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 given chemical reaction sequence needs to be broken down step-by-step to determine the product [D]. Let's analyze the sequence: 

• Step 1: Consider the starting material. Identify any major functional groups or structural information.
• Step 2: Analyze the first reaction conditions and reagents. Typically, these involve additions, eliminations, or substitutions. Implement any structural changes.
• Step 3: Proceed to the next reaction based on the new structure formed. Here, continue observing reagent-specific transformations.
• Step 4: Continue this process through each step, often finding that intermediate products influence subsequent reactions.
• Step 5: Reaching step [D], identify the reaction type (e.g., oxidative or reductive) to finalize the structure.

Through these transformations, we identify the correct compound corresponding to option 2, whose structural representation matches the final product obtained at the end of the sequence.

Answer 2

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.