Competition between Isomerization and Addition in the Sonication of Vinyl Sulfones in the Presence of Bromotrichloromethane

Article abstract of DOI:10.1002/prac.19953370178

(E)- and (Z)-vinyl sulfones isomerise under ultrasound irradiation in carbon tetrachloride in the presence of bromoform or bromotrichloromethane to give an E/Z equilibrium mixture via bromine radicals.Furthermore, the bromine radicals formed add to the C=C double bond (presumably of the Z isomer) to form vic-dibromo compounds.In pure CBrCl3 this addition reaction reaches a 99percent yield.In tetrahydrofurane/CBr4 (or CBrCl3) no isomerization is observed since the bromine radicals react probably with the THF.The addition is also favoured by highly efficient energy transmission.