Reactive silica. I. Formation of a reactive silica by the thermal collapse of the methoxy groups of methylated Aerosil

EPR and IR spectral properties of hydrogen-associated bulk and surface defects inSiO2:Ab initiocalculations

“…These modes are red-shifted compared to the monohydrosilane by Ϸ40-50 cm Ϫ1 . In the experiment a single band has been observed at 2225-2230 cm Ϫ1 , with a redshift of Ϸ70 cm Ϫ1 compared to the band at 2300 cm Ϫ1 , and attributed either to the monohydride [51][52][53] or to both s and as stretchings of the dihydride. 6,16 Again, our data are consistent with the assignment proposed by Radzig and co-workers.…”

“…A band around 2300 cm Ϫ1 has been observed on the surface of activated silica by Radzig and co-workers 6,16 and by Morterra and Low. [51][52][53] In their original work, Morterra and Low 51-53 assigned this band to the dihydride, while Radzig and co-workers 6,16 suggested that this band is due to the monohydride. Our results support this second assignment.…”

Quantitative estimation of the reactivity of the surface of solids on the basis of inductive constants

“…Compounds with type 1 and 3 fragments were synthesised by the reactions These reactions were monitored by IR spectroscopy directly in the IR cell serving as the reaction vessel, by following the disappearance of the absorption band for isolated Si7OH groups (3750 cm 71 ) and the appearance of bands for the methoxy group [n(C7H) = 2930 and 2970 cm 71 ]. During high-temperature treatment, the methoxy groups were detached as formaldehyde to give silica hydride 24 with n(Si7H) = 2280 cm 71 . The last reaction was accompanied by the appearance of absorption bands for the methyl groups with n(C7H) = 2920 cm 71 .…”

Silica hydride intermediate for octadecylsilica and phenyl bonded phase preparation via heterogeneous hydrosilation in supercritical carbon dioxide

“…Hydrosilation of alkynes has been exploited as a means of introducing a bidentate linkage onto a phase [20]. It has been reported that the successful conversion of surface silanols to surface silica hydride groups is the key to producing an effective bonded phase for chromatography [21]. Silica functionalisation must result in a high coverage of hydride groups on the surface as the amount of these hydride groups will determine the phase loading of the final bonded phase.…”