Halazone (4-(dichlorosulfamoyl)benzoic acid) is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one ele ...

whose formula can be written as either or . It has been widely used to disinfect drinking water. Other names for this compound include ''p''-sulfondichloramidobenzoic acid, 4- dichloroamino)sulfonylenzoic acid, and Pantocide.

Uses

Halazone tablets have been used to disinfect water for drinking, especially where treated tap water is not available. A typical dosage is 4 mg/L.Gripo Laboratories:
Water purification range: Halazone USP based Chlorine Tablets
". Product page, accessed on 2018-06-18Precise Health Care PVT LTD:

". Product page, accessed on 2018-06-18 Halazone tablets were commonly used during World War II by U.S. soldiers for

portable water purification Portable water purification devices are self-contained, easily transported units used to purify water from untreated sources (such as rivers, lakes, and wells) for drinking purposes. Their main function is to eliminate pathogens, and often als ...

, even being included in accessory packs for

C-ration The C-Ration, or Field Ration, Type C, was a prepared and canned wet combat ration intended to be issued to U.S. military land forces when fresh food (A-ration) or packaged unprepared food (B-ration) prepared in mess halls or field kitchens wa ...

s until 1945. Halazone has largely been replaced in that use by

sodium dichloroisocyanurate Sodium dichloroisocyanurate (INN: sodium troclosene, ''troclosenum natricum'' or NaDCC or SDIC) is a chemical compound widely used as a cleansing agent and disinfectant.. It is a colorless, water-soluble solid, produced as a result of reaction of ...

. The primary limitation of halazone tablets was the very short usable life of opened bottles, typically three days or less, unlike iodine-based tablets which have a usable open bottle life of three months. Dilute halazone solutions (4 to 8 ppm of available chlorine) has also been used to disinfect

contact lens Contact lenses, or simply contacts, are thin lenses placed directly on the surface of the eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct vision or for cosmetic ...

es, and as a

spermicide Spermicide is a contraceptive substance that destroys sperm, inserted vaginally prior to intercourse to prevent pregnancy. As a contraceptive, spermicide may be used alone. However, the pregnancy rate experienced by couples using only spermic ...

Mechanism of action

Halazone's disinfecting activity is mainly due to the

hypochlorous acid Hypochlorous acid (HClO, HOCl, or ClHO) is a weak acid that forms when chlorine dissolves in water, and itself partially dissociates, forming hypochlorite, ClO−. HClO and ClO− are oxidizers, and the primary disinfection agents of chlorine so ...

() released by

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

of the

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is ...

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...

bonds when the product is dissolved in water: : + → + The hypochlorous acid is a powerful

oxidizer An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxid ...

and chlorinating agent that destroys or denatures many organic compounds.

Production

Halazone can be prepared by chlorination of ''p''-sulfonamidobenzoic acid. Another synthesis route is the oxidation of

dichloramine-T Dichloramine-T or ''N'',''N''-Dichloro-''p''-toluenesulfonamide is a chemical used as a disinfectant starting at the beginning of the 20th century. The chemical contains toluene substituted by a sulfonamide In organic chemistry, the sulfonami ...

with

potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and , an intensely pink to purple solution. Potassium permanganate is widely used in the c ...

in a mild alkaline medium.

References

{{Antiseptics and disinfectants Antiseptics and disinfectants Benzoic acids Sulfonamides

Uses

Mechanism of action

Production

See also

References