Question

An alkene X on ozonolysis gives a mixture of Propan-2-one and methanal. What is X?

• A. Propene
• B. 2-Methylpropene
• C. 2-Methylbut-1-ene
• D. 2-Methylbut-2-ene

Answer 1

The Correct Option is B

The correct option is: (B): 2-Methylpropene.

The given products of ozonolysis, which are propan-2-one (acetone) and methanal (formaldehyde), provide important clues about the structure of the starting alkene X.

Ozonolysis of an alkene involves breaking the carbon-carbon double bond and forming carbonyl compounds (aldehydes or ketones) as the products. The specific products formed can help us deduce the structure of the alkene.

The reaction can be represented as follows:

Alkene (X) + O₃ (ozone) + Zn, H₂O (reduction) → Carbonyl Compounds

Given that the products are propan-2-one (CH₃COCH₃) and methanal (HCHO), let's analyze how the products relate to the structure of the alkene X.

Propan-2-one (Acetone): The presence of propan-2-one indicates that there must be a branch in the carbon chain of the alkene. This is because acetone has a ketone functional group (C=O) in its structure. The ketone group suggests that the alkene X must have a branch on one of the carbons of the double bond.

Methanal (Formaldehyde): Formaldehyde has an aldehyde functional group (H-C=O). The presence of formaldehyde suggests that the alkene X should have a terminal carbon-carbon double bond (i.e., the double bond should be at the end of the carbon chain).

Based on these observations, we can deduce that the alkene X has a terminal double bond and a methyl group attached to the second carbon from the end of the chain. This is consistent with the structure of 2-methylpropene.

In 2-methylpropene, the carbon-carbon double bond is terminal, and there's a methyl group attached to the second carbon atom. Therefore, the answer, 2-methylpropene, is justified by the presence of the specified products (propan-2-one and methanal) in the ozonolysis reaction, which match the expected products from the structure of 2-methylpropene.