hydroiodic acid
{{Short description|Aqueous solution of hydrogen iodide}}
{{chembox
| ImageFileL1 = Hydrogen-iodide-3D-vdW.svg
| ImageNameL1 = Space-filling model of hydrogen iodide
| ImageFileR1 = Water molecule 3D.svg
| ImageNameR1 = Space-filling model of water
| ImageFileL2 = Iodide_ion.svg
| ImageNameL2 = The iodide anion
| ImageFileR2 = Hydronium-3D-vdW.svg
| ImageNameR2 = Space-filling model of the hydronium cation
| ImageFile3 = Oxidized Hydriodic Acid.jpg
| ImageName3 = An oxidized solution of hydroiodic acid
| Name = Hydroiodic acid
| IUPACName =
| OtherNames = {{ubl|Aqueous hydrogen iodide|Hydriodic acid|Hydrogen iodide, hydrous|Hydronium iodide}}
| ImageFile =
| ImageSize = 100px
| ImageName = Hydroiodic acid
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 23224
| InChI = 1/BrH/h1H
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 43451
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/BrH/h1H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = CPELXLSAUQHCOX-UHFFFAOYSA-N
| SMILES = [OH3+].[I-]
| InChIKey = CPELXLSAUQHCOX-UHFFFAOYAZ
| CASNo = 10034-85-2
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|changed|FDA}}
| UNII = 694C0EFT9Q
| RTECS = MW3760000
| EINECS = 233-109-9
| PubChem = 24841
}}
| Section2 = {{Chembox Properties
| Formula = HI(aq)
| H=1|I=1
| MolarMass_notes = (HI)
| Appearance = colorless liquid
| Odor = acrid
| pKa = −9.3 (HI){{cite book|title=Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution|editor-first=D. D.|editor-last=Perrin|edition=2nd|series=IUPAC Chemical Data|issue=29|publisher=Pergamon|location=Oxford|year=1982|publication-date=1984|orig-date=1969|lccn=82-16524|isbn=0-08-029214-3|at=Entry 32}}
| Density = 1.70 g/mL, azeotrope
(57% HI by weight)
| Solubility = Aqueous solution
| MeltingPtC =
| MeltingPt_notes =
| BoilingPtC = 127
| BoilingPt_notes = 1.03 bar, azeotrope
}}
| Section7 = {{Chembox Hazards
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 0
| NFPA-S = ACID
| GHSPictograms = {{GHS05}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|314}}
| PPhrases = {{P-phrases|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|321|363|405|501}}
| FlashPt = Non-flammable
}}
| Section8 = {{Chembox Related
| OtherAnions = {{ubl|Hydrofluoric acid|Hydrochloric acid|Hydrobromic acid}}
| OtherCompounds = Hydrogen iodide
}}
}}
Hydroiodic acid (or hydriodic acid) is a colorless liquid. It is an aqueous solution of hydrogen iodide with the chemical formula {{chem2|HI(aq)|auto=1}}. 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.{{Ullmann|last = Lyday|first = Phyllis A.|year = 2005|title = Iodine and Iodine Compounds|pages = 382–390|doi = 10.1002/14356007.a14_381}}
Preparation
{{main|Hydrogen iodide#Synthesis}}
Reactions
Hydroiodic acid reacts with oxygen in air to give iodine:
:{{chem2|4 HI(aq) + O2 → 2 H2O + 2 I2}}
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.{{Cite journal|last1=Kumar|first1=J. S. Dileep|last2=Ho|first2=ManKit M.|last3=Toyokuni|first3=Tatsushi|date=2001|title=Simple and chemoselective reduction of aromatic nitro compounds to aromatic amines: reduction with hydriodic acid revisited|journal=Tetrahedron Letters|volume=42|issue=33|pages=5601–5603|doi=10.1016/s0040-4039(01)01083-8}}
=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.{{cite journal|title = The Cativa Process for the Manufacture of Acetic Acid|author = Jones, J. H.|journal = Platinum Metals Rev.|year = 2000|volume = 44|issue = 3|pages = 94–105|url = http://www.platinummetalsreview.com/pdf/pmr-v44-i3-094-105.pdf}}{{cite journal
| title = High productivity methanol carbonylation catalysis using iridium - The Cativa process for the manufacture of acetic acid
|author1=Sunley, G. J. |author2=Watson, D. J. | journal = Catalysis Today
| year = 2000
| volume = 58
| issue = 4
| pages = 293–307
| doi = 10.1016/S0920-5861(00)00263-7
}}
=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).{{cite journal |doi=10.1016/0379-0738(90)90104-7 |title=Methamphetamine synthesis via hydriodic acid/Red phosphorus reduction of ephedrine |year=1990 |last1=Skinner |first1=Harry F. |journal=Forensic Science International |volume=48 |issue=2 |pages=123–134}}
References
{{Reflist}}
External links
- [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc13/icsc1326.htm International Chemical Safety Card 1326]
- [https://web.archive.org/web/20110722200125/http://ecb.jrc.it/ European Chemicals Bureau]
- Viscosities of Aqueous Hydrochloric Acid Solutions, and Densities and Viscosities of Aqueous Hydroiodic Acid Solutions
{{Authority control}}