Distillation apparatus are used to heat and reflux solvents in order to obtain them in high purity. The combination of flammable solvents and heat sources creates a fire hazard. Fortunately, this hazard may be easily substituted by purchasing high purity solvents or by using column purification systems. Thermal distillation should only be performed as a last resort.
The following safety precautions apply to all distillations:
- Setup distillation apparatus in a fume hood
- Perform distillations of flammable solvents under inert gas
- Upon completion of a vacuum distillation, backfill the apparatus with inert gas
- Do not leave an active distillation unattended
- The apparatus should have an automatic high-temp shutoff whenever possible
Solvent stills are used to produce dry, oxygen free, high purity solvents. Their use involves reflux of organic solvents under inert atmosphere in the presence of a reactive metal. Additional precautions should be taken when operating:
- Use temporary shielding to protect workers from a serious accident
- Don hazard appropriate PPE (face shield, flame resistant lab coat, leather apron, etc.)
- Activate still under inert atmosphere
- Do not add drying agent, solvent, or indicator while still is hot
- Ensure cooling equipment is in good shape and operational
- Quench and clean still after each procedure
Push stills, or column purification systems, use column chromatography to remove impurities from a solvent. These apparatus use an inert pressurized atmosphere to force solvent through packed columns filled with drying media. These systems do not require heating elements, reactive metals, water cooling systems, or containment within a fume hood. Therefore they save water and electricity, free up space in a fume hood, and do not present a fire hazard.