In a round bottom flask, the alcohol (5 mmol) was dissolved in acetonitrile (5 mL). The following reagents were then added sequentially: aqueous pH 7.0 buffer (1.2 mL), 2,2,2,6-tetramethylpiperidin-1-oxyl (TEMPO) (0.5 mmol), and iodobenzene diacetate (IBD) (5.5 mmol). The reaction was stirred at room temperature, and progress was monitored at 10 minute intervals by TLC (8:2 hexane:ethyl acetate). When the reaction was complete, ethanol (20 mL) and saturated sodium bisulfite (5 ml) were added. The flask was placed in an ice-water bath, and the mixture was stirred for 30 minutes. Ethyl acetate (20 mL) was then added to the reaction mixture, and the solid was collected by vacuum filtration and washed well with additional ethyl acetate. UDPDATE: STOP HERE AND USE THE PROCEDURE DESCRIBED BELOW. The solid was then transferred to a 100 mL RBF and dissolved in water (50 mL). Acetaldehyde (125 mmol) and ethyl acetate (25 mL) were added, and the mixture was stirred vigorously at room temperature for 30 minutes. The aqueous and organic layers were then separated. The aqueous layer was extracted with ethyl acetate (2 x 25 mL). The combined organic layers were washed with brine, dried over sodium sulfate, filtered, and concentrated by rotary evaporation. The resulting product was characterized by IR, GC-MS, and NMR.
UPDATE 2/23/22: Our acetaldehyde has become contaminated. As a result, DO NOT use the acetaldehyde method to regenerate your product from the solid derivative. Instead, follow the procedure below exactly (no scaling required):
The solid derivative was transferred to a 100 mL round bottom flask and dissolved in water (20 mL). Ethyl acetate (10 mL) was added to the flask, and the mixture was refluxed for 30 minutes. After cooling slightly, the mixture was poured into a separatory funnel, and the layers were separated. The aqueous layer was extracted with ethyl acetate (2 x 10 mL). The combined organic layers were washed with brine, dried over sodium sulfate, filtered, and concentrated by rotary evaporation. The resulting product was characterized by IR, GC-MS, and NMR.
Reminders & Hints
1. Remember that you are NOT performing this procedure as written. You must apply the procedure to your assigned alcohol (geraniol or nerol) and scale the quantities used in the reaction so that your theoretical yield is 0.310 grams.
2. You must complete the Project 3A Prelab Quiz before entering the lab to perform this procedure.
3. Recall that “washing” is the same as a liquid-liquid extraction. The term is applied when the desired substance is NOT expected to migrate into the solution being added (e.g., brine). So, you add the solution (e.g. brine), mix the two layers, allow the layers to separate, and drain away the undesired solution.
4. Don’t forget that you need to determine the mass of your final product. Pre-weigh the round-bottom flask before the final rotary evaporation step to simplify this measurement!