Ozonolysis of which of the following alkene gives propan-2-one and methanal :

Question

Accepted Answer

To determine why Option 1, 2-Methyl Propene, is the correct answer for the ozonolysis reaction that yields propan-2-one and methanal, let's analyze the process of ozonolysis and the structure of the given alkenes.

### Explanation for Option 1: 2-Methyl Propene

1. **Structure of 2-Methyl Propene**: 
   - 2-Methyl Propene is an alkene with the structure CH3-C(CH3)=CH2. It has a double bond between the second and third carbon atoms.

2. **Ozonolysis Reaction**:
   - Ozonolysis involves the cleavage of the carbon-carbon double bond by ozone (O3), followed by reductive workup, typically with zinc and water, to yield carbonyl compounds.
   - For 2-Methyl Propene, the double bond between the second and third carbon atoms is cleaved. This results in the formation of two fragments:
     - One fragment is acetone (propan-2-one), CH3-CO-CH3, derived from the carbon atoms 1 and 2.
     - The other fragment is formaldehyde (methanal), H-CHO, derived from the carbon atom 3.

3. **Conclusion**:
   - The ozonolysis of 2-Methyl Propene perfectly matches the products given in the question: propan-2-one and methanal. Therefore, Option 1 is the correct answer.

### Explanation for Why Other Options are Incorrect

1. **Option 2: But-1-ene**:
   - Structure: CH2=CH-CH2-CH3
   - Ozonolysis of But-1-ene would yield two molecules of ethanal (acetaldehyde), CH3-CHO, not propan-2-one and methanal.

2. **Option 3: Propene**:
   - Structure: CH2=CH-CH3
   - Ozonolysis of Propene would yield one molecule of ethanal (CH3-CHO) and one molecule of formaldehyde (H-CHO), not propan-2-one.

3. **Option 4: But-2-ene**:
   - Structure: CH3-CH=CH-CH3
   - Ozonolysis of But-2-ene would yield two molecules of acetone (propan-2-one), not methanal.

In summary, the ozonolysis of 2-Methyl Propene is the only reaction that produces the specified products, propan-2-one and methanal, confirming that Option 1 is indeed the correct answer.