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Sodium chlorite

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Sodium chlorite
The sodium cation
The sodium cation
Space-filling model of the chlorite anion
Space-filling model of the chlorite anion
Names
IUPAC name
Sodium chlorite
Other names
Chlorous acid, sodium salt
Textone
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.942 Edit this at Wikidata
KEGG
RTECS number
  • VZ4800000
UNII
UN number 1496
  • InChI=1S/ClHO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1 checkY
    Key: UKLNMMHNWFDKNT-UHFFFAOYSA-M checkY
  • InChI=1/ClHO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1
    Key: UKLNMMHNWFDKNT-REWHXWOFAT
  • [Na+].[O-]Cl=O
Properties
NaClO2
Molar mass 90.44 g/mol
Appearance white solid
Density 2.5 g/cm3, solid
Melting point 180–200 °C decomp.
39 g/100 ml (17 °C)
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
1
0
1
OX
Flash point Non-flammable
Related compounds
Other anions
 Sodium chloride
Sodium hypochlorite
Sodium chlorate
Sodium perchlorate
Other cations
 Potassium chlorite
Barium chlorite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Sodium chlorite (NaClO2) is a chemical compound used in the manufacture of paper.

Use

The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after conversion to chlorine dioxide.[citation needed] An advantage in this application, as compared to the more commonly used chlorine, is that trihalomethanes (such as chloroform) are not produced from organic contaminants.[citation needed]

Sodium chlorite, NaClO2, sometimes in combination with zinc chloride, also finds application as a component in therapeutic rinses, mouthwashes,[1][2] toothpastes and gels, mouth sprays,[3] as a teat dip for control of mastitis in dairy cattle,[4] as preservative in eye drops,[5] and in contact lens cleaning solution under the trade name Purite. Under the brand name Oxine it is used for sanitizing air ducts and HVAC/R systems and animal containment areas (walls, floors, and other surfaces).

Chemical reagent

In organic synthesis, sodium chlorite is frequently used as a reagent in the Pinnick oxidation for the oxidation of aldehydes to carboxylic acids. The reaction is usually performed in monosodium phosphate buffered solution in the presence of a chlorine scavenger (usually 2-methyl-2-butene).[6]

Recently, sodium chlorite has been used as an oxidizing agent to convert alkyl furans to the corresponding 4-oxo-2-alkenoic acids in a simple one pot synthesis.[7]

Safety

Sodium chlorite, like many oxidizing agents, should be protected from inadvertent contamination by organic materials to avoid the formation of an explosive mixture.

Toxicity

Sodium chlorite is a strong oxidant and can therefore be expected to cause clinical symptoms similar to the well known sodium chlorate: methemoglobinemia, hemolysis, renal failure.[8] A dose of 10-15 grams of sodium chlorate can be lethal.[9] Methemoglobemia had been demonstrated in rats and cats [10] and recent studies by the EMEA have confirmed that the clinical symptomatology is very similar to the one caused by sodium chlorate in the rat, mouse, rabbit, and the green monkey. [11]

There is only one human case in the medical literature of chlorite poisoning.[12] It seems to confirm that the toxicity is equal to sodium chlorate. From the analogy with sodium chlorate, even small amounts of about 1 gram can be expected to cause nausea, vomiting and even life-threatening hemolysis in Glucose-6-Phosphate Dehydrogenase deficient persons.

Manufacture

The free acid, chlorous acid, HClO2, is only stable at low concentrations. Since it cannot be concentrated, it is not a commercial product. However, the corresponding sodium salt, sodium chlorite, NaClO2 is stable and inexpensive enough to be commercially available. The corresponding salts of heavy metals (Ag+, Hg+, Tl+, Pb2+, and also Cu2+ and NH4+) decompose explosively with heat or shock.

Sodium chlorite is derived indirectly from sodium chlorate, NaClO3. First, the explosive (only at concentrations greater than 10% in atmosphere) chlorine dioxide, ClO2 is produced by reducing sodium chlorate in a strong acid solution with a suitable reducing agent (for example, sodium sulfite, sulfur dioxide, or hydrochloric acid). The chlorine dioxide is then absorbed into an alkaline solution and reduced with hydrogen peroxide, H2O2 yielding sodium chlorite.


Availability

In the United States sodium chlorite is available in industrial quantities from DuPont.[13]

General references

  • "Chemistry of the Elements", N.N. Greenwood and A. Earnshaw, Pergamon Press, 1984.
  • "Kirk-Othmer Concise Encyclopedia of Chemistry", Martin Grayson, Editor, John Wiley & Sons, Inc., 1985

References

  1. ^ "New mouthwashes may help take bad breath away" article by Joyce Cohen in USA Today
  2. ^ SmartMouth 2 Step Mouth Rinse
  3. ^ Products entry Skin Deep cosmetic safety database
  4. ^ "Preventing Bovine Mastitis by a Postmilking Teat Disinfectant Containing Acidified Sodium Chlorite" J. Dairy Sci. 90:1201–1208
  5. ^ Blink Tears
  6. ^ Bal BS, Childers, Jr. WE, Pinnick HW (1981). "Oxidation of α,β-unsaturated aldehydes". Tetrahedron. 37: 2091. doi:10.1016/S0040-4020(01)97963-3. {{cite journal}}: |format= requires |url= (help)CS1 maint: multiple names: authors list (link)
  7. ^ Annangudi SP, Sun M, Salomon RG (2005). "An efficient synthesis of 4-oxo-2-alkenoic acids from 2-alkyl furans" (abstract). Synlett. 9: 1468. doi:10.1055/s-2005-869833.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ Goldfrank's Toxicologic Emergencies, McGraw-Hill Professional; 8th edition (March 28, 2006), ISBN 978-0071437639
  9. ^ http://www.poisoncentre.be/article.php?id_article=39
  10. ^ Clinical Toxicology of Commercial Products. Robert E. Gosselin, Roger P. Smith, Harold C. Hodge, Jeannet Braddock. Uitgever: Williams & Wilkins; 5 edition (September 1984) ISBN 978-0683036329
  11. ^ Sodium Chlorite - Summary Report of the Europena Agency for the Evaluation of Medicinal Products - Veterinary Medicines Evaluation Unit [1]
  12. ^ Acute sodium chlorite poisoning associated with renal failure. Lin JL, Lim PS. Ren Fail. 1993;15(5):645-8. PMID: 8290712
  13. ^ Chlorine Dioxide and Sodium Chlorite Supply
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