2‐Hydroxyacetophenone via fries rearrangement and related reactions: A comparative applied study

The feasibility of direct preparation of phenyl acetate ( I ) from phenol and acetic acid has been proved. Thermal rearrangement of I was tested in the presence of the proton acids methane sulphonic, sulphonic cation exchange resin, methane‐ trisulphonic, sulphuric acid and its monohydrate, phosphoric, oxalic, trichloroacetic, sodium hydrogen sulphate, and the potassium fluoride‐hydrogen fluoride complex (KFHF). All except oxalic and trichloroacetic acid and KFHF gave o ‐, and p ‐hydroxyacetophenone, with a larger proportion of the o ‐hydroxyketone at high temperatures. The rates, product ratios, and yields of these processes are recorded and compared. Aluminium chloride, zinc chloride, and boron trifluoride all gave faster reactions than the proton acids, and for low temperatures with the last at least, higher ortho: para ratios. All the Lewis acid catalysts were somewhat more intractable to use. Comparative results between the two sets of catalysts are presented together with the results of a few miscellaneous related experiments.