Freeze–pump–thaw | 冻抽脱气操作

1. 准备与安全规范

• 样品置于厚壁Schlenk烧瓶或溶剂储存瓶中（耐压瓶）。
• 溶剂填充体积≤50%容器容量（预留溶剂膨胀空间）。
• 连接至惰性气体正压（Ar/N₂）保护的Schlenk管线。

2. 循环脱气操作（≥3次循环）

• 保持烧瓶旋塞关闭。
• 浸入液氮浴至溶剂完全凝固。
• 开启高真空（≤10 Pa） 2–3分钟抽排顶部空间中的气体。
• 关闭旋塞隔离真空管路，确保严格密封。
• 移出液氮浴，自然解冻释放溶解气体。
• 重复以上操作≥3次。注意液氮温度下，烧瓶中不能充入惰性气体！

3. 完成与储存

• 最后一次解冻后，开启旋塞通入惰性气体恢复常压。
• 惰性气氛下平衡至室温。
• 关闭旋塞，将溶剂密封储存于瓶中。

1. Preparation and Safety

• Contain sample in a thick-walled Schlenk flask or Young’s tap tube to withstand pressure differentials.
• Fill ≤50% vessel capacity to accommodate solvent expansion during freezing.
• Connect to a Schlenk line under positive pressure of inert gas (Ar/N₂).

2. Iterative Degassing Cycle (≥3 cycles)

• Close flask stopcock.
• Immerse in liquid nitrogen bath until complete solvent solidification.
• Open to high vacuum (≤10 Pa) for 2–3 min to evacuate headspace.
• Close stopcock to isolate from vacuum; ensure hermetic sealing.
• Remove from bath; allow spontaneous thawing to release dissolved gases.
• Repeat ≥3 times.

3. Finalization

• After final thaw, open stopcock to re-pressurize with inert gas.
• Equilibrate to room temperature under inert atmosphere.
• Seal and store in flask.

Ref: Leonard, J., Lygo, B., & Procter, G. (2013). Advanced practical organic chemistry. CRC press.