Which of the following alcohols gives iodoform reactions ?

Options

A. n-Propyl alcohol
B. Isobutyl alcohol
C. sec. Butyl alcohol
D. n-Butyl alcohol

Answer

To determine which of the given alcohols gives an iodoform reaction, we need to follow these steps:

### Step 1: Understand the Iodoform Reaction
The iodoform reaction occurs with compounds that have the structure CH3CO- (a methyl ketone) or CH3C(=O)R, where R can be a hydrogen or an alkyl group. The key requirement is the presence of three alpha hydrogens on the carbon adjacent to the carbonyl group.

### Step 2: Analyze Each Alcohol Option
We will examine each alcohol option provided to see if it meets the criteria for the iodoform reaction.

1. **N-Propyl Alcohol (CH3CH2CH2OH)**:
- Structure: CH3-CH2-CH2-OH
- Analysis: This compound does not have a carbonyl group (C=O) and does not have the required structure for the iodoform reaction. It has no alpha hydrogens on a carbon that is attached to an oxygen atom.
- Conclusion: **Does not give iodoform reaction.**

2. **Isobutyl Alcohol (CH3CH(CH3)OH)**:
- Structure: CH3-CH(CH3)-OH
- Analysis: This compound also lacks a carbonyl group and does not have the required structure for the iodoform reaction. The carbon attached to the hydroxyl group is not connected to a carbonyl.
- Conclusion: **Does not give iodoform reaction.**

3. **Secondary Butyl Alcohol (CH3CH(OH)CH2CH3)**:
- Structure: CH3-CH(OH)-CH2-CH3
- Analysis: This alcohol has a secondary alcohol structure. Upon oxidation, it can form a ketone (specifically, 2-butanone), which has the structure CH3C(=O)R. It has three alpha hydrogens on the carbon adjacent to the carbonyl group.
- Conclusion: **Gives iodoform reaction.**

4. **N-Butyl Alcohol (CH3CH2CH2CH2OH)**:
- Structure: CH3-CH2-CH2-CH2-OH
- Analysis: Similar to N-propyl alcohol, this compound does not have a carbonyl group and does not meet the criteria for the iodoform reaction.
- Conclusion: **Does not give iodoform reaction.**

### Step 3: Final Conclusion
Based on the analysis, the only alcohol that gives an iodoform reaction is **Secondary Butyl Alcohol**.