Patent GB-735910-A (GB)
Title: Process for the manufacture of octaalkylpyrophosphoramides
Inventor: TOLKMITH HENRY
IPC: C07F9/24
Filed: 1953-03-18
Abstract: A pyrophosphoramide of the formula: <FORM:0735910/IV (b)/1> is obtained by subjecting a tris-(tetraalkyl-diamide phosphoryl) phosphate of the formula: <FORM:0735910/IV (b)/2> to a temperature greater than 135 DEG  C. while admixed with a hexaalkylphosphoramide of the formula: <FORM:0735910/IV (b)/3> each of the radicals R3 being an alkyl group containing from 1 to 4 carbon atoms and each R being identical.  It is preferred to employ at least 1 molecular proportion of the hexaalkylphosphoramide for each molecular proportion of the tris-(tetraalkyldiamidophosphoryl) phosphate.  The tris-(tetraalkyldiamidophosphoryl) phosphate may be obtained by reacting at least three molecular proportions of a compound of the formula <FORM:0735910/IV (b)/4> with one molecular proportion of a compound of the formula P(O)(Y)3 as disclosed in Specification 711,679, X being chlorine when Y is R1O or being R1O when Y is chlorine, and R and R1 being alkyl radicals containing 1 to 4 carbon atoms inclusive, each of the radicals R being identical and the radicals R and R1 being the same or different.  In carrying out the process for producing the octaalkylpyrophosphoramides it is not necessary to isolate the tris - (tetraalkyldiamidophosphoryl) phosphate when the latter is prepared by the above procedure.  Thus, the process may be carried out by subjecting the precursors of the tris-(tetraalkyldiamidophosphoryl) phosphates to a temperature greater than 135 DEG  C. while admixed with the hexaalkylphosphoramide, e.g. by heating a tetraalkyldiamidophosphoric chloride and a tri-(lower alkyl) phosphate to a temperature greater than 135 DEG  C. while admixed with the hexaalkylphosphoramide, or by subjecting phosphorus oxychloride and a suitable O-(lower alkyl) tetraalkyldiamidophosphate to a temperature greater than 135 DEG  C. while admixed with the hexaalkyl phosphoramide.  In each of the methods described the heating is generally carried out for a period of 2 to 12 hours or longer.  In examples, tris-(tetramethyldiamidophosphoryl) phosphate is mixed with hexamethyl phosphoramide and the mixture heated for 5 hours at 150 DEG  C. and then distilled under reduced pressure at temperatures up to 170 DEG  C. to yield a residue which is subjected to molecular distillation to yield octamethylpyrophosphoramide; (2), (3) and (4) octamethylpyrophosphoramide is obtained by heating a mixture of tetramethyldiamido phosphoric chloride, triethyl phosphate and hexamethylphosphoramide at temperatures up to 155 DEG  C. until the evolution of ethyl chloride is complete; (3) a mixture of O-ethyl tetramethyldiamidophosphate, phosphorus oxychloride and hexamethylphosphoramide is heated at 150 DEG  C. until the evolution of ethyl chloride is complete.  The mixture is then distilled under reduced pressure at temperatures up to 170 DEG  C. and the residue fractionated in a molecular still to yield octamethylpyrophosphoramide.  Other products specified are octabutyl-, octaethyl-, octapropyl-, octaisopropyl-, and octasecondarybutyl-, pyrophosphoramides and methods of preparing these are given.  The octaalkylpyrophosphoramides are stated to be of value as toxic constituents of parasiticide compositions. U.S.A. Specification 2,502,966 also is referred to.