Halazone

Halazone (4-((dichloroamino)sulfonyl)benzoic acid) is a chemical compound whose formula can be written as either C
₇H
₅Cl
₂NO
₄S or (HOOC)(C
₆H
₄)(SO
₂)(NCl
₂). It has been widely used to disinfect drinking water.

Halazone

Names
IUPAC name 4-((Dichloroamino)sulfonyl)benzoic acid
Other names Pantocide p-Sulfondichloramidobenzoic acid
Identifiers
CAS Number	80-13-7
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL1368146
ChemSpider	3431
ECHA InfoCard	100.001.140
EC Number	201-253-1
PubChem CID	3552
UNII	G359OL82VB
UN number	1479
CompTox Dashboard (EPA)	DTXSID9025370
InChI InChI=1S/C7H5Cl2NO4S/c8-10(9)15(13,14)6-3-1-5(2-4-6)7(11)12/h1-4H,(H,11,12)[1] Key: XPDVQPODLRGWPL-UHFFFAOYSA-N[1]
SMILES C1=CC(=CC=C1C(=O)O)S(=O)(=O)N(Cl)Cl
Properties
Chemical formula	C7H5Cl2NO4S
Molar mass	270.08 g·mol^−1
Appearance	Fine white powder with an odor of chlorine[2]
Melting point	213 °C (415 °F; 486 K);[3] 196 °C with decomposition.[4]
Solubility in water	Less than 1 g/L at 70 °F [2]
Hazards
GHS pictograms
GHS Signal word	Warning
GHS hazard statements	H315, H319
GHS precautionary statements	P264, P280, P302+352, P305+351+338, P321, P332+313, P337+313, P362
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Other names for this compound include p-sulfondichloramidobenzoic acid, 4-(dichlorosulfamoyl)benzoic 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.[5][6]

Halazone tablets were commonly used during World War II by U.S. soldiers for portable water purification, even being included in accessory packs for C-rations until 1945.[7]

Halazone has largely been replaced in that use by sodium dichloroisocyanurate. The primary limitation of halazone tablets was the very short usable life of opened bottles, typically 3 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 lenses,[8] and as a spermicide.

Mechanism of action

Halazone's disinfecting activity is mainly due to the hypochlorous acid (HClO) released by hydrolysis of the chlorine-nitrogen bonds when the product is dissolved in water:[8]

(R1)(R2)NCl + H
₂O → HOCl + (R1)(R2)NH

The hypochlorous acid is a powerful oxidizer and chlorinating agent that destroys or denatures many organic compounds.

Production

Halazone can be prepared by chlorination of p-sulfonamidobenzoic acid.[4]

Another synthesis route is the oxidation of dichloramine-T with potassium permanganate in a mild alkaline medium.[4]

See also

• Bleach
• Chlorine-releasing compound
• Chloramine-T (tosylchloramide sodium salt), another water disinfection agent.
• Water chlorination

References

1. PubChem: "Halazone". Accessed on 2018-06-18.
2. NTP (1992), cited by PubChem
3. Jean-Claude Bradley: Open Melting Point Dataset. Quoted by Chemspider.
4. Saljoughian, M.; Sadeghi, M. T. (1986). "An improved procedure for the synthesis ofp-(dichlorosulfamoyl)benzoic acid (Halazone)". Monatshefte für Chemie. 117 (4): 553. doi:10.1007/BF00810903.
5. Gripo Laboratories: "Water purification range: Halazone USP based Chlorine Tablets". Product page, accessed on 2018-06-18
6. Precise Health Care PVT LTD: "Halazone tablets". Product page, accessed on 2018-06-18
7. Hlavatá, L; Aguilaniu, H; Pichová, A; Nyström, T (2003). "The oncogenic RAS2val19 mutation locks respiration, independently of PKA, in a mode prone to generate ROS". The EMBO Journal. 22 (13): 3337–3345. doi:10.1093/emboj/cdg314. PMC 165639. PMID 12839995.
8. Rosenthal, Ruth Ann; Schlitzen, Ronald L; McNamee, Linda S; Dassanayake, Nissanake L; Amass, Roger (1992). "Antimicrobial activity of organic chlorine releasing compounds". Journal of the British Contact Lens Association. 15 (2): 81. doi:10.1016/0141-7037(92)80044-Z.