Question Details

C6H12O3 gives positive iodoform test on hydrolysis with dil. acid. The hydrolysis product formed gives Tollens’ and iodoform test both. Find the structure of C6H12O3.

Options

A

CH3COCH2CH2CH(OH)OCH3


B

CH3CH2COCH2CH(OH)CH3


C

CH3CH(OH)CH2CH2COOCH3

D

CH3CH2CH(OH)COCH(CH3)


Show Answer

Correct Answer :

Option A

CH3COCH2CH2CH(OH)OCH3


CH3COCH2CH2CH(OH)OCH3

Solution :

The correct answer is: CH3COCH2CH2CH(OH)OCH3

Step-by-Step Analysis:

1. Understanding the Functional Groups & Tests:
- Iodoform Test: A positive iodoform test is given by compounds containing either a methyl ketone group (CH3CO-) or a methyl carbinol group (CH3CH(OH)-).
- Tollens' Test: A positive Tollens' test (formation of a silver mirror) is characteristic of aldehydes (-CHO) and other easily oxidizable functional groups like hemiacetals.

2. Analyzing the Compound C6H12O3:
The given compound CH3COCH2CH2CH(OH)OCH3 contains:
- A methyl ketone group (CH3CO-) at one end, which is responsible for giving a positive iodoform test directly.
- A hemiacetal group (-CH(OH)OCH3) at the other end.

3. Hydrolysis with Dilute Acid:
Hemiacetals are unstable in the presence of dilute acids and readily undergo hydrolysis to form the corresponding aldehyde and alcohol.
The hydrolysis of the hemiacetal group in CH3COCH2CH2CH(OH)OCH3 proceeds as follows:

CH3COCH2CH2CH(OH)OCH3 + H2O (dil. acid) → CH3COCH2CH2CHO + CH3OH

The hydrolysis products formed are 4-oxopentanal (CH3COCH2CH2CHO) and methanol (CH3OH).

4. Characterizing the Hydrolysis Product:
Let us analyze the major organic product, 4-oxopentanal (CH3COCH2CH2CHO):
- It contains an aldehyde group (-CHO), which reduces Tollens' reagent to give a positive Tollens' test.
- It also retains the methyl ketone group (CH3CO-), which reacts with iodine and sodium hydroxide to give a yellow precipitate of iodoform (positive iodoform test).
Therefore, the hydrolysis product satisfies both conditions, confirming the initial structure.

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