Exchange of Halide for Pseudohalides

Triphenyl telluronium chloride or methyl diphenyl telluronium iodide dissolved in hot water precipitated the corresponding telluronium pseudohalide when mixed with an aqueous solution of an alkali metal or silver pseudohalide. 

IViphenyl Telluronium Cyanate 0.15 g (1 mmol) of silver cyanate are dissolved in 850 ml of boiling water, 0.394 g (1 mmol) of triphenyl telluronium chloride dissolved in 50 ml of hot water are added, the mixture is stirred for several minutes, then cooled, and filtered. The filtrate is concentrated to a volume of 5 ml under vacuum, and the concentrate is cooled to 5° and filtered. The filtrate is allowed to stand for 48 h open to the atmosphere, the crystals are collected, crushed, and dried at 24° over phosphorus pentoxide yield 0.34 g (90%) m.p. 152°. Recrystallization from chloroform yields crystals containing 0.5 molecule of solvent. Similarly prepared was diphenyl methyl telluronium thiocyanate (m.p. 125°).  

Triphenyl Telluronium Azide A solution of 2.6 g (40 mmol) sodium azide in 100 ml of water is shaken with a solution of 2.0 g (5 mmol) of triphenyl telluronium chloride in 200 ml of chloroform. The organic layer is separated, dried with anhydrous magnesium sulfate, filtered, and the filtrate concentrated to a volume of 40 ml. The concentrate is cooled and slowly mixed with cold petroleum ether (b.p. 30-60°), and the precipitate is filtered off yield 1.5 g (80%) m.p. 165° (from toluene). 

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