AS-Level Halogenoalkanes

Video Tutorial Halogenoalkanes - Elimination Reactions

Quick Notes Halogenoalkanes - Elimination Reactions

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 conditions and the hydroxide ion acts as a base (unlike in the hydrolysis of a halogenoalkane to form an alcohol).

Full Notes Halogenoalkanes - Elimination Reactions

Halogenoalkanes can be converted into alkenes by an elimination reaction.

elimination reaction halogenoalkane bromoethane with hydroxide ion to form ethene

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, accepting a proton from a C-H bond to form H₂O.

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.

halogenoalkane hydrolysis and elimination reaction conditions reagents