Oligomerization process chemistry

For a brief introduction to the oligomerization process, see a) J. P. Collman, L. S. He-gedus, J.R. Norton, R.G. Finke, in Principles and Applications of Organotransition Metal Chemistry, University Science Books Mill Valley, CA, 1987, 593-600 b) For a recent review, see ... 

Biphasic catalysis is not a new concept for oligomerization chemistry. On the contrary, the oligomerization of ethylene was the first commercialized example of a biphasic, catalytic reaction. The process is known under the name Shell Higher Olefins Process (SHOP) , and the first patents originate from as early as the late 1%0 s. 

Metal-catalyzed oligomerizations are important reactions concerning both their chemistry and practical applications.12 36 37 Since the catalysts [(Ti(IV), Zr(TV), Ni(I), and Ni(II) complexes] used in coordination polymerization can also be active in oligomerization, catalyst systems and mechanisms will be discussed in more detail in Section 13.2.4. A short discussion of oligomerization with emphasis on the most important processes of practical significance, however, is appropriate here. 

A new step in this story was linked to the oligomeric oxoalkoxocomplex-es, whose role in the chemistry of alkoxides and apparently in sol-gel processing is extraordinarily important. The reliable data on these compounds were received first in the 1960s due to determination of the molecular structures of the crystalline primary products of hydrolysis such as Ti7O4(OEt)20 [457, 1414, 1719], NbgO10(OEt)20 [219, 911], and Zr1308(OMe)36 [1173] (Fig. 4.14). 

The pioneer work in this field was carried out on polystyrene-supported acid catalysts [161]. Thereafter, several works on the use of sulfonic, strong acidic cation exchangers as acid catalysts were reported for alkylation, hydration, etherification, esterification, cleavage of ether bonds, dehydration, and aldol condensation [162,168-171], Besides, industrial applications of these materials were evaluated with reactions related to the chemistry of alkenes, that is, alkylation, isomerization, oligomerization, and acylation. [163,169], Also, Nation, an acid resin which has an acid strength equivalent to concentrated sulfuric acid, can be applied as an acid catalyst. It is used for the alkylation of aromatics with olefins in the liquid or gas phases and other reactions however, due to its low surface area, the Nation resin has relatively low catalytic activity in gas-phase reactions or liquid-phase processes where a nonpolar reactant or solvent is employed [166],... 

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