A tertiary alcohol is obtained when Grignard reagent react with

Options

A. Pentanone
B. Butanone
C. Propanone
D. all of these

Explanation

To determine which compound yields a tertiary alcohol when reacted with a Grignard reagent, we need to analyze the nature of the compounds involved and the reaction mechanism.

### Step-by-Step Solution:

1. **Understanding Grignard Reagents**:
- Grignard reagents are organomagnesium compounds represented as R-MgX, where R is an alkyl or aryl group, and X is a halogen. They act as strong nucleophiles.

2. **Identifying the Reaction**:
- Grignard reagents react with carbonyl compounds (aldehydes and ketones) to form alcohols. The type of alcohol formed (primary, secondary, or tertiary) depends on the structure of the carbonyl compound.

3. **Analyzing the Options**:
- The question provides four options:
1. Pentanone
2. Butanone
3. Propanone
4. All of the above

4. **Determining the Type of Alcohol Formed**:
- **Propanone (Acetone)**: When a Grignard reagent reacts with propanone, the nucleophile attacks the carbonyl carbon, leading to the formation of a tertiary alcohol.
- **Butanone**: Similar to propanone, the reaction of butanone with a Grignard reagent also leads to the formation of a tertiary alcohol.
- **Pentanone**: The same mechanism applies here; the reaction with a Grignard reagent will yield a tertiary alcohol.

5. **Conclusion**:
- Since all three ketones (propanone, butanone, and pentanone) will react with a Grignard reagent to produce tertiary alcohols, the correct answer is option 4: All of the above.

### Final Answer:
**The correct answer is option 4: All of the above.**