Hydroiodic acid

Hydroiodic acid
Space-filling model of hydrogen iodide	Space-filling model of water
The iodide anion	Space-filling model of the hydronium cation
Names
	IUPAC name Iodane
	Other names Hydronium iodide
Identifiers
CAS Number	10034-85-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:47266 ;
ChemSpider	255 ;
EC Number	233-109-9;
PubChem CID	260;
RTECS number	MW3760000;
UNII	3IY7CNP8XJ ;
	InChI InChI=1S/BrH/h1H Key: CPELXLSAUQHCOX-UHFFFAOYSA-N ; InChI=1/BrH/h1H Key: CPELXLSAUQHCOX-UHFFFAOYAZ;
	SMILES I;
Properties
Chemical formula	HI(aq)
Molar mass	127.91
Appearance	colorless liquid
Odor	acrid
Density	1.70 g/mL, azeotrope; (57% HI by weight)
Boiling point	127 °C (261 °F; 400 K) 1.03 bar, azeotrope
Solubility in water	Aqueous solution
Hazards
NFPA 704 (fire diamond)	3 0 0 ACID
Flash point	Non-flammable
Related compounds
Other anions	Hydrofluoric acid; Hydrochloric acid; Hydrobromic acid
Related compounds	Hydrogen iodide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Hydroiodic acid (or hydriodic acid) is a highly acidic aqueous solution of hydrogen iodide (H I) (concentrated solution usually 48 - 57% HI). It is the second strongest hydrohalic acid, after hydroastatic acid. Hydroiodic acid is a commonly used chemical reagent and is one of the strong acids that ionize completely in an aqueous solution.

Reactions

Hydroiodic acid readily reacts with oxygen in air, contributing to the deep colours associated with old samples;

4 HI + O₂ → 2 H
₂O + 2 I₂

HI + I₂ → HI₃^{[citation needed]}

Like other halogens, hydroiodic acid will perform addition reactions with unsaturated hydrocarbons such as alkenes. It can also be used as a reducing agent, for example in the reduction of aromatic nitro compounds to anilines.^[2]

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.^[3]^[4]

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).^[5]

References

^ Henri A. Favre; Warren H. Powell, eds. (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. Cambridge: The Royal Society of Chemistry. p. 131.
^ 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. doi:10.1016/s0040-4039(01)01083-8.
^ Jones, J. H. (2000). "The Cativa^TM Process for the Manufacture of Acetic Acid" (PDF). Platinum Metals Rev. 44 (3): 94–105.
^ Sunley, G. J.; Watson, D. J. (2000). "High productivity methanol carbonylation catalysis using iridium - The Cativa^TM process for the manufacture of acetic acid". Catalysis Today. 58 (4): 293–307. doi:10.1016/S0920-5861(00)00263-7.
^ Skinner, Harry F. "Methamphetamine Synthesis via HI/Red Phosphorus Reduction of Ephedrine". Forensic Science International, 48 128-134 (1990)

External links

[1] Henri A. Favre; Warren H. Powell, eds. (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. Cambridge: The Royal Society of Chemistry. p. 131.

[2] 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. doi:10.1016/s0040-4039(01)01083-8.

[Cativa-3] Jones, J. H. (2000). "The Cativa^TM Process for the Manufacture of Acetic Acid" (PDF). Platinum Metals Rev. 44 (3): 94–105.

[4] Sunley, G. J.; Watson, D. J. (2000). "High productivity methanol carbonylation catalysis using iridium - The Cativa^TM process for the manufacture of acetic acid". Catalysis Today. 58 (4): 293–307. doi:10.1016/S0920-5861(00)00263-7.

[5] Skinner, Harry F. "Methamphetamine Synthesis via HI/Red Phosphorus Reduction of Ephedrine". Forensic Science International, 48 128-134 (1990)

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