Sodium iodide (NaI) structure, properties, uses, risks

The sodium iodide It is an inorganic compound formed by a sodium Na atom and an iodine I atom. Its chemical formula is NaI. It is a white solid that tends to absorb water from the environment, that is, it is hygroscopic. So hygroscopic that it is said to be deliquescent, as over time it dissolves in the water it has absorbed.

Sodium iodide has several applications in the field of medicine, for example, it serves to thin bronchial secretions (mucus), which is why it is used to treat bronchitis and asthma.

Because the element iodine is a micronutrient for the body, sodium iodide NaI is used in solutions that are injected into patients who cannot feed themselves by mouth. It is also used in certain devices that are used to detect diseases through gamma radiation.

It has important use in veterinary medicine to treat various diseases in animals, mainly mammals. NaI is also used as a reagent in organic chemistry laboratories..

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 Chemical properties
  • 3.9 Other properties
• 4 Obtaining
• 5 Uses in medicine
  • 5.1 For the treatment of asthma and bronchitis
  • 5.2 In intravenous feeding
  • 5.3 In the diagnosis and treatment of the thyroid
  • 5.4 In gamma cameras
  • 5.5 In veterinary medicine
• 6 Other uses
  • 6.1 In organic chemistry reactions
  • 6.2 To extract microplastics from contaminated sand
• 7 Risks
• 8 References

Structure

Sodium iodide is made up of a sodium cation Na⁺ and an iodide anion I^-, therefore it is an ionic compound.

The iodide ion is much larger than the sodium ion, however, in the solid they are perfectly coupled to form cubic crystals..

Nomenclature

Sodium iodide

Properties

Physical state

White solid with deliquescent crystals (absorbs water quickly from the environment). Cubic crystals.

Molecular weight

149.89 g / mol

Melting point

661 ° C

Boiling point

1304 ° C

Density

3.67 g / cm³

Solubility

Very soluble in water: 184 g / 100 mL of water at 25 ° C. Soluble in alcohol: 42.57 g / 100 mL of alcohol. Soluble in acetone: 39.9 g / 100 mL of acetone.

pH

8-9.5 (prepares slightly alkaline to make it more stable).

Chemical properties

It turns brown if exposed to air, as it releases iodine I_two. Their aqueous solutions are similarly affected.

Sodium iodide NaI reacts with oxidizing agents producing iodine I_two. With very strong oxidizing agents such as perchloric acid, the reaction can be violent.

Other properties

It is deliquescent, that is, very hygroscopic. Quickly absorbs moisture from the environment. Can absorb up to 5% of its weight in water.

Taste saline and somewhat bitter.

Obtaining

Sodium iodide can be obtained from iodine I_two and sodium hydroxide NaOH. It can also be prepared by reaction between sodium carbonate and an acid solution of iodide..

Uses in medicine

For the treatment of asthma and bronchitis

NaI is used as an expectorant when there are very tenacious bronchial secretions, it serves to liquefy them or make them less thick, more liquid, and that they can exit towards the upper part of the respiratory tract.

It is used in bronchitis and asthma. It should not be given after the cough has "loosened up." But in patients with chronic bronchitis or asthma it can be prescribed more or less continuously if relief is achieved..

In intravenous feeding

Sodium iodide is a source of iodine and can be supplied as a supplement for total parenteral nutrition, which is a type of intravenous feeding.

In the diagnosis and treatment of the thyroid

In its radioactive form, NaI has been used as a diagnostic tool to evaluate the function and structure of the thyroid in some patients..

Sodium iodide therapy has been used to treat hyperthyroidism, but it usually does not completely control the manifestations of the disease and after a while its beneficial effect wears off..

By continuing iodide treatment, hyperthyroidism may return to its initial intensity or it may become more severe than at the beginning..

In gamma cameras

Gamma cameras are instruments that make it possible to capture images derived from gamma radiation. They are used in nuclear medicine for the diagnosis of some diseases.

The gamma camera uses a sodium iodide crystal as a detector for gamma radiation coming from the patient, into which a very small amount of a radioactive substance has been injected intravenously.

In veterinary medicine

In veterinary medicine it has been used to eliminate ringworms, in cancerous lesions and in certain inflammatory diseases in the brain of dogs.

It is used to treat mycosis, chronic inflammation of the joints, laryngitis, bronchitis and pleurisy in some species of animals. It is used to eliminate worms from the lungs of cats.

It is also used as a contrast medium for X-rays of the bladder of some animals..

Sodium iodide is used as an aid in the treatment of actinomycosis and actinobacillosis in cattle (it can be in cows, sheep and goats).

Actinomycosis or "rubber jaw" is an infection of the jaw bones, in which the bones increase in size, cause pain and the animal cannot feed properly.

Actinobacillosis or "wooden tongue" is an infection of the tongue which swells and the animal cannot chew the food.

Sodium iodide contributes with other medicines to cure both diseases.

Sodium iodide is also used as an expectorant in diseases of the lungs of cows, horses and sheep..

Other uses

In organic chemistry reactions

Sodium iodide was one of the first salts used to dehalogen or eliminate halogens for various purposes, such as obtaining alkenes, that is, compounds with double bonds..

To extract microplastics from contaminated sand

Sodium iodide has been used to extract microplastics (very small pieces of plastic) from sand contaminated with this material..

Microplastic pollution has been observed in various natural environments, such as rivers, lakes, seas, oceans, coasts and even in underwater environments, making it a global concern.

Microplastics are ingested by marine and terrestrial animals causing serious damage to health.

The measurement of the amount of microplastics that a given area has is done by taking a portion of sand and dipping it into the sodium iodide solution.

In this way the microplastic will float. Sodium iodide solutions have the right density for plastic microparticles to float, even the densest plastic ones.

Although sodium iodide is expensive, methods are being devised to reuse it and lower the costs of this procedure..

Risks

If sodium iodide comes into contact with perchloric acid HClO4 it ignites.

It is irritating to the eyes, the skin, and the respiratory tract. Ingested it can affect the thyroid. May cause sensitization in the body.

It is harmful to the fetuses of pregnant women, because if they ingest or inhale it, it can cause death to the baby or very severe and permanent damage..

Sodium iodide overdose can cause "iodism" characterized by excess saliva, sneezing, conjunctivitis, headache, fever, laryngitis, among other symptoms..

References

1. U.S. National Library of Medicine. (2019). Sodium iodide. National Center for Biotechnology Information. Recovered from pubchem.ncbi.nlm.nih.gov.
2. Cherry, S.R. et al. (2012). The Gamma Camera. In Physics in Nuclear Medicine (Fourth Edition). Recovered from sciencedirect.com.
3. Kedzierski, M. et al. (2016). Efficient microplastics extraction from sand. A cost effective methodology based on sodium iodide recycling. Marine Pollution Bulletin 2016, Recovered from elsevier.com.
4. Van Meter, D.C. et al. (2008). Infectious Diseases of the Gastrointestinal Tract. In Rebhun's Diseases of Dairy Cattle. Recovered from sciencedirect.com.
5. Fry, A.J. (1991). Reduction. In Comprehensive Organic Synthesis. Recovered from sciencedirect.com.
6. Young, J.A. (2004). Sodium Iodide. Journal of Chemical Education, Vol. 81, No. 3, March 2004. Retrieved from pubs.acs.org.