Thiourea is employed as a source of sulfide, such as for converting alkyl halides to thiols. The reaction capitalizes on the high nucleophilicity of the sulfur center and easy hydrolysis of the intermediate isothiouronium salt:
In this example, ethane-1,2-dithiol is prepared from 1,2-dibromoethane:
Like other thioamides, thiourea can serve as a source of sulfide upon reaction with metal ions. For example, mercury sulfide forms when mercuric salts in aqueous solution are treated with thiourea:
These sulfiding reactions, which have been applied to the synthesis of many metal sulfides, require water and typically some heating.