An organic compound with the molecular formula C₉H₁₀O forms 2,4-DNP derivative, reduces Tollens' reagent and undergoes Cannizzaro reaction. On vigorous oxidation, it gives 1,2-benzenedicarboxylic acid. Identify the compound.
The compound is 2-ethylbenzaldehyde (ortho-ethylbenzaldehyde).
The compound with molecular formula C₉H₁₀O forms a 2,4-DNP derivative, which indicates the presence of a carbonyl group (>C=O), confirming it is either an aldehyde or a ketone.
Since the compound reduces Tollens' reagent, it must be an aldehyde and not a ketone. Ketones do not reduce Tollens' reagent.
The compound undergoes Cannizzaro reaction, which is characteristic of aldehydes that do not have an α-hydrogen atom. This indicates that the aldehyde group is directly attached to the benzene ring without any α-hydrogens.
On vigorous oxidation, the compound gives 1,2-benzenedicarboxylic acid (phthalic acid). This indicates that the original compound must have substituents on adjacent positions (ortho positions) of the benzene ring. Both the aldehyde group and the alkyl group get oxidized to carboxylic acid groups.
Therefore, the compound is 2-ethylbenzaldehyde, where the ethyl group and the aldehyde group are present at ortho positions (positions 1 and 2) on the benzene ring. On vigorous oxidation, the ethyl group oxidizes to carboxylic acid and the aldehyde group also oxidizes to carboxylic acid, yielding 1,2-benzenedicarboxylic acid.
Explanation
The question tests understanding of aldehyde and ketone reactions. The key clues are: (1) 2,4-DNP formation indicates carbonyl group; (2) Tollens' reduction confirms aldehyde; (3) Cannizzaro reaction indicates aldehyde without α-H; (4) Oxidation to phthalic acid reveals ortho substitution pattern. The context provides information about 2,4-DNP derivatives, Tollens' test for aldehydes, and oxidation reactions, though the solution shown in context is for a different question (Example 8.4 about C₈H₈O).
Solution Steps
Step 1: 2,4-DNP derivative formation → compound has carbonyl group (aldehyde or ketone)
Step 2: Reduces Tollens' reagent → compound is an aldehyde
Step 3: Undergoes Cannizzaro reaction → aldehyde has no α-hydrogen (aromatic aldehyde)
Step 4: Vigorous oxidation gives 1,2-benzenedicarboxylic acid → substituents at ortho positions
Step 5: Structure is 2-ethylbenzaldehyde (C₉H₁₀O) with CHO and C₂H₅ at positions 1 and 2