The reaction in Williamson synthesis involves an SN₂ attack of an alkoxide ion on a primary alkyl halide. Primary alkyl halides are preferred as better results are obtained, whereas secondary and tertiary alkyl halides may lead to elimination reactions, with alkoxides acting as strong bases.
What is the key reaction involved in Williamson synthesis, and why is the use of primary alkyl halides preferred over secondary or tertiary alkyl halides?
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The key reaction in Williamson synthesis is the nucleophilic substitution reaction between an alkoxide ion and an alkyl halide to form an ether. This reaction is often represented as:
R−O⁻ + R’−X → R−O−R’ + X⁻
Primary alkyl halides are preferred over secondary or tertiary alkyl halides in Williamson synthesis because primary alkyl halides undergo nucleophilic substitution more readily. Steric hindrance in secondary and tertiary alkyl halides hinders the approach of the nucleophile, leading to slower reactions and potential elimination side reactions. The preference for primary alkyl halides ensures better yields and selectivity in the synthesis of ethers through Williamson synthesis.