日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

Orthosilicic acid, Si(OH)₄, and its small condensation compounds are among the most important silicon compounds. These compounds have long been known, but have never been isolated due to their instability. They would be highly useful compounds for advanced materials synthesis if they become available at high purity. We succeeded in developing a simple procedure to selectively synthesize orthosilicic acid, its dimer (disilicic acid), cyclic trimer, and tetramer by the hydrogenolysis reaction of benzyloxysilanes, as well as appropriate conditions to stabilize these species in organic solvents. Isolation of orthosilicic acid, dimer and the cyclic tetramer as hydrogen-bonded crystals with tetrabutylammonium halides (ⁿBu₄NX, X=Cl, Br) and of the cyclic trimer as solvent-containing crystals was achieved. The solid-state structures of these compounds were unambiguously clarified by single crystal X-ray diffraction analysis. The results make the family of silicic acid compounds available as building blocks for material synthesis.