In a Williamson ether synthesis, which substrate is most suitable for SN2 to form the ether?

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Multiple Choice

In a Williamson ether synthesis, which substrate is most suitable for SN2 to form the ether?

In a Williamson ether synthesis, the alkoxide attacks the alkyl halide in an SN2 process, so backside attack on a carbon with a good leaving group is key. SN2 works best when the carbon is not heavily hindered, allowing the nucleophile to approach directly. Primary alkyl halides are ideal because they offer minimal steric hindrance, enabling fast SN2 displacement of the halide by the alkoxide to form the ether. Secondary substrates can react but more slowly due to increased hindrance, while tertiary substrates are usually too hindered for SN2 and can lead to elimination instead. Aryl halides are not suitable for SN2 because the carbon bearing the halogen is sp2-hybridized, making backside attack very difficult. So the most suitable substrate for SN2 to form the ether is a primary alkyl halide.

In a Williamson ether synthesis, the alkoxide attacks the alkyl halide in an SN2 process, so backside attack on a carbon with a good leaving group is key. SN2 works best when the carbon is not heavily hindered, allowing the nucleophile to approach directly. Primary alkyl halides are ideal because they offer minimal steric hindrance, enabling fast SN2 displacement of the halide by the alkoxide to form the ether. Secondary substrates can react but more slowly due to increased hindrance, while tertiary substrates are usually too hindered for SN2 and can lead to elimination instead. Aryl halides are not suitable for SN2 because the carbon bearing the halogen is sp2-hybridized, making backside attack very difficult.

So the most suitable substrate for SN2 to form the ether is a primary alkyl halide.

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