Interlayer Silylation of Layered Octosilicate with Organoalkoxysilanes: Effects of Tetrabutylammonium Fluoride as a Catalyst and the Functional Groups of Silanes

Abstract

Interlayer silylation of layered sodium octosilicate (Na-Oct) with various organoalkoxysilanes was conducted using hexadecyltrimethylammonium ion-exchanged layered octosilicate (C 16 TMA-Oct) as an intermediate in the presence or absence of tetrabutylammonium fluoride (TBAF). The degree of silylation was increased by adding TBAF. It is suggested that F À ions perform a nucleophilic attack on the alkoxysilanes, which promotes the silylation reaction. C 16 TMA-Oct was silylated with octyltriethoxysilane (C 8 TES) or 3-mercaptopropyltriethoxysilane (MPTES) to compare the reactivity of the two organoalkoxysilanes in the presence or absence of TBAF. A higher degree of silylation of C 16 TMA-Oct was observed with MPTES, suggesting the higher accessibility of this silylating agent into the interlayer polar region of C 16 TMA-Oct. Overall TBAF appears as a relevant catalyst for the covalent interlayer surface modification of layered silicates with organic functional groups.

Novel Floating Adsorbent for Water Treatment: Organically Modified Layered Alkali Silicate by Facile Mechanochemical Reaction

“…29 Si MAS NMR spectra of octosilicate and F-octosilicate are shown in Figure B. The signals ascribable to Q 3 and Q 4 environments of Si were observed at −100 and −110 ppm for both samples, which is consistent with the previous studies. ,− After the surface modification, the decrease in the intensity of the Q 3 signal was much smaller when compared with those reported for the grafting of the interlayer space, ,, suggesting the grafting occurred only on the external surface. − The presence of F as shown by 19 F MAS NMR and XPS spectra (Supporting Information, Figure S1) supported the attachment of the ([3-(2,3,4,5,6-pentafluorophenyl)­propyl]­silyl group on the silicate.…”

“…The signals ascribable to Q 3 and Q 4 environments of Si were observed at −100 and −110 ppm for both samples, which is consistent with the previous studies. 17,38−41 After the surface modification, the decrease in the intensity of the Q 3 signal was much smaller when compared with those reported for the grafting of the interlayer space, 17,40,41 suggesting the grafting occurred only on the external surface. 34−41 The presence of F as shown by 19 The FT-IR spectrum and the XRD pattern of F-octosilicate are provided in the Supporting Information in Figure S2.…”

Immobilization of isolated dimethyltin species on crystalline silicates through surface modification of layered octosilicate

“…[57][58][59] For Me 2 Sn-Oct_X (Fig. 2(A)(b)-(e)), the band of Si-OH groups (960 cm −1 ) decreased from that of C 16 TMA-Oct. A similar decrease was observed upon silylation, 46 suggesting that a condensation reaction occurred between the SnCl and SiOH groups. These results suggest the immobilization of methyltin groups on the layer surfaces.…”

“…Na-Oct and hexadecyltrimethylammonium ion-exchanged octosilicate (C 16 TMA-Oct) were synthesized following the previous reports. 45,46 Fumed silica, NaOH, and deionized water were mixed at a molar ratio of 4 : 1 : 25.8 in a Teflon beaker, and the mixture was aged for 1 h. Hydrothermal treatment was conducted in a Teflon-sealed autoclave at 100 °C for 4 weeks. The product was washed with deionized water and air-dried at 45 °C to obtain Na-Oct.…”

“…Na-Oct and hexadecyltrimethylammonium ion-exchanged octosilicate (C 16 TMA-Oct) were synthesized following the previous reports. 45,46 Fumed silica, NaOH, and deionized water were mixed at a molar ratio of 4 : 1 : 25.8 in a Teflon beaker, and the mixture was aged for 1 h. Hydrothermal treatment was conducted in a Teflon-sealed autoclave at 100 °C for 4 weeks. C 16 TMA-Oct (0.2 g) in a Schlenk flask was dried by vacuum heating at 120 °C for 3 h. Dichloromethane (10 mL), pyridine (5 mL), and Me 2 SiCl 2 (0.44 mL) were added under the N 2 atmosphere, and the mixture was stirred at room temperature for 1 d under a nitrogen atmosphere.…”