Synthesis of higher silanes and higher germanes - by pyrolysis in a column packed with glass wool and fractionation of the

摘要

Crude tri-, tetra- and penta-silanes are vaporised under high vacuum in a boiler heated with warm water, passed through a vertical Pyrex column packed with glass wool catalyst and heated by external electrical heating elements, the products being collected in a receiver at the top of the column cooled to -196 degrees C. The mixed products are fractionated by vapour phase chromatography at 220 degrees C. To produce up to 7-Si chains (n- and iso-heptasilane) the column is run at 420 degrees C, for 8-si chains at 410 degrees C, for 9-Si chains at 360 degrees C, and for 10-Si chains with a glass wool-silica gel-platinum (5%) catalyst at 410 degrees C. For the prodn. of higher germanes from trigermane the column is run at 300 degrees C. The fractionated higher silanes are diluted with benzene and frozen at -80 degrees C for storage. To increase yields the pyrolysis is repeated several times by deep cooling the original boiler and heating the original receiver, and vice-versa.