. Important catalytic and polymerization variables, such as catalyst activity, selectivity to linear products, and molecular weight, are discussed. An ionic mechanism is proposed to explain the unusual features of this new process.