Pyrolysis of 1.3.5.7‐Cyclooctatetraene, Semibullvalene, and 1.5‐Dihydropentalene in Shock Waves and in a Flow System (Part I)

Dudek, D.; Glänzer, K.; Troe, J.

doi:10.1002/bbpc.19790830805

Cited by 19 publications

(18 citation statements)

References 36 publications

(19 reference statements)

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“…In laser flash photolysis experiments (1 = 265 nm) direct, i. e. time resolved, measurements of k ( E ) for the COT photoreactions were performed. The results reported below permit some conclusions about the reaction mechanism of excited COT molecules by comparison of the photochemistry and the pyrolysis [6] of COT and related CRH8 compounds.…”

Section: Photochemie / Reaktionskinetikmentioning

confidence: 70%

“…4 of Ref. [6]) was obtained. The spectrum is very similar to the previously reported UV spectrum of SBV in solution [IS] at short wavelengths (I i 250nm); the broad bands near 265, 272, 280, and 290nm of the present spectrum were not mentioned in the earlier work.…”

Section: Stationary Photolysis Of Cotmentioning

confidence: 89%

“…The initial pressures of COT before the experiment were measured in situ via absorption at I = 230nm using the extinction coefficient given in Ref. [6]; they were in the range 0.03 -0.2 Torr.…”

Section: Laser Flash Photolysis Experimentsmentioning

confidence: 99%

“…[6]) only short photolysis times of typically 1/2-5 min were required in our measurements. In a first series of experiments the photolysis products were analyzed depending on wavelength and COT pressure.…”

Section: Stationary Photolysis Of Cotmentioning

confidence: 99%

“…The reactants used were obtained commercially or prepaied (e. g. 1.5-DHP) as described in Part I (Ref. [6]). …”

mentioning

confidence: 99%

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Photolysis of 1.3.5.7‐Cyclooctatetraene and 1.5‐Dihydropentalene by Steady State and by Laser Flash Irradiation (Part II)

Dudek

Glänzer

Troe

1979

Ber Bunsenges Phys Chem

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of 1.3.5.7-Cyclooctatetraene etc. (Part 11) absorption spectrum [A. Langseth and S. Brodersen, Acta Chem. Scand. 3, 778 (194911. The latter would, however, not explain the decrease of absorption in the range 260 -280 nm observed in the present experiments at T z 650 K.Product distributions in the UV photolysis of cyclooctatetraene vapour have been measured. Two parallel reaction channels leading to decomposition into benzene + acetylene and to isomerization to dihydropentalene or semibullvalene have been observed. Equal isomer yields have been found at pressures of 2 -3 Torr; semibullvalene formation is, however, favoured at increasing pressures. and dihydropentalene formation becomes more important at decreasing pressures. Absolute quantum yields and specific rate constants k ( E ) for isomerization and decomposition of cyclooctatetraene have been determined under steady state photolysis conditions. Direct measurements of k ( E ) under collision-free conditions have been performed in the laser flash photolysis of cyclooctatetraene. In addition the steady state photolysis of dihydropentalene (main primary reaction product semibullvalene) has been studied; again quantum yields and specific rate constants have been determined.Die Produktverteilung bei der UV-Photolyse von Cyclooctatetraen in der Gasphase wurde gemessen. Dabei wurden die parallel ablaufenden Reaktionen zu den Zerfallsprodukten Benzol + Acetylen und den Isomeren Dihydropentalen bzw. Semibullvalen beobachtet. Beide Isomere entstehen mit etwa gleicher Ausbeute bei Drucken um 2-3Torr; bei ansteigendem Druck wird die Bildung von Semibullvalen und bei geringerem Druck die Bildung von Dihydropentalen bevorzugt. Absolute Quantenausbeuten und spezifische Geschwindigkeitskonstanten k ( E ) fur Isomerisierung und Zersetzung von Cyclooctatetraen wurden unter den Bedingungen der stationaren Photolyse bestimmt. Mit Hilfe der Laser-Blitzlicht-Photolyse von Cyclooctatetraen wurden zudem direkte Messungen von k ( E ) unter stoofreien Bedingungen durchgefuhrt. Weiterhin wurde die stationare Photolyse von Dihydropentalen untersucht. Als uberwiegendes Primarprodukt wurde das Isomer Semibullvalen gefunden. Auch in diesem System wurden Quantenausbeuten und spezifische Geschwindigkeitskonstanten bestimmt.Photolysis and photoisomerization reactions following electronic excitation of molecules are governed in many cases by excited electronic state kinetics. Often, however, also fast internal conversions to the electronic ground states are possible such that unimolecular reactions of vibrationally highly excited ground state species occur. The latter systems can be compared with thermal activation experiments and serve as ideal test cases for unimolecular rate theory. Polyenes like cycloheptatriene [l -31, substituted cycloheptatrienes [3, 41, cyclohexadiene and hexatrienes [5] have been found to be such examples. In the present work it was our intention to investigate whether cyclooctatetraene (COT) reacts in a similar way, i.e. whether the reactions after thermal an...

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Section: Photochemie / Reaktionskinetikmentioning

confidence: 70%

Section: Stationary Photolysis Of Cotmentioning

confidence: 89%

Section: Laser Flash Photolysis Experimentsmentioning

confidence: 99%

Section: Stationary Photolysis Of Cotmentioning

confidence: 99%

“…The reactants used were obtained commercially or prepaied (e. g. 1.5-DHP) as described in Part I (Ref. [6]). …”

mentioning

confidence: 99%

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Photolysis of 1.3.5.7‐Cyclooctatetraene and 1.5‐Dihydropentalene by Steady State and by Laser Flash Irradiation (Part II)

Dudek

Glänzer

Troe

1979

Ber Bunsenges Phys Chem

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1,2-Dihydropentalen aus 1,6-Cyclooctadien-3-in

Hanold

Molz

Meier

1982

Angew. Chem. Int. Ed. Engl.

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Thermolyse von Ansaran, Ansaren und Cuban

et al. 1983

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Die Thermolyse und Zerfallskinetik ringerweiterter Cubane, der Ansarane 1 -3, sowie des Cubans 4 selbst, werden beschrieben. Mit Hilfe von Kraftfeldrechnungen wird die Spannungserleichterung beim Bruch bestimmter Bindungen abgeschatzt, und wahrscheinliche Thermolysewege werden aufgezeigt. Das bei der Gasphasenthermolyse von Cuban 4 gebildete schwingungsangeregte Cyclooctatetraen 5 fragmentiert zu Benzol und Acetylen. Uber die Gasphasenkinetik von Cyclooctatetraen wird ebenfalls berichtet. Thermolysis of Ansarane, Ansarene and Cubanel)The thermolysis and kinetics of decomposition of cubane 4 and of ring enlarged cubanes, the ansaranes 1 -3, are described. The relief of strain which will be observed breaking specific bonds has been estimated by the aid of force-field calculations thereby disclosing probable reaction pathways. The gas phase pyrolysis of cubane 4 yields vibrationally excited cyclooctatetraene 5 which fragmentates to benzene and acetylene. The gas kinetics of cyclooctatetraene 5 is reported on as well.Die thermochemischen und kinetischen Eigenschaften polycyclischer, insbesondere kafigartiger Kohlenwasserstoffe sind von theoretischem und synthetischem Interesse und spielen eine bedeutende Rolle bei der Entwicklung molekularmechanischer und semiempirischer Methoden*).Vor einiger Zeit untersuchten wir den thermischen Zerfall des Ansaradiens 13), der aufgrund seiner vergleichsweise niedrigen Aktivierungsenergie (siehe Tab. 1) als Cycloreversionsprozel3 interpretiert wurde. Um zwischen einem pericyclischen Reaktionsweg einerseits und einem stufenweisen, diradikalischen andererseits unterscheiden zu konnen, war es notwendig, experimentell solche Kafigverbindungen zu thermolysieren, welche dem ersteren Reaktionsweg aus strukturellen Grunden nicht zu folgen vermogen. Wir berichten hier iiber die Thermolyse von Ansaran (2)4), Ansaren (3)4) und Cuban (4)5a).

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Pyrolysis of 1.3.5.7‐Cyclooctatetraene, Semibullvalene, and 1.5‐Dihydropentalene in Shock Waves and in a Flow System (Part I)

Cited by 19 publications

References 36 publications

Photolysis of 1.3.5.7‐Cyclooctatetraene and 1.5‐Dihydropentalene by Steady State and by Laser Flash Irradiation (Part II)

Photolysis of 1.3.5.7‐Cyclooctatetraene and 1.5‐Dihydropentalene by Steady State and by Laser Flash Irradiation (Part II)

1,2-Dihydropentalen aus 1,6-Cyclooctadien-3-in

Thermolyse von Ansaran, Ansaren und Cuban

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