Degassing, solvents vacuum

All solvents should be fully degassed by vacuum, helium sparging, or sonication prior to use. 

Even the best solvents need to be filtered. I have received HPLC-grade acetonitrile, from what I considered to be the best manufacturer of that time, that left black residue on a 0.54-/im filter. There is a second reason to filter solvents. Vacuum filtration through a 0.54-/im filter on a sintered glass support is an excellent way to do a rough degassing of your solvents. Because of filter... 

Dried, freeze-thaw degassed solvent (e.g. acetonitrile, 5 mL) is then vacuum transferred into the evacuated, cooled (-196°C) reaction vessel, which is then closed and allowed to warm to 25°. Our experience has been that gas evolution is visually evident at this temperature. While gas evolution is often complete within one hour, we have experienced cases where up to 24h is required. The most objective procedure would be to let the oxidation proceed with the reaction vessel open to a manometer, and use the cessation of pressure changes to signal completion of the reaction. 

The packing solvent (400 cm of methanol + 0.2 g of sodium ethanoate) is degassed under vacuum for 10 minutes and then placed in the solvent reservoir. The sodium ethanoate is added to prevent static build up on the stationary phase during packing, which can produce unstable column beds, especially with bonded phase packings,... 

Fig. 2 Different modes for degassing solvents A, off-line vacuum filtration and ultrasound B, online helium purging and C, online vacuum degassing system.

Antimony trichloride [10025-91-9] M 228.1, m 73", b 283", pK 1.4, pK j ll.O (11.8), PKI 12.95 (for Sb " " aquo). Dried over P2O5 or by mixing with toluene or xylene and distilling (water is carried off with the organic solvent), then distd twice under dry nitrogen at 50mm, degassed and sublimed twice in a vacuum into ampoules. Can be crystd from CS2. Deliquescent. Fumes in moist air. 

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