Lithium dimethylphosphide

Diethyl (trimethylsilyl) phosphine has been prepared by the reaction of lithium diethylphosphide with chlorotrimethyl-silane in ether solution.4 The lithium diethylphosphide may be prepared by the reaction of an ether solution of phenyllithium with diethylphosphine.6 However, the dialkylphosphines are most conveniently prepared by the reduction of the corresponding tetraalkyldiphosphine disulfides with lithium tetrahydro-aluminate in ether.6 7 An alternative method for the preparation of dimethyl(trimethylsilyl)phosphine which eliminates the handling of the volatile dimethylphosphine involves the preparation of lithium dimethylphosphide from tetramethyldiphosphine. The latter is prepared by the reduction of tetramethyldiphosphine disulfide8 with tributylphosphine.9 The reaction of chlorotrimethylsilane with lithium dimethylphosphide is most conveniently carried out in a vacuum system without solvent at -78°. 

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