The reactions occurring in an equilibrium mixture of 3-methyl-1-buten-
3-ol and 3-methyl-2-buten-1-ol in 24-49% aqueous solutions of H2SO4 yi
eld isoprene, 3-methyl-3-buten-1-ol, isobutylene, formaldehyde, 3-meth
ylbutane-1,3-diol. Isobutylene is rapidly hydrated to give 2-methylpro
pan-2-ol. The presence of formaldehyde in the reaction mixture indicat
es that the transformations involve the reverse Prins reaction. On the
basis of experimental and literature data, two most probable reaction
schemes were suggested.