Alkali-Metal-Directed Hydrolytic Condensation of 3-Mercaptopropyltrimethoxysilane

Abstract

A series of solid sodium and potassium cyclotetrasiloxanolates was synthetized with high yields by hydrolytic condensation of 3-mercaptopropyltrimethoxysilane in the presence of potassium or sodium hydroxide. The obtained materials were characterized using solid state 29 Si and 13 C NMR, wide angle X-ray scattering (WAXS), elemental analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The influence of reaction conditions on the structure and physiochemical properties of the obtained products was studied.

Architecture of Silsesquioxanes

“…Besides reaction parameters, such as amount of water, alkoxide groups, and solvent, metal ions appear to influence the ring size of products, since they behave as structure-directing agents (Pozdniakova et al 2004). Variable-sized rings were obtained with transition and rare earth metal ions, while Na + and K + enable the synthesis of tri-and tetracyclosiloxanes (Hirotsu et al 2005;Bilyachenko et al 2007;Murugavel et al 1996;Molodtsova et al 2003;Nowacka et al 2015).…”

Well-defined cyclic silanol derivatives

“…30 Nowacka and co-workers reported the alkali-metal-directed hydrolytic condensation reaction of 3-mercaptopropyltrimethoxysilane in the presence of KOH or NaOH to produce solid potassium and sodium cyclotetrasiloxanolates with 3-mercaptopropyl groups. 79 The structures of these compounds were analyzed by solid state 29 Si NMR (−60.4 ppm), 13 C NMR, IR, element analysis and wide-angle X-ray scattering (WAXS). Under proper reaction conditions, the all-cis-stereoisomer of potassium cyclotetrasiloxanolate was exclusively obtained.…”

“…30 Scheme 12 Synthesis of potassium all-cis-tetra(3-mercaptopropyl) cyclotetrasiloxanolate and its postulated interactions between molecules. 79…”