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| Names | |||
|---|---|---|---|
| Preferred IUPAC name Triiodomethane | |||
| Other names | |||
| Identifiers | |||
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3D model (JSmol) | |||
| 1697010 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.000.795 | ||
| EC Number |
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| KEGG |
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| MeSH | iodoform | ||
| RTECS number |
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| UNII | |||
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| Properties | |||
| CHI3 | |||
| Molar mass | 393.732 g·mol−1 | ||
| Appearance | Pale, light yellow, opaque crystals | ||
| Odor | Saffron-like[3] | ||
| Density | 4.008 g/cm3[3] | ||
| Melting point | 119 °C (246 °F; 392 K)[3] | ||
| Boiling point | 218 °C (424 °F; 491 K)[3] | ||
| 100 mg/L[3] | |||
| Solubility indiethyl ether | 136 g/L | ||
| Solubility inacetone | 120 g/L | ||
| Solubility inethanol | 78 g/L | ||
| logP | 3.118 | ||
Henry's law constant (kH) | 3.4 μmol·Pa−1·kg−1 | ||
| −117.1·10−6 cm3/mol | |||
| Structure | |||
| Hexagonal | |||
| Tetrahedral atC | |||
| Thermochemistry | |||
| 157.5 J/(K·mol) | |||
Std enthalpy of formation(ΔfH⦵298) | 180.1 – 182.1 kJ/mol | ||
Std enthalpy of combustion(ΔcH⦵298) | −716.9 – −718.1 kJ/mol | ||
| Pharmacology | |||
| D09AA13 (WHO) | |||
| Hazards | |||
| GHS labelling: | |||
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| Warning | |||
| H315,H319,H335 | |||
| P261,P280,P305+P351+P338 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 204 °C (399 °F; 477 K) | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | |||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | none[4] | ||
REL (Recommended) | 0.6 ppm (10 mg/m3)[4] | ||
IDLH (Immediate danger) | N.D.[4] | ||
| Related compounds | |||
Related compounds | |||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Iodoform (also known astriiodomethane) is theorganoiodine compound with thechemical formulaCHI3. 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 tochloroform, sweetish taste. It is occasionally used as adisinfectant.
The name iodoform originates with the "formyle radical," an archaic term for the HC moiety,[citation needed] 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,[2] though the IUPAC recommends against doing so, as "carbon triiodide" could also meanC2I6 (hexaiodoethane, a highly unstable compound).
The molecule adopts atetrahedral geometry with C3vsymmetry.
The synthesis of iodoform was first described byGeorges-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;[6] and at much the same time independently byJohn Thomas Cooper.[7] It is synthesized in thehaloform reaction by the reaction of iodine and sodium hydroxide with any one of these four kinds of organic compounds: a methylketone (CH3COR),acetaldehyde (CH3CHO),ethanol (CH3CH2OH), and certain secondaryalcohols (CH3CHROH, where R is an alkyl or aryl group).
The reaction of iodine and base withmethylketones is so reliable that theiodoform 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 specificsecondary alcohols containing at least onemethyl group inalpha-position.
Some reagents (e.g.hydrogen iodide) convert iodoform todiiodomethane. Conversion tocarbon dioxide is also possible.[8] Iodoform reacts with aqueoussilver nitrate to producecarbon monoxide. When treated with powdered elemental silver the iodoform is reduced, producingacetylene. Upon heating iodoform decomposes to produce diatomic iodine, hydrogen iodide gas, and carbon.
Theangel's bonnet mushroom contains iodoform, and shows its characteristic odor.
The compound finds small-scale use as a disinfectant.[5][9] 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 superiorantiseptics, it is still used inotolaryngology in the form ofbismuth subnitrate iodoformparaffin paste (BIPP) as an antiseptic packing for cavities.[10] It is the active ingredient in many ear powders fordogs andcats, along withzinc oxide andpropionic acid, which are used to prevent infection and facilitate removal of ear hair.[citation needed]
The retained names 'bromoform' for HCBr3, 'chloroform' for HCCl3, and 'iodoform' for HCI3 are acceptable in general nomenclature. Preferred IUPAC names are substitutive names.
