Toluene-p-sulfonic acid-catalysed reaction of but-1-ene with trifluoroacetic acid: return and elimination from the intimate ion pair

At short times, reaction of but-1-ene with toluene-p-sulfonic acid in trifluoroacetic acid gives 2-butyl tosylate 1, 2-butyl trifluoroacetate 2 and but-2-ene 3 in ratios of () 2.3:1: () 0.41; thus internal return is the major pathway and elimination is important for the tight 2-butyl cation–tosylate anion pair.