Decaborane, sublimation

Fig. 10. Apparatus for the sublimation of decaborane. (A) cold finger (B) ground-glass joint for connection to high-vacuum system (C) high-vacuum stopcock ...

Decaborane [J7702-41-9] M 122.2, m 99.7-100 . Purified by vacuum sublimation at 80°/0.1mm, followed by crystn from methylcyclohexane, methylene chloride, or dry olefin-free-n-pentane, the solvent being subsequently removed by storing the crystals in a vacuum desiccator containing CaCl2. 

Caution. The decaborane is purified by sublimation at 60° at 10 mm. The sublimation apparatus should he situated in a hood which is well shielded. If air should accidentally contact decaborane at elevated temperatures, a violent oxidative decomposition might result. Decaborane is toxic therefore one shoidd avoid breathing the vapor or allowing the compound to contact the skin. 

Decaborane can be satisfactorily purified by sublimation at 65-75° under high vacuum or by recrystallization from heptane. 

This reaction should be done in a well-ventilated hood, t The decaborane is purified by sublimation at 60° and lO" mm. t The n-propyl isocyanide is prepared by the method of Jackson and McKusick/ using 490 g. (2.S mole) of n-propyl iodide and 454 g. (3.3 mole) of silver cyanide. It is observed that, after a long induction period, the reaction becomes quite violent. It is suggested that one half of the propyl iodide be added initially and the other half be added drop by drop over a 2-hour period. The drj- product is used without the final fractional distillation indicated in the reference. 

All preparations are conducted under an atmosphere of prepurified nitrogen unless specified otherwise. Solvents are vacuum distilled from reservoirs containing appropriate drying agents. Decaborane(14) (See Chapter 5, Section 46) is freshly sublimed prior to use. 

In this study decaborane of research purity (99.8 moles%) was used in calibrating all the methods used. The decaborane was purified by subliming it twice, and the freezing point method was used to verify that not enough impurities were present to influence the results of this study significantly. 

Decaborane (Arfa Product) was sublimated by heating at about 70°C and was intfoduced into the vacuum chamber through a variable leak valve. Boron films were deposited on the heated substrate by thermal decomposition of the decaborane. 

---