Which reagent used to prepare propanamide to ethanamine ?

Options

A. `Br_2 +KOH`
B. `Na+C_2 H_5 OH`
C. `LiAlH_4`
D. `AlCl_3`

Answer

To prepare ethanamine from propanamide, we can utilize the Hofmann Bromide Degradation Reaction. Here’s a step-by-step solution to the question:

### Step 1: Identify the Reactants
We start with propanamide, which has the structure:
\[ \text{CH}_3\text{CH}_2\text{C(=O)NH}_2 \]
This compound contains three carbon atoms.

### Step 2: Understand the Reaction
We need to convert propanamide (3 carbons) to ethanamine (2 carbons). This means we will be reducing the number of carbon atoms by one.

### Step 3: Choose the Reagents
The Hofmann Bromide Degradation Reaction is the appropriate method for this transformation. The reagents required for this reaction are:
- Bromine (\( \text{Br}_2 \))
- Potassium hydroxide (\( \text{KOH} \))

### Step 4: Perform the Reaction
When propanamide is treated with bromine and potassium hydroxide, the reaction proceeds as follows:
1. The carbonyl group of the amide is converted to an isocyanate intermediate.
2. The isocyanate undergoes hydrolysis and rearrangement, leading to the loss of one carbon atom and the formation of ethanamine.

### Step 5: Write the Reaction Equation
The overall reaction can be summarized as:
\[ \text{CH}_3\text{CH}_2\text{C(=O)NH}_2 + \text{Br}_2 + 4 \text{KOH} \rightarrow \text{CH}_3\text{CH}_2\text{NH}_2 + \text{by-products} \]

### Conclusion
Thus, the reagent used to prepare ethanamine from propanamide is bromine (\( \text{Br}_2 \)) in the presence of potassium hydroxide (\( \text{KOH} \)).

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