Dedicated to Professor Helmut Dorfel on the occasion of his 60th birthdayZeolites have proved to be valuable technical catalysts in petrochemistry and in oil processing. The characteristic properties of zeolites, such as acidity, shape-selectivity and thermal stability also enable them to be used for highly selective synthesis in the fields of chemical intermediates and fine chemicals. This interesting area of application has grown continuously in recent years. The present article summarizes the various standard types of reaction involved in organic syntheses which can be catalyzed by zeolites; these include, inter alia, electrophilic and nucleophilic substitution reactions, isomerization of double bonds and carbon skeletons, as well as addition, elimination and hydrogenation reactions.
Once again we have found bulky substituents that enable the synthesis of a stable compound with a moiety that has virtually been discarded and contradicts the double bond rule. The silaimine 1, synthesized by thermal cleavage of LiCl, is an orange‐colored crystalline compound that melts without decomposition at 97–99°C.
Professor Helmut Dorfel zum 60. Gehurtstag gewidmetZeolithe als Katalysatoren haben sich in der Petrochemie und Mineralolverarbeitung groBtechnisch bewahrt. Die Zeolitheigenschaften wie Aciditat, Formselektivitat und Temperaturstabilitat lassen sich auch fur gezielte, hochselektive Synthesen im Zwischenproduktund Feinchemikalienbereich nutzen. Dieses interessante Einsatzgebiet hat sich in den letzten Jahren stetig ausgeweitet. Der vorliegende Beitrag faBt die in der organischen Synthese iiblichen Reaktionstypen zusammen, die mit Zeolithen katalysiert werden konnen; dazu gehoren z. B. elektro-und nucleophile Substitutionen, Doppelbindungs-und Skelettisomerisierungen sowie Additions-, Eliminierungs-und Hydrierungsreaktionen.
The sections in this article are
Introduction
General Principles Governing Precipitation from Solutions
Physico‐Chemical Considerations
Chemical Considerations
Process Considerations
Influencing the Properties of the Final Product
Influence of Raw Materials
Influence of Concentration and Composition
Solvent Effects
Influence of Temperature
Influence of
p
H
Influence of Aging
Influence of Additives
Prototypical Examples of Precipitated Catalysts and Supports
Silica as Support Material
Active Aluminas
Ni
/Al
2
O
3
Catalysts by Coprecipitation
V
/
P
/
O
Catalysts for Butane Oxidation to Maleic Anhydride
Conclusions
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