Dimethylhydrazino diphenylphosphine

Submitted by Haury H. Sisler and II. P. Nielsen Checked by T. H. DEXTERf and D. J. jAszKAf 

A 500-ml. three-necked flask is fitted with a pressureequalizing dropping funnel of about 200 ml. capacity, a glass-joint-type mechanical stirrer, and a desiccant-filled 

Stirring is begun and the flask is cooled in an ice bath. The contents of the addition funnel are added dropwise over a 90-minute period with constant stirring and cooling. When addition is complete, the ice bath is removed and the mixture is stirred for an additional 30 minutes at 40 to 50°. During this period, the crystals of unsj/m-dimethylhydra-zinium chloride increase in size and thus become easier to remove by filtration. 

Additional lower-melting product of 85 to 90% purity can be recovered by evaporation of the hexane mother liquor. 

Further purification can be effected by sublimation at 60 at 0.1 mm. of Hg. About 55 g. of purified product melting at 68.5 to 69.5° is normally obtained (84% yield). 

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Dimethylhydrazino)diphenylphosphine may be prepared by the action of wnsym-dimethylhydrazinet on diphenylphosphinous chloride in benzene at temperatures just below room temperature. A 2 1 mol ratio provides an extra mol of the free base to act as a hydrogen chloride acceptor. The M7Wi/m-dimethylhydrazinium chloride, which is only very slightly soluble in benzene, may be easily removed by filtration. The hydrazinophosphine may then be recovered from the filtrate in good yield by evaporation of the solvent at room temperature under reduced pressure. 

The (2,2-dimethylhydrazino)diphenylphosphine forms colorless needle-like or prismatic crystals. It is soluble in benzene, ether, chloroform, and alcohol. Hydrolysis occurs in water to yield free Mwsym-dimethylhydrazine and diphenylphosphinous acid, which is readily oxidized to diphenylphosphinic acid upon contact with air. 

Boiling a solution of (2,2-dimethylhydrazino)diphenyl-phosphine in benzene overnight in contact with dry air causes precipitation of the oxide, (C8H5)2P(0)NHN(CH3)2 (m.p. 167 to 168°). Addition of a stoichiometric amount of sulfur to a boiling benzene solution of (2,2-dimethylhydrazino) diphenylphosphine yields, on cooling, the sulfide, (C H5)2P(S)NHN(CH3)2 (m.p. 95.5 to 97.0°). Alkylation to [(C6H5)2(CH3)PNHN(CH3)2]I (m.p. 156 to 158°) occurs upon reaction with methyl iodide in ether. Reaction with chloramine in ether yields the aminophosphonivun salt, [(C,H,)2P(NH2)NHN(CH,)2]C1 (m.p. 195°). All of the above-described derivatives are colorless solids. 

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