For this assignment, the target compound that you should synthesize is methyl-2-methyl-3- oxobutanoate. This is a crossed carbonyl addition variation. Examine the product and determine which ester is the nucleophile and which is the electrophile. Keep in mind the mechanism and that you need to acidify the intermediate in order to isolate a neutral product. Synthesis Procedures
1. Start Virtual ChemLab and select Claisen Condensation --3 from the list of assignments in the electronic workbook. After entering the organic laboratory, go to the stockroom by clicking inside the Stockroom window. Next, select a round bottom flask and place it on the cork ring on the stockroom counter. Using the available reagents on the stockroom shelf, identify the appropriate starting materials required to synthesize the target compound and add them to the round bottom flask. Select the appropriate solvent and click on the green Return to Lab arrow to return to the laboratory.
2. The round bottom flask containing the starting materials should now be on the stir plate. Click on the handle located in the upper right corner of the laboratory to pull down the TV. The TV should already be in Tutorial mode and the starting materials and solvent should be listed. From the group of reagents found on the lab bench, select the correct reagent to synthesize the target compound and add it to the flask on the stir plate. Now attach the heater, condenser, and N2 gas to the round bottom flask so the reaction mixture can be heated.
3. Start the reaction by clicking on the Stir button on the front of the stir plate. You should be able to observe the reaction mixture stirring in the flask. Monitor the progress of the reaction using TLC measurements as necessary until the product has formed and the starting materials have been consumed. You can advance the laboratory time using the clock on the wall. With the electronic lab book open (click on the lab book on the lab bench), you can also save your TLC plates by clicking Save on the TLC window.
4. When the reaction is complete, "work up your reaction by first dragging and dropping the separatory funnel (located in a drawer) on the flask and then adding H2O to the funnel. Extract the organic layer in the funnel by clicking on the top layer and dragging it to the cork ring on the lab bench. Your target compound should now be in this flask. List the starting materials, solvent, reagent, and products formed: How long did it take to finish the reaction?