1. General

Make sure that you work on your final version of the report for the epoxidation project. If you have any questions, please stop by in my office asap. The final version of the paper is due on Friday, April 29, 2011 at 4:30 pm. Late papers will receive a 10% deduction per day. Make also sure that you don't forget to submit the electronic version for the final version (not for the draft!) online at www.turnitin.com (CourseID: 3878382, Password: Chem30CL, (case sensitive!)) by February 29, 2011 at 10:00 pm). Late online submission will also receive point deduction. If you do not have an account there, you will have to open one first before you can enroll in the class and submit your paper.

2. Experimental

Step 1 and step 2 have to be completed during the first meeting so that the anilide has enough time to dry. If the amide is wet, the formation of the final product (=lidocaine) does not work well!

Step 1: Formation of 2,6-Xylidine

It is crucial that concentrated hydrochloric acid is used to dissolve SnCl₂. If water or dilute hydrochloric acid were used, basic tin salts would precipitate which are not serving as a reducing reagent anymore. The nitro compound is dissolved in glacial acetic acid. Both solvents are used as proton source in the reaction which requires seven protons for each molecule of nitro compound being reduced.

The initial precipitate is filtered and not rinsed with water. Why? It is dissolved in a minimum amount of water, and then 8 M KOH is added until the solution is strongly basic. The mixture is allowed to cool to room temperature before it is extracted with diethyl ether (Hint: You can use an ice bath to speed up the cooling process!). A significant pressure will build up in the separatory funnel if the solution is extracted with diethyl ether while warm.

The use of an excessive amount of drying agent (K₂CO₃) has to be avoided. Also, it has to be removed prior to the distillation! Why?

The setup for the distillation should look like below.

The distillation setup consists of a 100 mL round-bottomed flask (containing the solution), a three-way adapter, a water-jacketed condenser, a vacuum adapter and a round-bottom flask to collect the liquid (=solvent here) that condenses. It is important that the connection of the three-way adapter with the water-jacketed condenser is tight in order to prevent a fire! The water supply (inlet) is connected on the bottom (lower) end, while the outlet goes either back to the sink or to the inlet of another condenser. Make sure that you have an opening at the end of your setup to release the pressure that will build up when you start to heat. Before you start, let the TA check on the setup.

Step 2:Formation of the Chloroanilide

Glacial acidic acid is used as a solvent here again. Why?

The bottle containing the a-chloroacetyl chloride has to be closed when not needed. Why?

After the reaction is completed, a dilute solution of sodium acetate is added. Why?

The obtained product has to be dried thoroughly. Why?