Question

Compound (A) \( \left( \text{C}_6\text{H}_{12}\text{O}_2 \right) \) on reduction with LiAlH4 gives two compounds (B) and (C). The compound (B) on oxidation with PCC gives compound (D) which upon treatment with dilute NaOH and subsequent heating gives compound (E). Compound (E) on catalytic hydrogenation gives compound (C). The compound (D) is oxidized further to give compound (F) which is found to be a monobasic acid (Molecular weight = 60). Identify the compounds (A), (B), (C), (D), (E) and (F).

Hint:

- Reduction with LiAlH\textsubscript{4} reduces ester and carboxyl groups to alcohols. - Oxidation with PCC selectively oxidizes alcohols to aldehydes. - Hydrogenation reduces aldehydes to alcohols.

Answer 1

Identifying Compound (A) 

The molecular formula of compound (A) is C₆H₁₂O₂, which could be either a carboxylic acid or an ester. Upon reduction with LiAlH₄, it gives two compounds, indicating the presence of both a carboxyl group and an ester group in compound (A). The most likely structure of compound (A) is ethyl acetate (CH₃COOCH₂CH₃).

Most likely structure of compound (A): CH₃COOCH₂CH₃ or CH₃CH₂COOCH₃

Identifying Compound (B)

Upon reduction with LiAlH₄, compound (A) gives compound (B), which is likely ethanol (CH₃CH₂OH).

Compound (B): CH₃CH₂OH

Identifying Compound (C)

Upon reduction with LiAlH₄, compound (B) (acetaldehyde) gets reduced to propyl alcohol (CH₃CH₂CH₂OH). LiAlH₄ is a strong reducing agent, typically used to reduce aldehydes to primary alcohols.

Compound (C): CH₃CH₂CH₂OH

Identifying Compound (D)

Compound (B) is ethanol (CH₃CH₂OH). When ethanol is oxidized using PCC (Pyridinium chlorochromate), it is converted to acetaldehyde (CH₃CHO). This reaction is typical for primary alcohols, where mild oxidants like PCC prevent further oxidation to carboxylic acids.

Compound (D): CH₃CHO

Identifying Compound (E)

Upon catalytic hydrogenation of acetaldehyde (CH₃CHO), acrolein (CH₃CH=CHCHO) is formed. This reaction involves the reduction of the carbonyl group in acetaldehyde into an alkene group while keeping the aldehyde functional group intact.

Compound (E): CH₃CH=CHCHO

Identifying Compound (F)

Upon further oxidation of acrolein (CH₃CH=CHCHO), acetic acid (CH₃COOH) is produced. This is a common reaction where aldehydes undergo oxidation to form carboxylic acids.

Compound (F): CH₃COOH