Phosphorus V Sulfochloride

Several procedures have been reported for the synthesis of phosphorus (V) sulfochloride. These include the reaction of phosphorus(V) chloride with hydrogen sulfide,1,2 of phosphorus (III) chloride with sulfur,3 4 of carbon tetrachloride with phosphorus(V) sulfide,5 and of phosphorus(V) chloride with phosphorus(V) sulfide.5 The second and fourth methods form the bases for the two syntheses presented here. 

---

Phosphorus(V) oxybromide, 2 151 Phosphorus(V) sulfobromide, 2 153 Phdsphorus(V) sulfobromodifluo-ride, formation of, from phosphorus (V) sulfobromide, 2 154 Phosphorus (V) sulfochloride, 4 71 from phosphorus (III) chloride, aluminum chloride, and sulfur, 4 71... 

The older literature reports the synthesis of phosphorus-(V) sulfochloride by reaction of phosphorus (V) chloride with phosphorus (V) sulfide in a sealed tube at 120°. Experience has shown that pressures as great as 700 p.s.i. may result under these conditions, indicating that an autoclave or bomb should be used. In the absence of these, the reactor shown in Fig. 8 is suitable. It consists of an oil bath containing a lecture bottle fitted with a pipe plug (iron pipe size, % in.), a thermometer, and a knife type of immersion heater. Although no difficulty has been experienced in the use of this reactor, it is well to keep it behind a barricade during the reaction. 

Phosphorus(V) sulfochloride is a colorless, fuming liquid with boiling point 125° and specific gravity 1.635. The alpha form solidifies at —40.8°, while the beta form solidifies at —36.2°.7 The compound hydrolyzes slowly in water and rapidly in alkaline solution. In water, the hydrolysis products are orthophosphoric acid, hydrochloric acid, and hydrogen sulfide. Phosphorus (Y) sulfochloride is soluble in benzene, carbon tetrachloride, carbon disulfide, and chloroform. It reacts with ethanol, yielding O-ethyl dichlorothiophosphate8 (synthesis 25). 

Fia. 8. Apparatus for the preparation of phosphorus (V) sulfochloride from phosphorus(V) sulfide and phosphorus (V) chloride. 

Phosphorus (V) sulfochloride, synthesis 24 0-Ethyl dichlorothiophosphate, synthesis 25... 

Phosphorus(V) sulfochloride can either be manufactured from phosphorus(lll) chloride and sulfur at 180°C in an autoclave or by passing phosphorus(III) chloride vapor through molten sulfur ... 

Catalysts such as e.g. aluminum chloride reduce the reaction temperature to such a degree that the reaction can be carried out in phosphorus(V) sulfochloride. Purification is by distillation. 

Application, Phosphorus(V) sulfochloride is mainly utilized in the manufacture of ester chlorides of thiophosphoric acids (precursors for pesticides). 

Alternatively the ester chloride can be produced from phosphorus(V) sulfochloride and an alcohol. 

Three hundred milliliters of a cool aqueous solution containing 40 g. of sodium hydroxide (1 mol) is added to 17.5 ml. of phosphorus(V) sulfochloride (0.17 mol)6 in a 1-1. three-necked round-bottomed flask equipped with a reflux condenser, a thermometer, and a motor-driven stirrer. The mixture is heated at 103 to 109° for 15 to 20 minutes, until the phosphorus (V) sulfochloride layer has disappeared. The solid hydrated sodium monothio-... 

---