Identify the correct order of acidic strength for the following compounds: (i) (ii) (iii)

Step-by-step solution

Boronic acids act as Lewis acids by accepting an OH^- ion from water to form a tetrahedral boronate anion, ArB(OH)₃^- . The acidic strength increases with the presence of electron-withdrawing groups, which increase the electron deficiency of the boron atom and stabilize the resulting conjugate base. The -NO₂ group is a strong electron-withdrawing group that exerts both -I (inductive) and -M (mesomeric) effects. In o-nitrophenylboronic acid (i), the -NO₂ group is at the ortho position. It exerts a strong -I effect d