Which one of the following compounds will not given iodoform by the reaction with iodine and NaOH?

Options

A. Ethanol
B. Methanol
C. Acetaldehyde
D. Acetone

Answer

To determine which compound will not give a positive iodoform test when reacted with iodine and NaOH, we need to analyze the compounds that typically yield this reaction. The iodoform test is used to identify methyl ketones and certain alcohols that can be oxidized to methyl ketones.

### Step-by-Step Solution:

1. **Understanding the Iodoform Test**:
The iodoform test is a qualitative test for the presence of a methyl ketone (RCOCH3) or a secondary alcohol that can be oxidized to a methyl ketone. When these compounds react with iodine (I2) in the presence of sodium hydroxide (NaOH), they produce a yellow precipitate of iodoform (CHI3).

**Hint**: Remember that the iodoform test specifically identifies methyl ketones and certain secondary alcohols.

2. **Identifying Common Compounds**:
Common compounds that give a positive iodoform test include:
- Methyl ketones (e.g., acetone, CH3COCH3)
- Ethanol (a secondary alcohol)
- Acetaldehyde (the only aldehyde that gives a positive test)

**Hint**: List down the types of compounds that are known to give a positive iodoform test.

3. **Analyzing the Given Compounds**:
Let's consider the following compounds:
- Ethanol (CH3CH2OH)
- Acetaldehyde (CH3CHO)
- Acetone (CH3COCH3)
- Methanol (CH3OH)

**Hint**: Check each compound to see if it fits the criteria for the iodoform test.

4. **Evaluating Each Compound**:
- **Ethanol**: Reacts with I2 and NaOH to give iodoform.
- **Acetaldehyde**: Reacts with I2 and NaOH to give iodoform.
- **Acetone**: Reacts with I2 and NaOH to give iodoform.
- **Methanol**: Does not have a methyl ketone structure and does not react to give iodoform.

**Hint**: Identify which of the compounds does not fit the criteria for producing iodoform.

5. **Conclusion**:
Among the listed compounds, methanol (CH3OH) will not give a positive iodoform test when reacted with iodine and NaOH.

**Final Answer**: Methanol (CH3OH) will not give iodoform by the reaction with iodine and NaOH.