dehydrohalogenation.pptx

Class 12
Chapter haloalkane and haloarenes
Topics - chemical property of haloalkane

1. Dehydrohalogenation

2. Dehydrohalogenation :- when haloalkanes are heated with concentrated alcoholic KOH to form alkene. (Beta- elimination reaction) The reactivity of haloalkanes towards elimination reaction is - 3° > 2° >1° This due to +I effect of the alkyl group which increases the polarity of C—X bond.

3. Stability of alkene Saytzeff’s rule :- In dehydrohalogenation of secondary and tertiary haloalkanes,where there is a possibility of formation of two isomers, the hydrogen is preferentially eliminated from the adjacent carbon atom with lesser number of hydrogen atoms. The more substituted alkene is more stable.

4. According to saytzeff’s rule.