How can the following reaction be made to proceed in forward direction ?
`B(OH)_(3) + NaOH hArr Na[B(OH)_(4)]`.

Options

A. `cis-1,2`diol
B. Trans`-1,2`diol
C. Borax
D. `Na_(2)HPO_(4)`

Answer

1

Explanation

If certain organic polyhydroxy compounds such as glycerol, manitol or sugars are added to the titration mixture, then `B(OH)_(3)` behaves as a strong monobasic acid and it can be now titrated with `NaOH` and the end point is detected using phenolphthalein as indicator `(pH=8.3-10.0)`.The added compound must be a cisdiol , to enhance the acid properties. The cid-diol forms very stable complex with the `[B(OH)_(4)]^(-)`, thus removing it form solution. The reaction is reversible and thus removal of one of the products shifts the equilibrium in the forward direction and thus all the `B(OH)_(3)` reacts with `NaOH`, in effect it acts as a strong acid in the presence of the cis-diol.
`B(OH)_(3)+NaOH rarr Na[B(OH)_(4)]+NaBO_(2)+2H_(2)O`