Interlayer Modification of a Layered Silicate RUB-18 with4-Phosphonophenylsilane and Its Surface Acidic Functions

The interlayer silylation of a layered silicate H-RUB-18 (Si4O7(OH)2) using a new aromatic silylating reagentcontaining a phosphonic acid group (4-phosphonophenylsilane:PPS) was demonstrated (H-PPS-RUB-18). The phosphonic acidgroups were attached to the silicate layers through the reaction ofH-RUB-18 with (4-diethoxyphosphorylphenyl)-triethoxysilane (p-PPS-E), and the ester moieties were subsequently hydrolyzed withhydrochloric acid. H-PPS-RUB-18 is a solid acid, as indicated bythe intercalation of various alkylamines and the catalyticacetalization of ketones. A systematic increase in interlayer spacingleading to surface acidic properties was obtained throughintercalation with a series of alkylamines. In addition, H-PPS-RUB-18 was exfoliated, resulting in single-layer nanosheets withca. 2.0 nm thickness. The catalytic acetalization of ketones was related to the interlayer spacing of the modified RUB-18

Automated summary

The interlayer silylation of a layered silicate H-RUB-18 using a new aromatic silylating reagent containing a phosphonic acid group (4-phosphonophenylsilane: PPS) resulted in a solid acid H-PPS-RUB-18, which was exfoliated into single-layer nanosheets with surface acidic properties. Control of the interlayer spacing of modified RUB-18 promoted the catalytic reaction of ketones.