N-Ethyl-N-(1,3,4-thiadiazol-2-yl)amidophosphoryl chloride is prepared by
refluxing 16.4 parts of 2-ethylamino-1,3,4-thiadiazole hydrochloride with 84
parts of phosphorus oxychloride for 6 h and then removing the excess
phosphorus oxychloride by distillation under reduced pressure. The residual oil
is washed with cold petroleum ether, dried and dissolved in 310 parts of dry
benzene.
The solution of N-ethyl-N-(1,3,4-thiadiazol-2-yl)amidophosphoryl chloride is
added slowly at 10°C to a mixture of 9.5 parts of ethylenimine, 30.3 parts of
triethylamine, and 44 parts of warm dry benzene. Agitation is continued for 2
h without cooling after which the triethylamine hydrochloride is filtered off.
The benzene is distilled from the filtrate under reduced pressure, and the
N,N'-diethylene-N''-ethyl-(N'-(1,3,4-thiadiazo-2-yl)phosphoramide is
recrystallized from hexane, melting point 95°-96°C.
