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 following alcohols gives a positive iodoform reaction, we need to follow these steps:

### Step 1: Understand the Iodoform Reaction
The iodoform reaction occurs when certain alcohols, aldehydes, or ketones react with iodine (I2) in the presence of a base (such as KOH or NaOH). The reaction produces iodoform (CHI3) and a carboxylate ion.

**Hint:** Remember that the iodoform reaction is specific to compounds that have the structure R-CO-CH3 or R-CHOH-CH3.

### Step 2: Identify the Structure of the Alcohols
We need to examine the structures of the given alcohols to see if they fit the criteria for the iodoform reaction. The alcohols in question are:
1. Normal Propyl Alcohol (CH3-CH2-CH2-OH)
2. Isobutyl Alcohol (CH3-CH(CH3)-CH2-OH)
3. Secondary Butyl Alcohol (CH3-CH(OH)-CH2-CH3)
4. Normal Butyl Alcohol (CH3-CH2-CH2-CH2-OH)

**Hint:** Look for the presence of the CH3-CO- or CH3-CHOH- group in the structures.

### Step 3: Analyze Each Alcohol
1. **Normal Propyl Alcohol**:
- Structure: CH3-CH2-CH2-OH
- Does not have the required structure (no CH3-CO- or CH3-CHOH-), so it will not give a positive iodoform reaction.

2. **Isobutyl Alcohol**:
- Structure: CH3-CH(CH3)-CH2-OH
- The OH group is attached to a carbon that does not have the required structure, so it will not give a positive iodoform reaction.

3. **Secondary Butyl Alcohol**:
- Structure: CH3-CH(OH)-CH2-CH3
- This alcohol has the structure CH3-CHOH-CH3, which fits the criteria for the iodoform reaction. Therefore, it will give a positive iodoform reaction.

4. **Normal Butyl Alcohol**:
- Structure: CH3-CH2-CH2-CH2-OH
- Similar to normal propyl alcohol, it does not have the required structure, so it will not give a positive iodoform reaction.

### Step 4: Conclusion
From the analysis, the only alcohol that gives a positive iodoform reaction is **Secondary Butyl Alcohol**.

**Final Answer:** Secondary Butyl Alcohol (C-part) gives a positive iodoform reaction.

---