Question

The number of optically active products obtained from the complete ozonolysis of the given compound is:

• A. 0
• B. 1
• C. 2
• D. 3

Answer 1

Answer: (C)

2

Answer 2

Step 1: Identify the double bonds and cleavage fragments
The molecule has three C=C bonds; complete ozonolysis cleaves each to give carbonyl fragments.

• Terminal alkene cleavage gives acetaldehyde (achiral).
• Internal alkenes linked to the chiral centers produce asymmetrically substituted diketone fragments that retain a stereogenic carbon.

Step 2: List all ozonolysis products

1. CH₃CHO (acetaldehyde) – achiral
2. HOCH₂CHO (glycolaldehyde) – achiral
3. CH₃COCOCH₃ (diacetyl) – achiral
4. CH₃COCHO (methyl glyoxal) – achiral
5. CH₃COCH₂CHO (3‐oxobutanal) – contains a stereogenic center at CH₂CHO end → optically active
6. HOCH₂COCH₃ (hydroxyacetone) – contains a stereogenic center at HOCH₂CO → optically active

Step 3: Count optically active products
Only fragments (5) and (6) are chiral → 2 optically active products.