Thermal unimolecular isomerization of 1-methylallyl vinyl ether in the gas phase and in solution

Abstract

1-Methylallyl vinyl ether isomerizes by a first-order process, both in the gas phase and in solution, to yield trans-hex-4-enal together with small amounts of cis-hex-4-enal. In the temperature range 117–168°C, the gas-phase rearrangement is homogeneous and independent of pressure in the range 3–150 torr. The rate constants fit the Arrhenius equation. k_gas= 10^11.32 exp(–27,870/RT) sec^–1 The reaction was also studied in solutions of 1-decene (D) and benzonitrile (B) in the temperature ranges 100–145°C and 84–135°C respectively; the measured rate constants fit the Arrhenius equations k_D= 10^10.78 exp (–25,740/RT) sec^–1, k_B= 10^10.91 exp (–25,300/RT) sec^–1. The steric course of the rearrangement and the effects of the solvent on the energetics of the process are discussed.