PHOSPHORYLATION OF PHENOLS WITH CYCLOTRIPHOSHPHATE

Phosphorylation of phenols (phenol, catechol, resorcinol, hydroquinone, cresols, hydroxybenzoic acids, and nitrophenols) with inorganic sodium cyclo-triphosphate hexahydrate (P3m), Na3P3O9.6H2O, was carried out under various reaction conditions (pH, temperature, and molar ratio). (1) The main products of these reactions were triphosphate derivatives of phenols produced by phosphorylation of a hydroxyl group. Reaction of catechol with P3m gave a five-membered cyclic phosphate formed by an intramolecular cyclization of a triphosphate derivative. (2) The optimum conditions for phosphorylation were found to be pH 12, and a molar ratio of P3m:phenols = 1:5. (3) The pK(a) values of phenols strongly affected the reaction rate and yield. The reactivity of phenols increased with an increase in their pK(a) values. A hydroxyl group on phenols with a pK(a) value of more than 8 would be reactive with P3m. (4) The reactivity of ortho-substituted phenols was less than those of meta- and para-substituted phenols, owing to the steric hinderance of ortho-substituents. (5) The mechanism of the reaction in the phosphorylation of phenols with P3m is discussed.