Organosiloxane oligomers synthesis

Starting in the 1950s a process was developed that leads from small-molecule silicon alkoxides such as tetraethoxysilane (tetraethyl orthosilicate), to organosiloxane oligomers and low polymers, and eventually to silica via a low temperature synthesis route.14 24 A simplified outline of the basic chemistry is shown in reactions (l)-(4), where R is an ethyl or higher alkyl unit. Any or all of the Si-OR bonds can be... 

In contrast to the hydrolysis technology, the methanolysis process allows for the one-step synthesis of organosiloxane oligomers and methyl chloride without formation of hydrochloric acid (64,65). The continuous methanolysis can also yield quantitatively linear silanol-stopped oligomers by recycle of the cyclic fraction into the hydrolysis loop. 

Synthesis of Organosiloxane Oligomers with Cyclic Fragments in the Side Chain by the Reaction of Catalytic Dehydrocondensation... 

As it is well known, the (Si-0) bond in organosiloxanes may be considered to be polar or partially ( 50%) ionic.(12) Therefore, it can be cleaved by the attack of strong acids or bases. This is the main rationale behind the "equilibration" route to the synthesis of a wide variety of functionally terminated siloxane oligomers(12-14) from cyclic siloxanes and a.ordifunctional disiloxanes as shown in Scheme 3. 

---