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Problems Set #5
ATTN: answers to the below questions are due at the start of your lab period of Meeting 5; these answers should be part of your pre-lab write-up.
Announcements (Please carefully because you will held fully responsible):
1. Quiz 2
The second quiz will be administered on Tuesday, January
19, 2016 at 9:00 am covering the ligand and the catalyst synthesis and characterization. Bring a ruler, non-graphing calculator and blue or black pen with you. Please make sure that you arrive on time (you should be seated by
8:55 am!). Late arrivals (even if it is only one minute) will not be allowed to take the quiz, which will result in an automatic zero score for the quiz. If you do not place your name on the quiz to assume authorship, you will receive a zero score as well! You cannot add the name after time was called because this is considered cheating. It is also not allowed to start writing (including writing down your name on the quiz) until you are allowed to do so by the instructor. Failure to follow these rules will result in an immediate dismissal from the quiz resulting in a zero score.
2. In-lab work
Students will only be allowed to attend their own lab section. This means that many of you have to be much better prepared when you come to the lab to get the work done in the allotted time (the lab closes at 5:00 pm and not at 5:30 pm or 6:00 pm!), which is easily possible if you know what you understand what you are doing. If there are questions, you should ask them during office hours. Most students do not have the experience to figure out things on the fly. It is also crucial to maintain focus on what has to be accomplished in a given lab meeting. Some students seem to have serious problems to set the proper priorities i.e., performing the characterization, cleaning glassware, etc. instead of setting up the reaction or the workup of the reaction.
3. Use of resources in the lab
It is in everybody's interest to utilize the resources more efficiently in the lab. This applies in particular to the use of solvents, TLC plates, melt temp, the use of the infrared
and UV-Vis spectrophotometer, etc. If materials are wasted in the beginning of the quarter, the course will run short in these things in the end of the quarter, which means that you will have to run a reaction without being able to monitor it for completion.
4. No Data-sharing
There is no data sharing unless permitted by the instructor. Everybody has to acquire her/his own spectra and data i.e., melting point, optical rotation, infrared spectrum, etc. Students, who share data will be reported to the Dean of Students, because this is considered cheating. This also means that the student name has to be denoted on the infrared spectrum, the UV-Vis spectrum, etc. when the spectrum is acquired. Spectra without proper label are unacceptable and will receive a zero score in the reports.
5. Draft for Report
Make sure that you make progress on your formal report as well in terms of literature research and writing the parts that you completed already in the lab. The draft version of paper is due by
January 22, 2016 at 4:30 pm. The draft version is worth 20 points, the final paper 60 points. For more information what the draft is supposed to contain see here. Late submission will receive less credit. The more of your work you submit in the draft, the more feedback you will get, which will beneficial for the final version. We will try to have the reports available by Monday,
January 25, 2016. The final version of the paper will be due by February
5, 2016 at 4:30 pm.
6. Podcast, Answer Keys and PP-slides for lectures
a. The lecture and the workshop are podcasted (see Bruincast website). The file is uploaded in the afternoon or the following day onto the bruincast website.
b. The instructor posts the answer keys for the homework assignments on the website as well (follow Chem 30CL link, Weekly Assignments)
c. The PP-slides for the lectures are posted on the website as well (follow Chem 30CL link, Lectures)
7. Safety
a. Make sure to be careful when you handle glassware, which applies to the use during a reaction as well as the cleaning. Broken glassware can cause very deep cuts which have often to be stitched up. If chemicals get into the open wound, the wound have to be specially treated and the healing process takes often more time as well.
b. It has come to the attention of the instructor that students pour acetone down the sink. This is entirely unacceptable. If a student will be caught doing this, s/he will receive an automatic zero for the entire lab meeting. Repeat offenders will be dismissed from the course due to safety issues (violation of CAL OSHA rules).
c. Waste has to be placed in the appropriate waste containers and
next to it. This applies to liquid waste and solid waste. If no waste
container is provided or the waste container is full, inform the TA
immediately.
And now to the fun part...the prelab questions that are due in your prelab for
January 19, 2016 and January 20, 2016 (=meeting 5):
1. Referring to the catalyst design, answer the following questions.
a. Which functions does the ligand have in Jacobsen's catalyst?
b. Why are transition metals frequently part of metal-organic catalysts?
c. What is the active specie in the epoxidation? How is it obtained in the experiment in Chem 30CL?
2. Referring to the epoxidation reaction carried out in the lab, answer the following questions.
a. A student uses 0.567 g of 4-acetoxystyrene for the epoxidation. How many grams of catalyst should the student use if the procedure recommends using 4.5 mole % of the catalyst?
b. Why is hexane a poor solvent for the reaction?
c. Why is it important to stir the reaction mixture vigorously?
d. Sketch the TLC plate (SiO2, hexane) for a incomplete reaction showing the alkene in lane 1 and a sample of the reaction mixture in lane 2.
e. Why is it important to optimize the solvent mixture? What is the student looking for here?
f. Why is it
important to work up the reaction mixture as soon as the reaction is
deemed complete?
g. How is crude product stored?
Note: There will be a separate prelab for meeting 6.