Vaccum filtration

The Erlenmeyer flask is charged with 100 mL of the 1.0 M stock solution of K[C2B9H12] (see this volume, Chapter 5, Section 53) and 31.2 g (0.4 mole) of dimethyl sulfoxide. While the solution is being stirred, 100 mL of concentrated sulfuric acid is added dropwise over a 1-hr period. Stirring is continued for an additional 5 hr. The resultant two-layer mixture is then set aside overnight. After dilution with 500 mL of cold water, the mixture is vacuum filtered, to isolate the solid residue, and this is washed with two 100-mL portions of water and recrystallized from 80% methanol. White needles separate which are isolated by vaccum filtration and dried in air at ambient temperature for 8 hr. The yield is 10.8 g (55.6%). 

Apparatus A 5-mL conical vial, 1-mL glass syringe with a needle, a screw-cap centrifuge tube, apparatus for magnetic stirring, simple distillation, vaccum filtration, and ffame/ess heating. 

The water sample is extracted with dichloromethane in the presence of sodium chloride. The dichloromethane extract is dried by passing it through a No. 1 filter paper containing anhydrous sodium sulphate, the filtrate being collected in a rotary evaporator flask. The extract is reduced to about one-tenth of its original volume in the rotary evaporator, under vaccum. This... 

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