Silaethene : VI. Gasphasenpyrolyse phenylsubstituierter silacyclobutane

Abstract Gas phase pyrolysis (625 and 700°C, respectively, 10 -2 mbar) of phenyl-substituted mono- and di-silacyclobutanes is described. With high as gas density head-to-tail combination of the silaethene intermediates takes place, giving 1,3-disilacyclobutanes in yields up to 35%. At low gas density intramolecular follow-up reactions of SiC with the phenyl groups are preferred, which via silacyclooctatetraene, silacycloheptatriene and silabenzene lead to the observed condensate with benzene, cycloheptatriene, toluene, and cyclopentadiene as components. The results of the pyrolysis experiments are supported by the observed mass spectrometric fragmentation of the starting silacyclobutanes.