Which of the following alcohols give iodoform test?

Options

A. Butan-1-ol
B. Propan-1-ol
C. Propan-2-ol
D. Ethanol

Explanation

To determine which alcohols give the iodoform test, we need to identify the structural requirements for this reaction. The iodoform test is specific for methyl ketones or alcohols that can be oxidized to form a methyl ketone (RCOCH3). Here’s a step-by-step solution:

### Step 1: Understand the Iodoform Test
The iodoform test is performed using sodium hydroxide (NaOH) and iodine (I2). It is used to identify the presence of a methyl ketone or a secondary alcohol that can be oxidized to a methyl ketone.

### Step 2: Identify the Structural Requirement
For an alcohol to give a positive iodoform test, it must have the structure R-C(=O)-CH3 (where R can be any alkyl group). This means that the alcohol must either be a methyl alcohol (which can be oxidized to a methyl ketone) or a secondary alcohol that can be oxidized to a methyl ketone.

### Step 3: Analyze Each Option
Let's analyze the given options:

1. **Butan-1-ol (CH3-CH2-CH2-CH2OH)**:
- Structure: CH3-CH2-CH2-CH2OH
- Oxidation: This alcohol does not have the required structure (R-C(=O)-CH3) and will not give a positive test.

2. **Propan-2-ol (CH3-CHOH-CH3)**:
- Structure: CH3-CHOH-CH3
- Oxidation: This can be oxidized to acetone (CH3-CO-CH3), which has the required structure. Therefore, it will give a positive iodoform test.

3. **Butan-2-ol (CH3-CH(OH)-CH2-CH3)**:
- Structure: CH3-CH(OH)-CH2-CH3
- Oxidation: This can also be oxidized to a ketone that contains a methyl group (CH3-CO-CH2-CH3), thus it will give a positive iodoform test.

4. **Ethanol (CH3-CH2OH)**:
- Structure: CH3-CH2OH
- Oxidation: Ethanol can be oxidized to acetaldehyde (CH3CHO), but it does not have the required structure for the iodoform test. Therefore, it will not give a positive test.

### Step 4: Conclusion
From the analysis, the alcohols that give a positive iodoform test are:
- **Propan-2-ol (Option 2)**
- **Butan-2-ol (Option 3)**

### Final Answer:
The alcohols that give the iodoform test are **Propan-2-ol and Butan-2-ol**.

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