Williamson ether synthesis: sodium ethoxide + 1-bromobutane → ethyl butyl ether
Reagent table at any scale. Enter how much 1-bromobutane you have, or pick another reagent, and every mass, volume and amount follows.
Notes on the reagents
- 1-Bromobutane
- 1-Bromobutane — limiting reagent; primary alkyl bromide is the textbook substrate. Distil before use to remove HBr and any 2-bromobutane impurity. Switching to the iodide (1-iodobutane) accelerates the SN2 ~10x but invites side reactions; the bromide is the safer bet.
- Sodium ethoxide
- Sodium ethoxide — nucleophile. Often generated in-situ from NaH + EtOH (cleaner than the commercial solid which absorbs CO2 + moisture). Slight excess to drive the SN2 to completion.
- Dimethylformamide
- DMF — polar aprotic, stabilises the alkoxide free of H-bond donor that would protonate it. DMSO is an alternative; THF works if the alkoxide is generated in situ but slows the SN2.
- Butyl ethyl ether
- Ethyl butyl ether — colourless liquid, bp 92 °C; ethereal smell; pungent at high concentrations. Dry over 4 Å sieves for use as an anhydrous solvent in subsequent steps.
How the amounts are calculated
The amount you enter is converted to millimoles with the molar mass, or with density and molar mass for a volume. Dividing by its equivalents gives the millimoles per equivalent; every other reagent is that times its own equivalents. Masses use the molar mass of the structure. Volumes are given for compounds that are liquid at room temperature and have a density on file. A reagent sold as a solution, such as n-BuLi in hexanes, gets the volume of that solution; enter your bottle's titre and every volume follows.
The theoretical yield assumes full conversion of the limiting reagent: the reactant with the fewest millimoles per stoichiometric coefficient. Change an equivalent and the limiting reagent may change with it.
Solvent volume and concentration
The concentration refers to the substrate, the limiting reagent: solvent volume = millimoles of substrate ÷ concentration, since 1 M is 1 mmol/mL. Liquid reagents add to the final volume, so the real concentration ends up slightly lower. Leave the field empty to leave the solvent out.
What the table cannot know
Purity, water content and reagents sold as solutions. Grignard reagents and organolithiums are bought as solutions: take the millimoles from the table and divide by the molarity on the bottle to get the volume to syringe out.