Dean Stark Trap

Usage

1. Calculate the amount of water expected to be produced and select a suitable size Dean-Stark trap for the scale of reaction and amount of water being produced.

2. Set up the round-bottomed flask containing the reaction to be heated to reflux and securely clamp above a hotplate/labjack with heating block. The flask size should be selected such that the solvent level is around half full.

3. Attach the Dean-Stark trap, and clamp the upper socket securely. Often it will be nescessary to insulate the trap, for example with foil, in order to keep the arm warm enough for solvent vapour to be able to reach the trap.

4. Ensure that the drain tap is closed (if fitted). Fill the trap with the reaction solvent (which is less dense than water) up to the level where it would overflow back into the flask.

5. Attach a reflux condenser to the trap. The condenser needs to be able to condense all the vapour being produced.

6. Ensure a suitable flow of water is passing through the condenser and begin heating the reaction. The reaction will need to be heated vigorously.

7. As water is produced, water and solvent will evaporate from the reaction flask and travel into the condenser. The condensed vapour will fall into the trap, with the water sinking to the bottom. This will displace some solvent back to the reaction flask in order to maintain the solvent level.

8. Over time, all the water will distil out of the flask and be caught in the trap. Once sufficient water has been removed, the reaction can be stopped by removing the heat.