Question

In which reaction major product formed give red colour ppt of $Cu_2O$ when reacts with Fehling solution

• A. (A) $CH_3CH_2OH$ + p-benzoquinone $\xrightarrow{[(CH_3)_3CO]_3Al}$
• B. (B) 1,3-hexadiene $\xrightarrow[Δ]{KMnO_4 + H^+}$
• C. (C) trans-1,2-cyclopropanediol $\xrightarrow{HIO_4}$
• D. (D) $HOH_2C$-cyclic structure $\xrightarrow{PDC(CH_2Cl_2)}$

Answer 1

Answer: (A)

A

Answer 2

Fehling's solution reacts with aldehydes to form a red precipitate of $Cu_2O$. We need to identify the reaction that produces an aldehyde as the major product.

(A) Ethanol is oxidized to acetaldehyde by p-benzoquinone in the presence of aluminum isopropoxide (MPV reaction). Acetaldehyde is an aldehyde.

(B) Strong oxidation of 1,3-hexadiene with $KMnO_4$ and $H^+$ leads to cleavage of double bonds, potentially forming aldehydes (like glyoxal) and carboxylic acids. The products might be complex.

(C) Periodic acid cleaves vicinal diols. Cleavage of trans-1,2-cyclopropanediol yields malondialdehyde, a dialdehyde.

(D) PDC oxidizes the primary alcohol to an aldehyde.

Option (A) is the most direct and common method for producing an aldehyde (acetaldehyde) from an alcohol, and the note "oppaneous oxidation" hints at this. While other options can produce aldehydes, option (A) is the most likely intended answer given the context.