(a) Write a suitable chemical equation to complete each of the following transformations: (i) Butan-1-ol to butanoic acid (ii) 4-Methylacetophenone to benzene-1, 4-dicarboxylic acid (iii) An organic compound with molecular formula C9H10O forms 2,4-DNP derivative, reduces Tollen's reagent and undergoes Cannizzaro's reaction. On vigorous oxidation it gives 1,2-benzene-dicarboxylic acid. Identify the compound.

(i) Butan-1-ol to butanoic acid:
The conversion of Butan-1-ol to butanoic acid involves oxidation. This can be achieved using an oxidizing agent like potassium dichromate (K₂Cr₂O₇) in acidic medium.
CH₃CH₂CH₂CH₂OH + [O] → CH₃CH₂CH₂COOH + H₂O

(ii) 4-Methylacetophenone to benzene-1, 4-dicarboxylic acid:
This transformation requires strong oxidation to break the carbon-carbon bonds in the alkyl side chain. Potassium permanganate (KMnO₄) in an alkaline or acidic medium is suitable for this purpose.

CH₃
│
C₆H₄-CO-CH₃ + KMnO₄ → HOOC-C₆H₄-COOH + other products
│
4

(iii) Identification of the organic compound with molecular formula C₉H₁₀O:
The given information indicates that the compound:
• Forms a 2,4-DNP derivative (indicating the presence of a carbonyl group).
• Reduces Tollen's reagent (indicating the presence of an aldehyde group).
• Undergoes Cannizzaro's reaction (indicating the presence of an aldehyde group without α-hydrogen).
• On vigorous oxidation gives 1,2-benzene-dicarboxylic acid (phthalic acid) This suggests the presence of an aldehyde group attached to a benzene ring, specifically in the 1-position.

Considering these points, the compound is likely 2-ethylbenzaldehyde.

The reaction with Tollen's reagent:

C₆H₅-CH(CH₃)-CHO + [Ag(NH₃)₂]⁺ → C₆H₅-CH(CH₃)-COO⁻ + Ag + NH₃ + other products

The Cannizzaro reaction:
2C₆H₅-CH(CH₃)-CHO + OH⁻ → C₆H₅-CH(CH₃)-CH₂OH + C₆H₅-CH(CH₃)-COO⁻

Vigorous oxidation:
C₆H₅-CH(CH₃)-CHO + [O] → C₆H₄(COOH)₂