Potassium hydroxide, deprotonation weak acids with

THE DEPROTONATION OF WEAK ACIDS WITH POTASSIUM HYDROXIDE APPLICATIONS TO THE SYNTHESIS OF ORGANOMETALLIC COMPOUNDS... 

Deprotonation of Weak Acids with Potassium Hydroxide 115... 

As carbonic acid is a weak acid with pKi = 6.2 [106], the presence of CO2 in any measurement system may influence the results. If the pK value for the acid or conjugate acid is less than that of carbonic acid, little or no influence will occur. However, for ionizable systems where the pKa value is greater than that of carbonic acid, the presence of dissolved CO2 will have marked effects, giving apparent values that are lower than the true values. This is especially so where potentiomet-ric titrations with sodium or potassium hydroxides are used. This is because the concentrations of protonated and deprotonated forms required for the Henderson-Hasselbalch equation [Eqs. (3), (4), and (9)] are calculated from the volumes of acid or base added to the titration system. The presence of dissolved CO2 (in either the titrant or titrated solution) will alter the volume required. Spectrophotometric and other methods of pfCg measurement are free from the influences of dissolved CO2, if the pH-dependent phenomenon is insensitive to its presence. Cases where this must be taken into account include drugs where the absorption spectra overlap... 

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