Why can't $$H_3BO_3$$ be titrated with $$NaOH$$ directly, and how does adding vicinal cis-diols (like glycerol or catechol) facilitate the titration?

Question

Why can't  $$H_3BO_3$$  be titrated with $$NaOH$$  directly, and how does adding vicinal cis-diols (like glycerol or catechol) facilitate the titration?

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Reason: Boric acid is a weak monobasic Lewis acid ( $$K_a \approx 10^{-9}$$  ).  Effect of Diols: Added cis-diols form a stable chelate complex with the$$[B(OH)_4]^- $$ion. This removes the ion from equilibrium, shifting the reaction forward to release more$$  H^+$$, effectively making it a strong acid that can be titrated against a strong base using phenolphthalein.

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