Question:
An alkene 'X' on ozonolysis gives a mixture of ethanal and pentan-3-one. The IUPAC name of alkene 'X' is
An alkene 'X' on ozonolysis gives a mixture of ethanal and pentan-3-one. The IUPAC name of alkene 'X' is
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Write the structures of the carbonyl products with their oxygen atoms pointing towards each other.
Erase the oxygens and draw a double bond between the carbons to get the correct alkene.
Erase the oxygens and draw a double bond between the carbons to get the correct alkene.
Updated On: Jul 22, 2026
- Pent-2-ene
- 3-Methylpent-2-ene
- 3-Ethylpent-2-ene
- 2-Ethylbut-1-ene
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Question:
This question is based on the ozonolysis of alkenes.
We are given the products of the ozonolysis of an alkene X and need to deduce the structure and IUPAC name of X.
Step 2: Key Formula or Approach:
During reductive ozonolysis, the carbon-carbon double bond (C=C) of an alkene is cleaved, and each carbon is converted into a carbonyl group (C=O).
To find the parent alkene, we remove the oxygen atoms from the carbonyl groups of the products and connect the two carbonyl carbons with a double bond.
Step 3: Detailed Explanation:
• The given products of ozonolysis are:
1. Ethanal ($\text{CH}_3\text{CHO}$):
Its carbonyl structure is:
\[ \text{CH}_3-\text{CH}=\text{O} \] 2. Pentan-3-one ($\text{CH}_3\text{CH}_2\text{COCH}_2\text{CH}_3$):
Its carbonyl structure is:
\[ \text{O}=\text{C}(\text{CH}_2\text{CH}_3)_2 \]
• Now, we remove both oxygen atoms and join the two carbonyl carbons with a double bond:
\[ \text{CH}_3-\text{CH}=\text{C}(\text{CH}_2\text{CH}_3)_2 \] This structural formula can be expanded as:
\[ \text{CH}_3-\text{CH}=\text{C}(\text{CH}_2\text{CH}_3)(\text{CH}_2\text{CH}_3) \]
• Let us find the IUPAC name for this alkene:
Find the longest carbon chain containing the double bond.
The longest continuous carbon chain has 5 carbon atoms (pentene).
Let us number the chain from left to right to give the double bond the lowest locant:
\[ \text{C}_1\text{H}_3-\text{C}_2\text{H}=\text{C}_3(\text{CH}_2\text{CH}_3)-\text{C}_4\text{H}_2-\text{C}_5\text{H}_3 \] The double bond starts at C2, so the parent name is pent-2-ene.
At C3, there is an ethyl group substituent ($-\text{CH}_2\text{CH}_3$).
Therefore, the IUPAC name is 3-Ethylpent-2-ene.
Step 4: Final Answer:
The IUPAC name of the alkene X is 3-Ethylpent-2-ene.
This question is based on the ozonolysis of alkenes.
We are given the products of the ozonolysis of an alkene X and need to deduce the structure and IUPAC name of X.
Step 2: Key Formula or Approach:
During reductive ozonolysis, the carbon-carbon double bond (C=C) of an alkene is cleaved, and each carbon is converted into a carbonyl group (C=O).
To find the parent alkene, we remove the oxygen atoms from the carbonyl groups of the products and connect the two carbonyl carbons with a double bond.
Step 3: Detailed Explanation:
• The given products of ozonolysis are:
1. Ethanal ($\text{CH}_3\text{CHO}$):
Its carbonyl structure is:
\[ \text{CH}_3-\text{CH}=\text{O} \] 2. Pentan-3-one ($\text{CH}_3\text{CH}_2\text{COCH}_2\text{CH}_3$):
Its carbonyl structure is:
\[ \text{O}=\text{C}(\text{CH}_2\text{CH}_3)_2 \]
• Now, we remove both oxygen atoms and join the two carbonyl carbons with a double bond:
\[ \text{CH}_3-\text{CH}=\text{C}(\text{CH}_2\text{CH}_3)_2 \] This structural formula can be expanded as:
\[ \text{CH}_3-\text{CH}=\text{C}(\text{CH}_2\text{CH}_3)(\text{CH}_2\text{CH}_3) \]
• Let us find the IUPAC name for this alkene:
Find the longest carbon chain containing the double bond.
The longest continuous carbon chain has 5 carbon atoms (pentene).
Let us number the chain from left to right to give the double bond the lowest locant:
\[ \text{C}_1\text{H}_3-\text{C}_2\text{H}=\text{C}_3(\text{CH}_2\text{CH}_3)-\text{C}_4\text{H}_2-\text{C}_5\text{H}_3 \] The double bond starts at C2, so the parent name is pent-2-ene.
At C3, there is an ethyl group substituent ($-\text{CH}_2\text{CH}_3$).
Therefore, the IUPAC name is 3-Ethylpent-2-ene.
Step 4: Final Answer:
The IUPAC name of the alkene X is 3-Ethylpent-2-ene.
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