Thermal isomerization of cyclobutenes. Part 12.—3,3-Diethylcyclobutene and 3-ethyl-3-methylcyclobutene

Abstract

The title compounds have been synthesized and their thermal isomerizations studied. 3,3-Diethylcyclobutene isomerizes by a unimolecular process in the temperature range 155–200°C to yield 4-ethylhexa-1,3-diene. The rate constants fit the Arrhenius equation k= 10^{13.53 ± 0.08} exp (–34,725 ± 162/RT) sec^–1. 3-Ethyl-3-methylcyclobutene isomerizes in the temperature range 160–205°C to yield cis and trans 4-methylhexa-1, 3-diene. The Arrhenius equations for the formation of these compounds were k_cis= 10^{13.50 ± 0.04} exp (–35,208 ± 81/RT)sec^–1, k_trans= 10^{13.53 ± 0.08} exp (–35,938 ± 160/RT) sec^–1. The results obtained are compared with those for other alkyl cyclobutenes.