Phenyl acetate Fries rearrangement liquid-phase

If the photo-Fries reaction would occur via a concerted mechanism, the absence of solvent should be of minor importance for the formation of rearranged products. However, conclusive evidence supporting the radical pair mechanism arises from the experiments carried out with phenyl acetate (10) in the vapor phase. The major product in the irradiations of 10 is phenol (13), which accounts for 65% of the photoproducts. Under these conditions, less than 1% of ortho -hydroxyace-tophenone (11) appears to be formed [19,20]. Conversely, when a high cage effect is expected, as in rigid matrixes (i.e., polyethylene), the result is completely different, and phenol is practically absent from the reaction mixtures [29]. In the intermediate situation (liquid solution), both rearranged products and phenol are formed in variable amounts depending on solvent properties. These observations... 

Table 3.7 Liquid phase Fries rearrangement of phenyl acetate (PA) over zeolite catalysts...

Figure 3.8 Liquid phase transformation of phenyl acetate (2.2 mol l-1 in sulfolane solvent) at 433 K. (a) Yield in o-hydroxyacetophenone, o-HAP ( ) and p-hydroxyacetophenone, p-HAP (X) versus reaction time, (b) Effect of the addition of phenol (P) on the p-HAP yield. [P] =0 mol l-1 (x) and [P] =0.6 mol l-1 ( ). Reprinted from Catalysis Letters, Vol. 41, Jayat et al., Solvent effects in liquid phase Fries rearrangement of phenyl acetate using a HBEA zeolite, pp. 181-187, copyright (1996), Kluwer Academic Publishers, with kind permission of Springer Science and Business Media...

Most studies in which acid solids were used concern the synthesis of hydroxyacetophenones either by Fries rearrangement of phenyl acetate [3,5-15] or by acylation of phenol with acetic acid or acetic anhydride [11,16-21]. These reactions were conducted in the gas or liquid phase, zeolites being generally chosen as catalysts (Section 5.3.1). These shape-selective catalysts can also be used... 

Jayat, R, Sabater Picot, M. J., and Guisnet, M. 1996. Solvent effects in liquid phase Fries rearrangement of phenyl acetate over a HBea zeolite. Catal. Lett. 41 181-187. 

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