Manufacture of tetraethyl pyrophosphate

Claim 1

IN A PROCESS FOR SEPARATING TETRAETHYL PYROPHOSPHATE FROM A MIXTURE COMPRISING PREDOMINANTLY TRIETHYL PHOSPHATE, TETRAETHYL PYROPHOSPHATE AND HIGHER POLYPHOSPHATES, THE STEPS COMPRISING DISSOLVING SAID MIXTURE CONTAINING TETRAETHYL PYROPHOSPHATE IN AN AQUEOUS SUBSTANTIALLY 9% SODIUM CHLORIDE SOLUTION AT SUBSTANTIALLY 30*C., APPROXIMATELY FIVE MINUTES THEREAFTER EXTRACTING SAID AQUEOUS SOLUTION WITH AN ALIPHATIC SOLVENT SELECTED FROM THE SATURATED ALIPHATIC HYDROCARBONS CONTAINING AT LEAST 6 AND NOT MORE THAN 8 CARBON ATOMS, SEPARATING SAID ALIPHATIC SOLVENT LAYER FROM THE AQUEOUS LAYER, EXTRACTING SAID AQUEOUS LAYER FROM THE ALIPHATIC SOLVENT EXTRACTION WITH MONOCHLOROBENZENE, SEPARATING THE MONOCHLOROBENZENE AND AQUEOUS LAYERS, WASHING SAID MONOCHLOROBENZENE LAYER WITH DILUTE SODIUM CARBONATE, AND FRACTIONALLY DISTILLING SAID MONOCHLOROBENZENE LAYER AND RECOVERING THE TETRAETHYL PYROPHOSPHATE THEREFROM.