Rearrangement of allylic alcohols

Three allylic type alcohols were rearranged in sulfuric acid (l, 10 and 50%) at 25 and 100C and their products identified. Specifically, 2-phenyl-lpropen-3-ol, 2-methyl-l-phenyl-l-propen-3-ol and 2-methyl-3-phenyl-l-propen-3-ol were studied. 2-Phenyl-l-propen-3-ol was found to rearrange to 2-phenylpropionaldehyde while 2-methyl-1-phenyl-l-propen-3-ol formed 2-methyl-2-phenylpropanal, isobutyrophenone and 2-methyl-3-phenyl-l-propen-3-ol. The final rearrangement of the 2-methyl-3-phenyl-lpropen- 3-ol allylic alcohol produced 2-methyl-2-phenylpropanal, isobutyrophenone, 2-methyl-l-phenyll- propen-3-ol and 2-(2-phenylisopropyl)-4-phenyl-5- methyl-1, 3-dioxane