In the same way, we investigated the effects of ortho- meta- and para- substituents on acylation reactions of benzoic acid derivatives and also Fries rearrangement in PPA (Scheme 2 and Tables 1, 2 and 3)
In conclusion, considering the above discussion and also G=OH, [NH.sub.2], Cl, Br, N[O.sub.2] and H, it could be clearly seen that the formation of hydroxybenzophenones from Fries rearrangement of the ester (B) occurs via an intermolecular mechanism.
E-mail: email@example.com Table 1: The effect of ortho-substituents on acylation reactions and Fries rearrangement in [P.sub.2][O.sub.5]-[H.sub.3]P[O.sub.4] mixtures.
[P.sub.2][O.sub.5]/[H.sub.3]P[O.sub.4] (PPA) was found to be an efficient new reagent for probing the mechanism of acylation reactions and Fries rearrangement of acyloxy benzene derivatives and also the direct acylation reactions of phenol derivatives with Carboxylic acids.
In the same way we have investigated the effects of ortho, meta and para substituents on the acylation reactions of benzoic acid derivatives and also Fries rearrangement in PPA.
Fries rearrangement is a synthetically useful reaction for the preparation of hydroxyaryl ketones, not only in laboratory but also in industrial processes .
The formation of Fries rearrangement by-products represents the main drawback affecting the melt synthesis of PC since these by-products present a significant light absorbance in the visible region and therefore produce discoloration in the final material.
In particular, according to the literature , the signal at 8.0 ppm was ascribed to 1H of the linear Fries rearrangement products, while the signal at 8.2 ppm was ascribed to the branched Fries adducts.
These conditions favor degradation reactions, yellowing, and sometimes branching of the product PC caused by Fries rearrangements by-products [8, 9].