SODIUM NITRITE

Sodium nitrite is an inorganic compound with the chemical formula NaNO2. 
Sodium nitrite is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. 
From an industrial perspective, Sodium nitrite is the most important nitrite salt. 

CAS:    7632-00-0
MF:    NaNO2
MW:    69
EINECS:    231-555-9

Synonyms
SODIUM NITRITE;NITRITE CONCENTRATE ION STANDARD;NITRITE ION CHROMATOGRAPHY STANDARD;NITRITE SOLUTION;NITRITE STANDARD;NITRITE STANDARD SOLUTION;Sodium nitrite, contains an anticaking reagent, extra pure, 99%;Sodium nitrite, for analysis ACS, 97+%

Sodium nitrite is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in processed meats and (in some countries) in fish products.
Sodium nitrite is similar in name and use to sodium nitrate. 
Both are preservatives used in processed meats, such as salami, hot dogs, and bacon. 
Sodium nitrite has been synthesized by several chemical reactions that involve the reduction of sodium nitrate. 
Industrial production of Sodium nitrite is primarily by the absorption of nitrogen oxides into aqueous sodium carbonate or sodium hydroxide. 
Over the years, sodium nitrite has raised some concerns about its safety in foods, but Sodium nitrite remains in use and there are indications that it may actually be healthy. 
Sodium nitrite was developed during the 1960s. 
In 1977, the US Department of Agriculture (USDA) considered banning Sodium nitrite but the USDA’s final ruling on the additive came out in 1984, allowing its use. 

Studies in the 1990s indicated some adverse effects of sodium nitrite, for instance the potential to cause childhood leukemia and brain cancers. 
In the late 1990s, the National Toxicity Program (NTP) began a review of sodium nitrite and proposed listing Sodium nitrite as a developmental and reproductive toxicant, but a report in 2000 by NTP proposed that sodium nitrite is not a toxic substance and removed it from the list of developmental and reproductive toxicants. 
Sodium nitrite is now believed that it can help with organ transplants and leg vascular problems, while preventing heart attacks and sickle cell disease.
Sodium nitrite is an inorganic sodium salt having nitrite as the counterion. 
Used as a food preservative and antidote to cyanide poisoning. 

Sodium nitrite has a role as an antimicrobial food preservative, an antihypertensive agent, a food antioxidant, a poison and an antidote to cyanide poisoning. 
Sodium nitrite is a nitrite salt and an inorganic sodium salt.
A yellowish white crystalline solid. 
Noncombustible but will accelerate the burning of combustible material. 
If large quantities are involved in a fire or if the combustible material is finely divided, an explosion may result. 
If contaminated by ammonium compounds, spontaneous decomposition can occur and the resulting heat may ignite surrounding combustible material. 
Prolonged exposure heat may result in an explosion.
Toxic oxides of nitrogen are produced in fires involving Sodium nitrite. 
Used as a food preservative, and to make other chemicals.

Sodium nitrite Chemical Properties
Melting point: 271 °C (lit.)
Boiling point: 320 °C
Density: 2.17g/cm3
Bulk density: 1200kg/m3
Vapor pressure: <0.0001 hPa ( 25 °C)
Refractive index: 1.65
Storage temp.: 2-8°C
Solubility: aqueous acid: 1 - 2μl acetic acid per ml H2Osoluble
Form: powder
Color: White or colorless
Specific Gravity: 2.168
Odor: Odorless
PH Range: 9
PH: 9 (100g/l, H2O, 20℃)
Water Solubility: 820 g/L (20 ºC)
Sensitive: Hygroscopic
Merck: 14,8648
Stability:: Stable. Incompatible with reducing agents, strong oxidizing agents, organics and other flammable materials, finely powdered metals. Contact with combustible material may lead to fire. Hygroscopic.
InChIKey: LPXPTNMVRIOKMN-UHFFFAOYSA-M
CAS DataBase Reference: 7632-00-0(CAS DataBase Reference)
EPA Substance Registry System: Sodium nitrite (7632-00-0)

Chemical formula is NaNO2, in which N has a valency is + III.
Sodium nitrite is colorless or yellow crystal, the relative density is 2.168 (0℃), the melting point is 271℃, and it is decomposed when 320℃. 
Sodium nitrite is soluble in water, and aqueous solution is alkaline because of nitrate hydrolysis. 
Sodium nitrite has the characteristics of reduction and oxidation and is mainly oxidation. 
In acidic solution, the main performance is oxidation. 
In alkaline solution or in case of strong oxidizing agent, its performance is reduction. 
With sulfur, phosphorus, organic matter and other friction or impact can cause combustion or explosion. 

Sodium nitrite can be placed in the air with the oxygen reaction, and gradually produce sodium nitrate: NaNO2+1/2O2=NaNO3.
When using strong acidic sodium nitrite, it can be nitrited to nitric acid. 
Sodium nitrite is very unstable, easily decomposed into nitrogen dioxide, nitric oxide and water. 
The nitrogen atoms and oxygen atoms all have a single pair of electrons, which can be used as ligands, and can be used as ligands to form complexes with many metal ions. 
Sodium nitrite is toxic, carcinogenic substances, using it must be attention. 
Sodium nitrite is used in printing and dyeing industry and organic synthesis. 
Sodium nitrite is obtained by the reaction of sodium nitrate and lead in a total of hot condtion.

NaNO3+Pb=NaNO2+PbO.
The reaction mixture obtained by hot water treatment, filtration to remove insoluble lead oxide, concentration and crystallization of sodium nitrite crystal can be obtained.
Sodium nitrite is an inorganic compound with the chemical formula NaNO2. 
Sodium nitrite is white or yellow patch on the orthorhombic crystal or powder. 
Micro salty and deliquescent. 
Sodium nitrite is soluble in water and liquid ammonia, its aqueous solution is alkaline.
Sodium nitrite is also found at low concentrations in most vegetables. 
Spinach and lettuce can have some of the highest concentrations but all vegetables will contain some levels of sodium nitrite. 
Sodium nitrite has been explored in human and veterinary medicines as a vasodilator, reducing blood pressure, and is also used as an antidote for cyanide poisoning.
Sodium nitrite, NaN02, is a fire-hazardous, air-sensitive, yellowish white powder that is soluble in water and decomposes at temperatures above 320°C (608 °F). 
Sodium nitrite is used as an intermediate for dye stuffs and for pickling of meat, in dyeing of textiles, in rustproofing, in medicine, and as a reagent in organic chemistry.

Uses    
Sodium nitrite is a commonly used meat preservative, particularly in cured meats such as ham, hot dogs, sausages, and bacon. 
The nitrite ion inhibits the growth of bacteria, particularly Clostridium botulinum, an organism that produces the deadly botulism toxin. 
Sodium nitrite is also used to treat packages of red meat, such as beef. 
Blood exposed to the air rapidly produces a brown color, but shoppers much prefer their meat purchases to look bright red.
Thus, the meat is treated with sodium nitrite; the nitrite ion is reduced to nitrogen monoxide, which then reacts with the hemoglobin to form a very stable bright red compound.
Sodium nitrite is true that the nitrite will prevent bacterial growth in this circumstance as well, but these days, the meat is kept at temperatures low enough to inhibit bacteria.
To persuade shoppers to prefer brownish rather than red meat will require a lot of re-education. 

Now that all meats are treated with sodium nitrite, there is concern that the cooking process will cause the nitrite ion to react with amines in the meat to produce nitrosamines,compounds containing the -NNO functional group. 
These compounds are known to be carcinogenic.
However, as long as preserved meats are consumed in moderation, it is generally believed that the cancer risk is minimal.
Sodium Nitrite is the salt of nitrous acid that functions as an antimicrobial agent and preservative. 
Sodium nitrite is a slightly yellow granular powder or nearly white, opaque mass or sticks. 
Sodium nitrite is deliquescent in air. 
Sodium nitrite has a solubility of 1 g in 1.5 ml of water. 
Sodium nitrite is used in meat curing for color fixation and development of flavor. 

Sodium nitrite is used to fix the colors in preserved fish and meats.
Sodium nitrite is also important(along with sodium chloride) in controlling the bacterium Clostridium botulinum, which causes botulism. Lunch meats, hams, sausages, hot dogs, and bacon are usually preserved this way.
In medicines, Sodium nitrite is a vasodilator, intestinal relaxant, bronchodilator, and an antidote to cyanide and hydrogen sulfide poisoning.
Sodium nitrite is produced in the human body by the action of saliva on sodium nitrate, and is important in controlling bacteria in the stomach, to prevent gastroenteritis. 
The body produces more sodium nitrite than is consumed in food.
Sodium nitrite can react with proteins in the stomach or during cooking, especially in high heat (such as frying bacon), to form carcinogenic N-nitrosamines.
To prevent this, ascorbic acid or erythorbic acid is commonly added to cured meats.
manufacture of diazo dyes, nitroso Compounds, and in many other processes of manufacture of organic chemicals; dyeing and printing textile fabrics; bleaching flax, silk, and linen.

Industrial chemistry
The main use of sodium nitrite is for the industrial production of organonitrogen compounds. 
Sodium nitrite is a reagent for conversion of amines into diazo compounds, which are key precursors to many dyes, such as diazo dyes. 
Nitroso compounds are produced from nitrites. 
These are used in the rubber industry.
Sodium nitrite is used in a variety of metallurgical applications, for phosphatizing and detinning.
Sodium nitrite is an effective corrosion inhibitor and is used as an additive in industrial greases, as an aqueous solution in closed loop cooling systems, and in a molten state as a heat transfer medium.

Food additive and preservative
Sodium nitrite is used to speed up the curing of meat, inhibit the germination of Clostridium botulinum spores, and also impart an attractive pink color.
Nitrite reacts with the meat myoglobin to cause color changes, first converting to nitrosomyoglobin (bright red), then, on heating, to nitrosohemochrome (a pink pigment).
Historically, salt has been used for the preservation of meat. 
The salt-preserved meat product was usually brownish-gray in color.
When sodium nitrite is added with the salt, the meat develops a red, then pink color, which is associated with cured meats such as ham, bacon, hot dogs, and bologna.

In the early 1900s, irregular curing was commonplace. 
This led to further research surrounding the use of sodium nitrite as an additive in food, standardizing the amount present in foods to minimize the amount needed while maximizing its food additive role.
Through this research, sodium nitrite has been found to give taste and color to the meat and inhibit lipid oxidation that leads to rancidity, with varying degrees of effectiveness for controlling growth of disease-causing microorganisms.
The ability of sodium nitrite to address the above-mentioned issues has led to production of meat with extended storage life and has improved desirable color and taste. 
According to scientists working for the meat industry, nitrite has improved food safety.
This view is disputed in the light of the possible carcinogenic effects caused by adding nitrites to meat.

Production    
Sodium nitrite may be prepared by the thermal decomposition of sodium nitrate, but the reduction of nitrate is usually effected by stirring lead parings or copper filings into the molten salt:
NaNO3+ Pb →PbO + NaNO2
After cooling, the mass is extracted with hot water,filtered and sodium nitrite crystallized after evaporation to small bulk.
Industrially，sodium nitrite is formed by the action of nitrogen oxide (nitric oxide) and nitrogen dioxide together, obtained by the catalytic oxidation of ammonia, on sodium hydroxide or sodium carbonate solutions:
NO+NO2+2OH- →2NO2-+ HO

Production Methods    
Sodium nitrite, yellowish-white solid, soluble, formed (1) by reaction of nitric oxide plus nitrogen dioxide and sodium carbonate or hydroxide, and then evaporating, (2) by heating sodium nitrate and lead to a high temperature, and then extracting the soluble portion (lead monoxide insoluble) with H2O and evaporating. 
Used as an important reagent (diazotizing) in organic chemistry.

Production
Industrial production of sodium nitrite follows one of two processes, the reduction of nitrate salts, or the oxidation of lower nitrogen oxides.
One method uses molten sodium nitrate as the salt, and lead which is oxidized, while a more modern method uses scrap iron filings to reduce the nitrate.

NaNO3 + Pb → NaNO2 + PbO
NO−3 + Fe + 2H+ → NO−2 + Fe2+ + H2O

A more commonly used method involves the general reaction of nitrogen oxides in alkaline aqueous solution, with the addition of a catalyst. 
The exact conditions depend on which nitrogen oxides are used, and what the oxidant is, as the conditions need to be carefully controlled to avoid over oxidation of the nitrogen atom.

2 NaOH + NO2 + NO → 2 NaNO2 + H2O
2 NaOH + N2O3 → 2 NaNO2 + H2O
Sodium nitrite has also been produced by reduction of nitrate salts by exposure to heat, light, ionizing radiation, metals, hydrogen, and electrolytic reduction.

NaNO3 + CaSO3 → NaNO2 + CaSO4

Reactivity Profile    
Sodium nitrite is an oxidizing agent. 
Mixtures with phosphorus, tin(II) chloride or other reducing agents may react explosively. 
If contaminated by ammonium compounds, spontaneous decomposition can occur and resulting heat may ignite surrounding combustible material. 
Reacts with acids to form toxic nitrogen dioxide gas. 
Mixing with liquid ammonia forms dipotassium nitrite, which is very reactive and easily explosive. 
Melting together wilh an ammonium salt leads to a violent explosion. 
A mixture with potassium cyanide may cause an explosion. 
Noncombustible but accelerates the burning of all combustible material. 
If large quantities are involved in fire or if the combustible material is finely divided, an explosion may result. 
When a little ammonium sulfate is added to fused potassium nitrite, a vigorous reaction occurs attended by flame.