Lesson eLearning

When 1-bromobutane () is treated with sodium metal in ethanol, what is the major product formed? Explain the mechanism briefly.

medium 3 marks Class 11 · Chemistry · Organic Chemistry Some Basic Principles and Techniques
Answer
Butane, formed by the Wurtz coupling reaction

The correct answer is Butane, formed by the Wurtz coupling reaction — The reaction is the Wurtz coupling, where two identical alkyl halides combine to form a higher alkane.

Step-by-step solution

  1. Sodium metal donates an electron to the C–Br bond, forming a benzyl (alkyl) radical and a bromide ion.
  2. The radical reacts with another molecule of 1-bromobutane, undergoing a second single-electron transfer and generating a second radical.
  3. Two alkyl radicals combine (radical–radical coupling) to give a new C–C bond, yielding butane.
  4. The reaction is the Wurtz coupling, where two identical alkyl halides combine to form a higher alkane.
Common mistake: Assuming a substitution occurs instead of coupling, predicting a polymer or alkene.

Concept tested: Wurtz reaction mechanism

Published · How this solution was prepared and checked

← All Organic Chemistry Some Basic Principles and Techniques questions