Dean-Stark Trap

1. Preparation

1. Take a 250 mL round bottom flask equipped with a magnetic stir bar.
2. Place an oil bath under the round bottom flask on a magnetic stirrer.
3. Fill the round-bottom flask with 7.5 g (0.05 mol) m-Nitrobenzaldehyde and add 75 mL of toluene.
4. Add 3.1 mL (3.45 g, 0.055 mol) ethylene glycol.
5. Attach the Dean-Stark trap to the round bottom flask.
6. Attach a reflux condenser on top of the Dean-Stark trap.

2. Running the Reaction

1. Set the oil bath temperature to 170 °C and heat the reaction mixture to reflux.
2. Monitor the reaction by measuring the water amount in the Dean-Stark trap.
3. The reaction is done when no further water becomes trapped in the side arm of the Dean-Stark trap.
4. After approximately 2 h, the total amount of collected water is approximately 0.8 mL.

3. Workup

1. Release the water and remove the combined organic solvent from the reaction mixture under reduced pressure in a rotary evaporator.
2. Dissolve the yellow residue in 8 mL ethanol under reflux.
3. Cool down the solution.
4. The desired acetal will crystallize.
5. Filter the solid and dry it under reduced pressure.