Butenes dimerization

Catalyst systems of the type [NiL X + AlEt Xj (where L = PR and X = halide) afford highly active catalysts for olefm dimerisation. However, when complex 11 (Scheme 13.8) is treated with AlEt Cl in the presence of 1-butene, in toluene at 20°C the only products observed were decomposition products, 12,13,14 no butene dimers were obtained [22], At low temperatures (-15°C) and using the complex with 1,3-diiso-propylimidazolin-2-ylidene as the NHC ligand, small amounts of butene dimers were observed. It is apparent from these results that Ni-NHC complexes are capable of olefin dimerisation, however, decomposition of the catalyst via reductive elimination predominates. 

Room temperature ionic liquids (RTILs), such as those based on A,A-dialkylimidazolium ions, are gaining importance (Bradley, 1999). The ionic liquids do not evaporate easily and thus there are no noxious fumes. They are also non-inflammable. Ionic liquids dissolve catalysts that are insoluble in conventional organic chemicals. IFP France has developed these solvents for dimerization, hydrogenation, isomerization, and hydroformylation reactions without conventional solvents. For butene dimerization a commercial process exists. RTILs form biphasic systems with the catalyst in the RTIL phase, which is immiscible with the reactants and products. This system is capable of being extended to a list of organometallic catalysts. Industrial Friedel-Crafts reactions, such as acylations, have been conducted and a fragrance molecule tra.seolide has been produced in 99% yield (Bradley, 1999). 

Butene, catalytic oxidation, 35 168-169 n-Butene dimerization, 31 36-37 composition change, 31 25-26 But-2-en-l-ol oxidation, 41 307 Butler-Volmer equation, 40 89 Butterfly cluster compounds, 38 294-295 Butyl alcohols... 

Another example is butene dimerization catalyzed by nickel complexes in acidic chloroaluminates 14). This reaction has been performed on a continuous basis on the pilot scale by IFF (Difasol process). Relative to the industrial process involving homogeneous catalysis (Dimersol process), the overall yield in dimers is increased. Similarly, selective hydrogenation of diene can be performed in ionic liquids, because the solubility of dienes is higher than that of monoene, which is higher than that of paraffins. In the case of the Difasol process, a reduction of the volume of the reaction section by a factor of up to 40 can be achieved. This new Difasol technology enables lower dimer (e.g., octenes) production costs 14). 

Helene Olivier at the French Petroleum Institute (IFP) at Rueil-Malmaison, near Paris, has developed a butene dimerization process that uses an ionic liquid as a catalyst support (Chauvin et al., 1996). The process offers economic benefits over an existing IFP butene dimerization process widely used in the petrochemical industry. 

More detailed information on 1-butene dimerization over NiX is given in a publication (186) by the same authors of the above-mentioned patent... 

Fig. 18. 1-Butene dimerization over a NiX/Li20 catalyst at 180°C. (Reproduced from Ref. 187 with permission from the authors and La Chimica e L Industrial)...

The ionic liquid can, for example, be added to the butene effluent from the Dimersol process to obtain octenes by butene dimerization the octene can be carbonylated (Section 4.6) and hydrogenated to wo-nonanol, used to make phthalate plasticizers. In the case of the Phillips trimerization process the use of an ionic liquid allows an easy separation of the trimers and the catalyst for recycling (see also reviews to Section 5.5). However, the industrial use as solvents of ionic liquids, containing halide species (especially anions such as Bp4, PFg, or AlCU ) has the disadvantage that they readily break down to give HX, which can adversely affect the reaction. New types of non-halide containing ionic liquids are being actively researched. 

TMP and 2,3,4-TMP in TMP distribution at 60°c (Figure 2) could be due to increased degree of self-alkylation and butene dimerization, followed by rapid hydride and methyl group transfers. Based on the extrapolations from these two figures, the RON of C5+ alkylate at -40°C was calculated to be 102.7. The RON... 

Treatment with oxalic acid has been described as a method for selective removal of the external acid sites of medium-pore zeolites 61). PER and ZSM-23 zeolites were treated with a 1-M solution of oxalic acid at 353 K overnight 39, 62). The characterization of the acid sites showed that the treated materials had a low number of external acid sites compared with the untreated materials and, when used in n-butene isomerization, they exhibited an improved isobutylene selectivity. It was also observed that acid-treated PER does not have a high selectivity for isobutylene formation. It was inferred (62) that the cavities in ferrierite at the intersections of 8- and 10-ring channels are large enough to accommodate butene dimer intermediates, thus favoring the unselective bimolecular path. In contrast, when the external acid sites are removed from a zeolite with a unidimensional pore system (e.g., ZSM-23), the initial isobutylene selectivity is higher (nearly 80%) than that of the untreated sample. 

Thus propene dimers, e. g., at 50 °C, have a composition of 22 % n-hexenes, 72 % 2-methylpentenes, and 6% 2,3-dimethylbutenes. Under the same conditions, isomer structures of n-butene dimers are 6 % n-octenes, 59 % 3-methylheptenes, and 34 % 3,4-dimethylhexenes propene-butene codimerization yields the following isomer distribution 12% n-heptenes, 12% 2-methylhexenes, 40% 3-methyl-hexenes and 35 % 2,3-dimethylpentenes. The relative rate constants for codimerization are... 

Isooctenes (butene dimers) and isoheptenes (propene-butene codimers) are used as feedstocks for oxo synthesis, giving respectively isononanols and isooctanols to produce valuable phthalates. By-product trimers such as isononenes (propene) and isododecenes (butenes) are also hydroformylated to the corresponding alcohols (cf. Section 2.1.1). 

The same acidic chloroaluminate ionic liquids have been used as solvent for tungsten aryl oxide complexes for the metathesis of alkenes [24]. Slightly acidic chloroaluminates also dissolve the [Cl2W=NPh(PMe3)3] complex which catalyze ethene oligomerization without the addition of co-catalysts [25]. In a similar way, Ni-catalyzed 1-butene dimerization into linear octenes was carried out in acidic chloroaluminates buffered with small amount of weak bases [26]. Neutral chloroaluminates (l-ethyl-3-methylimidazolium chloride/AlCl3 = 1) were employed to immobilize ruthenium carbene complexes for biphasic ADMET (acyclic diene metathesis) polymerization of an acyclic diene ester [27]. 

C9 Isononyl alcohol, n-butenes dimer derived alcohols... 

Alkylphenol ethoxylates are important kinds of nonionic surfactants. A characteristic feature of the catalytic ethoxylation of alkylphenols is the enhanced reactivity of phenol hydroxyl for ethylene oxide in comparison with alcohols. Esters of ethylene glycol and alkylphenol behave already as an alcohol. Therefore di-, tri-, and m-mers are allowed to form only after the complete consumption of the starting material. All commercial ethoxylated alkylphenols are mixtures of oligomer-homologues having a Poisson-like distribution with some PEG and catalyst as impurities. Both alkylphenols and dialkylphenols are useful for ethoxylation as a hydrophobic moiety. Among the alkylphenols, isooctylphenol and isononylphenol are most widely used. They are synthesized by the Friedel-Crafts alkylation of phenol with butene dimer and mixture of propene trimers, respectively. 

Scheme 2 Butene dimerization by cationic nickel complexes. Reaction pathways for oligomer formation.

In the Difasol technology, the catalyst is dissolved in IL reaction products are poorly soluble. The reactants miscibility remains adequate to ensure reaction. Batch laboratory experiments on butene dimerization demonstrated that no reaction occurs in the organic phase. This indicates that the reaction takes place at the interface or in the ionic liquid phase. Experiments also proved that rising the mixing efficiency increases the reaction rate but does not change the octene selectivity. So excellent mixing is necessary to ensure good conversion by rapid mass transfer and efficient interaction of the ionic catalyst with the substrate. 

During 2003 we saw the first published process based on ILs [6], In its BASIL process (see Section 5.3.2), BASF has disclosed the involvement of an imidazolium-based ionic-liquid in the production of alkoxyphenylphosphines. This constitutes an impressive demonstration that IL technology can result in significant financial savings. Another process said to be poised for licensing is the French Petroleum Institute s butene dimerization process, the Difasol process (see Section 5.3.1). Besides these, some more promising applications are currently under investigation, and are hoped to be disclosed in the near future. Notable examples of research areas are in electrochemistry (batteries), biocatalysis, and the application of ILs in extraction processes, e.g., the deep desulfurization of diesel oil. 

IFF France has developed dimerization, hydrogenation, isomerization, and hydro-formylation reactions without conventional solvents. For butene dimerization a commercial process exists. There is formed a biphasic system with the catalyst in the IL phase, which is immiscible with the reactants and products. This system can be extended to a number of organometalhc catalysts. 

Linear 1-butene dimers can be selectively obtained from an [Ni(GOD)(hfacac)j catalyst precursor (Figure 14) immobilized in [G4-4-GiPyr]AlGl4 salt buffered by the addition of weak organic bases (such as A-methylpyrrole, quinoline, or pyridines). ... 

The alcohol part comes from variorrs synthetic sources. One source described in ht-erature is Cg alcohol mixture that is obtained by the hydroformylation and Itydrogenation of Cg olefin mixture obtained by dimerization of butene fraction. Two processes of purification are used by this technology. First corrsisterrt octene fraction obtained by the butene dimerization is purified by distillatiort. This is followed by rectification of reaction mixture obtained from alcohol productiorr. After the plasticizer is produced it is still purified by usual methods used in plastieizer syrrthesis. ... 

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