- Structure
- Nomenclature
- Properties
- Physical state
- Molecular weight
- Melting point
- Boiling point
- Density
- Solubility
- pH
- Other properties
- Obtaining
- Presence in the body
- Applications
- In the food industry
- As an emergency treatment for cyanide poisoning
- For the dilation of blood vessels
- Against some parasites
- To avoid organ damage
- To avoid infections from wearing contact lenses
- In various uses
- Risks or inconveniences
- References
The sodium nitrite is a crystalline inorganic solid comprises a sodium ion Na + and nitrite ion NO 2 -. Its chemical formula is NaNO 2. 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 NaNO 3. It has oxidizing properties (it oxidizes other compounds) and also reducing properties (it is oxidized by other compounds).
Sodium nitrite NaNO 2. Aleksander Sobolewski via Wikimedia Commons. Source: Wikimedia Commons.
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 this 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.
Structure
Sodium nitrite is made up of the sodium cation Na + and the nitrite anion NO 2 -.
In the nitrite anion NO 2 - nitrogen has a valence of +3 and oxygen of -2, for this reason the anion has a single global negative charge.
The nitrite anion NO 2 - has an angular structure, that is, the bonds of nitrogen (N) with oxygen atoms (O) form an angle.
Structure of sodium nitrite NaNO 2, where the angular shape of nitrite anion NO 2 - can be observed. Eschenmoser. Source: Wikimedia Commons.
Nomenclature
- Sodium nitrite
- Sodium nitrite
- Sodium salt of nitrous acid.
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 / cm 3 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 2 ion - tries to take a proton H + from the water to form HNO 2, which leads to the formation of OH ions - which produce alkalinity.
NO 2 - + H 2 O → HNO 2 + OH -
Other properties
Sodium nitrite NaNO 2 in the presence of air slowly oxidizes to sodium nitrate NaNO 3. 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 NaNO 3 with lead Pb:
NaNO 3 + Pb → NaNO 2 + 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 as it controls the growth of microorganisms, preventing in particular the development of Clostridium botulinum that causes botulism disease.
The sodium nitrite in meats reacts with the hemoglobin in the red blood cells or red blood cells in this food. It is also used in cured smoked fish.
Smoked fish. Author: Reinhard Thrainer. Source: Pixabay.
As an 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 the 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.
Intravenous treatment. Michaelberry at English Wikipedia. Source: Wikimedia Commons.
For the dilation of blood vessels
It is used to treat pulmonary arterial hypertension as it works by dilating the blood vessels, thus lowering the 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
Researchers found that sodium nitrite inhibits the growth and multiplication of the intestinal parasite Blastocystis hominis even if it is resistant to other drugs.
It was found that NaNO 2 causes 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 potent 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 because it is a biological reservoir 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 an organ transplant.
To avoid infections from wearing contact lenses
NaNO 2 has been found to prevent film build-up of pathogens Staphylococcus aureus and Pseudomonas aeruginosa on contact lenses.
Contact lenses can become contaminated with bacteria or fungi. Contact lens Photographed on 7 January 2006. Source: Photographed by Bpw. Source: Wikimedia Commons.
In various uses
Sodium nitrite is used to make dyes, drugs, and various organic compounds.
It 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 2 would aggravate the condition of low oxygen 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 meat 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
- Bhattacharya, R. and Flora, SJS (2015). Cyanide Toxicity and its Treatment. In Handbook of Toxicology of Chemical Warfare Agents (Second Edition). Recovered from sciencedirect.com.
- US National Library of Medicine. (2019). Sodium nitrite. Recovered from: pubchem.ncbi.nlm.nih.gov.
- Kim, DJ et al. (2017). The Antibiofilm efficacy of nitric oxide on soft contact lenses. BMC Ophthalmol 17, 206 (2017). Recovered from bmcophthalmol.biomedcentral.com.
- Ramis-Ramos, G. (2003). Antioxidants. Synthetic Antioxidants. In Encyclopedia of Food Sciences and Nutrition (Second Edition). Recovered from sciencedirect.
- Barozzi Seabra, A. and Durán, N. (2017). Nitric Oxide Donors for Treating Neglected Diseases. In Nitric Oxide Donors. Recovered from sciencedirect.com.
- Duranski, MR 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.
- Cotton, F. Albert and Wilkinson, Geoffrey. (1980). Advanced Inorganic Chemistry. Fourth Edition. John Wiley & Sons.