Hydroiodic Acid: Formulas, Characteristics and Uses

He Hydroiodic acid Is formed when the hydrogen iodide gas dissolves in water. Hydrogen iodide (its aqueous form) and hydrogen iodide (its gaseous or anhydrous form) are interconvertible.

Its anhydrous form is a molecule made up of an iodine atom (I) and a hydrogen atom (H). It is an important reagent in organic chemistry. It is one of the primary sources in obtaining iodine. It is also used as a reducing agent.

Reacts with metals or their hydroxides, carbonates and other salts to produce metallic iodides. It is very corrosive to tissues. Its vapors severely irritate sensitive tissues (such as the eyes and respiratory system). It is typically available in 47% solution of hydrogen iodide

• Formula HI
• CAS number : 10034-85-2
• WILDEBEEST : 1787 (hydroiodic acid)
• WILDEBEEST : 2197 (hydrogen iodide)

2D structure

3D structure

characteristics

Physical and chemical properties

Molecular weight:	127,912 g / mol
Boiling point:	-35.5 ° C
Melting point:	-50.8 ° C
Solubility in water, g / 100 ml at 20 ° C:	42.5 (high)
Vapor pressure, kPa at 20 ° C:	733
Relative vapor density (air = 1):	4.4

• Iodide acid belongs to the group of strong non-oxidizing acids (together with hydrochloric acid and hydrobromic acid).
• These acids provide anions that do not act as oxidants.
• They have a pKa value of less than -2, or a pH value of less than 2.
• In its dissolved form (hydroiodic acid), it is a solution between colorless and yellow.
• It has an acrid smell.
• It is corrosive to metals and tissues.
• In its anhydrous form (hydrogen iodide), it is a colorless to yellow / brown gas.
• It is not flammable, but prolonged exposure to fire or intense heat can cause its container to rupture and explode.

Inflammability

• Strong non-oxidizing acids are generally non-flammable. Hydrogen hydroxide is not combustible on its own, but may decompose on heating and produce corrosive and / or toxic fumes.
• Some of these fumes are oxidizing and can ignite fuels (such as wood, paper, oil, clothing, etc.).
• On contact with metals, they can produce hydrogen gas (flammable).
• Containers may explode when heated.
• Hydrogen iodide in some cases can burn, but it does not turn on easily.
• The liquefied gas vapors are initially heavier than air and extend along the ground, being able to react violently with water.
• Fire exposed cylinders may release toxic and / or corrosive gases through pressure relief devices.
• Containers may explode when heated.

Reactivity

• Strong non-oxidizing acids are generally soluble in water with the release of hydrogen ions. The resulting solutions have a pH of 1 or close to 1.
• Acids neutralize chemical bases (eg, amines and inorganic hydroxides) forming salts, and dangerously large amounts of heat can be generated in small spaces.
• Dissolving acids in water (or further dilution of their concentrated solutions) can generate enough heat to cause some of the water to boil explosively, producing dangerous acid splashes.
• These materials react with active metals, including structural metals such as aluminum and iron, releasing hydrogen (flammable gas).
• They also release hydrogen cyanide gas by reacting with cyanide compounds.
• They generate flammable and / or toxic gases upon contact with strong dithiocarbamates, isocyanates, mercaptans, nitrides, nitriles, sulfides and reducing agents.
• Iodide acid reacts with organic bases (amines, amides) and inorganic bases (metal oxides and hydroxides), releasing heat from the reaction.
• It also reacts with carbonates (including limestone and building materials containing limestone) and hydrogen carbonates, generating carbon dioxide and releasing heat from that reaction.
• Mixtures with concentrated sulfuric acid can produce toxic hydrogen iodide gas.
• Reacts with sulfides, carbides, borides and phosphides, generating toxic or flammable gases.
• Reacts with many metals (including aluminum, zinc, calcium, magnesium, iron, tin and all alkali metals) generating flammable hydrogen gas.
• Reacts violently with acetic anhydride, 2-aminoethanol, ammonium hydroxide, calcium phosphide, chlorosulfonic acid, 1,1-difluoroethylene, ethylenediamine, ethyleneimine, oleum, perchloric acid, b-propiolactone, propylene oxide, silver perchlorate Carbon tetrachloride, uranium (IV) phosphate, vinyl acetate, calcium carbide, rubidium carbide, cesium acetylide, rubidium acetylide, magnesium boride, mercury (II) sulfate.
• At high temperatures it decomposes and emits toxic products.
• Hydrogen iodide is a strongly acidic gas.
• Reacts quickly and exothermically with bases.
• Reacts with active metals in the presence of moisture (including structural metals such as aluminum and iron) to release hydrogen (flammable gas).
• Reacts with cyanide compounds to release hydrogen cyanide gas.
• Reacts with dithiocarbamates, isocyanates, mercaptans, nitrides, nitriles, sulfides and reducing agents, generating flammable and / or toxic gases.
• It also reacts with sulfites, nitrites, thiosulfates, dithionites and carbonates, producing gas.
• Reacts with oxidizing agents to give iodine.
• It can initiate the polymerization of certain alkenes.
• It can catalyze chemical reactions among other materials.
• It decomposes at high temperatures to generate toxic products.
• It comes on contact with fluorine, nitrogen trioxide, nitrogen dioxide / nitrogen tetraoxide.

Toxicity

• Hydrogen iodide and hydrogen iodide are toxic.
• Inhalation, ingestion or skin contact with these substances can cause serious injury or death.
• Contact with the solution may cause severe burns to the skin and eyes.
• Under fire effect, irritating, corrosive and / or toxic gases are produced.
• The solution vapors are extremely irritating and corrosive. Irritant eyes and mucous membranes.
• The gas is toxic by inhalation.
• Contact with gas or liquefied gas can cause burns, serious injury and / or frostbite.
• Strongly irritate skin, eyes and mucous membranes.
• Long-term inhalation of low concentrations (or short-term inhalation of high concentrations) may result in adverse health effects.
• The effects of contact with the dissolution or inhalation of the gas may appear late.
• Runoff from fire control or dilution water can be corrosive and / or toxic and cause contamination.

Applications

Chemical Uses

• Hydrogen iodide is used in the preparation of iodides.
• It is used to convert the primary alcohol to alkyl iodide.
• It is also used to cleave the ethers to obtain iodides and alkyl alcohols.
• It is used as a reducing agent.

Industrial applications

• It is used in metal refining, plumbing, bleaching, etching, electroplating, photography, disinfection, ammunition, fertilizer manufacturing, metal cleaning and oxide removal.
• It is used in clandestine methamphetamine laboratories.

Uses in the home

• It is used in the manufacture of toilet, metal and drain cleaners, rust removers, batteries, and as a primer for artificial nails.

Therapeutic Uses

• It was previously used as a syrup as an expectorant for helping to fluidify secretions (sputum) in patients with chronic bronchitis and bronchial asthma.
• It is thought to act by irritating the gastric mucosa, which in turn, reflexively stimulates the secretion of the respiratory tract.

Clinical effects

Its inadvertent ingestion occurs with moderate frequency in children, and is less common than exposure to alkaline substances.

In developed countries, only low-concentration acids are available in the home, so severe exposures are rare. Serious effects are more common in developing countries.

Moderate oral toxicity

• Patients with mild ingestion only develop grade I irritation or burns (superficial hyperemia and edema) of the oropharynx, esophagus, or stomach. Acute or chronic complications are unlikely.
• Patients with moderate toxicity may develop Grade II burns (superficial blisters, erosions and ulcerations) and are at risk of subsequent stenosis, particularly of the gastric outlet and esophagus. Some patients (especially young children) may develop edema in the upper respiratory tract.

Severe oral toxicity

• It is generally limited to deliberate intakes in adults.
• It can develop deep burns and necrosis of the gastrointestinal mucosa.
• Complications often include perforation (esophageal, gastric, rarely duodenal), fistula formation (tracheoesophageal, aortoesophageal) and gastrointestinal bleeding.
• Upper respiratory tract edema is common and often life threatening.
• Hypotension, tachycardia, tachypnea, and, rarely, fever may develop.
• Other rare complications include metabolic acidosis, hemolysis, renal failure, disseminated intravascular coagulation, elevated liver enzymes, and cardiovascular collapse.
• It is likely that long-term stenosis develops, primarily at the gastric and esophageal outlet, and less frequently oral.
• Esophageal carcinoma is another long-term complication.

Inhalation exposure

• Mild exposure may cause dyspnea, pleuritic chest pain, cough, and bronchospasm. Severe inhalation may cause burns and upper respiratory tract edema, hypoxia, stridor, pneumonitis, tracheobronchitis and, rarely, acute lung injury or persistent pulmonary function abnormalities.
• Pulmonary dysfunction similar to asthma has been described.

Eye exposure

• Ocular exposure may produce severe conjunctival irritation and chemosis, epithelial defects of the cornea, limbic ischemia, permanent loss of vision and in severe cases perforation.

Dermal exposure

• Minor exposure may cause irritation and partial thickness burns.
• Longer exposure or higher concentration may cause full thickness burns.
• Complications may include cellulitis, sepsis, contractures, osteomyelitis, and systemic toxicity.

Safety and risks

Hazard statements of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS).

The Globally Harmonized System of Classification and Labeling of Chemicals (GHS) is an internationally agreed system created by the United Nations designed to replace the various classification and labeling standards used in different countries through the use of globally consistent criteria.

(United Nations, 2015, p.345).

The hazard classes (and their corresponding GHS chapter), classification and labeling standards, and recommendations for hydroiodic acid are as follows (European Chemicals Agency, 2017, United Nations, 2015, PubChem, 2017):

(United Nations, 2015, p.381). (United Nations, 2015, p.378).

References

1. Anon, (2006). Hydrogen iodide [image] Retrieved from wikipedia.org.
2. Anon, (2007). Water-3D-vdW [image] Retrieved from wikipedia.org.
3. Anon, (2017). [Image] Retrieved from nih.gov.
4. European Chemicals Agency (ECHA). (2017). Summary of Classification and Labeling.
5. Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Hydrogen iodide. Recovered on January 16, 2017, from echa.europa.eu.
6. Hazardous Substances Data Bank (HSDB). TOXNET. (2017). Hydrogen iodide. Bethesda, MD, US: National Library of Medicine. Retrieved from nih.gov.
7. National Institute of Occupational Safety (INSHT). (2010). International Chemical Safety Cards. Hydrogen iodide. Ministry of Employment and Security. Madrid. IS; Recovered from insht.es.
8. Lyday, P.A., & Kaiho, T. (2000). Iodine and Iodine Compounds. In Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag GmbH & Co. KGaA. Recovered from dedx.doi.org.
9. United Nations (2015). Globally Harmonized System of Classification and Labeling of Chemicals (SGA) Sixth Revised Edition. New York, USA: United Nations publication. Retrieved from unece.org.
10. National Center for Biotechnology Information. PubChem Compound Database. (2017). Hydriodic acid. HI. Bethesda, MD, US: National Library of Medicine. Retrieved from nih.gov.
11. National Oceanic and Atmospheric Administration (NOAA). CAMEO Chemicals. (2017). Chemical Datasheet. Acids, Strong Non-oxidizing. Silver Spring, MD. EU; Recovered from cameochemicals.noaa.gov.
12. National Oceanic and Atmospheric Administration (NOAA). CAMEO Chemicals. (2017). Chemical Datasheet. Hydriodic acid. Silver Spring, MD. EU; Recovered from cameochemicals.noaa.gov.
13. National Oceanic and Atmospheric Administration (NOAA). CAMEO Chemicals. (2017). Chemical Datasheet. Hydrogen iodide, anhydrous. Silver Spring, MD. EU; Recovered from cameochemicals.noaa.gov.
14. Wikipedia. (2017). Hydriodic acid. Retrieved January 17, 2017, from wikipedia.org.
15. Wikipedia. (2017). Hydrogen iodide. Retrieved January 17, 2017, from wikipedia.org.