The Question is from neet-chemistry hydrocarbons , and it was created by the author Mr. S M HUSSAIN

Question

An alkyne 'X' with molecular formula $C_5H_8$ on ozonolysis yields a mixture of propanoic acid and acetic acid.  The alkyne 'X' is:

Mr. S M HUSSAIN · Accepted Answer

## CORE INFORMATION
✓ **Answer**: 2
## CONCEPT FRAMEWORK
 **Primary Concept**: Ozonolysis of alkynes
 **Related Topics**: Alkyne structure, carboxylic acid formation
 **Prerequisites**: Understanding of ozonolysis reaction mechanism and structural formulas of alkynes and carboxylic acids.
## SOLUTION PATHWAY
**Given Information**:
  Molecular formula of alkyne X: $C_5H_8$
  Products of ozonolysis: Propanoic acid ($CH_3CH_2COOH$) and acetic acid ($CH_3COOH$)
**Method & Steps**:
 1. Determine the structure of the alkyne based on the ozonolysis products.
Ozonolysis of alkynes cleaves the carbon-carbon triple bond and adds oxygen atoms to form carboxylic acids.  The products indicate that the alkyne must have been cleaved into two fragments that correspond to the carbon skeletons of propanoic acid and acetic acid.
  Reasoning: The carbon atoms in propanoic acid ($CH_3CH_2COOH$) and acetic acid ($CH_3COOH$) must have originated from the alkyne's triple bond.
  Formula/Rule: Ozonolysis of alkynes: $R_1C≡CR_2 \overset{O_3}{\longrightarrow} R_1COOH + R_2COOH$
 2. Reconstruct the alkyne structure.
  Working: To obtain propanoic acid ($CH_3CH_2COOH$) and acetic acid ($CH_3COOH$) from ozonolysis, the original alkyne must have been $CH_3CH_2C≡CCH_3$. This corresponds to pent-2-yne.
  Key Point: The position of the triple bond determines the products of ozonolysis.
 3. Verify the molecular formula.
  Result: The molecular formula of pent-2-yne ($CH_3CH_2C≡CCH_3$) is $C_5H_8$, which matches the given information.
  Verification: The structure is consistent with the given products of ozonolysis.
 ## OPTION ANALYSIS
[A] :x: Pent-1-yne ($CH≡CCH_2CH_2CH_3$) would yield ethanoic acid and propanoic acid upon ozonolysis, not propanoic acid and ethanoic acid.
[B] ✓: Pent-2-yne ($CH_3CH_2C≡CCH_3$) yields propanoic acid and acetic acid upon ozonolysis, matching the given information.
[C] :x: 3-Methylbut-1-yne ($(CH_3)_2CHC≡CH$) would yield 2-methylpropanoic acid and formic acid.
[D] :x: 2-Methylbut-1-yne ($CH_3CH(CH_3)C≡CH$) would yield propanoic acid and acetic acid, but this is not the only product.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Incorrectly identifying the alkyne structure from the ozonolysis products: Carefully consider the carbon skeleton of each carboxylic acid to reconstruct the alkyne.
  2.Ignoring the position of the triple bond: The position of the triple bond significantly affects the ozonolysis products.
 **Quick Tips**:
  1.Draw the structures of the carboxylic acids and work backward to reconstruct the alkyne.
  2.Remember that ozonolysis of alkynes yields carboxylic acids.

Mr. S M HUSSAIN · Answer

Pent-1-yne

Mr. S M HUSSAIN · Answer

The correct Option is "Pent-2-yne"

Mr. S M HUSSAIN · Answer

3-Methylbut-1-yne

Mr. S M HUSSAIN · Answer

2-Methylbut-1-yne

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