Iodoform

{{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{{cite book | title = Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = 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 HCBr₃, ‘chloroform’ for HCCl₃, and ‘iodoform’ for HCI₃ are acceptable in general nomenclature. Preferred IUPAC names are substitutive names.| chapter = Front Matter }}|Carbon hydride triiodide|Carbon triiodide{{cite web | url=https://pubchem.ncbi.nlm.nih.gov/compound/Iodoform | title=Iodoform }}}}

| 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{{GESTIS|ZVG= 491168}}

| Density = 4.008 g/cm³

| MeltingPtC = 119

| MeltingPt_ref =

| BoilingPtC = 218

| BoilingPt_ref =

| Solubility = 100 mg/L

| 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⁻¹·kg⁻¹

| MagSus = −117.1·10⁻⁶ cm³/mol

}}

| Section3 = {{Chembox Structure

| CrystalStruct = Hexagonal

| MolShape = Tetrahedral at 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)|1180 mg/kg (dermal, rat)|1.6 mmol/kg(s.c., mouse)Merck Index, 12 Edition, 5054}}

| IDLH = N.D.{{PGCH|0343}}

| REL = 0.6 ppm (10 mg/m³)

| PEL = none

}}

| Section8 = {{Chembox Related

| OtherFunction_label = haloalkanes

| OtherCompounds = {{ubl||Methyl iodide|Diiodomethane|Carbon tetraiodide|Fluoroform|Chloroform|Bromoform}}

}}

File:Iodoform.jpg]]

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, 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 geometry with C_3v 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;{{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}} and at much the same time independently by John Thomas Cooper.{{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}} 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 alcohols ({{chem2|CH3CHROH}}, where R is an alkyl or aryl group).

:Image:Iodoform synthesis.svg

The reaction of iodine and base with methyl ketones 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 alcohols containing at least one methyl group in alpha-position.

Some reagents (e.g. hydrogen iodide) convert iodoform to diiodomethane. Conversion to carbon dioxide is also possible.{{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 }} 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.{{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 }} 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 antiseptics, it is still used in otolaryngology in the form of bismuth subnitrate iodoform paraffin paste (BIPP) as an antiseptic packing for cavities.{{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 }} It is the active ingredient in many ear powders for dogs and cats, along with zinc oxide and propionic acid, which are used to prevent infection and facilitate removal of ear hair.{{Citation needed|date=October 2014}}