The Pyrolysis of Ethlcyclobutane in the Gas Phase at High Pressures,

Theoretical work in the field of unimolecular reactions raises some doubt whether or not high pressure limits to unimolecular rates do exist. The objective of the work was to study the unimolecular decomposition of some alkyl-substituted cyclobutanes at pressures as high as two hundred atmospheres, using nitrogen as a diluent gas, in an attempt to determine if the proposed limits actually exist. Small partial pressures twenty to fifty mm Hg of ethylcyclobutane were mixed from one hundred to four thousand psi of oxygen-free nitrogen and pyrolyzed at approximately four hundred ten degrees centigrade. Analyses were done on a Varian Aerograph six hundred D chromatograph with flame ionization detection. Despite serious experimental problems the search was successful and the predicted decrease of the rate constant was observed and verified. Measurements of this sort can provide kineticists with a new type of information about the nature of the transition state in unimolecular gas reactions. Author