Hydroiodic acid (or hydriodic acid) is an

aqueous solution An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would ...

of hydrogen iodide (HI). It is a

strong acid Acid strength is the tendency of an acid, symbolised by the chemical formula HA, to dissociate into a proton, H+, and an anion, A-. The dissociation of a strong acid in solution is effectively complete, except in its most concentrated solutio ...

, one that is

ionize Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule ...

d completely in an aqueous solution. It is colorless. Concentrated solutions are usually 48% to 57% HI. Oxidized Hydriodic Acid

Reactions

Hydroiodic acid reacts with oxygen in air to give iodine: :4 HI + O₂ → 2 + 2 I₂ Like other hydrogen halides, hydroiodic acid adds to

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s to give alkyl iodides. It can also be used as a reducing agent, for example in the reduction of aromatic nitro compounds to anilines.

Cativa process

The Cativa process is a major end use of hydroiodic acid, which serves as a co-catalyst for the production of

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main componen ...

by the

carbonylation Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbo ...

of methanol. Cativa-process-catalytic-cycle

Illicit uses

Hydroiodic acid is listed as a U.S. Federal DEA List I Chemical, owing to its use as a

reducing agent In chemistry, a reducing agent (also known as a reductant, reducer, or electron donor) is a chemical species that "donates" an electron to an (called the , , , or ). Examples of substances that are commonly reducing agents include the Earth m ...

related to the production of

methamphetamine Methamphetamine (contracted from ) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a second-line treatment for attention deficit hyperactivity disorder and obesity. Meth ...

from

ephedrine Ephedrine is a central nervous system (CNS) stimulant that is often used to prevent low blood pressure during anesthesia. It has also been used for asthma, narcolepsy, and obesity but is not the preferred treatment. It is of unclear benefit in n ...

pseudoephedrine Pseudoephedrine (PSE) is a sympathomimetic drug of the phenethylamine and amphetamine chemical classes. It may be used as a nasal/sinus decongestant, as a stimulant, or as a wakefulness-promoting agent in higher doses. It was first charac ...

(recovered from nasal decongestant pills).

References

{{Reflist

External links

International Chemical Safety Card 1326

European Chemicals Bureau
Iodides Acids Nonmetal halides Reducing agents nl:Waterstofjodide pl:Kwas jodowodorowy