A rotary evaporator, or rotovap, gently removes solvents from a sample under reduced pressure. By rotating the flask in a heated bath while a vacuum lowers the solvent's boiling point, it evaporates solvent quickly at mild temperatures — protecting heat-sensitive compounds. It's a workhorse in chemistry, natural-product extraction, and sample concentration, and the right unit balances capacity, control, and safety.
How it works — and why that matters
Rotation spreads a thin film of liquid across the flask wall, increasing surface area for fast, even evaporation and preventing bumping. Vacuum reduces the boiling point so solvents come off well below their normal temperature. Understanding this helps you spec the pieces that matter: bath temperature, vacuum level, and condenser capacity all work together.
Key factors to consider
- Flask capacity: Match evaporating and receiving flask sizes to your batch volumes; larger flasks suit prep-scale work, smaller ones for concentrating precious samples.
- Heating bath: Confirm the temperature range and uniformity fit your solvents, and consider whether you need water or oil.
- Vacuum control: A controlled, adjustable vacuum — ideally with a vacuum controller — improves recovery and prevents bumping and foam-over.
- Condenser type: Vertical (coil) condensers save space, diagonal designs are versatile, and cold-trap/dry-ice condensers handle low-boiling solvents. Adequate condenser surface area maximizes solvent recovery.
- Lift mechanism and safety: A motorized lift automatically raises the flask from the bath if power is lost, and chemically resistant seals and coated glassware protect against your solvents.
Building a complete setup
A rotovap performs best as part of a system: pair it with a vacuum pump sized to your solvents and a reliable chiller or recirculator to keep the condenser cold. Set bath temperature, vacuum, and rotation together — a common rule of thumb balances them so the solvent distills smoothly without bumping.
Explore our Laboratory Rotary Evaporators and complete the setup with a matched vacuum pump.