Transesterification metal alkoxide synthesis

The scope of organic synthesis, essentially, is the synthesis of new molecules from existing molecules. The addition reactions could be realized as a very important category in which two or more different molecules reacted with each other to form a new compound. Transesterification and cyclization reactions also have been used for the synthesis of new compounds, sometimes. There are excessively other reactions in this area but we only consider some of them which could be catalyzed or co-catalyzed with metal alkoxides. There are also many routs for the classification of these reactions but the focus of this chapter is on metal alkoxides so we use particular types of metal for this purpose and divide metals to four categories of s-block (alkali and alkaline earth), p-block, d-block (transition), and f-block (actinides and lanthanides) metals. 

In addition to the above, alcoholysis or transesterification reactions of metal alkoxides themselves have been widely used for obtaining the targeted homo- and heteroleptic alkoxide derivatives of the same metal. Since the 1960s, the replacement reactions of metal dialkylamides with alcohols has provided a highly convenient and versatile route (Section 2.9) for the synthesis of homoleptic alkoxides of a number of metals, particularly in their lower valency states. 

Higher alkoxides, such as tetra(2-ethylhexyl) titanate, TYZOR TOT [1070-10-6]9 can be prepared by alcohol interchange (transesterification) in a solvent, such as benzene or cyclohexane, to form a volatile azeotrope with the displaced alcohol, or by a solvent-free process involving vacuum removal of the more volatile displaced alcohol. The affinity of an alcohol for titanium decreases in the order primary > secondary > tertiary, and branched > unbranched. Exchange processes are more convenient than direct synthesis of tetraalkoxide from TiCl an alcohol, and a base because a metal chloride need not be handled. However, in general, traces of impurities of mixed tetraalkyl titanates can result. 

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