Academic session 2026-27, Chapter 6 in the current curriculum.
Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter Haloalkanes and Haloarenes. This page offers a step-by-step solution to the specific question from Exercise 2, Question 20:
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.
. With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.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.
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.
The reaction between A and B is first order with respect to A and zero order with respect to B. Fill in the blanks in the following table:
| Experiment |
A/ mol L - 1 |
B/ mol L - 1 |
Initial rate/mol L - 1 min - 1 |
| I | 0.1 | 0.1 |
2.0 × 10 - 2 |
| II | -- | 0.2 |
4.0 × 10 - 2 |
| III | 0.4 | 0.4 | -- |
| IV | -- | 0.2 |
2.0 × 10 - 2 |
NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:
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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....
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Comments
Basic medium does not mean RO-. There can be many sources of OH-. Poor explanation..
After searching in diff sites finally find a perfect answer to the question
Thanks for making me understand
Ghosh