Abstract

The hydrolysis of chlorine gives rise to a pH-dependent complex system involving no less than six equilibria in which the oxidizing power of the parent element is preserved in hypochlorous acid, chlorine monoxide, and hypochlorite ion. The physical and chemical aspects of this unique family of compounds, including organic and other nonmetal hypochlorites, are outlined, their preparation and manufacturing processes are surveyed, and important uses are cited. Corrosion problems and potential hazards in handling and use of these compounds are also discussed. Hypochlorous acid is the active biocidal agent when hypochlorites are employed in disinfection and sanitation. It is an intermediate in the manufacture of hypochlorites, chloramines, and chlorohydrins. A process for production of HOCl in concentrations as high as 60% has been developed. The commercially important hypochlorites are Ca(OCl)₂, NaOCl solution, LiOCl, chlorinated trisodium phosphate, and to a lesser extent hemibasic Ca(OCl)₂ and bleaching powder. They are used primarily in sanitation and bleaching applications. The most important solid hypochlorite is Ca(OCl)₂, which along with lithium hypochlorite is used mainly for swimming pool and spa sanitation. Several new processes for manufacture of Ca(OCl)₂ are described. Continued research interest involves use of hypochlorites for selective epoxidation, oxidation, and chlorination, and use of chlorine monoxide as a highly selective agent for aromatic ring and side-chain chlorination.