Organic 2 Review Problem 84

Organic 2 Review Problem 84 - vacuum apparatus (Fig. 48(A))...

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68 PRACTICAL ORGANIC CHEMISTRY cylindrical tube T (Fig. 47) furnished with a filter-plate or sinter. The tube T can be fitted into an adaptor B (Fig. 47), or it may be inserted directly through the disc D (Fig. 45) so that the filtrate collects in a suitable tube placed in the receiver A (Fig. 45). Adaptors such as B (Fig. 47) are of considerable use in many kinds of micro-chemical work. 12 cm. Mem. FIG. 45. FIG. 46. FIG. 47. Drying of crystals. Whenever possible crystals should be dried in a small vacuum desiccator containing a suitable desiccant. The latter depends upon the nature of the solvent used (cf. p. 19). However for most purposes anhydrous calcium chloride is satisfactory. If a hydrocarbon has been used in the recrystallisation, a few thin fresh shavings of paraffin wax are efficacious. For more efficient drying at elevated temperatures, the
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Unformatted text preview: vacuum apparatus (Fig. 48(A)) is often used. The sample to be dried is placed in an inner tube surrounded by a heating jacket. The latter is connected above to a water-condenser and below to a flask which contains a liquid of appropriate boiling-point. The inner tube is connected to a water- pump. A more satisfactory 'pistol' (Fig. 48(6)) consists of a wide glass tube A closed at each end by ground-glass caps. The tube is fitted with a two-way tap, so that B can be used for evacuating the tube, and the capillary tube C for the subsequent re-entrance of air. The boat D contains the drying-agent (e.g., P 4 O 10 ), and a pad of glass-wool E is held in position as shown. The material to be dried (usually in an open specimen tube) is placed in the smaller boat F. Air should be FIG....
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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