Drying tube

If the drying tube is bent the bend is oriented so that solid desiccant does not fall into the reaction vessel.

Drying tubes are usually fitted on top of the reflux condenser, allowing the pressure to be relieved while excluding atmospheric moisture.

While the reaction is often carried out at room temperature, the solvent, usually volatile diethyl ether or tetrahydrofuran is already able to displace air directly, making additional measures to exclude atmospheric moisture less important.

In this case, gases are allowed to escape, but air is not able to enter because the bubbler acts as a one-way valve.

[3] For more demanding applications, a Schlenk line or glovebox may be used to provide an atmosphere of dry, inert gas such as argon or nitrogen.