Monofunctional (Dimethylamino)silane as Silylating Agent

Abstract

SumrnuryThe reaction of triorganyl(dimethy1amino)silanes with surface-hydrated silicon dioxide has been studied. These silylating agents are easy to prepare from the corresponding chloro or bromosilanes with dimethylamine. The resulting products are thermally stable and relatively volatile. Reaction with surface-hydrated silicon-dioxide preparations at 150-250°C for 170 h yields a dense grafted layer. However, with (dimethy1amino)silanes having strongly polar substituents, a retreatment of the surfacemodified silica seems to be necessary in order to attain maximum coverage.Introduction. -In recent studies, surface-modified silicon-dioxide preparations prepared by heating surface-hydrated silica with triorganyl(dimethybamino)silanes [ 1-51 were applied. In the present paper we describe the synthesis and properties of these silylating agents giving some typical examples.

Purification of monoclonal antibodies from whole hybridoma fermentation broth by fluidized bed adsorption

“…For the large scale experiment, the amount of silanization reagent used was reduced from 135 pmol/m2 of specific surface (34-fold excess to the maximum ligand density, as theoretically derived by Szab6 et al 23) to 45 pmoYm2 (10-fold excess). The surface ligand density was calculated to be 3.4 *mourn2 in the small batch and to 1.6 pmoVm2 in the larger scale preparation.…”

Effect of acid pretreatment of the silica substrate on the stability of octadecyl modified reversed phases

“…Part of the silica that had been hydrated according to standard procedures was dehydrated at 450 ~ Subsequent hydrothermal treatment with a 0.1% (w/w) solution of hydrofluoric acid in deionized water at 95 ~ for 2 hours, increased the amount of the more reactive geminal silanol groups, Q2-groups, at the silica surface and drastically decreased the amount of ionic impurities present in the substrate (see Table I). The two substrates, untreated and pretreated, were modified with dimethylamine-dimethyloctadecylsilane (DMA-DMODS) [7,8] under identical experimental conditions. An excess of the mono-reactive silane was dissolved in n-pentane and added to the silica substrate under an atmosphere of nitrogen.…”

Characterization and stability of silanized and polymercoated octadecyl reversed phases

“…This silica was modified with dimethylamine-dimethyloctadecylsilane (DMA-DMODS) [18] to obtain a conventional monodentate bonded n-octadecyldimethylsilane phase for the comparison with the polymer-coated phases. The two polymethyloctadecylsilane (0.25 molar ratio noctadecyl groups, carbon coating = 53.8%) coated phases, one precapped with trimethylsilyl-2,4-pentanedione enolate [13], were prepared according to the procedures described previously [12,14], the non-precapped phase being meant as a model (see Introduction).…”

“…The chromatographic characterization was performed with the same equipment as described previously [3,7. For the Cis/A and CJPMSCis phases, adsorption isotherms of ethanol were determined to evaluate the amounts of accessible silanol groups left at the silica surface after modification [18]. Two columns (150 mm x 4.6 mm I.D.)…”