Thermal and UV-induced isomerization of fluorinated hexatrienes

Abstract Irradiation of octafluoro-1,3,5-hexatriene ( I ) in the gas phase with a high-pressure mercury lamp gave a mixture of octafluoro-2-vinylcyclobutene ( III ) and octafluorobicyclo[2.2.0]hex- 2-ene ( V ). The analogous photolysis of hexatriene I in the liquid phase led to an equilibrium mixture of the starting compound I ( cis -isomer) and the trans -isomer II , respectively. Photolysis of 2,3,4,5-tetrafluoro-1,3,5-hexatriene ( VI ) gave a mixture of cis - and trans - isomers, both in the vapour and liquid phases. Thermal reaction of hexatriene I gave octafluoro-1,3-cyclohexadiene ( IV ) as the sole product.