Interaction of boric acid and borates with carbohydrates and related substances
Association constants for the mannitol–borate and glucose–borate complexes were determined from potentiometric titration measurements using Antikainem's equation. The results obtained indicated that mannitol was a much stronger borate complexant than glucose, as predicted from their molecular structures. The analyses for the dissociation constants of the complexes H3BO3 indicated that the complexed H3BO3 was not a simple monobasic acid but probably a mixture of different acids, the composition of which depends on the ratio of undissociated to dissociated H3BO3 in solution. Infrared spectra of solid mixtures of H3BO3 and borate ions with mannitol, glucose and ribose indicated that only ribose formed a stable solid complex with undissociated H3BO3. All three polyols formed solid complexes with borate ions. The i.r. spectra indicated that the complexes were polymeric.