Which of the following can be used to differentiate between ethanal and propanal-

Options

A. Ammonical `AgNO_(3)`
B. Ammonical `AgNO_(3)` in presence of tartrate ions
C. `I_(2)` in presence of base
D. Ammonical `AgNO_(3)` in presence of citrate ions

Answer

To differentiate between ethanal (acetaldehyde) and propanal (propionaldehyde), we can use the Iodoform test. Here’s a step-by-step solution:

### Step 1: Understand the Structures
- **Ethanal (Acetaldehyde)**: The chemical formula is CH₃CHO. It has a methyl group (CH₃) attached to the carbonyl group (C=O).
- **Propanal (Propionaldehyde)**: The chemical formula is CH₃CH₂CHO. It has an ethyl group (CH₃CH₂) attached to the carbonyl group.

### Step 2: Identify the Functional Groups
Both ethanal and propanal are aldehydes, which means they contain the carbonyl group (C=O) at the end of the carbon chain.

### Step 3: Perform the Iodoform Test
- The Iodoform test is used to identify the presence of a methyl group adjacent to a carbonyl group (C=O).
- When ethanal is treated with iodine (I₂) in the presence of a base (like NaOH), it undergoes a reaction to form iodoform (CHI₃), which is a yellow precipitate.

**Reaction for Ethanal**:
\[ CH₃CHO + I₂ + NaOH \rightarrow CHI₃ (yellow precipitate) + other products \]

### Step 4: Analyze the Reaction with Propanal
- When propanal is treated with iodine and base, it does not produce iodoform because it does not have a methyl group adjacent to the carbonyl group.

**Reaction for Propanal**:
\[ CH₃CH₂CHO + I₂ + NaOH \rightarrow \text{No reaction (no yellow precipitate)} \]

### Step 5: Conclusion
- **Ethanal** gives a positive Iodoform test (yellow precipitate), indicating the presence of a methyl group adjacent to the carbonyl.
- **Propanal** gives a negative Iodoform test (no precipitate), indicating the absence of such a methyl group.

### Final Statement
Thus, the Iodoform test can be used to differentiate between ethanal and propanal. Ethanal will yield a yellow precipitate, while propanal will not.

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