Question

The products obtained by the ozonolysis of 2-methylbut-1-ene are:

• A. Propanone and ethanal
• B. Propanone and methanal
• C. Butanone and methanal
• D. Ethanal and propanal
• E. Butanone and methanol

Hint:

Ozonolysis of alkenes breaks the double bond and forms two carbonyl compounds, typically aldehydes and/or ketones, depending on the structure of the alkene.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Ozonolysis is a reaction where the double bond of an alkene is completely cleaved by ozone ($O_3$), followed by a reductive workup (usually $Zn/H_2O$). The double bond ($C=C$) is replaced by two $C=O$ bonds.
Step 2: Key Formula or Approach
To find the products, draw the structure of the alkene, "cut" the double bond in half, and add an oxygen atom to each of the two carbon atoms that were part of the double bond.
Step 3: Detailed Explanation
1. Structure of 2-methylbut-1-ene: The parent chain is but-1-ene ($CH_2=CH-CH_2-CH_3$) with a methyl group at the second carbon: \[ CH_2 = C(CH_3) - CH_2 - CH_3 \] 2. Cleavage: - The left side of the double bond is $CH_2$. Adding an oxygen gives HCHO (Methanal). - The right side of the double bond is $C(CH_3) - CH_2 - CH_3$. Adding an oxygen to that central carbon gives CH\(_3\) - CO - CH\(_2\) - CH\(_3\) (Butanone).
Step 4: Final Answer
The products are Butanone and Methanal.