Lead rhodanate

At the beginning of the twentieth century the thiocyanates (rhodanates) of certain metals (e.g. mercury, copper) were recommended as components of cap compositions with potassium chlorate. The rhodanates were intended as a substitute for mercury fulminate, but only lead rhodanate acquired any practical significance. 

Lead rhodanate, Pb(CNS)2 is formed, when a solution of lead nitrate, slightly acidified with nitric acid, is treated with a moderately concentrated solution of the rhodanate of an alkali metal. 

When exposed to long day-light or ultraviolet irradiation lead rhodanate becomes yellow. When boiled in water it is converted into a basic salt Pb(CNS)2Pb(OH)2 which behaves as a weak initiator. It is used as a constituent in some cap compositions. 

One of the earliest preparations of the 1,2,4-dithiazole (30) was by acid treatment of a concentrated aqueous solution of 2-thioxo-l,3-thiazolidin-4-one ( rhodanic acid ) (1842LA(43)76) or of one of its salts Ac20 with the> ammonium salt gave the /V-acetyl derivative (1873CB902). Thermolysis of 2-phenyl-l,3-tbiazoline-4,5-dio ne leads via loss of CO to thiobenzoylisocyanate, which with sulfur or P4S10 yields a dithiazolinethione (Scheme 4D. 

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