General Announcement (Please read since you will be held responsible for the content!)

1. Questions in the course

It has come to my attention that some students are not clear about certain policies in this course. There is no such policy in this lab course which discourages students from asking questions. The reason why you are here is to learn. This should also result in questions from the the student's side, which are welcome by the teaching assistants and the instructor. However, it is expected that the student comes prepared to the lab section in order to be able to complete the experiment in a timely fashion. The majority of the questions regarding the experiment (theory and practical issues) can be answered during lecture or office hours (there are a total of 7 for this class). A question also should demonstrate the student's ability to analyze the problem and be as specific as possible in his/her inquiry. A simple comment like "I don't understand this" is not particularly helpful for the person that you are asking for help since they do not know which part of the topic you are having problems with. Also, please also understand that your TA and instructor have to other responsibilities i.e. conduct research, administrative responsibilities, attend meetings, etc, which means that they are not available 24/7 contrary to many students' believes.

2. Glassware return

One issue that has to be address here is the return of glassware. The lab support usually closes at 5 pm sharp every day. If you do not return the glassware by then, you will not be able to retrieve your student ID. This can become a huge problem if this is your access key to your university apartment and your dinner, which means that you might go on a diet for this evening then or live on fast food. So please make sure to return the glassware clean and on time.

3. Experimental Changes

a. The filtrate from the recrystallization of TPCP should be collected in a separately marked container (not in the regular waste container!). This also means that it is imperative that the filter flask is clean for this filtration!

b. The samples should be dissolved in ethyl acetate instead of dichloromethane when it comes to running the TLC.

4. Safety

a. The glasswaste has to properly disposed of in the blue-white boxes and not in the regular trash! We had problems with waste management in the past quarters, which led to the refusal of the janitors to empty the trash bins because they are afraid that they get injured.

b. Do not pour any organic solvents down the sink. This rule also applies to solvent like acetone.

5. Work shop

The next workshops will take place on April 26, 2010 at 5-5:50 pm in CS 24. It will cover C-NMR spectroscopy.

ATTN: answers to the below questions are due at the start of your lab period; these answers should be part of your pre-lab write-up.

1. Take the online quiz for recrystallization below one hour prior to the 5th meeting.

http://bacher.chem.ucla.edu/TakeQuiz/?id=aab3238922bcc25a6f606eb525ffdc56

In order to take the quiz, you have to go through a UCLA ICP address. This means that you either have to use your Bruin-Online account or go through the VPN (Vitual Private Network, software can be found here: http://www.bol.ucla.edu/services/vpn/) to have this UCLA ICP address.

To log in, use your last name and your student ID. If you are experiencing problems, contact the instructor via email and include your full name (indicated which one is your last name), your student ID, section and TA. (Hint: Think very careful about each response since many of the questions have more than one answer to them! Many students come up with the most obvious one and miss some of the details which leads to a zero score for the question!) Even though you can take the quiz until one hour prior to meeting 2 of your section, you should not delay taking it since there might be some problems with the server or the login. Also, there seem to be problems with MAC systems, Safari and Google Chrome Browser. The best is using IE 7.0 or Firefox. After you submit the answers, your score has to appear on your screen. If this does not happen, you will have to retake the quiz. (There will not be any possibility to retake the quiz weeks later since you are supposed to show preparedness at the point in time when you enter the lab!). The quiz is worth 10 points.

2. Referring to the Aldol reaction carried out in the lab, answer the following questions. Show pertinent balanced chemical equations where appropriate.

a. The procedure emphasizes to use absolute ethanol as solvent. What is this and why is this important?

b. Why should the solution be brought to a gentle reflux prior to the addition of the catalyst?

c. What is used as catalyst in the reaction? What does this catalyst exactly do?

d. Which observations will the student make if the reaction is proceeding according to plan?

e. Why is a solvent mixture used to recrystallize the crude product? Which solvent mixture is used?

f. After boiling the mixture for ten minutes, he is finally able to dissolve the crude. What would he observe afterwards?

g. What is the proper concentration for the UV-Vis spectrum here (Hint: the range from 280-600 nm will be measured here)? What is used as solvent here?

h. The final product is tested with TLC using different solvents. What would you expect observe using the three mobile phases given in the reader?

i. Which solvent is used to dissolve the samples? What is the desirable concentration here?