The Formation and Properties of some Cyclic Compounds of Silicon and Tin

Abstract

Six and seven membered cyclic compounds of silicon and tin were prepared and investigated at low temperatures, using nuclear magnetic resonance spectroscopy. An attempt was made to prepare a suitable cyclic compound of tin, which would be capable of existing in geometrically isomeric forms. It was hoped that,having prepared such a compound,it would be of great value in studying the reaction mechanisms of tin.However, the compound was not successfully prepared and it was therefore decided to investigate further cyclic compounds of silicon, such as the siloxanes. Siloxanes are obtained principally from the hydrolysis of diorganohalosilanes.The hydrolysis of certain diorganohalosilanes, such as dimethyldichlorosilane and methylphenyldichlorosilane has been extensively investigated but little work has been reported on the hydrolysis of ethylmethyldichlorosilane. In this work, the hydrolysis of ethylmethyldichlorosilane has been investigated and the results obtained were found to be in agreement with those obtained for other diorganohalosilanes. The interest in the hydrolysis of this halosilane, was due to the possibility of the products existing in stereoisomeric forms, but although a considerable amount of time was spent in finding suitable instrumental conditions, no separation of the isomers was achieved. The addition of glycerol to the hydrolysis of diorganohalosilanes was investigated. A study was made, of both the hydrolysis of ethylmethyldichlorosilane and dimethyldichlorosilane with added glycerol and the results obtained were compared with previous experiments. Siloxanes were also obtained from both the hydrolysis and hydrogenolysis of bis(benzyloxy)ethylmethylsilane. The proportions of siloxanes obtained, from both reactions, were compared with those obtained from the hydrolysis of the diorganohalosilane. A further investigation was carried out into the hydrogenolysis of bis(benzyloxy )methylphenylsilane.