Question

What will be the major product obtained from the reaction of Br₂ with 1-butene if the reaction is carried out in

a. dichloromethane?

b. water?

c. ethyl alcohol?

d. methyl alcohol?

Short answer

• The solvent CH₂Cl₂ is utilised to dissolve both reactants but is not involved in the reaction.

• The intermediate cyclic bromonium ion will react with Br^- (nucleophile).

Step-by-step solution

a) If the reaction is carried out in a Dichloromethane medium, Br2 reacts with 1-butene-

• The solvent CH₂Cl₂ is utilised to dissolve both reactants but is not involved in the reaction.

• The intermediate cyclic bromonium ion will react with Br^- (nucleophile).

If the reaction is carried out in a water medium, Br2 reacts with 1-butene.

• The first step is the electrophilic assault of H₃O⁺ on the alkene, which results in the formation of a carbocation intermediate.
• Water reacts with carbocation in the second stage, which is a quick reaction.

The third stage is deprotonation, which produces a neutral product (fast reaction

Br2 reacts with 1-butene if the reaction is carried out in the presence of 1-butene-

The first step is the electrophilic assault of H₃O⁺ on the alkene, which results in ethyl alcoholthe formation of a carbocation intermediate.

• reacts with carbocation in the second stage, which is a quick reaction.
• The third stage is deprotonation, which produces a neutral product (fast reaction).

If the reaction is carried out in methyl alcohol medium, Br2 reacts with 1-butene-

• The first step is the electrophilic assault of H₃O⁺ on the alkene, which results in the formation of a carbocation intermediate.
• The second step is when methanol reacts with the carbocation.

The third stage is deprotonation, which produces a neutral product (fast reaction