旋转蒸发仪Rotary evaporator

三个因素共同加快蒸发：减压降低溶剂沸点，使热敏性化合物在较低温度下浓缩；烧瓶旋转使溶液在内壁形成大面积薄液膜，增大蒸发面积；水浴加热提供汽化热。旋转还能防止暴沸。蒸气经冷凝器（冷却水或干冰-丙酮冷阱）冷凝后流入接收瓶回收。

Three effects speed evaporation: vacuum lowers the solvent's boiling point so heat-sensitive compounds can be concentrated cool; rotation spreads the solution as a thin film over the inner wall, enlarging the evaporating area; and a water bath supplies the heat of vaporisation. Rotation also prevents bumping. Vapour condenses on a condenser cooled by water or dry ice–acetone and collects in a receiving flask.

1950 年美国化学家莱曼·克雷格提出旋转蒸发的思想，1957 年瑞士步琦（Büchi）公司推出第一台商品化旋转蒸发仪，此后迅速普及。

The American chemist Lyman Craig proposed rotary evaporation in 1950, and the Swiss company Büchi brought out the first commercial rotary evaporator in 1957, after which it spread rapidly.

经验“20/40/60 规则”：水浴温度比溶剂在操作压力下的沸点高约 20 °C，冷凝水温度比沸点低约 20 °C。溶液不超过烧瓶容积的一半；先抽真空再开始旋转和加热，逐步降压防止暴沸冲料；结束时先停止加热和旋转，再放气、取下烧瓶。挥发性产物可能随溶剂损失。

A rule of thumb (the 20/40/60 rule): set the bath about 20 °C above the solvent's boiling point at the working pressure and the coolant about 20 °C below it. Fill the flask no more than half; apply vacuum, then start rotation and heating, lowering the pressure gradually to avoid bumping; at the end stop heating and rotation before venting and removing the flask. Volatile products can be lost with the solvent.