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Williamson ether synthesis: sodium ethoxide + 1-bromobutane → ethyl butyl ether

Et–O⁻ Na⁺ + n-Bu–Br → Et–O–Bu + NaBr↓

Textbook SN2 ether-formation. Sodium ethoxide (typically generated in situ from NaH + EtOH or used as a solid) attacks the primary alkyl bromide via backside attack; the bromide leaves as NaBr, precipitating from DMF as the reaction advances. Primary substrates only — secondary alkyl halides give E2 elimination at these conditions because the alkoxide is sterically demanding.

Conditions: Generate the alkoxide: under N2, suspend NaH (60% in mineral oil, 1.05 equiv) in dry DMF (~3 mL per mmol substrate). Add ethanol (1.05 equiv) dropwise — vigorous H2 evolution; control addition rate. Once H2 stops, add 1-bromobutane (1.0 equiv) via syringe. Stir at 50–80 °C for 6–24 h until starting material is consumed (TLC). NaBr precipitates as a fine white solid. Workup — Quench with sat. NH4Cl; partition into Et2O / water; wash organic with water + brine; dry MgSO4; concentrate. Distil at atmospheric pressure (bp 92 °C) to isolate. Substrate-scope reminder: Williamson works ONLY for primary alkyl halides.

Expected yield

70–88 %

Expected duration

6–24 h at 50–80 °C after in-situ alkoxide generation

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