In the reaction of hypobromite with amide, the carbonyl carbon is lost as
(a) CO3^2-
(b) HCO3^-
(c)

Q: Why is the reagent called hypobromite instead of bromine and sodium hydroxide?

When bromine ($Br_2$) reacts with sodium hydroxide ($NaOH$), it forms sodium hypobromite ($NaOBr$), which is the actual active oxidizing agent in the Hofmann degradation.

Q: Does the alkyl group ($R$) change during this reaction?

No, the alkyl group migrates intact from the carbonyl carbon to the nitrogen atom. Its structure and stereochemistry are completely retained.

Q: Why doesn't the reaction stop at the isocyanate intermediate?

Isocyanates are highly reactive towards nucleophiles. In the strongly basic aqueous medium of the reaction, the isocyanate rapidly undergoes hydrolysis to form the amine and carbonate ion.

Q: Can this reaction be used to prepare secondary or tertiary amines?

No, the Hofmann bromamide degradation is strictly used for the preparation of primary amines from primary amides.

Q: What happens if we use $KOH$ instead of $NaOH$?

The reaction works perfectly well with $KOH$. The only difference is that the byproducts will be potassium carbonate ($K_2CO_3$) and potassium bromide ($KBr$), but the carbonyl carbon is still lost as the carbonate ion ($CO_3^{2-}$).

Question

In the reaction of hypobromite with amide, the carbonyl carbon is lost as

Options:

(A) $CO_3^{2-}$

(B) $HCO_3^-$

(C) $CO_2$

(D) $CO$

Sigma Percentile · Accepted Answer

The Hofmann bromamide degradation is one of the most elegant and widely used reactions in organic chemistry for stepping down a carbon chain. But have you ever wondered what exactly happens to the carbon atom that gets "lost" during this process? Let's embark on a molecular journey to track down this missing carbon!

### The Setup: Amide Meets Hypobromite

Imagine you have a primary amide, $R-CONH_2$. You introduce it to a mixture of bromine ($Br_2$) and a strong base like sodium hydroxide ($NaOH$). When these reagents mix, they form sodium hypobromite ($NaOBr$), a powerful oxidizing agent.

This reaction is famously known as the **Hofmann bromamide degradation**. Its primary purpose is to convert a primary amide into a primary amine ($R-NH_2$). The magic of this reaction lies in the fact that the resulting amine has exactly one carbon atom less than the starting amide.

### Tracking the Missing Carbon

Let's look at the complete balanced chemical equation for this transformation:

$$R-CONH_2 + Br_2 + 4NaOH \rightarrow R-NH_2 + Na_2CO_3 + 2NaBr + 2H_2O$$

Notice the carbonyl carbon in the starting amide—the carbon double-bonded to oxygen. As the reaction proceeds through a fascinating mechanism involving an isocyanate intermediate ($R-N=C=O$), this carbonyl carbon is cleaved off from the main alkyl chain.

If we trace its path to the product side of our balanced equation, we find it safely tucked away inside a molecule of sodium carbonate ($Na_2CO_3$).

### The Final Form: The Carbonate Ion

The reaction doesn't just happen in a vacuum; it takes place in an aqueous, strongly basic medium. In such an environment, sodium carbonate doesn't stay as a single intact unit. It dissociates completely into its constituent ions:

$$Na_2CO_3 \rightarrow 2Na^+ + CO_3^{2-}$$

Therefore, the carbonyl carbon that was once proudly part of the amide backbone is ultimately lost to the solution as the **carbonate ion** ($CO_3^{2-}$).

Understanding the fate of every atom in a reaction not only helps in balancing equations but also deepens your appreciation for the conservation of mass in chemical transformations. The next time you see a step-down reaction, you'll know exactly where that missing carbon went!

Animated Solution for Chemistry - Organic Chemistry: In the reaction of hypobromite with amide, the carbonyl carbon is lost as

Select Answer:

Visualized Solution

$H o f mann B r o mami d e D e g r a d a t i o n$

$T h e C o m pl e t e R e a c t i o n$

$T r a c k in g t h e C a r b o n y l C a r b o n$

$F or ma t i o n o f C a r b o na t e$

$T h e C a r b o na t e I o n$

$C o n c l u s i o n$

The Sigma Insight: Amines

The Setup

Tracking the Missing Carbon

The Final Form

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