# 1-chloropropane can react with aqueous sodium hydroxide to form propan-1-ol. However, when 1-chloropropane reacts with ethanolic sodium hydroxide instead, a different type of reaction occurs and propene is formed. Explain why changing the solvent changes the type of reaction that takes place, and describe the difference between the two reactions.

> WJEC A-Level Chemistry (Wales) — 2.6 Halogenoalkanes · Explain · 5 marks

> 1-chloropropane undergoes different reactions depending on whether aqueous or ethanolic sodium hydroxide is used as the reagent.

## Mark scheme (5 marks)

1. Aqueous sodium hydroxide provides hydroxide ions (OH⁻) that act as a nucleophile
2. In aqueous conditions the reaction is nucleophilic substitution, where the OH⁻ replaces the chlorine atom
3. Ethanolic sodium hydroxide provides hydroxide ions that act as a base
4. In ethanolic conditions the reaction is elimination, where a hydrogen atom and the chlorine atom are removed from adjacent carbon atoms
5. Elimination produces a C=C double bond, forming an alkene (propene)

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