1,4-Pentadiyne

1,4-Pentadiin.svg 150px Penta-1,4-diyne-3D-balls.png Chemical structure of 1,4-pentadiyne Penta-1,4-diyne 24442-69-1 correct CAS 141112 124473 C#CCC#C InChI=1S/C5H4/c1-3-5-4-2/h1-2H,5H2 MDROPVLMRLHTDK-UHFFFAOYSA-N DTXSID20179202 5 4 colorless liquid −21 – −19 61–64 1.4283 (23 °C) 0.516 D 1,4-Pentadiyne (penta-1,4-diyne) is a chemical compound belonging to the alkynes. The compound is the structural isomer to 1,3-pentadiyne. Preparation Until the late 1960s, no successful synthesis of this seemingly simply preparable molecule was described. Although long-chain and more complex 1,4-diynes had been synthesized successfully before,H. Taniguchi I. M. Mathai S. I. Miller Synthesis and spectral properties of 1,4- and 1,3-pentadiynes Tetrahedron 22 3 1966 867–878 10.1016/0040-4020(66)80058-3 synthesis approaches starting from sodium acetylide or the acetylene Grignard reagent and propargyl bromide or methylene chloride failed, even with the inclusion of copper(I) chloride.J. M. Todd Attempted preparation of 1, 4-pentadiyne 1961 MA Boston University 2144/18627 https://hdl.handle.net/2144/18627 Mostly 1,3-pentadiyne was obtained as rearrangement product.D. A. Ben-Efraim F. Sondheimer The synthesis and some reactions of a series of "skipped" polyacetylenes containing terminal acetylene groups Tetrahedron 25 14 1969 2823–2835 10.1016/0040-4020(69)80026-8 The first successful isolation reacted propargyl bromide and ethynylmagnesium bromide, with a copper(I) chloride catalyst in THF. This gave a 70% yield in solution, but the product was difficult to separate from the solvent. Compared to previous attempts, the successful approach included an additional round of flash distillation and gas-liquid chromatography of the distillate.H. D. Verkruijsse M. Hasselaar An Improved Synthesis of 1,4-Diynes Synthesis 4 1974 4 292–293 10.1055/s-1979-28653 95166709 An improved synthesis method was published by Verkruijsse and Hasselaar in 1979. Copper chloride was substituted by copper(I) bromide as well as propargyl bromide by propargyl tosylate. At lower reaction temperatures and fewer by-products, the alkiyne was obtained after multistep extraction. According to the publication’s authors, this circumvented the problem that the solvent THF and the main compound share similar boiling points. 500px|thumb|center|Preparation of 1,4-pentadiyne by Verkruijsse and Hasselaar Moreover, a flash vacuum pyrolysis starting from 3-ethynylcycloprop-1-ene at 550 °C yields the compound and penta-1,2-dien-4-yne as sideproduct.Synthesis of Alkenyl- and Alkynylcyclopropenes Michael M. Haley Bluegrass Biggs Will A. Looney Robert D. Gilbertson Tetrahedron Lett. 36 20 3457–3460 1995 10.1016/0040-4039(95)00634-O 500px|thumb|center|Pyrolytic or photochemical decomposition of 3ethynyl­cyclo­prop-1ene gives 5:1 1,4penta­diyne and a dienyne sideproduct. Alternatively, a photolytic decomposition of cyclopentadienylidene via UV radiation is possible.Photochemistry of matrix-isolated cyclopentadienylidene revisited G. Maier J. Endres J. Mol. Struct. 556 2000 1–3 179–187 10.1016/S0022-2860(00)00631-1 2000JMoSt.556..179M The compounds forms also during the exothermic reaction of allene and the ethynyl radical. This reaction is mainly of interest for astrochemistry.A crossed molecular beams study of the reaction of the ethynyl radical (C2H(X2Σ+)) with allene (H2CCCH2(X1A1)) Fangtong Zhang Seol Kim Ralf I. Kaiser Phys. Chem. Chem. Phys. 10.1039/B822366A 11 2009 23 4707–4714 19492123 2009PCCP...11.4707Z Reactions of ethynyl radicals as a source of C4 and C5 hydrocarbons in Titan's atmosphere F. Stahl P. v. R. Schleyer H. F. Schaefer III R. I. Kaiser Planet. Space Sci. 50 2002 7–8 685–692 10.1016/S0032-0633(02)00014-4 2002P&SS...50..685S Detection of pentatetraene by reaction of the ethynyl radical (C2H) with allene (CH2=C=CH2) at room temperature Fabien Goulay Satchin Soorkia Giovanni Meloni David L. Osborn Craig A. Taatjes Stephen R. Leone Phys. Chem. Chem. Phys. 2011 13 46 20820–20827 10.1039/C1CP22609F 22002654 Properties At room temperature the substance discolors from a colorless to a yellowish liquid, however, storage in diluted solutions at 0 °C is possible for multiple weeks. While for 1,4-pentadiene the sp2-hybridization leads to a bond angle of 120° between the single and double bond, in 1,4-pentadiyne it is a 180° angle due to the sp-hybrid orbital. Both triple bonds in 1,4-position destabilize each other according to another study by 3.9 kcal · mol−1, a repulsion between the p orbital lobes close to the sp3-hybridized carbon has been postulated.Donald W. Rogers Nikita Matsunaga Frank J. McLafferty Andreas A. Zavitsas Joel F. Liebman On the Lack of Conjugation Stabilization in Polyynes (Polyacetylenes) J. Org. Chem. 2004 69 21 7143–7147 10.1021/jo049390o 15471463 According to a QCSID(T) calculation, the alkiyne is destabilized relative to 1,3-pentadiyne by 25 kcal · mol−1.Identification of C5Hx Isomers in Fuel-Rich Flames by Photoionization Mass Spectrometry and Electronic Structure Calculations Nils Hansen Stephen J. Klippenstein James A. Miller Juan Wang Terrill A. Cool Matthew E. Law Phillip R. Westmoreland Tina Kasper Katharina Kohse-Höinghaus 10.1021/jp0569685 J. Phys. Chem. A 2006 110 13 4276–4388 16571041 2006JPCA..110.4376H Although microwave spectroscopy revealed besides a dipole moment of 0.516 D no significant distortions compared to an ideal tetrahedron, three different ionization energies are reported for the π-system.Robert L. Kuczkowski Frank J. Lovas R. D. Suenram The microwave spectrum, structure and dipole moment of 1,4-pentadyine J. Mol. Struct. 1981 72 143–152 10.1016/0022-2860(81)85014-4 1981JMoSt..72..143K 2027.42/24440 free Usage 1,4-pentadiyne is a common starting material for the synthesis of heterobenzenes such as stiba-, arsa- and phosphabenzene and their substituted derivatives.The group 5 heterobenzenes Arthur J. Ashe III Acc. Chem. Res. 1978 11 4 153–157 10.1021/ar50124a005Preparation of 2-substituted arsabenzes Arthur J. Ashe III Woon-Tung Chan J. Org. Chem. 44 9 1979 1409–1413 10.1021/jo01323a010 450px|thumb|center|1,4-Pentadiin is used in the preparation of heterobenzenes References Category:Diynes