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Organic Chemistry Lab 315 Fall, 2014 Note that the reading for this experiment is Technique 12. The experiment (Extraction of Caffeine) is in the Manual. DUE DATES Today At beginning of lab – Identification of an Unknown Report Problem #1, Part II, Spectroscopy Problem Set At end of lab -- copy of laboratory notebook pages for todays experiment (do not turn in your pre-lab notes or in-class notes) Next Week Part II, #2 Spectroscopy Problem Set Extraction of Caffeine Report Report Notes – Last Week Pay attention to significant figures in calculations. Properly labeled vial example in Pavia (page number was written on the blackboard). It must include the melting point range – you always report ranges (and it is an indication of purity). In Lab Today Learn the new technique of extraction Drying organic solvents (See p. 697 in Pavia) Experiment Notes Beaker containing dissolved caffeine and insoluble binder Funnel with glass wool as filter Separatory funnel supported on iron ring on ring stand Stopcock closed Beaker underneath “just in case” Experiment Notes Beaker containing dissolved caffeine and insoluble binder Funnel with glass wool as filter Separatory funnel supported on iron ring on ring stand Stopcock closed Beaker underneath “just in case” Separatory funnel with stopper Aqueous layer on top Methylene chloride layer on bottom (contains caffeine) Drain off CH2Cl2 bottom layer into beaker Total 3 extractions (8 ml x 3) Experiment Notes Extractions in a Separatory funnel Add liquids using a glass funnel in order to not contaminate the neck of the sep. funnel. After replacing the stopper, turn the sep. funnel upside down to vent. Repeat if audible gas escapes. Shake/swirl gently, but thoroughly, to mix the immiscible liquid phases. Emulsion may form in this experiment. Caffeine is in the bottom CH2Cl2 layer. Drain bottom layer through stopcock into 100 ml beaker. [This is one extraction.] Add additional CH2Cl2 (using glass funnel) f