Problems Set (Meeting 9)
Announcements
1. The next quiz (= quiz 4) will be administered on February 4, 2009 at 8 am and will cover step 1 and step 2 of the Lidocaine project. Make sure that you are in the room by 7:55 am! Last week, three students were late for the quiz and therefore not allowed to take it.
2. The final paper will be due on Friday February 13, 2009 at 5 pm in YH 3077E as hardcopy. Late papers will receive 10% off per day late including the weekend. The papers have to be submitted online to www.turnitin.com by Monday, February 16, 2009 at 10 pm. The course ID is "2596847" for Winter 2009 and the password is "Chem30CL".
3. You should finish the first two steps of the lidocaine project on the first day of the project.
4. The instrumentation room in the first floor (YH 1102) should be left in proper conditions. Lately, there has been an increasing mess i.e. Kim wipes all over the place, unclaimed solutions and glassware, etc. In addition, students do not seem to feel that it is necessary to wear goggles in this room, which is not acceptable either. Please keep in mind that you are still handling chemicals!
Questions:
1. Referring to the conversion of 2,6-dimethylnitrobenzene to 2,6-dimethylaniline (step 1), answer the following questions. Show pertinent chemical equations where appropriate.
a. Why is 3M hydrochloric acid not suitable for this reaction?
b. What is the function of glacial acetic acid here?
c. How many equivalents of SnCl2 are required to perform the reaction?
d. The initial reaction affords a white solid. Identify the salt.
e. In the second part of the reaction a solution of the salt from d. is reacted with concentrated potassium hydroxide solution. Which purpose does this serve?
f. Student X attempts to dissolve the salt, but seems to have a lot of problems to do so. What is the problem and how should he proceed?
g. How is the final product isolated after the drying step? Why is this technique used?
h. How does the final product appear?
2. Referring to the conversion of 2,6-dimethylaniline to a-chloro-2,6-dimethylacetanilide (step 2), answer the following questions. Show a pertinent chemical equations where appropriate.
a. Why is glacial acetic acid used as solvent in this reaction?
b. Why does the amide precipitate upon the addition of sodium acetate solution?
c. Why has the product to be dried very thoroughly before moving on to the next step?.