By Reaction with Metals and Alkylating Agents

In contrast to the liquid ammonia reaction trisodiumphosphide, Na3P, is the major product resulting from the reaction of white phosphorus (red phosphorus, proved less satisfactory) with sodium potassium alloy or with sodium dispersions in inert organic media (e.g. toluene) at temperatures varying from 80 to 145 °C The phosphide Na3P reacts readily with methyl halides in glyme solvents to afford methylphosphorus compounds in ca. 60% overall yields under optimum 

The claim that trialkylphosphine oxides are obtained by treating elementary phosphorus with sodium and alkyl halide during heating at 400 °C in an organic solvent is surprising 

From this type of reaction one would have expected the formation of tertiary phosphines. 

---