Syntheses and Structural Analyses of 1,3-Diphenyldisiloxanes as a Building Block of Silsesquioxanes

Syntheses of novel 1,3-diphenyldisiloxanes were investigated. 1,1,3,3-Tetrachloro-1,3-diphenyldisiloxane (1) and 1,1,3,3-tetraisocyanato-1,3-diphenyldisiloxane (2) were obtained by vapor-phase hydrolytic condensation of trichloro(phenyl)silane and triisocyanato(phenyl)silane, respectively. The reactions of 1 with 2-propanol, t-butyl alcohol, and diethylamine provided 1,1,3,3-tetraisopropoxy-1,3-diphenyldisiloxane (3), 1,3-di-t-butoxy-1,3-dichloro-1,3-diphenyldisiloxane (5a), and 1,1,3,3-tetrakis(diethylamino)-1,3-diphenyldisiloxane (6), respectively. 1,3-Diisocyanato-1,3-diisopropoxy-1,3-diphenyldisiloxane (4) and 1,3-di-t-butoxy-1,3-diisocyanato-1,3-diphenyldisiloxane (5b) were synthesized by the reactions of 2 with 2-propanol and with t-butyl alcohol, respectively. Hydrolysis of 5a or 5b afforded 1,3-di-t-butoxy-1,3-diphenyldisiloxane-1,3-diol (7). 1,3-Diphenyldisiloxane-1,1,3,3-tetrol (8) was isolated from the hydrolysis of 1. A single crystal X-ray diffraction of 8 showed that four hydroxy groups are facing each other to form a ladder-type network by the intermolecular hydrogen bondings.