Browsing by Author "Holbrook, Kenneth A."

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    Gas-phase Unimolecular Pyrolyses of cis- and trans-'l,'i- Dimethyloxetan
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Holbrook, Kenneth A.; Scott, Robert A.
    The gas phase pyrolyses of both cis and trans isomers of 2,3-dimethyloxetan have been studied at temperatures from 415–483°C and at initial pressures from 2 to 32 Torr. Both isomers undergo two modes of decomposition producing either propene and acetaldehyde or but-2-ene (cis and trans) and formaldehyde. The cis—trans isomerisation of the starting material is relatively unimportant. The reactions all appear to be unimolecular processes in their first-order regions and the following rate expressions were obtained: cis isomer→C3H6+ CH3CHO : logl0(kl/S–l)=(15.70 ± 0.22)–(63 216 ± 621) K/4.576T, cis isomer→C4H8+ CH2O : logl0(k2/S–l)=(15.24 ± 0.25)–(62 493 ± 715) K/4.576T, trans isomer→C3H6+ CH3CHO : loglO(k3/S–1)=(15.91 ± 0.25)–(64 652 ± 664) K/4.576T, trans isomer→C4H8+ CH2O : 1og10(k4/S–1)=(15.49 ± 0.26)–(63 676 ± 745) K/4.576T. Possible mechanisms involving 1 + biradical intermediates are discussed.
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    Thermolysis of 2-ethyloxetan
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (06), 1977) Clarke, Michael J.; Holbrook, Kenneth A.
    The gas-phase thermolysis of 2-ethyloxetan has been studied at temperatures between 699 and 752 K and at initial pressures from 0.45 to 32.5 Torr.† The stoichiometries of the reactions involved correspond closely with the two expected modes of decomposition to give either but-1-ene and formaldehyde or ethylene and propanal. Small amounts of products such as methane, ethane and propene are found and are probably secondary products arising from radical attack on the parent molecule. The average ratio of ethylene/but-1-ene formed in a seasoned reaction vessel is 0.87 ± 0.04 in the temperature range studied and is independent of the amount of decomposition between 4 and 40 %. This ratio is very different in a clean vessel packed with Pyrex tubes when the production of but-1-ene is favoured. The total rate constant for the disappearance of reactant is expressed by the Arrhenius equation log10(k/s–1)=(14.47 ± 0.28)–(246 513 ± 3632) J mol–1/2.303 RT, the limits being the 95 % confidence limits (i.e., ± 2σ). The major modes of decomposition are probably unimolecular reactions and involve biradical intermediates.