Olah, G.A., Farooq, O., Husain, A. et al. Catal Lett (1991) 10: 239. doi:10.1007/BF00772077
Superacid catalyzed isomerization of butane was studied. Highly efficient isomerization of butane to 2-methylpropane (isobutane) was achieved using fluorosulfuric acid containing up to 5% of hydrogen fluoride acting as a protic co-acid. The isomerization when carried out in excess FSO3H at 21 ° C in a flow system gave ∼70% conversion to 2-methylpropane with generally less than 3% cracking. When 2-methylpropane was isomerized under similar conditions about 12% butane was formed. Attempted isomerization of pentane and hexane with prolonged reaction times in a static system results in predominant protolytic cleavage (cracking).