The kinetics of the thermal gas phase reactions of methylspiro[2,2]-pentane at low pressure

Abstract

A study of the thermal unimolecular reactions of methylspiro[2,2]pentane has been carried out at three temperatures in the range 347·6 to 387·1 °C and at pressures between 3·8 and 0·004 Torr. As the pressure is reduced de-composition products, allene, ethylene, propene, and buta-1,2-diene, are formed in increasing amounts at the expense of the isomerization products ethylidenecyclobutane, 2-methyl(methylene) cyclobutane, and 3-methyl-(methylene)cyclobutane. A similar increase in the proportion of 2-ethylbuta-1,3-diene and 2-methylpenta-1,4-diene relative to the methylenecyclobutanes is also observed. Calculations using the RRKM theory of unimolecular reactions are carried out in an attempt to confirm the detailed reaction mechanism.