Organic 2 Review Problem 80

Organic 2 Review Problem 80 - water is then run out of the...

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6 4 PRACTICAL ORGANIC CHEMISTRY vapour envelopes the bulb of the thermometer for a sufficiently long time to enable the thermometer to register the correct temperature. It is for this reason that the side-arm of the flask proceeds upwards before passing downwards. By this device a "cushion" of vapour can be maintained round the bulb of the thermometer before the required fraction is distilled. Reflux Distillation Unit, The apparatus shown in Fig. 38 is a specially designed distillation-unit that can be used for boiling liquids under reflux, followed by distillation. The unit consists of a vertical water-condenser A, the top of which is fused to the side-arm condenser B. The flask C is attached by a cork to A. This apparatus is particularly suitable for the hydrolysis of esters (p. 99) and anilides (p. 109), on a small scale. For example an ester is heated under reflux with sodium hydroxide solution while water is passed through the vertical condenser;
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Unformatted text preview: water is then run out of the vertical condenser and passed through the inclined condenser. The rate of heating is increased and any volatile product will then distil over. Fractional Distillation. Fractional distillation on a semi-micro scale can be carried out satisfactorily with the fractionating column shown in Fig. 39. The column is 10 cm. long and is filled with pieces IOcm. to Pump FIG. 39. FIG. 40. (3-4 mm. long) of very narrow glass tubing. As in all fractionations the distillation must be carried out very slowly and in this connection, particular use is made of the ''upward" bend of the side-arm so as to record the maximum temperature of the issuing vapour. The apparatus shown in Fig. 38 can also be used for fractionation by placing a secure plug of glass wool at the base of the vertical con-denser and then filling it with short pieces of glass tubing....
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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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