Buchner flask

This type of filtration is almost invariably performed with the aid of a Buchner flask and funnel, by means of which a rapid and almost complete separation can be obtained. The Buchner flask A (Fig. 4) consists of a simple thick-walled conical flask with a short side-arm for connection to a water-pump. Into the neck of the flask is fitted the Buchner funnel B which consists usually of a cylindrical porcelain funnel, the bed of which is pierced by a... 

In place of the conical flask G, a small Buchner flask may be used with the calcium chloride tube fitted to the side-arm, but in either case a duplicate flask for the second fraction should be available. 

Fit securely to the lower end of the condenser (as a receiver) a Buchner flask, the side-tube carrying a piece of rubber tubing which falls well below the level of the bench. Steam-distil the ethereal mixture for about 30 minutes discard the distillate, which contains the ether, possibly a trace of unchanged ethyl benzoate, and also any biphenyl, CeHs CgHs, which has been formed. The residue in the flask contains the triphenyl carbinol, which solidifies when the liquid is cooled. Filter this residual product at the pump, wash the triphenyl-carbinol thoroughly with water, drain, and then dry by pressing between several layers of thick drying-paper. Yield of crude dry product, 8 g. The triphenyl-carbinol can be recrystallised from methylated spirit (yield, 6 g.), or, if quite dry, from benzene, and so obtained as colourless crystals, m.p. 162. ... 

Cool the flask in ice-water and pour the ethereal solution into a mixture of about 6 ml. of dil. H2SO4 and 10 g. of crushed ice contained in a 50 ml. flask fitted for steam-distillation, taking care to leave behind any unchanged magnesium. Fit to the lower end of the condenser a small Buchner flask or boiling-tube with side-arm (45°) carrying a piece of rubber tubing which falls well below the level of the bench. 

The technique of the filtration of hot solutions has already been described in Section 11,28. The filtration of cold solutions will now be considered this operation is usually carried out when it is desired to separate a crystalline solid from the mother liquor in which it is suspended. When substantial quantities of a solid are to be handled, a Buchner funnel of convenient size is employed. The ordinary Buchner fimnel (Fig. 11,1, 7, a) consists of a cylindrical porcelain funnel carrying a fixed, flat, perforated porcelain plate. It is fitted by means of a rubber stopper or a good cork into the neck of a thick-walled filtering flask (also termed filter flask, Buchner flask or suction flask) (Fig. 11,1, 7, c), which is connected by means of thick-walled rubber tubing (rubber pressure tubing) to a similar flask or safety bottle, and the latter is attached by rubber pressure tubing to a filter pump the safety bottle or trap is essential since a sudden fall in water pressure may result in the water sucking back. The use of suction renders rapid filtration possihle... 

Charcoal is generally satisfactorily activated by heating gently to red heat in a crucible or quartz beaker in a muffle furnace, finally allowing to cool under an inert atmosphere in a desiccator. Good commercial activated charcoal is made from wood, e.g. Norit (from Birch wood), Darco and Nuchar. If the cost is important then the cheaper animal charcoal (bone charcoal) can be used. However, this charcoal contains calcium phosphate and other calcium salts and cannot be used with acidic materials. In this case the charcoal is boiled with dilute hydrochloric acid (1 1 by volume) for 2-3h, diluted with distilled water and filtered through a fine grade paper on a Buchner flask, washed with distilled water until the filtrate is almost neutral, and dried first in air then in a vacuum, and activated as above. To improve the porosity, charcoal columns are usually prepared in admixture with diatomaceous earth. 

M sodium hydroxide solution terf-butylmethylether (TBME, 100 mL) anhydrous magnesium sulfate two 100 mL round-bottomed flasks two magnetic stirring hotplates one Buchner flask, 100 mL one Buchner funnel one 100 mL separating funnel rotary evaporator. 

Remove both the Suba-Seal and polythene cap and place the filter tube in the rubber cone adapter (42 x 27 mm) used with the adapter funnel attached to the Buchner flask, or other suitable device. Wash any particles from the polythene cap into the filter tube, apply just sufficient suction to remove the gamanase-cellulase solution, then wash the residual undigested fibre with hot distilled water (approximately 80°C). Finally wash well with acetone, leave to air dry in a fume cupboard, and when no smell of acetone can be detected, dry in an oven overnight at 100°C ( 2°C). Cool in a desiccator and weigh the filter tube plus residue. 

Magnetic stirrer plate 200 mL separating funnel Two 200 mL Erlenmeyer flasks Buchner funnel, diameter 4 cm 250 mL Buchner flask Filter paper... 

Dry ice-acetone bath Two Buchner funnels, diameter 2 cm Two lOOmL Buchner flasks Filter paper... 

Hydrogen pressure autoclave, 15mL One glass sintered funnel One Buchner flask, 50 mL... 

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