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词条 Iodoform
释义

  1. Structure

  2. Synthesis and reactions

     Natural occurrence 

  3. Applications

  4. See also

  5. References

  6. External links

{{for|use of the term "iodoform" in cryptography|Group key}}{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 444991229
| ImageFile = Iodoform.svg
| 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|??}}
| ImageName2 = Sample of crystalline iodoform in a watchglass
| PIN = Triiodomethane
| OtherNames = Iodoform[1]
|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[2]
| Density = 4.008 g cm−3[2]
| MeltingPtC = 119
| MeltingPt_notes =[2]
| BoilingPtC = 218
| BoilingPt_notes =[2]
| Solubility = 100 mg L−1[2]
| Solvent1 = diethyl ether
| Solubility1 = 136 g L−1
| Solvent2 = acetone
| Solubility2 = 120 g L−1
| Solvent3 = ethanol
| Solubility3 = 78 g L−1
| LogP = 3.118
| HenryConstant = 3.4 μmol Pa−1 kg−1
| MagSus = −117.1·10−6 cm3/mol
}}
|Section3={{Chembox Structure
| CrystalStruct = Hexagonal
| Coordination = Tetragonal
| MolShape = Tetrahedron
}}
|Section5={{Chembox Thermochemistry
| DeltaHf = 180.1–182.1 kJ mol−1
| DeltaHc = −716.9 – −718.1 kJ mol−1
| HeatCapacity = 157.5 J K−1 mol−1
}}
|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 = 0
| NFPA-R = 1
| FlashPtC = 204
| LD50 = {{unbulleted list|355 mg/kg (oral, rat)[2]|1180 mg/kg (dermal, rat)[2]|1.6 mmol/kg(s.c., mouse)[3]}}
| IDLH = N.D.[4]
| REL = 0.6 ppm (10 mg/m3)[4]
| PEL = none[4]
}}
|Section8={{Chembox Related
| OtherFunction_label = haloalkanes
| OtherFunction = {{unbulleted list|Methyl iodide|Diiodomethane|Carbon tetraiodide|Chloroform|Bromoform}}
| OtherCompounds = {{unbulleted list|Guanidine|Pimagedine}}
}}
}}

Iodoform (also known as tri-iodomethane, carbon triiodide, and methyl triiodide{{citation needed|date=October 2018}}) is the organoiodine compound with the formula CHI3. A pale yellow, crystalline, volatile substance, it has a penetrating and distinctive odor (in older chemistry texts, the smell is sometimes referred to as the smell of hospitals, where the compound is still commonly used) and, analogous to chloroform, sweetish taste. It is occasionally used as a disinfectant.

Structure

The molecule adopts tetrahedral molecular geometry with C3v 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;[5] and at much the same time independently by John Thomas Cooper.[6] 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 (CH3COR), acetaldehyde (CH3CHO), ethanol (CH3CH2OH), and certain secondary alcohols (CH3CHROH, where R is an alkyl or aryl group).

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. Also conversion to carbon dioxide is possible: 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.[3][7] Around the beginning of the 20th century, it was used in medicine as a healing and antiseptic dressing for wounds and sores, although this use is now superseded by superior antiseptics. It is the active ingredient in many ear powders for dogs and cats, along with zinc oxide and propanoic acid, which are used to prevent infection and facilitate removal of ear hair.{{Citation needed|date=October 2014}}

See also

  • Iodoform reaction
  • Chloroform

References

1. ^{{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 }}
2. ^{{GESTIS|ZVG= 491168}}
3. ^Merck Index, 12 Edition, 5054
4. ^{{PGCH|0343}}
5. ^{{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}}
6. ^{{cite web|last=James|first=Frank A. J. L.|title=Cooper, John Thomas (1790–1854), chemist|url=http://www.oxforddnb.com/view/article/39361|work=Oxford Dictionary of National Biography|publisher=Oxford University Press|accessdate=26 January 2012}}
7. ^{{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 }}

External links

  • {{PGCH|0343}}
  • MSDS at JT Baker
  • A Method for the Specific Conversion of Iodoform to Carbon Dioxide
  • {{Cite EB1911 |wstitle=Iodoform |volume=14 |page=726 |short=1}}
  • Preparation
{{medicated dressings}}{{halomethanes}}{{Use dmy dates|date=April 2017}}

3 : Iodoalkanes|Halomethanes|Antiseptics

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