Silane, silica-supported

Silica reinforced rubber, 22 703 Silica sheets, 22 383-385 Silica-silane system, 22 377-378 Silica sol-gel fiber processing, 23 80 Silica sols, 22 383, 473-474 applications of, 22 394 modification of, 22 393-394 preparation of, 22 392-393 properties of, 22 391-392 purification of, 22 393 Silica, solubility in steam, 23 212-213 Silica-supported activated manganese dioxide, 76 568... 

Most traditional methods use hydrochloric acid solutions as the acid reagent for the hydrolysis or alcoholysis of fi-lactams. Methanolic solutions of trimethylchloro-silane are able to generate HCI in situ, and the trick has been employed successfully for the methanolysis of fi-lactams in a route to aspartic acid derivatives [60, 61] and 2-oxazolidinones[62], respectively. Recently the use of silica-supported acid reagent has been reported as a convenient alternative. The reagent (Si02-Cl) prepared from admixing silica gel and SOCl2 in dichloromethane and subjected to dryness, is able to run the methanolysis of (1-lactams at room temperature in 20 min [63]. 

Representative silica-supported metal complex catalysts prepared by use of ligand silane coupling agentf 35... 

Fig. 4.11. (A) Generic representation of silane chemistry used to bond stationary phases onto silica supports. (B) Examples of packing materials that will enhance EOF. (C) Mixed-mode phase designed by El Rassi s group. Adapted from ref. [95] with permission. Copyright Wiley-VCH 1998.

Most often, pentanol or butyronitrile is used as the stationary phase loaded onto a hydrophobic support such as silanized silica. 

More usually, the liquid stationary phase is chemically bound to the inert support to give a bonded phase. This involves the formation of a (hydrolytically) stable bond, often, for example, between the surface silanol group of a silica support and a chlorosilane. The silane usually carries a hydrocar-... 

A recently developed thin-layer electrophoresis system which employs silanized silica gel with a 1-octanol surface coating as support, and aqueous borate as buffer, has been examined for the separation of mono-, oligo-, and poly-saccharides as well as phenolic compounds and other degradation products from the hydrolythermolysls of biomass. As expected, mobility depended upon the ability to complex... 

Separation of acid and neutral polysaccharides, e.g., those of food hydrocolloids (thickening agents, e.g., guar, gum arabic, carrageen, etc.) and pectins. The best supports are silanized glass fiber paper or silanized silica gel-l-octanol. 

The linear polymers and copolymers prepared by this approach were spin-coated onto various vinyl-silanized silica materials and subsequently cross-linked employing azobis-/-butyronitrile (AIBN) to yield a poly(succinic acid)-derivatized support (Figure 2). 

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