Fries rearrangement: Phenyl ester (PhOCOR) + AlCl3 -> o-acylphenol + p-acylphenol. Product distribution depends on temperature: low T favours para-product (kinetic control); high T favours ortho-product (thermodynamic control, intramolecular H-bonding stabilises ortho). Claisen rearrangement: Allyl phenyl ether heated to 200°C -> o-allylphenol (a [3,3]-sigmatropic rearrangement). If both ortho positions are blocked, the allyl group migrates to para position (with inversion). This is a thermal (no catalyst), intramolecular rearrangement — suprafacial in a chair-like transition state.