Phosphorylation of Phenols with cyclo-Triphosphate

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Phosphorylation of phenols (phenol, catechol, resorcinol, hydroquinone, cresols, hydroxybenzoic acids, and nitrophenols) with inorganic sodium cyclo-triphosphate hexahydrate (P_<3m>), Na_3P_3O_9・6H_2O, was carried out under various reaction conditions (pH, temperature, and molar ratio). (1)The main products of these reations were triphosphate derivatives of phenols produced by phosphorylation of a hydroxyl group. Reaction of catechol with P_<3m> 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 P_<3m> : 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 P_<3m>. (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 P_<3m> is discussed.
公益社団法人日本薬学会の論文
1992-12-25