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Publication costs assisted by Colgate UniversityThe rate of thermal dehydrogenation of cyclopentene was studied in a single-pulse shock tube. Reactant mixtures consisted of 0.25 and 1.00% cyclopentene in argon, and total gas pressures were about 1 atm. Reaction temperatures were determined uia the comparative rate technique, using the decomposition of tert-butyl alcohol as the internal standard reaction. Over the temperature range 1020-1189°K the data support a first-order rate equation, with rate constants in units of sec-l given by log k(C5Hg -C5H6 + Hz) = 13.35 -[60.0 X 103/4.58T"K]. The reaction was essentially free of complications over this temperature range, but significant concentrations of side products were formed a t higher temperatures. A separate study of the products formed from cyclopentadiene decomposition suggests that these side products were produced primarily from cyclopentene. Possible mechanisms are discussed.

The homogeneous unimolecular isomerization of cyclopropane has been studied in two independent sets of single-pulse shock tube relative rate experiments. Concentration of cyclopropane in argon ranged from 0.25 to 10%, total final pressures were 0.5-7 atm, and temperatures were 970-1265°K, with residence times of 180-900 psec. The results, corrected by RRK theory for falloff, are in excellent agreement with conventional, lower temperature investigations and are consistent with a rate constant k" = 1015•2 X exp(-65,000/jf?T) sec-1.

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