927-98-0Relevant academic research and scientific papers
Thermal isomerisations, XXIV. Gas phase kinetics of the pyrolysis of some 3,3-dimethyl-1-alkyl-cyclopropenes: Some surprising substituent activation effects and the intramolecular trapping of vinylidene intermediates
Hopf, Henning,Plagens, Andreas,Walsh, Robin
, p. 825 - 835 (2007/10/03)
The gas phase pyrolyses of four 3,3-dimethyl-1-alkylcyclopropenes were studied for which the 1-alkyl substituents are ethyl- (6), isopropyl- (7), 1′-butyl- (8) and 1′-isoamyl- (9). Rate data over a 50°C temperature range were obtained and Arrhenius parameters are reported both for overall reactions and individual pathways for all compounds. Tests confirm all reactions to be unimolecular and homogeneous. For 8 and 9, noteworthy products are cyclopentenes, whose presence demonstrates the involvement of vinylidene intermediates. The substantial product yields of 2,4-alkadienes together with dramatic rate enhancement effects of these 1-alkyl substituents (relative to 1-methyl) are explained by the involvement of vinylcarbene intermediates in this pathway. Minor, transient products from 6, 8 and 9 are probably isomeric cyclopropenes. This suggests further pathways for vinylidene intermediates, whose reactivity pattern is briefly reviewed. VCH Verlagsgesellschaft mbH, 1996.
