AS-Level Halogenoalkanes

  • Halogenoalkanes can be converted to alkenes in an elimination reaction.

  • By reacting halogenoalkanes with hydroxide ions in ethanolic conditions (anhydrous), an alkene and not an alcohol is formed.

  • The reaction is carried out under reflux and the hydroxide ion acts as a base (unlike in the hydrolysis of a halogenoalkane to form an alcohol).

QUICK NOTES

Elimination Reactions of Halogenoalkanes

 

Halogenoalkanes can be converted into alkenes by an elimination reaction.

 

 

 

 

 

 

 

 

 

A halogenoalkane is reacted with hydroxide ions under reflux in ethanol. Ethanol is used as a solvent to ensure the conditions are anhydrous (no water!).

 

The hydroxide ion acts as a base and accepts a proton from a C-H bond to form H O.

 

The important thing to note is that the OH⁻ ion can act as either a nucleophile or as a base depending on the conditions it’s reacting in.

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