Compound $P$ gives a red-orange precipitate with 2,4-DNP reagent and does not reduce Fehling's reagent. On drastic oxidation with chromic acid, $P$ gives an aromatic product $Q$ which produces effervescence on treating with aqueous $\ce{NaHCO3}$. Compounds $P$ and $Q$, respectively, are:

Question

The major product formed in the following reaction is-

Answer 1

Step 1: Understanding the Topic:
This problem focuses on the qualitative analysis of organic compounds. It uses specific chemical tests (2,4-DNP, Fehling's, and Sodium Bicarbonate) to determine the functional groups of unknown molecules. It also requires understanding the oxidation of alkyl/acyl side chains in aromatic compounds. Deciphering these tests is essential for identifying substances in organic chemistry labs.
Step 2: Key Formulas and Approach:
The approach involves translating each chemical test into a functional group:
2,4-DNP Positive $\rightarrow$ Carbonyl group present (Aldehyde or Ketone).
Fehling's Negative $\rightarrow$ Not an aliphatic aldehyde (likely a Ketone).
NaHCO$_3$ Positive $\rightarrow$ Carboxylic acid group present.
Oxidation of $Ar-R$ or $Ar-CO-R$ $\rightarrow$ $Ar-COOH$.

Step 3: Detailed Explanation:

Identify P: The molecular formula $C_8H_8O$ indicates a high degree of unsaturation (likely a benzene ring). A positive 2,4-DNP test confirms a carbonyl. A negative Fehling's test indicates a ketone rather than an aldehyde. Acetophenone ($C_6H_5COCH_3$) perfectly fits these observations and the formula $C_8H_8O$.
Identify Q: Strong oxidation of acetophenone with chromic acid ($H_2CrO_4$) cleaves the side chain and oxidizes the carbon attached to the ring to its highest state. \[ C_6H_5COCH_3 \xrightarrow{[O]} C_6H_5COOH \] The product $Q$ is thus Benzoic Acid.
Verification: Benzoic acid is a carboxylic acid, so it will react with sodium bicarbonate to release carbon dioxide gas, causing the observed effervescence.
Step 4: Final Answer:
P is acetophenone and Q is benzoic acid, matching option (A).

Compound \(P\) gives a red-orange precipitate with 2,4-DNP reagent and does not reduce Fehling's reagent. On drastic oxidation with chromic acid, \(P\) gives an aromatic product \(Q\) which produces effervescence on treating with aqueous \(\ce{NaHCO3}\). Compounds \(P\) and \(Q\), respectively, are:

Show Hint

The Correct Option is A

Solution and Explanation

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