Propyne: Difference between revisions

{{Short description|Hydrocarbon compound (HC≡C–CH3)}}

{{distinguish|propane|propene}}

| Verifiedfields = changed

| verifiedrevid = 406858995

| Name = Propyne

| ImageFile = PROPYNE.png

| ImageSize = 120px

| ImageName = Methylacetylene

| ImageFile1 = Propyne-3D-vdW.png

| ImageSize1 = 180px

| PIN = Propyne<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry|The Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 374 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4| chapter = Front Matter }}</ref><ref group="note">"Prop-1-yne" mistake fixed in the [https://www.qmul.ac.uk/sbcs/iupac/bibliog/BBerrors.html errata] {{Webarchive|url=https://web.archive.org/web/20190801093648/https://www.qmul.ac.uk/sbcs/iupac/bibliog/BBerrors.html |date=2019-08-01 }}. The locant is omitted according to P-14.3.4.2&nbsp;(d), p.&nbsp;31.</ref>

| SystematicName =

| OtherNames = Methylacetylene<br />Methyl acetylene<br />Allylene

| IUPACName =

| Section1 = {{Chembox Identifiers

| CASNo = 74-99-7

| CASNo_Ref = {{cascite|correct|CAS}}

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

| UNII = 086L40ET1B

| ChEMBL_Ref = {{ebicite|changed|EBI}}

| ChEMBL = 116902

| SMILES = CC#C

| EINECS = 200-828-4

| PubChem = 6335

| ChemSpiderID = 6095

| InChI = 1/C3H4/c1-3-2/h1H,2H3

| InChIKey = MWWATHDPGQKSAR-UHFFFAOYAI

| StdInChI = 1S/C3H4/c1-3-2/h1H,2H3

| StdInChIKey = MWWATHDPGQKSAR-UHFFFAOYSA-N

| RTECS =

| MeSHName = C022030

| ChEBI = 48086

| ChEBI_Ref = {{ebicite|correct|ebi}}

| Beilstein = 878138

| Section2 = {{Chembox Properties

| Formula = {{chem2|C3H4}}

| MolarMass = 40.0639 g/mol

| Density = 0.53 g/cm³

| MeltingPtC = -102.7

| BoilingPtC = -23.2

| Appearance = Colorless gas<ref name=NIOSH/>

| Odor = Sweet<ref name=NIOSH/>

| VaporPressure = 5.2 atm (20°C)<ref name=NIOSH/>

| Section3 = {{Chembox Hazards

| PEL = TWA 1000 ppm (1650 mg/m³)<ref name=NIOSH>{{PGCH|0392}}</ref>

| ExploLimits = 1.7%-?<ref name=NIOSH/>

| IDLH = 1700 ppm<ref name=NIOSH/>

| REL = TWA 1000 ppm (1650 mg/m³)<ref name=NIOSH/>

}}

| Section4 =

| Section5 =

| Section6 =

'''Propyne''' ('''methylacetylene''') is an [[alkyne]] with the [[chemical formula]] {{chem2|CH3C\tCH}}. It is a component of [[MAPP gas|MAPD gas]]—along with its [[isomer]] [[propadiene]] (allene), which was commonly used in [[gas welding]]. Unlike [[acetylene]], propyne can be safely [[Condensation|condensed]].<ref name=Ullmann>Peter Pässler, Werner Hefner, Klaus Buckl, Helmut Meinass, Andreas Meiswinkel, Hans-Jürgen Wernicke, Günter Ebersberg, Richard Müller, Jürgen Bässler, Hartmut Behringer, Dieter Mayer, "Acetylene" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim 2007 ({{doi|10.1002/14356007.a01_097.pub2}}).</ref>

==Production and equilibrium with propadiene==

Propyne exists in equilibrium with [[propadiene]], the mixture of propyne and propadiene being called MAPD:

:<chem>H3CC#CH <=> H2C=C=CH2</chem>

The coefficient of equilibrium ''K''_eq is 0.22 at 270&nbsp;°C or 0.1 at 5&nbsp;°C.

MAPD is produced as a side product, often an undesirable one, by [[cracking (chemistry)|cracking]] [[propane]] to produce [[propene]], an important [[feedstock]] in the [[chemical industry]].<ref name=Ullmann/> MAPD interferes with the [[Ziegler–Natta catalyst|catalytic]] [[polymerization]] of propene.

===Laboratory methods===

Propyne can also be synthesized on laboratory scale by reducing [[1-propanol]],<ref>{{cite journal|author1=Keiser, Edward |author2=Breed, Mary |name-list-style=amp |title=The Action of Magnesium Upon the Vapors of the Alcohols and a New Method of Preparing Allylene|journal=Journal of the Franklin Institute|year=1895|volume=CXXXIX|issue=4 |pages=304–309|url=https://books.google.com/books?id=jn-VkwcIt5QC&q=allylene+franklin+magnesium&pg=PA309|access-date=20 February 2014|doi=10.1016/0016-0032(85)90206-6}}</ref> [[allyl alcohol]] or [[acetone]]<ref>{{cite journal|last=Reiser, Edward II.|title=The preparation of Allylene, and the Action of Magnesium upon Organic Compounds|journal=The Chemical News and Journal of Industrial Science|year=1896|volume=LXXIV|pages=78–80|url=https://books.google.com/books?id=TxgAAAAAMAAJ&q=allylene+magnesium+preparing&pg=PA78|access-date=20 February 2014}}</ref> vapors over magnesium.

European space companies have researched using light [[hydrocarbons]] with [[liquid oxygen]], a relatively high performing [[liquid rocket propellant]] combination that would also be less toxic than the commonly used MMH/NTO ([[monomethylhydrazine]]/[[nitrogen tetroxide]]). Their research showed{{citation needed|date=September 2013}} that propyne would be highly advantageous as a [[rocket fuel]] for craft intended for [[low Earth orbit]]al operations. They reached this conclusion based upon a [[specific impulse]] expected to reach 370 [[second|s]] with oxygen as the oxidizer, a high [[density]] and [[power density]]—and the moderate [[boiling point]], which makes the chemical easier to store than [[cryogenic fuel]]s that must be kept at extremely low temperatures.<ref>{{Cite web |last=Valentian |first=Dominique |last2=Sippel |first2=Martin |last3=Grönland |first3=Tor-Arne |last4=Baker |first4=Adam |last5=van Den Meulen |first5=Jaap |last6=Fratacci |first6=Georges |last7=Caramelli |first7=Fabio |date=2004 |title=Green propellants options for launchers, manned capsules and interplanetary missions |url=http://www.la.dlr.de/ra/sart/publications/pdf/esa02-2004.pdf |url-status=dead |archive-url=https://web.archive.org/web/20060110171612/http://www.la.dlr.de/ra/sart/publications/pdf/esa02-2004.pdf |archive-date=2006-01-10 |website=la.dlr.de |publisher=[[German Aerospace Center|DLR]] Lampoldshausen}}</ref>

Propyne is a convenient three-carbon building block for [[organic synthesis]]. Deprotonation with [[n-Butyllithium|''n''-butyllithium]] gives [[propynyllithium]]. This [[nucleophilic]] reagent adds to [[carbonyl]] groups, producing [[Alcohol (chemistry)|alcohol]]s and [[ester]]s.<ref>{{OrgSynth | author1 = Michael J. Taschner|author2=Terry Rosen|author3=Clayton H. Heathcock | title = Ethyl Isocrotonate | collvol = 7 | collvolpages = 226| year = 1990 | prep = CV7P0226}}</ref> Whereas purified propyne is expensive, MAPP gas could be used to cheaply generate large amounts of the reagent.<ref>{{US patent reference | number = 5744071 | y = 1996 | m = 11 | d = 19 | inventor = Philip Franklin Sims, Anne Pautard-Cooper | title = Processes for preparing alkynyl ketones and precursors thereof }}</ref>

Propyne, along with [[2-butyne]], is also 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 |name-list-style=amp |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>

The chemical shift of an alkynyl proton and propargylic proton generally occur in the same region of the [[Proton nuclear magnetic resonance|¹H NMR]] spectrum. In propyne, these two signals have almost exactly the same chemical shifts, leading to overlap of the signals, and the ¹H NMR spectrum of propyne, when recorded in deuteriochloroform on a 300&nbsp;MHz instrument, consists of a single signal, a sharp singlet resonating at 1.8 ppm.<ref>{{Cite book|title=Organic chemistry|first1=Marc|last1=Loudon|first2=Jim|last2=Parise|others=Parise, Jim, 1978-|isbn=9781936221349|edition= Sixth|location=Greenwood Village, Colorado|publisher=W. H. Freeman|oclc=907161629|date = 2015-08-26}}</ref>

==Notes==

<references group="note" />

==External links==

* [http://webbook.nist.gov/cgi/cbook.cgi?ID=C74997 NIST Chemistry WebBook page for propyne]

* [https://web.archive.org/web/20060110171612/http://www.la.dlr.de/ra/sart/publications/pdf/esa02-2004.pdf German Aerospace Center]

* [https://web.archive.org/web/20070928144135/http://www.novachem.com/ProductServices/docs/CrudePropylene_MSDS_EN.pdf Nova Chemicals]

* [https://www.cdc.gov/niosh/npg/npgd0392.html CDC - NIOSH Pocket Guide to Chemical Hazards]

{{Molecules detected in outer space}}

{{Hydrides by group}}

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