A berzelius reagent, phosphorus decasulfide (P₄S₁₀), in organic syntheses

Berzelius has synthesized P₄S₁₀ by reaction of white phosphorus and sulfur. P₄S₁₀ has been used widely in organic syntheses for a wide range of purposes such as a thionating agent of organic compounds and for the syntheses of various heterocycles, including thiophenes, thiazines, thiazoles, thiazolines, imidazolines, pyrimidines, imides, dithiazoles, thiadiazoles, and dithiins. The usual method of thionation using P₄S₁₀ has been conducted in refluxing solvents such as benzene, toluene, dioxane, xylene, THF, pyridine, acetonitrile, and CS ₂. The reaction of α, β-unsaturated ketone with P ₄S₁₀ in CS₂ gives an intramolecular Diels-Alder reaction to yield the cyclo adduct possibly through the thione intermediate. Trithiapentalenes has been obtained from 1,3,5-triketones and the treatment of the triketones with P₄S₁₀ in refluxing toluene yielded the trithiapentalenes.