Return to Contents Chapter 6: Reactions of Alkenes: Addition Reactions Ch 6 contents

Halohydration of Alkenes

halohydration of alkenes
Reaction type: Electrophilic Addition

Summary

Related reactions
MECHANISM FOR REACTION OF ALKENES WITH Br2 / H2O

Step 1:
Same first step as for the reaction of Br2/CH2Cl2
The π electrons act as a nucleophile, attacking the bromine, displacing a bromide ion but forming a cationic cyclic bromonium ion as an intermediate.

formation of a bromohydrin by reaction of Br2 in H2O with C=C
Step 2:
Attack of the nucleophilic water molecule from the side away from the bromonium center in an SN2 like fashion opens the cyclic bromonium ion to give overall trans addition.
Step 3:
An acid / base reaction converts the oxonium into the alcohol.

 


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organic chemistry © Dr. Ian Hunt, Department of Chemistry University of Calgary