Dimerization of olefins

Flowever, information concerning the characteristics of these systems under the conditions of a continuous process is still very limited. From a practical point of view, the concept of ionic liquid multiphasic catalysis can be applicable only if the resultant catalytic lifetimes and the elution losses of catalytic components into the organic or extractant layer containing products are within commercially acceptable ranges. To illustrate these points, two examples of applications mn on continuous pilot operation are described (i) biphasic dimerization of olefins catalyzed by nickel complexes in chloroaluminates, and (ii) biphasic alkylation of aromatic hydrocarbons with olefins and light olefin alkylation with isobutane, catalyzed by acidic chloroaluminates. 

Isobutylene could be dimerized in the presence of an acid catalyst to diisobutylene. The product is a mixture of diisobutylene isomers, which are used as alkylating agents in the plasticizer industry and as a lube oil additive (dimerization of olefins is noted in Chapter 3). 

Treatment of 19 with ethy(aluminum sesquichloride or aluminum bromide results in the formation of a new catalyst, which is active for the dimerization of olefins such as ethylene or propene but inactive for the dimerization of cyclooctene. 

Periana and Goddard et al. also found that the iridium(III) vinyl bis-acetylace-tonate complex (Vinyl-Ir-Py, 26) catalyzes dimerization of olefins (e.g., 21) [106, 107]. Analogously to the hydroarylation of Scheme 8, the mechanism is proposed to... 

We have emphasized that the Diels-Alder reaction generally takes place rapidly and conveniently. In sharp contrast, the apparently similar dimerization of olefins to cyclobutanes (5-49) gives very poor results in most cases, except when photochemically induced. Fukui, Woodward, and Hoffmann have shown that these contrasting results can be explained by the principle of conservation of orbital symmetry,895 which predicts that certain reactions are allowed and others forbidden. The orbital-symmetry rules (also called the Woodward-Hoffmann rules) apply only to concerted reactions, e.g., mechanism a, and are based on the principle that reactions take place in such a way as to maintain maximum bonding throughout the course of the reaction. There are several ways of applying the orbital-symmetry principle to cycloaddition reactions, three of which are used more frequently than others.896 Of these three we will discuss two the frontier-orbital method and the Mobius-Huckel method. The third, called the correlation diagram method,897 is less convenient to apply than the other two. 

Ordinary aldehydes and ketones can add to olefins, under the influence of uv light, to give oxetanes. This reaction, called the Patemo-Btichi reaction,781 is similar to the photochemical dimerization of olefins discussed at 5-49. In general, the mechanism consists of the... 

All-carbon 2 + 3 cycloadditions 5-49 Dimerization of olefins 5-50 Addition of carbenes or carbenoids to olefins or alkynes 5-51 Tetramerization of alkynes... 

Phenanthroline in the presence of heavy metals acts as an activator of the polymerization of vinyl compounds558,559 and other olefins.560-564 It also assists the dimerization of olefins in the presence of titanium catalysts.565,566 It enhances the metal catalyzed oxidation of ascorbic acid567 and dimethyl sulfoxide.568 On the other hand, on its own it can inhibit several polymerization processes.545,569 It also stabilizes butadiene and isoprene and prevents their dimerization.570 It prevents peroxide formation in ether,571 inhibits the vinylation of alcohol572 and stabilizes cumyl chloride.573 It accelerates the vulcanization of diene rubbers574 and copolymers.575 1,10-Phenanthroline catalyzes the autooxidation of linoleic and ascorbic acids in the absence of metals.567... 

A comparable positive influence as experienced with anodic dimerization of olefins, styrene in particular, exerts carbon anodes on the anodic formation of trisarene sulfonium cations by anodic coupling of diarylsulfide radical cations to arenes (226-228). 

The alkylation of alkyl-substituted aromatic hydrocarbons by propylene and isobutylene described by Pines and Schaap (1960), and the dimerization of olefins with organo-alkali metal compounds, are also found to proceed most easily when primary carbanions are formed since they are more stable than secondary and particularly tertiary carbanions. 

Kinetics of the photochemical dimerization of olefins to cyclobutane derivatives. I. Intramolecular addition. J. Amer. chem. Soc. 84, 4141 (1962). 

Bonneviot, L., Ohvier, D. and Che, M. Dimerization of olefins with nickel surface complexes in X-type zeohte or on silica, J. Mol. Catal., 1983, 21, 415 130. 

The dimerization of olefins is among the earliest systematically documented reactions that occur in organic solids, with examples dating back to 1877 [23,24]. More recently, the potential of correlating information from x-ray structural analysis and photochemical reactivity to obtain insight into the reaction mecha-... 

The tetramethylene diradical was also proposed as the intermediate for dimerization of olefins and [2 + 2] mixed additions between olefins. Hospool [105] suggested that if a triplet mechanism was operative, the produced diradical intermediate would undergo free rotation before the closure of the final bond and... 

Table 7.2 Dimerization of Olefins and Aromatic Compounds Singlet and Triplet...

Arene complexes have been found to be catalysts for the polymerization, hydrogenation, dismutation, and oxidative dimerization of olefins... 

Another reaction of this type is the nonoxidative dimerization of olefins. They very likely proceed via palladium-hydride species which may be formed by a small amount of oxidation of the olefin. Often Pd(II)-olefin 7T complexes are used. Kawamoto et al. (155) have recently reported the dimerization of styrene and vinyl compounds using the styrene Pd(II) tt complex. Also, it has been reported (254) that phosphine complexes, Pd(PPh3)4 or (PPh3)aPdX2 (X = Ng or NCO), have been employed to give a novel dimerization of malonotrile ... 

The dimerization of olefins catalyzed by noble metal compounds is a non-oxida-tive reaction (eq. (32)). It takes place in the absence of any other reactant and often accompanies other reactions [78],... 

The dimerization of olefins in the presence of potassium or sodium graphites is also important, and has been used as the basis of an industrial process. The products of reaction depend on the temperature with, for example, propylene giving 4-methylpent-l-ene (>100 C, <140°C), 4-methylpent-2-ene (> 140 °C, < 160 °C) or 2-methylpenet-2-ene (> 160 °C) over sodium graphite. 

Anionic metal complexes such as those of Co(I) (including vitamin Bijs often exhibit high nucleophilic reactivities in reactions such as equation (j) and have been termed supemucleophiles . Protonation constitutes an important route for formation of metal hydrides, reflected in the roles of acids as cocatalysts, e.g., in the Rh(I)-catalyzed isomerization and dimerization of olefins ... 

Air oxidation of a variety of aliphatic and alkyl aromatic compounda air oxidation of p-nitrotoluene sulfuric acid substitution chlorination of a variety of organic compounds reaction between isobutylene and acetic acid oxidation of ethylene to acetaldehyde (Wacker processes) hydrochlorination of olehns absorption of phosphine in an aqueous soluhon of formaldehyde and hydrochloric acid acehc acid from the carbonylation of methanol oxidation of tri-alkyl phosphine dimerization of olefins. 

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