- 1 2 Pts 4 8 Grams Of A Compound Containing Mithril Is Dissolved In 60 Ml Of Water The Partition Coefficient For The 1 (89.59 KiB) Viewed 46 times
- 1 2 Pts 4 8 Grams Of A Compound Containing Mithril Is Dissolved In 60 Ml Of Water The Partition Coefficient For The 2 (56.39 KiB) Viewed 46 times
1. (2 pts) 4.8 grams of a compound containing mithril is dissolved in 60 mL of water. The partition coefficient for the compound between dichloromethane and water is 5.2. a) How much of this compound will be in the dichloromethane if you extract it from the water one time with 60 mL of dichloromethane? 4 b) How much of this compound will be in the dichloromethane if you extract it from the water with three successive extractions using 20 mL of dichloromethane each time, and then combine the dichloromethane extracts? 2. (1 pt) Imagine you want to crystallize 2.5 grams of the compound from the above question using boiling water. The solubility of this compound is 17 g per 100 mL in boiling water and 1.4 g per 100 mL in water at 0 °C. a) What volume of boiling water is needed to dissolve the 2.5 g of this compound? b) How much of this compound will crystallize after cooling to 0 °C? 3. (1 pt) It is usually desirable to minimize the number of transfer steps while conducting an extraction. For extracting an organic compound from an aqueous solution to an organic solvent, what solvent(s) diethyl ether, dichloromethane, ethanol or hexane would require fewer transfers? Briefly explain your answer. (1 pt) Why do we wash organic layer with sodium bicarbonate solution? What precautions need to be observed when using aqueous sodium bicarbonate? 5. (1 pt) In the course of a synthesis of an important antibiotic, an impure solid was obtained as one of the intermediates. The solubility of this material in various solvents is shown below. Which of the solvents below would be the most suitable for recrystallization of the impure solid? Explain your reasoning. Cold Hot Water Insoluble Slightly soluble Ethanol Soluble Soluble Toluene Insoluble Soluble Petroleum Ether Insoluble Insoluble 2-Butanone Soluble Soluble Acetic Acid Slightly soluble Soluble
6. (1 pt) A student used benzene to recrystallize a compound. As the hot solution cooled to room temperature, very few crystals appeared. The flask was then placed in an ice-water bath. Suddenly a large amount of solid material appeared in the flask. Then, the student filtered the solid with vacuum, but only a few crystals remained on the filter paper. Explain these results. 7. (1 pt) Calculate the Ken for the following reaction from the pK,'s given. Will this reaction take place as written? Explain. CH₂ + H₂CH pk = 24 NH₂ CH3 OCH₂ 4-methoxyaniline 8. (2 pts) Provide a flowchart (analogous to the one in your lab manual, p. 81) for separating a diethyl ether solution containing 4-methoxyaniline, benzoic acid, and benzophenone. Draw the structures where necessary and marked what layer your final products are in pk = 41.2 +H3C C OH benzoic acid ob benzophenone