Sodium nitrite
From Wikipedia, the free encyclopedia
| Sodium nitrite | |
|---|---|
 |
|
| General | |
| Molecular formula | NaNO2 |
| Molar mass | 69.00 g/mol |
| Appearance | White solid. |
| CAS number | [7632-00-0] |
| Properties | |
| Density and phase | 2.2 g/cm3, solid |
| Solubility in water | 82 g/100 ml (20 °C) |
| Melting point | 270°C |
| Boiling point | 320°C decomp. |
| Structure | |
| Coordination geometry |
? |
| Crystal structure | ? |
| Hazards | |
| MSDS | External MSDS |
| EU classification | Oxidant (O) ,Toxic (T), Dangerous for the environment (N) |
| NFPA 704 | |
| R-phrases | R8, R25, R36, R37, R38, R50 |
| S-phrases | S26, S36, S45, S61 |
| Flash point | Non-flammable. |
| 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 nitrate |
| Other cations | Potassium nitrite Ammonium nitrite |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
Sodium nitrite, with chemical formula NaNO2, is used as a color fixative and preservative in meats and fish.
When pure, it is a white to slight yellowish crystalline powder. It is very soluble in water and is hygroscopic. It is also slowly oxidized by oxygen in the air to sodium nitrate, NaNO3.
It is also used in manufacturing diazo dyes, nitroso compounds, and other organic compounds; in dyeing and printing textile fabrics and bleaching fibers; in photography; as a laboratory reagent and a corrosion inhibitor; in metal coatings for phosphatizing and detinning; and in the manufacture of rubber chemicals. Sodium nitrite also has been used in human and veterinary medicine as a vasodilator, a bronchodilator, an intestinal relaxant or a laxative, and an antidote for cyanide poisoning.
Contents |
[edit] Uses
[edit] Food additive
As a food additive, it serves a dual purpose in the food industry since it both alters the color of preserved fish and meats and also prevents growth of Clostridium botulinum, the bacteria which causes botulism. In the European Union it may be used only as a mixture with salt containing at most 0.6 % sodium nitrite. It has the E number E250. Potassium nitrite (E249) is used in the same way.
While this chemical will prevent the growth of bacteria, it is also toxic for mammals. (LD50 in rats is 180 mg/kg.)
Various dangers of using this as a food additive have been suggested and researched by scientists, although no conclusive evidence has been put forth. A principal concern is the formation of carcinogenic N-nitrosamines by reaction with sodium nitrite; other ingredients are often added to prevent nitrosamine-generating reactions.
Recent studies have found a link between high processed meat consumption and colon cancer, possibly due to preservatives such as sodium nitrite. [1]
[edit] Disease treatment
Recently, sodium nitrite has been found to be an effective means to increase blood flow by dilating blood vessels, acting as a vasodilator. Research is ongoing to investigate its applicability towards treatments for sickle cell anemia, cyanide poisoning, heart attacks, brain aneurysms, and pulmonary hypertension in infants [2] [3]
[edit] Synthetic reagent
Sodium nitrite is used to convert amines into azides. The synthetic utility of such a reaction is to render the amino group labile for nucleophilic substitution, as the azide group is a better leaving group.
[edit] References
- ^ http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16991129&query_hl=7&itool=pubmed_docsum
- ^ http://www.usatoday.com/news/health/2005-09-05-hot-dog-drug_x.htm
- ^ http://www.newscientist.com/article.ns?id=dn8643
[edit] See also
[edit] External links
- International Chemical Safety Card 1120.
- European Chemicals Bureau.
- National Center for Home Food Preservation Nitrates and Nitrites.
- TR-495: Toxicology and Carcinogenesis Studies of Sodium Nitrite (CAS NO. 7632-00-0) Drinking Water Studies in F344/N Rats and B6C3F1 Mice.
- FOX news article concerning carcinogicity and hot dogs
- Links to external chemical sources
