{{Chembox | Reference = | PIN = Selenophene<ref>{{cite book |author=International Union of Pure and Applied Chemistry |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=The Royal Society of Chemistry |pages=141 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}</ref> | OtherNames = | ImageFileL1= Selenophene Structural Formula V1.svg | ImageFileR1 = Selenophene-3D-spacefill.png | ImageFile2 = Selenophene-3D-balls.png |Section1={{Chembox Identifiers | Identifiers_ref = | CASNo = 288-05-1 | CASNo_Comment = | ChEBI = 30857 | ChEBI_Comment = | ChEMBL = | ChEMBL_Comment = | ChemSpiderID = 119907 | ChemSpiderID_Comment = | KEGG = | KEGG_Comment = | PubChem = 136130 | PubChem_Comment = | SMILES = C1=C[Se]C=C1 | SMILES_Comment = | Jmol = | StdInChI = | StdInChI_Comment = | StdInChIKey = | InChI=1S/C4H4Se/c1-2-4-5-3-1/h1-4H | InChI_Comment = | InChIKey = MABNMNVCOAICNO-UHFFFAOYSA-N | UNII = UYZ3M5T8L7 | UNII_Comment = | 3DMet = | Abbreviations = | Beilstein = 103223 | EC_number = | EC_number_Comment = | Gmelin = 100994 | MeSHName = | RTECS = | UNNumber = }} | Section2={{Chembox Properties | C=4 | H=4 | Se=1 | Appearance = colorless liquid | Odor = | Density = 1.52 g/cm<sup>3</sup> | MeltingPtC =-38 | BoilingPtC = 110 | Solubility = | SolubleOther = | VaporPressure = | MagSus = | ThermalConductivity = | RefractIndex = 1.58 | Viscosity = | Dipole = }} | Section7 = {{Chembox Hazards | Hazards_ref = | ExternalSDS = | GHSPictograms = {{GHS02}}{{GHS06}}{{GHS08}}{{GHS09}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|225|301|331|373|410}} | PPhrases = {{P-phrases|210|233|240|241|242|243|260|261|264|270|271|273|280|301+310|303+361+353|304+340|311|314|321|330|370+378|391|403+233|403+235|405|501}} | MainHazards = | FlashPtC = | AutoignitionPtC = | ExploLimits = | LD50 = | LDLo = | LC50 = | LCLo = | PEL = | REL = | IDLH = | NIOSH_id = | NIOSH_ref = }} | Section8 = {{Chembox Related | OtherFunction =selenolane<br/>2-selenolene<br/>3-selenolene | OtherFunction_label = more saturated | OtherCompounds = furan<br/>thiophene<br/>tellurophene }} }}

'''Selenophene''' is an organic compound with the chemical formula {{chem2|C4H4Se|auto=1}}. It is an unsaturated compound containing a five-member ring with four carbon atoms and one selenium atom. It is a selenium analog of furan {{chem2|C4H4O}} and thiophene {{chem2|C4H4S}}. A colorless liquid, it is one of the more common selenium heterocycles.

==Nomenclature== Atoms in selenophene are numbered sequentially around the ring, starting with the selenium atom as number 1 following normal systematic nomenclature rules. Oxidized forms include selenophene 1,1-dioxide.<ref>{{Cite book|doi=10.1016/B978-008044992-0.00313-8|title=Comprehensive Heterocyclic Chemistry III|last=Pelkey|first=E. T.|date=2008|publisher=Elsevier|isbn=9780080449920|editor-last=Katritzky|editor-first=Alan R.|location=Oxford|pages=975–1006|editor-last2=Ramsden|editor-first2=Christopher A.|editor-last3=Scriven|editor-first3=Eric F. V.|editor-last4=Taylor|editor-first4=Richard J. K.}}</ref> Related ring structures include those with only one double bond (2-selenolene and 3-selenolene) and the fully saturated structure selenolane.<ref name=taid>{{cite book|last1=Hartough|first1=H. D.|title=Thiophene and Its Derivatives|date=2009|publisher=John Wiley & Sons|isbn=9780470188026|url=https://books.google.com/books?id=QUgfYi95al4C&pg=PA480|language=en}}</ref>

==Production== Mazza and Solazzo reported the first confirmed synthesis in 1927. By treating selenium with acetylene and at about 300&nbsp;°C yields up to 15% selenophene were obtained. Benzoselenophene (analogue of benzothiophene) was also produced.<ref name=taid/>

Substituted selenophenes can be made using a Fiesselman procedure in which a β-chloro-aldehyde reacts with sodium selenide, and then ethyl bromoacetate.<ref name=tcah>{{cite book|last1=Eicher|first1=Theophil|last2=Hauptmann|first2=Siegfried|last3=Speicher|first3=Andreas|title=The Chemistry of Heterocycles: Structures, Reactions, Synthesis, and Applications|date=2013|publisher=John Wiley & Sons|isbn=9783527669868|pages=69–70|url=https://books.google.com/books?id=lAt_Y09iW-4C&pg=PA69|language=en}}</ref>

==Properties== The selenophene molecule is flat.<ref name=tcah/> Being aromatic, it undergoes electrophilic substitution reactions. As for thiophene, electrophiles tend to attack at the carbon positions next to the chalcogen. Such reactions are slower than that of furan, but faster than thiophene.<ref name=tcah/>

==References== {{Reflist}}

Category:Selenium(−II) compounds Category:Heterocyclic compounds with 1 ring Category:Selenium heterocycles