CIE A Level Chemistry复习笔记3.3.3 Elimination Reactions of Halogenoalkanes
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
Exam 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.
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