Acylation of Phenols with Salicylic acid using polyphosphoric acid

Abstract

Acylation of 2-naphthol (2), 1-naphthol(6) and resorcinol (11) with salicylic acid (1) in the presence of PPA affords salicylate esters (4,7,13 and 14), 1,2-benzoxanthone (5), 3,4-benzoxanthone(8), 3-hydroxyxanthone(12), 2-salicyloyl-1-naphthol(9) and 11-hydroxy-12H-benzo[b]xanthen-12-one (10). Compounds (4,5,7,8,12,13 and 14) are identical with those obtained by heating a mixture of phenyl salicylate(3) and phenols(2,6 and 11).