A NEW APPROACH FOR THE PREPARATION OF A HYDRIDE-MODIFIED SUBSTRATE USED AS AN INTERMEDIATE IN THE SYNTHESIS OF SURFACE-BONDED MATERIALS

A new approach to produce a hydride-modified support which serves as an intermediate for the synthesis of chromatographic bonded phases is investigated. The procedure, referred to as ''silanization'', involves the controlled deposition of the hydrolysis product of triethoxysilane (TES) or related silanes to preferentially form an SI-H monolayer on inorganic oxide substrates such as silica. Chemical and spectroscopic, as well as thermal, analyses are employed for the characterization of the intermediate. This synthetic route was developed to improve an existing method for producing a surface uniformly covered with active sites required for further modification via SIH addition to terminal olefins. With the new approach the time-consuming processes associated with the previously reported chlorination/reduction procedure are eliminated. In addition to its greater simplicity, silanization with TES provided superior SIH coverages as compared to the previous method. A number of commercially available silica substrates were subjected to an optimum silanization procedure, and the resulting materials were further derivatized with 1-octene in the presence of a platinum catalyst. The octyl-bonded phases obtained were shown to have good ligand density as well as enhanced resistance to phase deterioration as compared to conventional octyldimethylsilyl silicas.