Dr. O’Neal is collecting data on the success of Project 4. After you have isolated your products and finished your analysis, please report your yields and any comments in this data table.
Step 1 Reaction. In a 50 mL round bottom flask, a mixture of benzoylacetone (6.2 mmol), glycine (6.8 mmol) and potassium hydroxide (6.8 mmol) in methanol (5 mL) was refluxed for 1 hour. (Note: Lightly grease the joint between the flask and the condenser. See Reminder #2 below.) After the reflux period, the flask was cooled briefly, then water (15 mL) was added. The mixture was stirred at room temperature to dissolve any solids. The flask was then chilled in an ice-water bath, and the product was precipitated by incremental addition of 3M HCl (~1.5 mL total) until the mixture was strongly acidic to pH paper. Additional water was added if necessary to ensure good mixing. The resulting solid was collected by vacuum filtration, and allowed to dry under vacuum for at least 45 minutes. The mass was recorded, then an IR spectrum and ¹H NMR spectrum (solvent: d6-DMSO) were collected.
Step 2 Reaction. Note: Scale your reaction based on the amount of enamine obtained from Step 1. In a 100 mL round bottom flask, a mixture of the Step 1 enamine product (5.8 mmol), triethylamine (5.4 mL), and acetic anhydride (17 mL) was refluxed for 30 minutes. After the reflux period, the mixture was allowed to cool for 10 minutes before 1:1 methanol:water (50 mL) was added to the flask. The flask was then placed in an ice-water bath and stirred for 30 minutes. The resulting precipitate was collected by vacuum filtration and allowed to dry under vacuum for at least 45 minutes. The product was weighed and fully characterized by IR, GC-MS, and NMR (CDCl3).
Reminders & Hints
1. You must complete the associated prelab quiz before beginning work on each step of this project.
2. Strongly basic conditions can etch glassware and cause joints to stick together. The grease will prevent this from happening in your apparatus. Use a VERY light coating of grease on the condenser joint. At the end of your reaction, use a paper towel to wipe down the condenser joint with acetone to remove the grease.
2. Remember that the NMR sample from the Step 1 Reaction must be dissolved in d6-DMSO rather than the usual CDCl3. You should check here to see where to expect the DMSO peak in your NMR spectrum.