O-Ethyl dichlorothiophosphate

Submitted bt Donald Rat Martin, Harold Simmons Booth,f and 

O-Ethyl dichlorothiophosphate is prepared most conveniently by allowing ethanol to react with phosphorus (V) sulfochlori.de.1-8 

One hundred four milliliters of phosphorus(V) sulfochlo-ride (1.0 mol) is placed in a 500-ml. three-necked flask. The flask is fitted with a mercury-sealed stirrer, a water-cooled condenser to which a drying tube containing barium oxide is attached in a horizontal position, and a 250-ml. dropping funnel containing 58 ml. of anhydrous ethanol (1.0 mol). All joints may be rubber stoppers or, preferably, nonlubricated standard-taper ground-glass joints. 

The reactor is placed in an ice bath in a hood. The contents of the reactor are stirred vigorously while the ethanol is added at a rate of about 0.5 ml./min. The ice bath is removed after all the ethanol has been added, and stirring is continued until the reaction mixture reaches room temperature. 

The apparatus originally attached to the three necks of the reactor is quickly replaced by stoppers (rubber or ground glass) and a Vigreux fractionating column adapted for vacuum distillation. The pressure within the system is slowly reduced to about 25 mm. After the dissolved hydrogen chloride and the unreacted ethanol have been removed, the contents of the still pot are heated slowly. A fraction obtained over the range from room temperature up 

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O-Ethyl dichlorothiophosphate reacts with sublimed antimony (III) fluoride in the presence of a small amount of antimony(V) chloride to yield O-ethyl chlorofluorothio-phosphate and O-ethyl difluorothiophosphate.3 No reaction has been observed when the vapors are in contact with mercury. Steel is attacked very slightly by the liquid. The liquid in small quantities has no vesicant action upon the hands. 

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