Hydroiodic acid explained

Hydroiodic acid (or hydriodic acid) is a colorless liquid. It is an aqueous solution of hydrogen iodide with the chemical formula . It is a strong acid, in which hydrogen iodide is ionized completely in an aqueous solution. Concentrated aqueous solutions of hydrogen iodide are usually 48% to 57% HI by mass.

Reactions

Hydroiodic acid reacts with oxygen in air to give iodine:

Like hydrogen halides, hydroiodic acid adds to alkenes to give alkyl iodides. It can also be used as a reducing agent, for example in the reduction of aromatic nitro compounds to anilines.^[1]

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 by the carbonylation of methanol.^{[2] [3]}

Illicit uses

Hydroiodic acid is listed as a U.S. Federal DEA List I Chemical, owing to its use as a reducing agent related to the production of methamphetamine from ephedrine or pseudoephedrine (recovered from nasal decongestant pills).^[4]

External links

• International Chemical Safety Card 1326
• European Chemicals Bureau
• Viscosities of Aqueous Hydrochloric Acid Solutions, and Densities and Viscosities of Aqueous Hydroiodic Acid Solutions

Notes and References

1. Kumar. J. S. Dileep. Ho. ManKit M.. Toyokuni. Tatsushi. 2001. Simple and chemoselective reduction of aromatic nitro compounds to aromatic amines: reduction with hydriodic acid revisited. Tetrahedron Letters. 42. 33. 5601–5603. 10.1016/s0040-4039(01)01083-8.
2. The Cativa Process for the Manufacture of Acetic Acid. Jones, J. H.. Platinum Metals Rev.. 2000. 44. 3. 94–105.
3. High productivity methanol carbonylation catalysis using iridium - The Cativa process for the manufacture of acetic acid. Sunley, G. J. . Watson, D. J. . Catalysis Today. 2000. 58. 4. 293–307. 10.1016/S0920-5861(00)00263-7.
4. 10.1016/0379-0738(90)90104-7 . Methamphetamine synthesis via hydriodic acid/Red phosphorus reduction of ephedrine . 1990 . Skinner . Harry F. . Forensic Science International . 48 . 2 . 123–134.