last updated Thursday, February 06, 2014

Problem set  Meeting 11 

Announcement

1. Quiz 5

Quiz 5 will be administered on Tuesday, February 11, 2014 at 9 am. It will cover the entire lidocaine project. Let's hope that the results will be much better than in the previous one :-)

2. Lidocaine Project

a. The postlab report for the lidocaine project has to be written in the lab notebook and submitted to the teaching assistant. The due dates are February 13, 2014 or February 14, 2014 in your regular lab section. The report has to be written in the lab notebook and is worth 15 points.

3. Grignard Project

a. The Grignard project will start on February 11, 2014.

b.The instructor will provide an in-lab demonstration of the Grignard setup (setup, heating, etc.) on Monday, February 10, 2014 at 4:00 pm in YH 6086. Attendance in this demonstration is voluntary (no credit) and is highly advisable for students that feel intimidated by the larger setup. Part of the demonstation will already discussed in lecture prior to this in-lab demo, but certain aspects like heating cannot be shown in the lecture.

4. Research project (Week 9)

a. Please look start looking for a partner for the Ferrocene project. Your partner should be in a different time slot than yourself i.e., if you are in the T/R afternoon section, you will have to find somebody in the W/F afternoon section. This way nobody has to put in additional time outside their regular schedule, which means that each group has four lab meetings to complete the project. We have to avoid as much as possible to have the entire class running around in the lab (Safety!).

...and now back to the chemistry part of this course....the homework questions due on 2/11/2014 or 2/12/2014

1. Referring to the Grignard reaction, answer the following questions. Show chemical equations when appropriate.

a. The presence of water poses a significant problem in this reaction. Provide three sources of water in the reaction.

b. How does the student know that the reaction initiated?

c. How can the student initiate the reaction in case it does not initiate on its own?

c. Why is it important to add the ethereal bromobenzene solution at the proper rate? What is the student looking for here?

d. Why is it important to use a large beaker when reacting the Grignard solution with the dry ice?

e. After the mixture obtained in d., was allowed to warm up, chipped ice and concentrated sulfuric acid are added. Which purpose does this step serve?

f. The combined organic layers are extracted with sodium hydroxide solution.Which layer contains the product then? In which form?

g. Why is it important to dry the benzoic acid very thoroughly?

h. The ¹H-NMR spectrum of the product displays a signal at d=12.1 ppm (in CDCl₃) for the acidic proton. Rationalize this location.