Tetraphenylarsonium bromide

The hydrolysis product consists mainly of tetraphenylarsonium bromide, which is converted to tetraphenylarsonium chloride hydrochloride by crystallization from concentrated hydrochloric acid. 

A solution of tetraphenylarsonium bromide is prepared by dissolving 5 g (0.011 mole) of the bromide in 20 ml of anhydrous methanol. This solution is placed on the column and eluted to a total volume of 220 ml. Again, the flow rate from the column should not exceed 2 drops/sec. The eluate is evaporated to dryness under dynamic vacuum (10 torr) at ambient temperature. The yield, based on tetraphenylarsonium bromide, is 4.31 g (94%). If necessary, recrystallization is accomplished by dissolving the crude product in 20 ml of acetonitrile, followed by precipitation of the pure product by the addition of 75 ml of ethyl acetate. The cyanate is isolated by filtration, and the product is dried under dynamic vacuum at ambient temperature for 24 hr. Both recrystallization and filtration steps should be performed in a dry-box. Anal. Calcd. for C25H2oAsNO C, 70.59 H, 4.75 N, 3.29 As, 17.61. Found C, 70.3 H, 4.7 N, 3.2 As, 17.6. 

An equimolar amount of bromodiphenylbismuthine and tetraphenylarsonium bromide were dissolved in boiling acetone. By gradually evaporating the solution, the arsonium salt separated out as pale yellow needles, m.p. 179-182°C [69JOM(20)99]. 

Wittig and Clauss499 obtained pentaphenylarsenic by the action of phenyl lithium on triphenylarsine dichloride or tetraphenylarsonium bromide. The analogous reaction of methyllithium with trimethylarsine dibromide or tetra-methylarsonium iodide gave no isolable amount of pentamethylarsine, although the formation of small amounts of this product could be demonstrated among the others.500... 

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