solvent-still | 溶剂除水装置

1. 准备与装置检查

• 将装置连接至惰性气体（Ar/N₂）保护下的 solvent still 系统。
• 检查玻璃仪器、冷凝管和加热装置连接是否牢固。
• 开启加热前，确认装置不得处于密闭状态。
• 装置连接处不要涂抹真空脂。

2. 除水操作

• 在惰性气体保护下加入待处理溶剂和对应除水试剂。
• 确认装置末端鼓泡器工作正常，使系统在惰性气体保护下保持排气，避免加热时处于密闭状态。
• 开启冷凝与加热，保持体系处于稳定回流状态。
• 持续回流，直到达到干燥标准：
  • 取样进行水分测试，确认水含量低于规定标准；
  • 或在 Na / 二苯甲酮 体系下观察是否显持续蓝色。

3. 常见溶剂与除水试剂

• 甲醇、乙醇：3 Å 分子筛
• 丙酮：P₂O₅
• 乙腈：CaH₂
• 甲苯、正己烷：Na / 二苯甲酮
• 乙醚：Na / 二苯甲酮
• 二氯甲烷、氯仿：CaH₂
• 乙酸乙酯：分子筛
• DMF、DMSO：分子筛
• NaK：熔点低、活性高，使用时需特别谨慎

4. 完成

• 干燥完成后，在惰性气体保护下继续储存或转移溶剂。

1. Preparation and Setup

• Connect the apparatus to a solvent still system under inert gas (Ar/N₂).
• Check that all glassware, condenser, and heating components are properly secured.
• Before heating, ensure that the apparatus is not a closed system.
• Do not apply vacuum grease to the joints.

2. Drying Procedure

• Add the solvent and the appropriate drying agent under inert atmosphere.
• Ensure that the bubbler is functioning properly so that the system can vent under inert gas and is not heated as a closed system.
• Start condenser flow and heating, and maintain steady reflux.
• Continue reflux until the solvent meets the dryness criterion:
  • sample and confirm that the water content is below the required limit; or
  • in a Na / benzophenone system, check whether a persistent blue color appears.

3. Common Solvents and Drying Agents

• Methanol, Ethanol: 3 Å molecular sieves
• Acetone: P₂O₅
• Acetonitrile: CaH₂
• Toluene, n-Hexane: Na / benzophenone
• Diethyl ether: Na / benzophenone
• Dichloromethane, Chloroform: CaH₂
• Ethyl acetate: molecular sieves
• DMF, DMSO: molecular sieves
• NaK: low melting point and highly reactive; handle with extra caution

4. Finalization

• After drying, store or transfer the solvent under inert atmosphere.

Ref: Leonard, J., Lygo, B., & Procter, G. (2013). Advanced practical organic chemistry. CRC press. See also: Armarego, W. L. (2017). Purification of laboratory chemicals. Butterworth-Heinemann.