2-Butyne: Difference between revisions

| verifiedrevid = 403365671

| Reference=<ref>[https://www.sigmaaldrich.com/US/en/product/aldrich/254339] at [[Sigma-Aldrich]]</ref><ref>[http://webbook.nist.gov/cgi/cbook.cgi?ID=C503173 NIST Chemistry WebBook page for 2-butyne]</ref>

| Name = 2-Butyne

| ImageFile1 = <chem>H3C-C#C-CH3</chem>

| ImageSize1 = 180px

| ImageName1 = Structural formula

| ImageFile2 = 2-butyne-3D-balls-B.png

| ImageSize2 = 150px

| ImageName2 = Ball-and-stick model

| PIN = But-2-yne <!-- Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) -->

| OtherNames = Dimethylacetylene<br />Crotonylene

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = LKE6D3018E

| SMILES = C(#CC)C

|Section2={{Chembox Properties

| Formula = C₄H₆

| MolarMass = 54.0904 g/mol

| Density = 0.691 g/mL

| MeltingPtC = -32

| BoilingPtC = 27

'''2-Butyne''' ('''dimethylacetylene''', '''crotonylene''' or '''but-2-yne''') is an [[alkyne]] with [[chemical formula]] CH₃C≡CCH₃. Produced artificially, it is a colorless, volatile, pungent liquid at [[standard temperature and pressure]].

2-Butyne is of interest to physical chemists because of its very low [[torsional barrier]] and the problem of determining that barrier using high-resolution infrared spectroscopy. Analysis of its spectrum<ref>{{cite journal | last = di Lauro | first = C.|display-authors=etal| year = 1997 | title =The rotation-torsion structure in the ν11/ν15 (Gs) methyl rocking fundamental band in dimethylacetylene

| journal = J. Mol. Spectrosc.| volume = 184 | issue = 1

| pages = 177–185 | doi =10.1006/jmsp.1997.7321}}</ref>

leads to a determination that the torsional barrier is only 6 cm⁻¹ (1.2{{e|-22}} J or 72 J mol⁻¹). However, it has not been determined whether the equilibrium structure is eclipsed (D_3h) or staggered (D_3d). Symmetry analysis using the Molecular Symmetry Group<ref name=Longuet-Higgins1963>{{cite journal | last1 = Longuet-Higgins | first1 = H.C. | year = 1963 | title = The symmetry groups of non-rigid molecules | journal = Molecular Physics | volume = 6 | issue = 5| pages = 445–460 | doi = 10.1080/00268976300100501 | bibcode = 1963MolPh...6..445L | doi-access = free }}</ref><ref>{{cite journal | author1=P. R. Bunker | year=1964

| title=The Rotation-Torsion Wavefunctions of Molecules that have two Identical Rotors

| journal=Mol. Phys. | volume=8 | page=81 | doi = 10.1080/00268976400100091}}</ref> G₃₆ shows that one would need to analyse its high resolution [[Rotational–vibrational spectroscopy|rotation-vibration]] [[Raman spectrum]] to determine its equilibrium structure.

2-Butyne (''dimethylethyne'') forms with [[5-decyne]] (''dibutylethyne''), [[4-octyne]] (''dipropylethyne'') and [[3-hexyne]] (''diethylethyne'') a group of symmetric alkynes.

==Synthesis==

2-Butyne can be synthesized by the [[rearrangement reaction]] of [[ethylacetylene]] in a solution of [[ethanol]]ic [[potassium hydroxide]].<ref>{{cite book|author1=Victor von Richter |author2=Hans Meerwein|title=Organic Chemistry: Chemistry of the aliphatic series Vol. I: Smith's 3rd American Ed.|year=1916|publisher=P. Blakiston's Sons & Co.|location=Philadelphia|page=89|url=https://books.google.com/books?id=UWlZAAAAYAAJ&q=dimethylacetylene+preparation&pg=PA89}}</ref>

==Applications==

2-Butyne, along with [[propyne]], is used to synthesize [[alkylated]] [[hydroquinone]]s in the [[total synthesis]] of [[Vitamin E]].<ref name=Cyclization>{{cite journal|author1=Reppe, Walter |author2=Kutepow, N |author3=Magin, A |title=Cyclization of Acetylenic Compounds|journal=Angewandte Chemie International Edition in English|year=1969|volume=8|issue=10|pages=727–733|doi=10.1002/anie.196907271}}</ref>

*[[Acetylenedicarboxylic acid]]

*[[1-Butyne]], a position isomer

*[[1,4-Butynediol]]

*[[Hexamethylbenzene]], a product of 2-butyne [[trimerization]]

*[[Hexafluoro-2-butyne]]

{{DEFAULTSORT:Butyne2}}