Question

In Hoffmann bromamide degradation reaction, find the number of moles of $NaOH$ and $B{r_2}$ used to produce one mole of amine.
A) Four moles of $NaOH$ and two moles of $B{r_2}$
B) Two moles of $NaOH$ and two moles of $B{r_2}$
C) Four moles of $NaOH$ and one moles of $B{r_2}$
D) One moles of $NaOH$ and one moles of $B{r_2}$

Answer 1

Hint: Hoffmann bromamide degradation reaction, as the name suggests is the degradation of an amide by treating it with bromine in an aqueous or ethanolic solution of sodium hydroxide to form a primary amine. By finding out the equation for this reaction, we can find the number of moles of $NaOH$ and $B{r_2}$ used.

Complete answer:
In Hoffmann bromamide degradation reaction, an amide is treated with bromine in presence of aqueous solution of sodium hydroxide to produce a primary amine. We can write the general equation for this reaction as follows.

$RCON{H_2} + B{r_2} + 4NaOH \to RN{H_2} + N{a_2}C{O_3} + 2NaBr + 2{H_2}O$ where R is taken as a general aliphatic or aromatic organic compound.

From the above equation, it is clear to us that four moles of $NaOH$ and one mole of Bromine are used to produce one mole of amine in Hoffmann bromamide degradation reaction. Therefore the answer is four moles of Sodium hydroxide and one mole of Bromine are required.

Hence the correct answer is option ‘C’

Note: It should be noted that the final equation of the reaction should always be balanced before calculating the amount of moles of Sodium hydroxide and Bromine. In the above Hoffmann bromamide reaction, one mole of amide is reacting with one mole of bromine and four moles of sodium hydroxide to produce one mole of amine.