Fries Rearrangement
Phenolic esters on heating with lewis acid gives ortho and para acyl phenol (i.e. hydroxyaryl ketones). In practice, both the ortho and para products are obtained. At high temperature (>100°C), ortho isomer is major product while at low temperature (<100°C), para isomer is the major product.
Similar conversion of phenolic esters into hydroxy ketones in the presence of UV light without catalyst takes palce is known as Photo-Fries rearrangement.
Ortho-Product
Similar attack of acyl group at para position to para product.
Similar conversion of phenolic esters into hydroxy ketones in the presence of UV light without catalyst takes palce is known as Photo-Fries rearrangement.
Mechanism of Fries Rearrangement
The possible mechanism is given below-Ortho-Product
Similar attack of acyl group at para position to para product.