Sodium chlorite
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| Sodium chlorite | |
|---|---|
| Image:Sodium chlorite.jpg | |
| General | |
| Systematic name | Sodium chlorite |
| Other names | Sodium chlorate(III) |
| Molecular formula | NaClO2 |
| Molar mass | 90.44 g/mol |
| Appearance | white solid |
| CAS number | [7758-19-2] |
| Properties | |
| Density and phase | 2.5 g/cm3, solid |
| Solubility in water | 39 g/100 ml (17 °C) |
| Melting point | 180–200 °C decomp. |
| Structure | |
| Coordination geometry |
? |
| Crystal structure | ? |
| Hazards | |
| MSDS | External MSDS |
| EU classification | not listed |
| NFPA 704 |
0
1
1
OX
|
| Flash point | non flammable |
| RTECS number | VZ4800000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | Sodium chloride Sodium hypochlorite Sodium chlorate Sodium perchlorate |
| Other cations | Potassium chlorite Barium chlorite |
| Related compounds | Chlorine dioxide Chlorous acid |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
Sodium chlorite is a chemical compound used in the manufacture of paper.
Contents |
[edit] 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 explosively unstable gas chlorine dioxide, ClO2 is produced by reducing sodium chlorate in a strong acid solution with a suitable reducing agent (for example, sodium chloride, sulfur dioxide, or hydrochloric acid). The chlorine dioxide is then absorbed into an alkaline solution and reduced with hydrogen peroxide, H2O2 yielding sodium chlorite.
[edit] Usage
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 in a few municipal water treatment plants after conversion to chlorine dioxide. An advantage in this application, as compared to the more commonly used chlorine, is that trihalomethanes are not produced from organic contaminants. Sodium chlorite, NaClO2 also finds application as a component in therapeutic rinses, mouthwashes, toothpastes and gels, mouth sprays chewing gums and lozenges, and also in contact lens cleaning solution under the trade name purite.
In organic synthesis, sodium chlorite is frequently used for the oxidation of aldehydes to carboxylic acids. The reaction is usually performed in the presence of a chlorine scavanger.
Sodium chlorite, like many oxidizing agents, should be protected from inadvertent contamination by organic materials to avoid the formation of an explosive mixture.
[edit] 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
[edit] External links
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