Problems Set - Meeting #6

General:

Since there were several inquiries about how to study for the final exam, here are a few pointers:

1. Make sure that you understand the procedures carried out in the lab well. This does not mean that you have to memorize the exact amounts added at some point, but why certain steps are performed and how they are performed correctly (see lecture, workshop and Survival Kit reader). If things are not clear to you, make sure to ask questions (TA, instructor, etc.) asap and not the day before the exam.

2. The exams in the exam reader (the light green thing that you paid for when you bought in the package and have not looked at up to this point) give you a good idea about the subjects that you are expected to master by the end of this course. However, memorizing the answers to the questions does not guarantee a higher grade in the final since there are always changes in the questions.

3. One of the most important things is to write your own prelab and postlabs, and not just copy it from a friend/roommate/etc and include your own numbers. You are not learning anything this way and most likely fail the exam miserably, which also means that you are automatically going to fail the course.

4. Finally, make sure that you take enough time aside to study for the final exam. A lot of the students that failed the exam in the past quarters just did not spent enough time to review the material and tried to "wing" the exam, not very successfully as mentioned earlier in the quarter already.

Bottomline: If you do your own work and understand reasonably well what you are doing in the lab, you should not have any problems to get a passing (and decent) grade in the course. Please keep in mind that many of you are going on to take the MCAT, DAT, PSAT, GRE, etc. and some of the material covered in this course will show up there as well.

And now to something entirely different.....the homework questions:

1. Theory of Diels-Alder Reactions

a. Diels-Alder reactions are considered stereoselective. What does this mean? Give an example other than the one shown in the reader.

b. Why is a reaction of cyclopentadiene with maleic anhydride faster than the reaction of ethene with butadiene?

2. After reviewing the TLC chapter in the reader, take the online quiz (http://bacher.chem.ucla.edu/TakeQuiz/?id=d3d9446802a44259755d38e6d163e820). The quiz is worth 10 points, and has to be taken until one hour prior to the in-lab meeting 6.

3. Referring to the reaction carried out in the lab, answer the following questions.

a. What is the function of benzyne in the reaction and how is it obtained?

b. Why is 1,2-dimethoxyethane used in the reaction?

c. Why is it imperative that the isoamyl nitrite solution is added slowly?

d. Which observation is the student going to make throughout the reaction?

e. The final product exhibits a double-melting point. How can this observation be rationalized?

f. What is the proper concentration for the UV-Vis measurement for TPN? Which solvent is used here?