Fries rearrangement template

AlCl₃ binds the ester oxygen of phenyl acetate and releases an acylium ion, which acylates the aluminium phenoxide at the para (or ortho) carbon; acid work-up frees the phenol.

Mechanism step by step

AlCl₃ moves the acyl group of a phenyl ester onto the ring: hydroxyaryl ketones

1. Lewis acid complex – AlCl₃ binds the ester (phenolic) oxygen
2. Acylium ion – The C–O bond breaks: acylium ion and aluminium phenoxide
3. Electrophilic attack – The O lone pair pushes the ring onto the acylium ion (para)
4. Deprotonation – Loss of H⁺ restores aromaticity
5. Work-up – Acid breaks the O–Al bond and frees the phenol

Key points

• AlCl₃ first binds the more basic C=O oxygen and moves to the phenolic oxygen; the drawing starts from there.
• Low temperature (below about 60 °C) favours the para product; high temperature (above about 160 °C) favours ortho, held as a stable Al chelate.
• Crossover experiments show the acylium ion can move between molecules (intermolecular).
• Photo-Fries: UV light does the same rearrangement by a radical pathway.

Drawn with 176 atoms, 17 arrows, 10 shapes – every one editable in MolDraw.

Sources

• Kürti & Czakó, Strategic Applications of Named Reactions in Organic Synthesis, Elsevier 2005 Textbook
• Smith, March's Advanced Organic Chemistry, 8th ed., Wiley 2020 Textbook