Dimerization ethylene to 1-butene

Alphabutol Also called IFP-SABIC. A process for dimerizing ethylene to 1-butene. It operates under pressure at 80°C, using a complex Ziegler-Natta catalyst, a titanium alkoxide. Developed by the Institut Frangais du Petrole. First operated in Thailand in 1987. Seven plants had been licensed by 1993, of which three were operating. 

Mixtures of A1(C2H5)3 and Ti(0-iC3H7)4 will dimerize ethylene to 1-butene but they do not catalyze the isomerization of the 1-butene produced (129). Under the right set of conditions, only small amounts of polyethylene are produced with this latter mixture. On the other hand, solutions of compound 10 or 3 have been found to catalytically convert ethylene to ethane and butadiene (130). 

The Ta"" complex, formulated as Ta(C2H4)2(Bu)(PMe3)2 (except R = Cl, Me), catalytically dimerizes ethylene to 1-butene, confirming the tendency of these complexes to undergo 8-hydrogen transfer. 

It is claimed that very high yields of pure 1-butene are obtained at low conversions of ethylene [23-26]. Thus it is possible to dimerize ethylene to 1-butene to a 10% extent and use the resulting mixture for the production of ethylene copolymers [25]. At higher conversions of ethylene (>20%), appreciable amounts of Q and Cg alkenes are produced along with 1-butene [27]. 

Cyclopentadienyltitanium trichloride associated with amalgams or alkali metals dimerizes ethylene to 1-butene [93]. 

Interestingly, the analogous niobium system fails to dimerize ethylene to 1-butene because of its inability to form a metallacyclopentane complex. 

Nickellocene dimerizes ethylene to 1-butene under 500 psi at 200°C however, ferrocene does not. Why ... 

See Table VIII. Titanium based catalysts dimerize ethylene to 1-butene and codimerize ethylene and 1-butene into mixed hexenes (probably for steric reasons titanium is unable to homodimerize 1-butene or other... 

Feed and product quality from dimerization of ethylene to 1-butene ... 

The 7r-back donation stabilizes the alkene-metal 7c-bonding and therefore this is the reason why alkene complexes of the low-valent early transition metals so far isolated did not catalyze any polymerization. Some of them catalyze the oligomerization of olefins via metallocyclic mechanism [25,30,37-39]. For example, a zirconium-alkyl complex, CpZrn(CH2CH3)(7/4-butadiene)(dmpe) (dmpe = l,2-bis(dimethylphosphino)ethane) (24), catalyzed the selective dimerization of ethylene to 1-butene (Scheme I) [37, 38]. 

Ta1 adducts with ethylene have been obtained as highly air sensitive solids by reduction of the corresponding Ta111 compounds under argon (equation 85),292 or by reductive elimination of H2 from [TaH2ClL4] (Scheme 9). A similar procedure, but under dinitrogen, gave Tav nitrenes (Section 34.2.3.6). The same Tam precursor (60) provided o alkyl derivatives (equation 86). Complex (63) catalyzes the selective dimerization of ethylene to 1-butene. 

Ceder, R., Muller, G., Saleh, J. and Vidal, J. Catalytic dimerization of ethylene to 1-butene by square-planar nickel-complexes. J. Mol. Catal., 1991, 68, 23-31. 

Dimerization of Ethylene to 1-Butene Catalyzed by Titanium Complexes... 

Dimerization of ethylene. Rhodium(IlI) chloride supported on silica gel is an active heterogeneous catalyst for dimerization of ethylene to 1-butene and then to 2-butene the transfcis ratio is 2.9. The active catalyst may have the structure depicted in (1). ... 

As the next example of soft catalysis, we shall discuss the dimerization of ethylene to 1-butene, which is catalyzed by rhodium complexes in a redox cycle (Scheme 2-6). The active Rh catalyst A undergoes oxidative addition of HCl and insertion of ethylene into the Rh-H bond to give the Rh alkyl complex B. The following ethylene insertion reaction is the rate-determining step and is favored by the medium-hard Rh center. The resulting Rh butyl complex C has a hard-soft dis-... 

Titanium alkoxide complexes in the presence of triethylaluminium as activator have been reported as selective catalyst systems for the dimer-isation of ethylene to 1-butene with a selectivity higher than 99% towards 1-butene. It was observed that the bulkier the substituent at the ortho position, the lower the catalytic activity of the complex compared to... 

The dimerization of ethylene to form a mixture of butene isomers is not particularly useful in the field of commodity chemicals at this time because this mixture of butenes is usually cheaper than ethylene. Selective dimerization of ethylene to 1-butene using a titanium catalyst is practiced, but this chemistry occurs through metallacycles and is described in the next section. The dimerization of propylene by migratory insertion chemistry typically produces the mixture of isomeric olefins shown in Equation 22.32. Four skeletal isomers of the intermediate metal alkyl can arise from the two different directions of M-H insertion, followed by two different inodes of M-R insertion. The dimerization of ethylene is particularly fast when catalyzed by the combination of NiBr(-r) -C3H5)(PCy3) and EtAlCl this dimerization in chlorobenzene at 25 °C occurs witii turnover frequencies up to 60,000 per second. The more selective dimerization of propene to 2,3-dimethylbutene is conducted on an industrial scale with titanium catalysts, again via metallac clic intermediates described in the next section. 

Alkene and Alkyne Dimerization and Trimerization. The low-valent mono-Cp zirconium compound CpZrMe(DMPE)2 (DMPE = l,2-bis(di-methylphosphino)ethane) catalyzes the dimerization of ethylene to 1-butene at low frequency (3 t.o./d), a process wherein the 1,3-butadiene complex 64 is presumed to be the catalyst (256). The clean dimerization of olefins using the Cp2ZrCl2/MAO (Al/Zr = 1) catalyst has recently been reported (257). Recently,... 

R.R. Schrock - Rapid Selective Dimerization of Ethylene to 1-Butene by a Tantalum Catalyst and a New Mechanism for Ethylene Oligomerization,/. Am. Chem. Soc. 101, 5099, 1979 S.J. McLain, J. Sancho, R.R. Schrock - Metallacyclopentane to Metallacyclobutane Ring Contraction, J. Am. Chem. Soc. 101,5451,1979 ... 

Tantalum complex D not only converts ethylene to 1-butene but selectively transforms all the a-olefins into a mixture of t,t or h,t dimers, depending on the size of the substituent (Table IX). 

Depending on the solvent Ni(PPR3)2(ethylene) catalyzes the dimerization of ethylene to 1-butene (chlorobenzene) or to cyclobutane (toluene). It is the only case of cyclodimer formation from an unstrained olefin (R. H. Grubbs). 

The Alphabutol process [23] selectively dimerizes ethylene into 1-butene by means of a titanium based catalyst (Table VUI). Hexenes, the only by-products of the reaction, represent 5 to 8% of the converted ethylene. 

Immobilization of ions on supports may be an elegant way to stabilize unusual oxidation states and/or coordination numbers. A particular system to mention here is the preparation of a well-defined Ni(l) complex coordinated to two surface oxygen atoms on silica, for the selective dimerization of ethylene to 1-butene. In this system it is possible to control the selectivity to 1-butene by coordination of two alkylphosphine ligands at a Ni(l) center which has been smoothly reduced from a Ni(II) precursor complex. 

Many heterogeneous catalysts have been commercialized to dimerize ethylene to selectively yield 1-butene or 2-butene (66—70). Since ethylene is generally priced higher than butylenes, economics favor the production of butylenes from steam crackers, not from ethylene. An exceUent review on... 

In the codimerization reaction, both reactants are present in large excess compared to the catalyst concentration. The selectivity toward a 1 1 codimerization to form 1,4-hexadiene, instead of a random oligomerization, represents a rather unique reaction, especially in view of the fact that the same catalyst also dimerizes ethylene to butene (3) at about the same rate as the codimerization. The explanation forwarded by Cramer (4, 7) is based on the overwhelmingly favored stability of the tt-... 

Practical Applications. IFP s Alphabutol process is used to dimerize ethylene selectively to 1-butene.43,85 The significance of this technology is the use of 1-butene as a comonomer in the polymerization of ethylene to produce linear low-density polyethylene (see Section 13.2.6). Under the reaction conditions applied in industry (50-60°C, 22-27 atm), the selectivity of 1-butene formation is higher than 90% at the conversion of 80-85%. Since no metal hydride is involved in this system, isomerization does not take place and only a small amount of higher-molecular-weight terminal alkenes is formed. 

---