Lab performed: 1/22/15 Chem 2203-012
Report due: 1/29/15
TA: Kavitha Akula
Experiment 4A: Determination of a Partition Coefficient for Benzoic Acid in Methylene Chloride and Water, and Experiment 4B: Solvent Extraction I: Acid-Base Extraction Using the System Benzoic Acid, Methylene Chloride, and Sodium Bicarbonate Solution
The purpose of this experiment is to familiarize oneself with the general procedures determining a partition coefficient at the microscale level and learn in weighing milligram quantities of materials on an electronic balance, the use of automatic pipets, the use of transfer pipet, and the use of a vortex mixer. Also, to familiarize oneself with extraction technique in which a reversible reaction is employed to alter the solubility characteristics of the substance of interest.
Experiments 4A and 4B were followed as described in Mayo, pages 144-147, with the modifications listed in the Blackboard document. Additional modifications to the procedure included the following: The amount of benzoic acid was 76 mg for experiment 4A and 74 mg for experiment 4B instead of 75 mg for both experiments.
Data and Results
Data and Results Table
Benzoid acid Initial
10% NaHCO3 solution (mL)
Benzoid Acid in CH2Cl2 (mg)
Benzoic acid in remaining aqueous (mg)
KpCH2Cl2/aq. NaHCO3 *
*Note that for Experiment 4B, this calculation does not provide a true partition coefficient because benzoic acid is chemically modified in the procedure. The value is still useful for illustrating the distribution of benzoic acid and its derivatives between the two phases.
After dissolving benzoic acid in 1.0mL CH2Cl2 and 1.0mL H2O, two layers are created, the top layer is H2O and...
Cited: 1. Mayo, D. W.; Pike, R. M.; Forbes, D. C. Microscale Organic Laboratory with Multistep and Multiscale Syntheses, 5th ed.; John Wiley & Sons, Inc., 2011; pp 141-147.
2. Modifications for Expts 4A and 4B: Partition Coefficient Determination and Solvent Extraction I, Blackboard document.
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