2.4- dihydroxybenzophenone Fries rearrangement

Another example of commercial interest is the Fries rearrangement of the benzoate ester of resorcinol to afford 2,4-dihydroxybenzophenone, the precursor of the UV-absorbent 4-0-octyl-2-hydroxybenzophenone. Reaction of benzoic acid with one equivalent of resorcinol (see Fig. 2.22), over various solid catalysts, in chlorobenzene as solvent, with continuous removal of water, was investigated by Hoefnagel and van Bekkum [68]. H-Beta was slightly less active than the ion-ex-... 

The industrially significant 2,4-dihydroxybenzophenone can be prepared in 88% yield by the Fries rearrangement of the resorcinol benzoate formed in situ by the reaction of benzoic acid and resorcinol using zeolite-H-beta catalyst (equation 71). A variety of solvents such as butylbenzene and n-decane are used successfully for these reactions. ... 

Direct Photochemistry of PC Excitation of PC at short wavelength (e.g., 254 nm) involves mainly two consecutive photo-Fries rearrangements of the aromatic carbonate units leading successively to the formation of phenylsalicylate (Li) and dihydroxybenzophenone (L2) units as shown in Scheme 15.9. Photo-Fries products have been well defined by definite maxima in the UV and in the carbonyl range of the IR domain Lj at 320 nm and 1689 cm-1 andL2 at 355 nm and 1629 cm-1. 

Bolognini, M., Cavani, F, Cimini, M., Dal Pozzo, L., Maselli, L., Venerito, D., Pizzoli, F, and Veronesi, G. 2004. An environmentally friendly s)mthesis of 2,4-dihydroxybenzophenone by the single-step O-mono-benzoylation of 1,3-dihydroxybenzene (resorcinol) and Fries rearrangement of intermediate resorcinol monobenzoate the activity of acid-treated montmorillonite clay catalysts. C. R. Chim. 7 143-150. 

The archetypal photochemical lateral-nuclear rearrangement in aromatic compounds is the photo-Fries rearrangement, and a relatively simple example is reported in which /Mjhlorophenyl salicylate (189) gives 5-chloro-2,2 -dihydroxybenzophenone. Use is made of the photo-Fries rearrangertient of 1-naphthyl esters (190) in the regioselective synthesis of tricyclic analogues of... 

Chamoumi and Brunei investigated the liquid phase rearrangement of 1,2-epoxyalkenes over various zeolites [96]. H-Offretite gave the best selectivity for the formation of octanal in the reaction with 1,2-epoxyoctane. The esterification of resorcinol with benzoic acid derivatives is followed by a Fries rearrangement to give benzophenones [97]. The reaction is catalysed by Amberlyst-15 ion-exchange resin or Nafion-17 acidic exchange resin. 2,4-Dihydroxybenzophenone has been synthesised in 88% yield by this method. 

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