Sodium chlorite

Sodium chlorite
IUPAC name Sodium chlorite
Other names Chlorous acid, sodium salt Textone
Identifiers
CAS number	7758-19-2 Y
PubChem	24452
ChemSpider	22860 Y
UNII	G538EBV4VF Y
UN number	1496
KEGG	C19523 N
RTECS number	VZ4800000
Jmol-3D images	Image 1
SMILES [Na+].[O-]Cl=O
InChI InChI=1S/ClHO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1 Y Key: UKLNMMHNWFDKNT-UHFFFAOYSA-M Y InChI=1/ClHO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1 Key: UKLNMMHNWFDKNT-REWHXWOFAT
Properties
Molecular formula	NaClO2
Molar mass	90.44 g/mol
Appearance	white solid
Density	2.5 g/cm3, solid
Melting point	180–200 °C decomp.
Solubility in water	39 g/100 ml (17 °C)
Hazards
MSDS	ICSC 1045
EU Index	Not listed
NFPA 704	0 1 1 OX
Flash point	Non-flammable
Related compounds
Other anions	Sodium chloride Sodium hypochlorite Sodium chlorate Sodium perchlorate
Other cations	Potassium chlorite Barium chlorite
Related compounds	Chlorine dioxide Chlorous acid
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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.^[1] 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]} . Chlorine dioxide generated from sodium chlorite is approved by FDA under some conditions for disinfecting water used to wash fruits, vegetables, and poultry. ^[2]

Sodium chlorite, NaClO₂, sometimes in combination with zinc chloride, also finds application as a component in therapeutic rinses, mouthwashes,^[3][4] toothpastes and gels, mouth sprays,^[5] as a teat dip for control of mastitis in dairy cattle,^[6] as preservative in eye drops,^[7] 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).^[8]

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.^[9]

Safety

Sodium chlorite, like many oxidizing agents, should be protected from inadvertent contamination by organic materials to avoid the formation of an explosive mixture. The chemical explodes on percussive impact^[10], and will ignite if combined with a strong antioxidant (reducing agent).

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.^[11] A dose of 10-15 grams of sodium chlorate can be lethal.^[12] Methemoglobemia had been demonstrated in rats and cats ^[13] 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. ^[14]

There is only one human case in the medical literature of chlorite poisoning.^[15] 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.^[16]

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. ^ [1]
2. ^ [2]
3. ^ "New mouthwashes may help take bad breath away" article by Joyce Cohen in USA Today
4. ^ SmartMouth 2 Step Mouth Rinse
5. ^ Products entry Skin Deep cosmetic safety database
6. ^ "Preventing Bovine Mastitis by a Postmilking Teat Disinfectant Containing Acidified Sodium Chlorite" J. Dairy Sci. 90:1201–1208
7. ^ Blink Tears
8. ^ Bal BS, Childers, Jr. WE, Pinnick HW (1981). "Oxidation of α,β-unsaturated aldehydes" (abstract). Tetrahedron 37: 2091. doi:10.1016/S0040-4020(01)97963-3. 
9. ^ 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. http://www.thieme-connect.com/ejournals/se/abstract/synlett/doi/10.1055/s-2005-869833. 
10. ^ http://pubs.acs.org/doi/abs/10.1021/ie50367a007
11. ^ Goldfrank's Toxicologic Emergencies, McGraw-Hill Professional; 8th edition (March 28, 2006), ISBN 978-0071437639
12. ^ http://www.poisoncentre.be/article.php?id_article=39
13. ^ 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
14. ^ Sodium Chlorite - Summary Report of the Europena Agency for the Evaluation of Medicinal Products - Veterinary Medicines Evaluation Unit [3]
15. ^ Acute sodium chlorite poisoning associated with renal failure. Lin JL, Lim PS. Ren Fail. 1993;15(5):645-8. PMID: 8290712
16. ^ Chlorine Dioxide and Sodium Chlorite Supply

External links

• International Chemical Safety Card 1045