Condensation reaction between silane

In our search for a simple preparation of acrylated PDMS, the condensation reaction between silane I and a model compound, nonamethyltetrasiloxane-l-ol (II), 24) was studied. The model compound was chosen since its reactions can be easily monitored by gas chromatography. The silanol of the model compound is configurationally similar to the silanol of the readily available silanol terminated PDMS. The reaction of silane I with the model compound therefore should be an excellent barometer for reactions with silanol terminated PDMS. To further simulate the kinetic effect of the model reaction, octamethyltrisiloxane (MDM) was used as the solvent/diluent as well as the GC internal standard for the progres of the reaction. Surprisingly, the condensation reaction proceeded instantaneously upon mixing to form the desired 1-acryloxymethyl-undecamethylpentasiloxane with the concomitant liberation of one equivalent of acrylic acid as shown below ... 

At present, the only synthetic method leading to high molecular weight polysilanes is based on the Wurtz condensation reaction between dichlorodisubstituted silanes and alkali metals (low molecular weight oligomers were also prepared by dehydrogenation of secondary... 

Poly(w-carboranyl-siloxane) elastomers containing a mixture of di-methyl-and methyl(phenyl)-silyl units were synthesised using the Ferric Chloride catalyzed condensation reaction between di-chloro-di-organosilane and 1,7-bis(di-methyl(methoxy)silyl)-/w-carborane. Silica Nano tubes synthesised using i 7situ growth of DL Tartaric acid nanocrystals and concurrent sol-gel hydrolysis and condensation of silane. 

When moisture is present, then the picture becomes far more complex with hydrolysis and condensation reactions between both silane and the surface and with itself the main processes. 

A facile preparation of acrylate terminated silicones by the condensation reaction between the readily available silanol terminated silicone fluids and acryloxymethyldimethylacryloxysilane is described. The simplicity of the reaction provides a practical route for the preparation of UV curable silicones. The surprising ease of the reaction between the silane and silanol is attributed to the possible hypervalent silicon transition state even though Si-NMR evidence suggests the silane is tetracovalent. 

A silane-coupling agent improves the suitability of jute fibers as a reinforcing material. The reaction mechanism of silane treatment of jute fibers and silane treated jute-PP composites is shown in Scheme 7.2. Silane treatment of the jute fibers increased the fiber-matrix interaction through a condensation reaction between hydrolyzed silane and hydroxyl groups of jute cellulose. During the fracture process of silanized composites, the jute fibers were broken without complete... 

The main differences which made the Figure 3(d) and 3(e) stand out among all other figures are the peak of spectra at around 1017 cm and 1610 cm V Both absorption bands for both figures represented the appearance of C-N and C=N respectively. The presence of C-N stretching of amines confirms the condensation reaction between the hydrolyzed silane and hydroxyl groups of wood. Such reaction between Z-6011 with PC has been studied in our previous research [5]. 

Si(OC2H5). In the two-step process of hydrolysis of the silane to the silanol species and the condensation (silanols to siloxane), the reaction-determining step is the rate of hydrolysis [54]. However, for polyfunctional silanes, hydrolysis and condensation overlap. Under defined reaction conditions, the reaction between the surface hydroxyl groups of the sihca and the silane compound follows a distinct stochiometry, which can be expressed by the number of surface hydroxyl groups that react with the organosilane. For monofunctional silanes this ratio is unity. 

After hydrolysis, the silanol groups are able to condense with the reactive methylol groups in hydroxymethylated di- and trimelamine as well as with unbridged methylolated melamine species (Scheme 4) to yield the rigid and infusible three-dimensional networks between resin and silane after final curing. Of course, reactions between silanol groups and hydroxyl groups of the cellulose in the paper would seem to be possible, but this has never been proven without doubt. 

---