Question

Identify the final product [D] obtained in the following sequence of reactions.

• A.
• B.
• C.
• D. \(\text{C}_{4}\text{H}_{10}\)

Answer 1

The Correct Option is B

The correct answer is option (B):

Correct Answer: Option 2 (Ethylbenzene)

The given reaction sequence involves a multi-step transformation beginning with acetaldehyde (CH₃CHO) and ending in the formation of an organic compound after a coupling reaction. Let's break it down step-by-step to understand the underlying chemistry and determine the final product [D].

Step 1: The first step is treatment of CH₃CHO with lithium aluminium hydride (LiAlH₄) followed by hydrolysis with H₃O⁺. This is a well-known reduction step:

CH₃CHO (acetaldehyde) → CH₃CH₂OH (ethanol)

Product [A]: Ethanol

Step 2: Ethanol is treated with concentrated sulfuric acid (H₂SO₄) under heat (Δ). This is a classic dehydration reaction, where ethanol is converted to ethene:

CH₃CH₂OH → CH₂=CH₂ + H₂O

Product [B]: Ethene

Step 3: Ethene undergoes addition reaction with HBr, forming bromoethane via electrophilic addition:

CH₂=CH₂ + HBr → CH₃CH₂Br

Product [C]: Bromoethane

Step 4: Bromoethane is reacted with bromobenzene in the presence of sodium and dry ether. This is a Wurtz-Fittig reaction — a coupling reaction between an aryl halide and an alkyl halide to form an aryl-alkane:

C₆H₅Br + CH₃CH₂Br + 2Na → C₆H₅CH₂CH₃ + 2NaBr

Product [D]: Ethylbenzene

Final Answer: The product obtained at the end of this sequence is ethylbenzene, which matches with Option 2 in the given choices.