Browsing by Author "Egger, Kurt W."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Reactions of Group 3 Metal Alkyls in the Gas Phase*: Part 8.—Homogeneous Thermal Unimolecular Elimination of Ethylene from Triethylaluminium
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (3), 1972) Cocks, Alan T.; Egger, Kurt W.
    The kinetics of the homogeneous gas-phase elimination of ethylene from triethylaluminium have been studied in the presence of excess propene in the temperature range 426-488 K. The observed first-order rate constants based on the loss of ethyl groups fit the Arrhenius relationship, log k'o/s"1 10.93 ±0.13-(30.05 ±0.27)/0, where 0 = 4.58 x 10-3 Tin units of kcal mol"1t [= 10.93 ± 0.13 —(125.7 ±1.1)/19.15 x 10-3 T in units of kJ mol-1]- These activation parameters arc compatible with the 4-centrc polar transition state proposed for olefin eliminations from other Group 3 metal alkyls, and the ctTect of ^-substitution on the rate of elimination is additive. The activation energy for the back-addition of ethylene to dialkylaluminium hydride is estimated to be 4.9 kcal mol-1.
  • No Thumbnail Available
    Item
    Reactions of Group 3 Metal Alkyls in the Gas Phase: Part 9.—Addition of Propene to Trimethylaluminium
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (6), 1972) Egger, Kurt W.
    The thermal gas phase reaction of propene with monomeric trimethylaluminium has been studied at temperatures from 455 to 549 K using a static reaction system and Teflon coated reaction vessels. Initial propene pressures ranged from 190 to 370 Torr (25.33 to 49.33 kN m-2) and the ratio of propene to A1Mc3 varied from 4.9 to 24.1. Overall conversions between 0.4 and 12.4 % with respect to alkyl groups were observed. In excess propene the overall reaction involves the rate determining addition of propene to the Al—CH3 bond (ki) to give Mc2AIBu> followed by the fast elimination of isobutene and subsequent addition of propene to Me2AlH, yielding Mc2AlPrn. The rate constant A'i, corrected for path degeneracy, is given (with standard errors) by the Arrhenius relationship