629-20-9Relevant articles and documents
Avram et al.
, (1964)
Mukai,Kurabayashi
, p. 4493,4494 (1970)
Mehta,Srikrishna
, p. 3187,3188, 3189 (1979)
Paquette,L.A. et al.
, p. 5806 - 5815 (1974)
Moriarty et al.
, p. 3085 (1971)
Quantitative Investigation of the Decomposition of Cyclooctene on Pt(111) Using BPTDS
Frei, Nathan,Campbell, Charles T.
, p. 8402 - 8407 (1996)
Other researches have reported (J.Am.Chem.Soc. 1993, 115, 2044; J.Phys.Chem. 1994, 98, 2952) that cyclooctene dehydrogenates on Pt(111) to stable adsorbed cyclooctatetraene, which then undergoes ring contraction to produce benzene but without any calibrated measurements of the yield.Here, quantitative thermal desorption mass spectrometry (TDS) and bismuth postdosing thermal desorption mass spectrometry (BPTDS) are used to investigate the conversion of cyclooctene to benzene on the Pt(111) surface.Our results show that although benzene is formed, it is a very minor product, corresponding to less than 2percent of a monolayer (including both adsorbed and gas-phase benzene).Most of the adsorbed cyclooctene either desorbs intact at low temperatures (ca. 10percent) or simply dehydrogenates (ca. 90percent), ultimately to surface carbon by 800 K, but without going through adsorbed benzene as an intermediate.Stable intermediates with stoichiometries C8H12 and C8H6 are identified by TDS to be present at 350 and 430 - 560 K, respectively, but BPTDS shows that neither of these correspond to a simple molecularly adsorbed state of a stable gaseous molecule.During the conversion between these two species, however, cyclooctatetraene is produced transiently at 430 K, suggesting that both of these species still have an intact C8 ring.
Cyclooctatetraene made easy
Gottfriedsen, Jochen,Miloslavina, Alesia,Edelmann, Frank T.
, p. 3583 - 3584 (2004)
Cyclooctatetraene, C8H8, has been made readily available from 1,5-cyclooctadiene in 65% yield without the need of using hazardous or toxic reagents by the straightforward oxidation of the intermediate [Li(tmeda)]2C8/
3 + 2 Cycloaddition via a Diels-Alder/retro-Diels-Alder sequence: Tandem cyclopentadienyl annulation of a 1,5-cyclooctadiyne synthetic equivalent
Davila, Alfonso,Ramezanian, Merrikh S.,Fronczek, Frank R.,McLaughlin, Mark L.
, p. 2517 - 2520 (1996)
A novel method of synthesizing a 1,2-bis(ethano) bridged bis(cyclopentadienyl) compound, 6,13-diisopropylidenetricyclo[9.3.0(1,11).0(4,8]tetradeca-1(14),4,7,11 -tetraene, 5, via a tandem Diels-Alder/retro-Diels-Alder sequence using a 1,5-cyclooctadiyne synthetic equivalent and 6,6-dimethylfulvene is reported.
Photochemical Unmasking of Polyyne Rotaxanes
Woltering, Steffen L.,Gawel, Przemyslaw,Christensen, Kirsten E.,Thompson, Amber L.,Anderson, Harry L.
supporting information, p. 13523 - 13532 (2020/09/02)
Bulky photolabile masked alkyne equivalents (MAEs) are needed for the synthesis of polyyne polyrotaxanes, as insulated molecular wires and as stabilized forms of the linear polymeric allotrope of carbon, carbyne. We have synthesized a novel MAE based on phenanthrene and compared it with an indane-based MAE. Photochemical unmasking of model compounds was studied at different wavelengths (250 and 350 nm), and key products were identified by NMR spectroscopy and X-ray crystallography. UV irradiation at 250 nm leads to unmasking of both MAEs. Irradiation of the phenanthrene system at 350 nm results in quantitative dimerization via [2 + 2] cycloaddition to form a [3]-ladderane; irradiation of this ladderane at 250 nm generates a dihydrotriphenylene, which can be oxidized easily to a triphenylene. Irradiation of the indane-based MAE at 350 nm in the presence of traces of oxygen forms an endoperoxide and a bisepoxide. Both MAEs have been incorporated into rotaxanes via copper-mediated active metal template Glaser or Cadiot-Chodkiewicz coupling. The identity of the rotaxanes was confirmed by NMR spectroscopy and mass spectrometry. The phenanthrene rotaxane decomposes during attempted photochemical unmasking, whereas photolysis of the indane rotaxane results in unmasking of the polyyne thread to form a rotaxane with a chain of 16 sp-hybridized carbon atoms. This approach opens avenues toward the synthesis of encapsulated carbon allotropes.
The rearrangement of the cubane radical cation in solution
Schreiner, Peter R.,Wittkopp, Alexander,Gunchenko, Pavel A.,Yaroshinsky, Alexander I.,Peleshanko, Sergey A.,Fokin, Andrey A.
, p. 2739 - 2744 (2007/10/03)
The rearrangement of the cubane radical cation (1.+) was examined both experimentally (anodic as well as (photo)chemical oxidation of cubane 1 in acetonitrile) and computationally at coupled cluster, DFT, and MP2 [BCCD(T)/cc-pVDZ//B3LYP/6-31G* + ZPVE as well as BCCD(T)/cc-pVDZ//MP2/6-31G* + ZPVE] levels of theory. The interconversion of the twelve C2v degenerate structures of 1.+ is associated with a sizable activation energy of 1.6 kcal mol-1. The barriers for the isomerization of 1.+ to the cuneane radical cation (2.+) and for the C-C bond fragmentation to the secocubane-4,7-diyl radical cation (10.+) are virtually identical (ΔH0? = 7.8 and 7.9 kcal mol-1, respectively). The low-barrier rearrangement of 10.+ to the more stable syn-tricyclooctadiene radical cation 3.+ favors the fragmentation pathway that terminates with the cyclooctatetraene radical cation 6.+. Experimental single-electron transfer (SET) oxidation of cubane in acetonitrile with photoexcited 1,2,4,5-tetracyanobenzene, in combination with back electron transfer to the transient radical cation, also shows that 1.+ preferentially follows a multistep rearrangement to 6.+ through 10.+ and 3.+ rather than through 2.+. This was confirmed by the oxidation of syn-tricyclooctadiene (3), which, like 1, also forms 6 in the SET oxidation/rearrangement/electron-recapture process. In contrast, cuneane (2) is oxidized exclusively to semibullvalene (9) under analogous conditions. The rearrangement of 1.+ to 6.+ via 3.+, which was recently observed spectroscopically upon ionization in a hydrocarbon glass matrix, is also favored in solution.
