The gas-phase thermal unimolecular elimination of keten from bicyclo[3·2.0]heptan-6-one

Abstract

The gas-phase thermal decomposition of bicyclo[3·2.0]heptan-6-one to yield cyclopentene and keten as primary products was studied in the temperature range 564–652 K. First-order rate constants for the depletion of bicycloheptanone, obtained by an internal standard technique, were independent of initial starting pressure in the range 3·8–40 Torr and fit the Arrhenius relationship (i). The activation parameters, when compared with those, log k/s^–1= 14·21 ± 0·10 –(48·55 ± 0·29 kcal mol^–1)/(2·303RT)(i) for cyclobutanone itself, indicate that alkyl groups have a relatively small stabilizing influence on the transition state, in contrast to the large effect found previously for the vinyl group.