Question

Help with PreLab questions 1-4

Procedure Esterification Each group will be assigned an unknown alcohol by the instructor. Record the unknown number and then add the contents of the vial (25 mmol of alcohol) to a 50 mL round bottom flask with a stir bar Then add 2.75 mL (approx. 50 mmol) of acetic acid followed by 0.25 mL of concentrated sulfuric acid Add a reflux condenser then reflux the mixture in a sand bath with stirring for one hour. After one hour of heating, turn off the heat (but not the water running through the condenser) and allow the mixture to cool to room temperature. Once cooled to room temperature, you may then turn off the water. Transfer the cooled solution to a separatory funnel and wash it with 25 mL of water. After separating the aqueous layer from the organic layer, wash the organic layer with two successive 25 mL portions of 5% aqueous sodium bicarbonate, swirling the layers together until gas evolution ceases (NOTE: if you shake the separatory funnel vigorously with the cap on the funnel at this juncture, you will build up gas in the funnel and potentially blow the cap off and cause a spill. Remember: PVenRT; if V is constant and n increases, P has to increase since it is directly proportional). Again, make sure that you save the correct layer. Dry the crude ester with magnesium sulfate or sodium sulfat (whichever is provided) and filter the drying agent by gravity filtration. If you have to add a large amourt of drying agent there is a chance that there will be very little liquid present compared to the drying agent, which makes filtration difficult. If this happens, add 5-10 mL of dichloromethane to the solid before filtering. Determination of product Obtain an IR spectrum of the product from your instructor or from SDBS Waste Disposal The aqueous layer from the extraction in the 'Esterification" step can be disposed of in the sink. At the end of lab, your product can be disposed of in the non-halogenated waste Results l. Based on the IR and smell of the compound determine the identity of the ester product. Compare and contrast the IR of the starting material and product and identify the major functional groups that were converted in the reaction. Determine the yield of the reaction. 2. Pre-lab Questions I. What is the purpose of the sulfuric acid? 2. How many equivalents of acetic acid were used relative to alcohol? Wintergreen extract is made of primarily of one ester. What is the name and structure of this este and how could it be synthesized using a Fischer esterification 3. During the extraction if you made isopentyl acetate, which layer is the top and the bottom laye Which layer would you expect the product to be found?

Answer 1

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