Chemistry 30A3 Fall 2011 Labs Dr. Troendle 66

Chemistry 30A3 Fall 2011 Labs Dr. Troendle 66 - the top is...

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Chemical Biology 3OA3, September 2009 Page 66 Note that the apparatus is clamped at the condenser rather than at the flask, as one would do for a macroscale experiment using conventional ground- glass joint glassware. The apparatus can be clamped in this way because of the screw-cap connection between the condenser and reaction vial, which prevents the connection from falling apart. Heating is provided by a sandbath atop a magnetic stirrer/heater. A thermometer should be clamped in contact with the sand so as to allow monitoring of the bath temperature. The bath contains slightly more than 1 cm of sand - it is important to have enough to ensure good thermal contact with the reaction vial, but not so much that it is difficult to see the contents. Extractions In microscale experiments, the conical reaction vial is the glassware item used for extractions. The two immiscible liquid layers are placed in the vial, and
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Unformatted text preview: the top is sealed with a cap and a Teflon insert (with the Teflon side toward the inside of the vial). The vial is shaken to provide thorough mixing between the two liquid phases. As the shaking continues, the vial is vented periodically by loosening the cap and then tightening it again. After about 5-10 seconds of shaking, the cap is loosened to vent the vial, retightened, and the vial is allowed to stand upright in a beaker until the two liquid layers separate completely. Two basic procedures are possible, depending on whether the solvent being used to extract the desired product is heavier or lighter than water. Method A is employed for extractions where the lower layer is a heavy solvent such as dichloromethane . Method B is employed for extraction with a solvent which is lighter than water, such as diethyl ether ....
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