Glass columns fittings attached

In flash chromatography 40-63 /u,m silica is placed into a glass column fitted at the top with a joint to which a nitrogen tank line can be attached. The sample is layered on the top of the column and then solvent is flushed through the column at a rapid flow rate (as great as 50 mL/min). Flash chromatography is claimed to be fast, cheap, and more efficient than other... 

B. 1,4-Cyclohexanedione. The purified 2,5-dicarbethoxy-l,4-cyclohexanedione (170 g., 0.66 mole) (Note 5) and 170 ml. of water are placed in a glass liner (vented) of a steel pressure vessel of 1.5-1. capacity (fitted with a pressure-release valve). The vessel is sealed, heated as rapidly as possible to 185-195°, and kept at this temperature for 10-15 minutes (Note 6). The reaction vessel is immediately removed from the heater, placed in a large tub of ice water, and cooled to room temperature. The gas pressure then is carefully released. The resulting yellow to orange liquid is transferred to a distillation flask with the aid of a minimum volume of ethanol, and most of the water and ethanol is removed under reduced pressure by means of a rotary evaporator. The flask is attached to a short heated column fitted with a short air condenser. The remainder of the water and ethanol is removed under reduced pressure, and the 1,4-cyclohexanedione is distilled, b.p, 130-133° (20 mm.). The product solidifies to a white to pale-yellow solid, m.p. 77-79°, deld 60-66 g. (81-89% yield from 2,5-dicarbethoxy-l,4-cyclohexanedione). The compound may be conveniently recrystallized from carbon tetrachloride (7 ml. per gram of dione) the purified product is obtained as white plates, m.p. 77-79° (90% recovery). 

The process to convert a packed-column injector for use with wide-bore columns is relatively simple. The packed column is removed from the GC along with any injector (or detector) fittings attached to the base injector (or detector) body. A glass, direct-injection liner is placed into the packed... 

When the adsorbent has been introduced into the tube, the latter is fitted into a filter flask (see Fig. 77, 46, 2) to which a pump is attached the pump is run slowly and the column is again pressed down gently with the wooden pestle. The circumference of the upper surface is gently and uniformly tapped, especially where it is in contact with the glass surface, for about one minute air bubbles and channels are thus avoided when the solution is poured in. Some workers place a loose plug of cotton wool or a circle of filter paper at the top of the column in order to protect the solid from disturbance when the liquid is introduced. 

To a 500-ml. round-bottomed flask fitted with a 25- to 30-cm. column packed with glass helices to which is attached a water... 

C. 3-Chloro-2-(chloromethyl)-1-propene. Tris(chloromethyl)acetic acid (205 g, 1.00 mol) is transferred to a 500-mL, two-necked, round-bottomed flask. On top of the powdery acid, which nearly fills the flask, is placed a football magnetic stir bar (1.25 x 0.5 in.). The neck of the flask to be clamped is wrapped well with aluminum foil and is fitted with a glass stopper. A standard taper 24/40 short path still head, to which is attached a Drierite drying tube, is attached at the second neck. The upper flask and short path column are wrapped with aluminum foil, and the flask is immersed in a high temperature oil bath (Note 14) that has been preheated to a stable 210°C. As the solid melts, the reaction mixture becomes yellow, and the oil bath temperature drops (IQ-... 

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