Zeolites function

There are several examples known where methylenecyclopropanes have been employed as cosubstrates in reactions of the Khand—Pauson type. Generally, this cobalt-mediated reaction is performed with hexacarbonyldicobalt complexes of alkynes, preferably strained alkenes such as norbornene or cyclobutene, and carbon monoxide to produce cyclopent-2-enones. Stoichiometric amounts of cobalt (in the form of the alkyne complexes) are normally needed. Methylenecyclopropane (1) can be employed as the strained alkene and reacts with a variety of alkynes to yield spiro-fused products. Silica gel or zeolites function as promoters of the reaction, giving rise to improved yields. ... 

Zeolites function as Bronsted or Lewis acid catalysts or (less frequently) as basic catalysts. Examples of the former are alkylation and isomerization of aromatics, such as the isomerization of xylenes an example of the latter is the use of cesium zeolite in the synthesis of the key intermediate, 4-methylthiazole, used in the preparation of the anthelmintic, thiabendazole. 

The object of this article is to review the present stage of mimicking the zeolitic functions, to highlight the achievement, although very preliminary, in constructing catalytic organic and metal-organic solids, and to discuss the problems... 

How does a zeolite function as a Lewis acid catalyst ... 

Fe-Zeolite Functionality, Durability, and Deactivation Mechanisms in the Selective Catalytic Reduction (SCR) of NOx with Ammonia... 

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