The treatment of alkyl chlorides with aq | Class 12 Chemistry Chapter Haloalkanes and Haloarenes, Haloalkanes and Haloarenes NCERT Solutions

Question:

The treatment of alkyl chlorides with aqueous KOH leads to the formation of alcohols but in the presence of alcoholic KOH, alkenes are major products. Explain.

Answer:

In an aqueous solution, KOH almost completely ionizes to give OH - ions. OH - ion is a strong nucleophile, which leads the alkyl chloride to undergo a substitution reaction to form alcohol.

On the other hand, an alcoholic solution of KOH contains alkoxide (RO - ) ion, which is a strong base. Thus, it can abstract a hydrogen from the β-carbon of the alkyl chloride and form an alkene by eliminating a molecule of HCl.

OH - ion is a much weaker base than RO - ion. Also, OH - ion is highly solvated in an aqueous solution and as a result, the basic character of OH - ion decreases. Therefore, it cannot abstract a hydrogen from the β-carbon.


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Comments

  • Himani Shukla
  • 2019-03-10 12:10:08

Basic medium does not mean RO-. There can be many sources of OH-. Poor explanation..


  • Rajan lubana
  • 2019-03-09 14:08:15

After searching in diff sites finally find a perfect answer to the question


  • Paresh
  • 2019-02-15 22:11:16

Thanks for making me understand


  • Mother diary
  • 2018-02-02 22:11:53

Ghosh


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 2 , Question 20: The treatment of alkyl chlorides with aqueous KOH leads to the formation of alcohols but in the pres....