Ethylene oligomers hydrogenation

Functionalized ethylene oligomer ligated rhodium(I) complexes were prepared and the hydrogenation of various alkenes including 1-octene, delta-2-cholestene, cyclooctene, cyclododecene, styrene, alpha-methylstyrene was studied 94). 

The products of reduction of salt anions are typically inorganic compounds like LiF, LiCl, Li20, which precipitate on the electrode surface. Reduction of solvents results, apart from the formation of volatile reaction products like ethylene, propylene, hydrogen, carbon dioxide, etc., in the formation of both insoluble (or partially soluble) components like Li2C03, semicarbonates, oligomers, and polymers.281 283 359 A combination of a variety of advanced surface (and bulk) analytical tools (both ex situ and in situ) is used286-321 332 344 352 353 360-377 to gain a comprehensive characterization... 

With monoalkyl-aluminum dichloride, on the other hand, no reduction occurs at room temperature and below. The catalyst remains in solution and in the presence of ethylene oligomer is formed. Evidently, the relatively low electrmi density at the Ti(IV) center (high electron affinity, high acidity, or however one wishes to express the situation) favors the molecular weight-reducing -hydrogen abstraction, Eq.(2). Not only the valency of the titanium ion itself, but also the presence of the acceptor ligands Cl at the titanium center and at the aluminum alkyl contribute to the acidity of the catalyst center. 

Grown Ethers. Ethylene oxide forms cycHc oligomers (crown ethers) in the presence of fluorinated Lewis acids such as boron tritiuoride, phosphoms pentafluoride, or antimony pentafluoride. Hydrogen fluoride is the preferred catalyst (47). The presence of BF , PF , or SbF salts of alkah, alkaline earth, or transition metals directs the oligomerization to the cycHc tetramer, 1,4,7,10-tetraoxacyclododecane [294-93-9] (12-crown-4), pentamer, 1,4,7,10,13-pentaoxacyclopentadecane [33100-27-6] (15-crown-6), andhexamer, 1,4,7,10,13,16-hexaoxacyclooctadecane [17455-13-9]... 

Watson et al.124-1261 studied the polymerization of ethylene and propylene with Lu(n5-C5Me5)2(CH3) ether in toluene or cyclohexane at 30-80 °C. The Lu complex produced polymers of Mn = 10M04 for ethylene, and oligomers for propylene. In the oligomerization of propylene an unusual chain transfer reaction due to 0-alkyl elimination was found together with P-hydrogen elimination from Lu-alkyls as chain-terminating processes 125). 

Recently it has been reported (5,66) that ethylene oxide leads to a mixture of cyclic oligomers of D. P. 3,4, 5,6,7,8 and 9 (7 4 6 6 2 1), unaccompanied by open-chain oligomers and polymers, when treated with fluorine-containing catalysts such as antimony pentafluoride or a 1 1 mixture of borontrifluoride and hydrogen fluoride. 

Chain Extenders and Cross-linkers. In addition to the two principal components of most urethane coatings, isocyanate and polyol components, a number of di- or polyfunctional, active hydrogen components may be used as chain extenders or cross-linkers. The most important classes of compounds for this use are diols or polyols (monomers or oligomers), diamines, and alkanolamines. Typical examples of diols are ethylene, dlethylene, dlpropylene glycol, 1,4-butanedio1, 1,5-hexanediol, neopentyl glycol,... 

Grown Ethers. Ethylene oxide forms cyclic oligomers (crown ethers) in the presence of fluorinated Lewis acids such as boron trifluoride, phosphoms pentafluoride, or antimony pentafluoride. Hydrogen fluoride is the preferred catalyst (47). The presence of PF , or SbF salts of... 

The rate of removal from a rhodium surface was much higher than from the surfaces of less active metals, in conformity with the kinetic model. Morever, the product obtained from the rhodium surface was largely ethane, whereas from the less active surfaces of other metals, saturated oligomers of ethylene were obtained also. This showed that the "acetylenic complexes" could polymerize on the surface, thus providing a route toward the known phenomenon of carbonization of catalyst surfaces during hydrogenation. 

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