Question

When 1,2-dibromo-3,5-dinitrobenzene is treated with excess NaOH at 50 °C, only one of the bromine atoms is replaced. Draw an equation for this reaction, showing the product you expect. Give a mechanism to account for the formation of your proposed product.

Short answer

Formation of 1-Bromo-2-hydroxy-3,5-dinitrobenzene

Step-by-step solution

Reaction of 1,2-dibromo-3,5-dinitrobenzene

The equation for the reaction of 1,2-dibromo-3,5—dinitrobenzene with excess NaOH at forms 1-Bromo-2-hydroxy-3,5 dinitrobenzene as the only product.

Formation of 1-Bromo-2-hydroxy-3,5-dinitrobenzene

Mechanism for the reaction

The bromide at 2-position is replaced by a hydroxy group, this is because in this case the reaction intermediate gets stabilized by two nitro groups. But in the case of 1-Bromo, such stabilization does not arise because it is meta to both nitro groups.