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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. The compound is a strong reducing agent.
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.
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. A principal concern is the formation of carcinogenic N-nitrosamines by the reaction of sodium nitrite with amino acids in the presence of heat in an acidic environment.
Recent studies have found a link between high processed meat consumption and colon cancer, possibly due to preservatives such as sodium nitrite. publication from wiley
Recent studies have also found a link between frequent ingestion of meats cured with nitrites and the COPD form of lung disease.
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.
Sodium nitrite is used to convert amines into diazo compounds. The synthetic utility of such a reaction is to render the amino group labile for nucleophilic substitution, as the N2 group is a better leaving group.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sodium_nitrite". A list of authors is available in Wikipedia.|