Question

$B(OH{)}_3+NaOH\to Na[B(OH{)}_4{]}_{\left(aq\right)}$

Then addition of which of the following proceeds the reaction in the forward direction :

• A. cis-1, 2 diol
• B. trans 1, 2 diol
• C. borax
• D. $N{a}_{2}HP{O}_4$

Answer 1

Answer: (A)

cis-1, 2 diol

$B(OH{)}_3+NaOH\to Na[B(OH{)}_4{]}_{\left(aq\right)}$

This reaction is reversible reaction because sodium metaborate, $Na\left[B\right(OH{)}_4]$ formed by the reaction between $B(OH{)}_3$ and NaOH gets hydrolysed to regenerate $B(OH{)}_3$ and NaOH.

$Na\left[B\right(OH{)}_4]$ $\stackrel{hydrolysis}{\to }$ $NaOH$ + $B(OH{)}_3$

If, some quantity of polyhydroxy compounds like cis- 1, 2-diol, catechol, glycerol etc is added to the reaction mixture then the $B(OH{)}_3$ combines with such polyhydroxy compounds to give chelated complex compound. Due to complex compound formation, stability increases and due to higher stability of complex, reaction moves in forward direction.