Sodium nitrite (NaNO2) structure, properties, uses, risks

The sodium nitrite is a crystalline inorganic solid formed by a sodium ion Na⁺ and a nitrite ion NO_two^-. Its chemical formula is NaNO_two. It is a white crystalline solid that tends to absorb water from the environment, that is, it is hygroscopic.

In the presence of air it slowly oxidizes to sodium nitrate NaNO₃. It has oxidizing properties (it oxidizes other compounds) and also reducing properties (it is oxidized by other compounds).

It is present in the human body naturally and is used as a preservative for cured meats and smoked fish as it prevents the growth of harmful microorganisms.

It has an important use in the emergency treatment of cyanide poisoning, since it reduces the toxic and lethal effect of said compound. However, it must be administered with great caution and does not work in all cases.

It has been found that it could prevent eye infections caused by contamination of contact lenses by microorganisms. Some studies indicate that its consumption with food can cause cancer, but it is estimated that this can be avoided by ingesting vitamin C with such foods.

Article index

• 1 Structure
• 2 Nomenclature
• 3 Properties
  • 3.1 Physical state
  • 3.2 Molecular weight
  • 3.3 Melting point
  • 3.4 Boiling point
  • 3.5 Density
  • 3.6 Solubility
  • 3.7 pH
  • 3.8 Other properties
• 4 Obtaining
  • 4.1 Presence in the body
• 5 Uses
  • 5.1 In the food industry
  • 5.2 As emergency treatment in cyanide poisoning
  • 5.3 For the dilation of blood vessels
  • 5.4 Against some parasites
  • 5.5 To avoid organ damage
  • 5.6 To avoid infections due to the use of contact lenses
  • 5.7 In various uses
• 6 Risks or inconveniences
• 7 References

Structure

Sodium nitrite is made up of the sodium cation Na⁺ and the nitrite anion NO_two^-.

In the nitrite anion NO_two^- nitrogen has a valence of +3 and oxygen of -2, for this reason the anion has a single global negative charge.

Nitrite anion NO_two^- has an angular structure, that is, the bonds of nitrogen (N) with oxygen atoms (O) form an angle.

Nomenclature

- Sodium nitrite

- Sodium nitrite

- Nitrous acid sodium salt.

Properties

Physical state

Yellowish-white crystalline solid. Orthorhombic crystals.

Molecular weight

68.995 g / mol

Melting point

271 ºC

Boiling point

It does not boil. It decomposes above 320 ºC

Density

2.17 g / cm³ at 20 ºC

Solubility

Soluble in water: 84.8 g / 100 g of water at 25 ºC. Slightly soluble in ethanol. Moderately soluble in methanol. Sparingly soluble in diethyl ether.

pH

Its aqueous solutions are alkaline, with a pH of approximately 9. This is because nitrous acid is a weak acid that tends not to dissociate, so the NO ion_two^- try to take a proton H⁺ of water to form HNO_two, which leads to the formation of OH ions^- that produce alkalinity.

NOT_two^- + H_twoO → HNO_two + Oh^-

Other properties

Sodium Nitrite NaNO_two in the presence of air slowly oxidizes to sodium nitrate NaNO₃. It is a hygroscopic solid, as it absorbs water from the environment.

It has oxidizing properties (it can oxidize other compounds) and also reducing properties (it can be oxidized by other compounds).

If it comes in contact with materials such as wood, paper or textiles, it can cause them to ignite dangerously..

With acids its decomposition takes place, generating a mixture of brown toxic gases of nitrogen oxides (NO_x).

Obtaining

It can be obtained by heating sodium nitrate NaNO₃ with lead Pb:

Elder brother₃ + Pb → NaNO_two + PbO

Presence in the body

Nitrite anion is naturally present in blood and tissues, as it is formed as a consequence of NO oxidation..

Applications

In the food industry

It is used to marinate meats as it acts as a color and flavor retention agent, and as a preservative because it controls the growth of microorganisms, avoiding in particular the development of Clostridium botulinum causing botulism disease.

Sodium nitrite in meats reacts with hemoglobin in red blood cells or red blood cells in this food. Also used in cured smoked fish.

As emergency treatment for cyanide poisoning

Sodium nitrite is used to treat acute cyanide poisoning. It is an antidote to this serious problem.

Its action is due to the fact that it favors the formation of methemoglobin (a type of hemoglobin) in the blood, which traps cyanide ions and does not release them, and thus prevents them from being released into cells, making them less toxic.

In case of cyanide poisoning, sodium nitrite is applied intravenously, taking about 12 minutes to generate methemoglobin. Despite this delay, it also offers protection due to its vasodilator effect..

For the dilation of blood vessels

It is used to treat pulmonary arterial hypertension as it works by dilating blood vessels, thus lowering blood pressure. It is estimated that this effect is due to the fact that it is transformed into nitric oxide NO which acts by relaxing the soft muscles.

However, the causes of its effectiveness are still under study..

Against some parasites

Certain researchers found that sodium nitrite inhibits the growth and multiplication of the intestinal parasite Blastocystis hominis even if it is resistant to other medications.

NaNO was found_two generates the death of this parasite by apoptosis, which is a kind of suicide of the parasite cell. Sodium nitrite causes intestinal cells to produce NO, which appears to be important in this process..

To avoid organ damage

According to some studies, nitrite is a powerful inhibitor of damage to the heart and liver in ischemic processes (decreased blood flow in a part of the body). This is believed to be due to the fact that it is a biological reserve of NO.

It was concluded that it can be used to prevent organ damage after restoring blood flow that has been interrupted by a heart attack, high-risk abdominal surgery, or organ transplantation..

To avoid infections from wearing contact lenses

NaNO has been found_two prevents the formation of films of pathogenic microorganisms Staphylococcus aureus Y Pseudomonas aeruginosa about contact lenses.

In various uses

Sodium nitrite is used to make dyes, drugs, and various organic compounds.

Also serves as a corrosion inhibitor in all-purpose greases.

Risks or inconveniences

One of the problems with using sodium nitrite for cyanide poisonings is that it causes serious cardiovascular disorders in children..

Not recommended for fire victims where simultaneous exposure to both cyanide and carbon monoxide (CO) occurs. CO reduces the ability of the blood to carry oxygen, so the administration of NaNO_two would aggravate the low oxygen condition in the patient's blood.

Inhaled sodium nitrite is irritating and toxic, it can damage the cardiovascular system and the central nervous system. In addition, it is harmful to the environment.

Sodium nitrite taken with food can be harmful. Nitrite, upon reaching the stomach, reacts with certain compounds forming nitrosamines, which can cause cancer.

These reactions can be avoided in the presence of vitamin C.

According to certain sources consulted, the risk of consuming nitrites with cured meats or fish is minimal because nitrite is naturally present in saliva.

The sources indicate that this risk is also minimal compared to the great benefits of consuming food free of harmful microorganisms.

References

1. Bhattacharya, R. and Flora, S.J.S. (2015). Cyanide Toxicity and its Treatment. In Handbook of Toxicology of Chemical Warfare Agents (Second Edition). Recovered from sciencedirect.com.
2. U.S. National Library of Medicine. (2019). Sodium nitrite. Recovered from: pubchem.ncbi.nlm.nih.gov.
3. Kim, D.J. et al. (2017). The Antibiofilm efficacy of nitric oxide on soft contact lenses. BMC Ophthalmol 17, 206 (2017). Recovered from bmcophthalmol.biomedcentral.com.
4. Ramis-Ramos, G. (2003). Antioxidants. Synthetic Antioxidants. In Encyclopedia of Food Sciences and Nutrition (Second Edition). Recovered from sciencedirect.
5. Barozzi Seabra, A. and Durán, N. (2017). Nitric Oxide Donors for Treating Neglected Diseases. In Nitric Oxide Donors. Recovered from sciencedirect.com.
6. Duranski, M.R. et al. (2005). Cytoprotective effects of nitrite during in vivo ischemia-reperfusion of the heart and liver. J Clin Invest 2005; 115 (5): 1232-1240. Recovered from ncbi.nlm.nih.gov.
7. Cotton, F. Albert and Wilkinson, Geoffrey. (1980). Advanced Inorganic Chemistry. Fourth Edition. John Wiley & Sons.