Halazone

Halazone (4-(dichlorosulfamoyl)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
Preferred IUPAC name
4-(Dichlorosulfamoyl)benzoic acid
Other names
  • Pantocide
  • p-Sulfondichloramidobenzoic acid
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.001.140
EC Number
  • 201-253-1
UNII
UN number 1479
  • 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]
  • C1=CC(=CC=C1C(=O)O)S(=O)(=O)N(Cl)Cl
Properties
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]
Less than 1 g/L at 70 °F [2]
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319
P264, P280, P302+P352, P305+P351+P338, P321, P332+P313, P337+P313, 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-[(dichloroamino)sulfonyl]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 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 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

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 Archived 2020-06-27 at the Wayback Machine". Product page, accessed on 2018-06-18
  6. Precise Health Care PVT LTD: "Halazone tablets Archived 2021-09-01 at the Wayback Machine". 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.
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