Halogenoalkanes: Elimination Reactions
- In an elimination reaction, an organic molecule loses a small molecule
- In the case of halogenoalkanes this small molecule is a hydrogen halide (eg. HCl)
- The halogenoalkanes are heated with ethanolic sodium hydroxide causing the C-X bond to break heterolytically, forming an X- ion and leaving an alkene as an organic product
- For example, bromoethane reacts with ethanolic sodium hydroxide when heated to form ethene
Hydrogen bromide is eliminated to form ethene
Examiner Tip
The reaction conditions in a reaction are extremely important.If NaOH(ethanol) is used, an elimination reaction takes place to form an alkene from a halogenoalkane.If NaOH(aq) is used, a nucleophilic substitution reaction takes place to form an alcohol from a halogenoalkane.
