NEET 2020 · ChemistryPrevious Year Question
Which of the following alkanes cannot be made in good yield by the Wurtz reaction?
Answer: (A) (A) n-Heptane. The Wurtz reaction, , couples two alkyl halides and gives good yields only for symmetrical alkanes made from two identical halides.
- A.(A) n-Heptane✓
- B.(B) n-Butane
- C.(C) n-Hexane
- D.(D) 2,3-dimethylbutane
Correct Answer
(A) (A) n-Heptane
Solution & Explanation
The Wurtz reaction, , couples two alkyl halides and gives good yields only for symmetrical alkanes made from two identical halides. n-Butane (two ), n-hexane (two ) and 2,3-dimethylbutane (two isopropyl) each have an even, symmetrically divisible chain. n-Heptane has 7 carbons (odd), so it would need two DIFFERENT halides, giving a mixture of products and poor yield. Hence it cannot be made in good yield.
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