View source for Iodoform

{{for|use of the term "iodoform" in cryptography|Group key}}
{{Use dmy dates|date=April 2017}}
{{chembox
| Verifiedfields = changed
| Watchedfields  = changed
| verifiedrevid  = 444991229
| ImageFile      = Iodoform.svg
| ImageClass     = skin-invert
| ImageFile_Ref  = {{chemboximage|correct|??}}
| ImageSize      = 100
| ImageName      = Stereo, skeletal formula of iodoform with the explicit hydrogen added
| ImageFileL1    = Iodoform-GED-3D-balls.png
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageNameL1    = Ball and stick model of iodoform
| ImageFileR1    = Iodoform-GED-3D-vdW.png
| ImageFileR1_Ref = {{chemboximage|correct|??}}
| ImageFile2_Ref = {{chemboximage|correct|??}}
| ImageFile2     = Iodoform in a test tube.jpg
| ImageSize2     =
| ImageName2     = Freshly made iodoform from an iodine tincture.
| PIN            = Triiodomethane
| OtherNames     = {{ubl|Iodoform<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry|The Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 661 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4 | quote = The retained names ‘bromoform’ for HCBr<sub>3</sub>, ‘chloroform’ for HCCl<sub>3</sub>, and ‘iodoform’ for HCI<sub>3</sub> are acceptable in general nomenclature. Preferred IUPAC names are substitutive names.| chapter = Front Matter }}</ref>|Carbon hydride triiodide|Carbon triiodide<ref name=pubchem>{{cite web | url=https://pubchem.ncbi.nlm.nih.gov/compound/Iodoform | title=Iodoform }}</ref>}}
| Section1       = {{Chembox Identifiers
| CASNo = 75-47-8
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 6374
| ChemSpiderID = 6134
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| UNII = KXI2J76489
| UNII_Ref = {{fdacite|correct|FDA}}
| EINECS = 200-874-5
| KEGG = D01910
| KEGG_Ref = {{keggcite|correct|kegg}}
| MeSHName = iodoform
| ChEBI = 37758
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 1451116
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| RTECS = PB7000000
| Beilstein = 1697010
| SMILES = IC(I)I
| StdInChI = 1S/CHI3/c2-1(3)4/h1H
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = OKJPEAGHQZHRQV-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
}}
| Section2       = {{Chembox Properties
| C=1|H=1|I=3
| Appearance = Pale, light yellow, opaque crystals
| Odor = Saffron-like<ref name=GESTIS>{{GESTIS|ZVG= 491168}}</ref>
| Density = 4.008 g/cm<sup>3</sup><ref name=GESTIS/>
| MeltingPtC = 119
| MeltingPt_ref =<ref name=GESTIS/>
| BoilingPtC = 218
| BoilingPt_ref =<ref name=GESTIS/>
| Solubility = 100 mg/L<ref name=GESTIS/>
| Solvent1 = diethyl ether
| Solubility1 = 136 g/L
| Solvent2 = acetone
| Solubility2 = 120 g/L
| Solvent3 = ethanol
| Solubility3 = 78 g/L
| LogP = 3.118
| HenryConstant = 3.4 μmol·Pa<sup>−1</sup>·kg<sup>−1</sup>
| MagSus = −117.1·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
| Section3       = {{Chembox Structure
| CrystalStruct = Hexagonal
| MolShape = [[Tetrahedral molecular geometry|Tetrahedral]] at [[carbon|C]]
}}
| Section5       = {{Chembox Thermochemistry
| DeltaHf = 180.1 – 182.1 kJ/mol
| DeltaHc = −716.9 – −718.1 kJ/mol
| HeatCapacity = 157.5 J/(K·mol)
}}
| Section6       = {{Chembox Pharmacology
| ATCCode_prefix = D09
| ATCCode_suffix = AA13
}}
| Section7       = {{Chembox Hazards
| GHSPictograms = {{gHS exclamation mark}}
| GHSSignalWord = '''WARNING'''
| HPhrases = {{h-phrases|315|319|335}}
| PPhrases = {{p-phrases|261|280|305+351+338}}
| NFPA-H = 2
| NFPA-F = 1
| NFPA-R = 1
| FlashPtC = 204
| LD50 = {{ubl|355 mg/kg (oral, rat)<ref name=GESTIS/>|1180 mg/kg (dermal, rat)<ref name=GESTIS/>|1.6 mmol/kg([[subcutaneous injection|s.c.]], mouse)<ref name=Merck>''[[Merck Index]]'', 12 Edition, '''5054'''</ref>}}
| IDLH = N.D.<ref name=PGCH>{{PGCH|0343}}</ref>
| REL = 0.6 ppm (10 mg/m<sup>3</sup>)<ref name=PGCH/>
| PEL = none<ref name=PGCH/>
}}
| Section8       = {{Chembox Related
| OtherFunction_label = haloalkanes
| OtherCompounds = {{ubl||[[Methyl iodide]]|[[Diiodomethane]]|[[Carbon tetraiodide]]|[[Fluoroform]]|[[Chloroform]]|[[Bromoform]]}}
}}
}}
[[File:Iodoform.jpg|thumb|Iodoform stored in an [[ampoule]]]]
'''Iodoform''' (also known as '''triiodomethane''') is the [[organoiodine compound]] with the [[chemical formula]] {{chem2|CHI3|auto=1}}. It is a pale yellow, crystalline, volatile substance, with a penetrating and distinctive odor (in older chemistry texts, the smell is sometimes referred to as that of hospitals, where the compound is still commonly used) and, analogous to [[chloroform]], sweetish taste. It is occasionally used as a [[disinfectant]].

==Naming==
The name iodoform originates with the "formyle radical," an archaic term for the HC moiety,{{citation needed|date=February 2025}} and is retained for historical consistency. A full, modern name is triiodomethane. Another possible name is "carbon hydride triiodide". The "hydride" in the latter is sometimes omitted,<ref name="pubchem"/> though the IUPAC recommends against doing so, as "carbon triiodide" could also mean {{chem2|C2I6}} ([[hexaiodoethane]], a highly unstable compound).

== Structure ==
The molecule adopts a [[tetrahedral molecular geometry|tetrahedral geometry]] with C<sub>3v</sub> [[symmetry group|symmetry]].

==Synthesis and reactions==
The synthesis of iodoform was first described by [[Georges-Simon Serullas]] in 1822, by reactions of iodine vapour with steam over red-hot coals, and also by reaction of potassium with ethanolic iodine in the presence of water;<ref>{{citation| first = Georges-Simon|last = Surellas| url = http://gallica.bnf.fr/ark:/12148/bpt6k6137757n/f2.image |title = Notes sur l'Hydriodate de potasse et l'Acide hydriodique. -- Hydriodure de carbone; moyen d'obtenir, à l'instant, ce composé triple|trans-title= Notes on the hydroiodide of potassium and on hydroiodic acid -- hydroiodide of carbon; means of obtaining instantly this compound of three elements| language = French| publisher = Metz, France: Antoine| year= 1822| pages= 17–20, 28–29}}</ref> and at much the same time independently by [[John Thomas Cooper]].<ref name=ODNB>{{cite ODNB|last=James|first=Frank A. J. L.|title=Cooper, John Thomas |url=http://www.oxforddnb.com/view/article/39361 |access-date=26 January 2012 |doi=10.1093/ref:odnb/39361|year=2004}}</ref> It is synthesized in the [[haloform reaction]] by the reaction of iodine and sodium hydroxide with any one of these four kinds of organic compounds: a methyl [[ketone]] ({{chem2|CH3COR}}), [[acetaldehyde]] ({{chem2|CH3CHO}}), [[ethanol]] ({{chem2|CH3CH2OH}}), and certain secondary [[Alcohol (chemistry)|alcohol]]s ({{chem2|CH3CHROH}}, where R is an alkyl or aryl group).

:[[Image:Iodoform synthesis.svg|450px|class=skin-invert-image]]

The reaction of iodine and base with [[methyl]] [[ketone]]s is so reliable that the [[iodoform test]] (the appearance of a yellow precipitate) is used to probe the presence of a methyl ketone. This is also the case when testing for specific [[secondary alcohol]]s containing at least one [[methyl]] group in [[Alpha and beta carbon|alpha-position]].

Some reagents (e.g. [[hydrogen iodide]]) convert iodoform to [[diiodomethane]]. Conversion to [[carbon dioxide]] is also possible.<ref>{{cite journal |doi= 10.1021/ja01129a067 |title= A Method for the Specific Conversion of Iodoform to Carbon Dioxide |journal= J. Am. Chem. Soc. |year= 1952 |volume= 74 |issue= 9 |pages= 2404 |first1= W. W. |last1= Shreeve |first2= F. |last2= Leaver |first3= I. |last3= Siegel |bibcode= 1952JAChS..74.2404S }}</ref> Iodoform reacts with aqueous [[silver nitrate]] to produce [[carbon monoxide]]. When treated with powdered elemental silver the iodoform is reduced, producing [[acetylene]]. Upon heating iodoform decomposes to produce diatomic iodine, hydrogen iodide gas, and carbon.

===Natural occurrence===
The [[angel's bonnet]] mushroom contains iodoform, and shows its characteristic odor.

==Applications==
The compound finds small-scale use as a disinfectant.<ref name=Merck/><ref>{{citation| first = Phyllis A.| last = Lyday |publisher = Wiley-VCH, Weinheim| year = 2005 | doi = 10.1002/14356007.a14_381.pub2 | title = Ullmann's Encyclopedia of Industrial Chemistry | pages = 1–13 | isbn = 9783527306732 | chapter = Iodine and Iodine Compounds }}</ref> Around the beginning of the 20th century, it was used in medicine as a healing and antiseptic dressing for wounds and sores and, although this use is now largely superseded by superior [[antiseptic]]s, it is still used in [[otolaryngology]] in the form of [[bismuth subnitrate]] iodoform [[Liquid paraffin (drug)|paraffin]] paste (BIPP) as an antiseptic packing for cavities.<ref>{{cite journal |last1= Randhawa |first1= G. K. |last2= Graham |first2= R. |last3= Matharu |first3= K. S. |title= Bismuth Iodoform Paraffin Paste: History and uses |journal= British Journal of Oral and Maxillofacial Surgery |year= 2019 |volume= 57 |issue= 10 |pages= E53–E54 |doi= 10.1016/j.bjoms.2019.10.153 }}</ref> It is the active ingredient in many ear powders for [[dog]]s and [[cat]]s, along with [[zinc oxide]] and [[propionic acid]], which are used to prevent infection and facilitate removal of ear hair.{{Citation needed|date=October 2014}}

==See also==
* [[Fluoroform]]
* [[Chloroform]]
* [[Bromoform]]

==References==
{{Reflist}}

==External links==
* {{PGCH|0343}}
* [https://www.creative-chemistry.org.uk/documents/N-ch3-16.pdf Preparation]
* {{Cite EB1911 |wstitle=Iodoform |volume=14 |page=726 |short=1}}

{{medicated dressings}}
{{halomethanes}}
{{Authority control}}

[[Category:Iodoalkanes]]
[[Category:Halomethanes]]
[[Category:Antiseptics]]
[[Category:Iodine-containing natural products]]
[[Category:Organoiodides]]