Q. 19 The major product 𝐌 in the reaction

is

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Question Overview

In the given reaction, an alkene-containing cyclic compound undergoes ozonolysis:

Reagents:

1. O₃ (ozone)

2. Zn / AcOH (reductive workup)

The reaction produces:

• Major product M

• Formaldehyde (CH₂O) as a side product

You are asked to identify the correct structure of M from the given options.

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Key Concept: Ozonolysis (Reductive Workup)

🔬 What Happens in Ozonolysis?

• O₃ cleaves all C=C double bonds

• Each alkene carbon converts into a carbonyl group

• With Zn/AcOH, aldehydes and ketones are formed (no further oxidation)

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Analysis of the Given Alkene

From the structure shown:

• The molecule contains two C=C double bonds

• One double bond is terminal (–CH₂=) → produces formaldehyde (CH₂O)

• The other double bond is internal → forms ketone/aldehyde fragments

• The ring opens completely after ozonolysis

Since CH₂O is explicitly shown, cleavage of a terminal alkene is confirmed.

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Carbonyl Product Prediction

Step-by-Step Breakdown

1. Terminal alkene cleavage

   • Produces CH₂O

2. Internal alkene cleavage

   • Produces ketone and aldehyde groups

3. Reductive workup

   • Prevents oxidation to acids

   • Final product contains only aldehydes and ketones

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✅ Correct Answer

✔️ Option (C)

Option (C) correctly shows:

• One aldehyde group (–CHO)

• Two ketone groups (C=O)

• Proper carbon chain length

• Carbonyl positions matching alkene cleavage points

Hence, Option (C) represents the major product M.

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Why Other Options Are Incorrect

❌ Option (A)

• Shows incorrect placement of carbonyl groups

• Does not match the alkene cleavage pattern

• Carbon skeleton is inconsistent with ring opening

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❌ Option (B)

• Carbonyl groups are misplaced

• Does not account properly for terminal alkene cleavage

• Fails to justify formation of CH₂O

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❌ Option (D) (if applicable)

• Either missing a carbonyl group

• Or introduces functional groups not formed under reductive ozonolysis

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Final Conclusion

✔️ Since:

• The molecule contains two alkenes

• Ozonolysis with Zn/AcOH cleaves both

• A terminal alkene forms CH₂O

• The remaining fragment must contain one aldehyde and two ketones

✅ Correct Answer: Option (C)