GB833566A - Improvements in or relating to the purification or recovery of diborane - Google Patents

Abstract

Ethane is removed from diborane by contacting with pyridine in excess so as to form a pyridine-diborane complex, removing the ethane and excess pyridine from the complex by fractional distillation, treating the complex with boron trifluoride in excess, preferably via a gas diffuser, so as to form a pyridine-boron trifluoride complex and liberate the diborane as a gas, passing the gaseous diborane through 1,4-dioxane in excess, so as to remove boron trifluoride therefrom by the formation of a 1,4-dioxane-boron trifluoride complex, cooling the still gaseous diborane so as to fractionally condense dioxane therefrom, e.g. by passing through a dry ice trap, and recovering the diborane, e.g. by collecting it as a liquid in a liquid nitrogen trap. The diborane may be distilled through a one metre packed column to give a product of 99.9% purity. An example is given (see Group IV (b)).ALSO:A pyridine-diborane complex (m.p. 11 DEG C.) is produced by introducing diborane containing ethane as impurity into an evacuated reaction vessel containing pyridine in excess, while the vessel is immersed in ice water, at a rate such that the temperature does not exceed 70 DEG C. during the reaction, cooling to 20 DEG C., and pumping off the ethane impurity together with excess pyridine. A pyridine-boron trifluoride complex is produced by melting the above complex in the reaction vessel, introducing boron trifluoride in excess into the vessel, while the vessel is again immersed in ice water, at a rate such that the temperature does not exceed 70 DEG C. When the pressure in the vessel reaches 100-150 p.s.i., the introduction of the boron trifluoride is interrupted and the vessel shaken until the pressure becomes constant. The liberated diborane is then pumped from the vessel. The process of introducing the boron trifluoride and removing the diborane liberated is then repeated until all the boron trifluoride has been added.