Poisoning Effect of Acid Soluble Oil on Triflic Acid-Catalyzed Isobutane Alkylation

The rate of the isobutane alkylation reaction with secondary butenes catalyzed by trifluoromethanesulfonic acid at –20°C is experimentally found to depend on the concentration of acid soluble oil (ASO), which poisons TfOH. With an increase in the ASO molar fraction from 0.13 to 0.16, the reaction rate decreases by a factor of ten. The Hammett acidity function was determined for TfOH solutions at 25°C in the concentration range from 0 to 0.2 ASO molar fractions. The results obtained suggest that the alkylation reaction rate is proportional to the proton activity in the acid phase determined by the Hammett acidity function.