Question: What alkene can be used to prepare each alkyl halide or dihalide as the exclusive or major product of an addition reaction?

a.

b.

c.

d.

The alkenes are very reactive towards the electrophilic addition reaction. The pi electrons of the alkene are weakly bonded. Therefore, the pi electrons can be donated which makes the alkene reactive.

The preparation of alkene can be done by the dehalogenation reaction. In this type of reaction, the halogen acids or halogen molecule is eliminated by the reaction of an alkyl halide with the base.

a. The chlorine molecule is eliminated in this reaction which forms an alkene product. The reagent may be electron-rich metals.

Alkene, in reaction a

b. The HBr molecule is eliminated in this reaction which forms a less substituted alkene product. The reagent is a base.

c. The HCl molecule is eliminated in this reaction which forms a substituted alkene product. The reagent is a base.

Formation of alkene

d. The HBr molecule is eliminated in this reaction which forms a substituted alkene product. The reagent is a base.

Formation of alkene