Chem 201 - 202

Lab continues to meet this week as normally scheduled.

Lab lecture on Thursday night, Nov 19, is cancelled.

The only lab operations scheduled for the following week, M-W, Nov 23-25, are wrapping up the acetylferrocene experiment. If students are unable to finish this experiment this week, they can perform any and all operations -- run the reaction, separate the compounds on a column, analyze the results by TLC, measure melting points, or make NMR samples for us -- they can do that next week during the scheduled lab periods.

Special request - my lab assistants will be in the lab starting at 1:10 PM. I will let them leave the lab, however, if no students show up by 1:30 PM. So please come on time. If you need to make up lab work, but can't get to the lab until after 1:30, please send me an email now so that I can pass this info along to my lab assistants. Thanks

I will answer your questions on the material in chapters 1-9 on Tuesday, 6-7 PM, in Eliot 314.

By the way, I will be running for the door immediately afterwards to make it to an off-campus appointment at 7:30 so please don't wait until afterwards to ask special questions.

I just noticed that the Registrar's Office has posted dates and times for final exams. The final exam in this class will start at 6 PM on Tuesday, Dec 15 in the Psych auditorium and adjoining rooms. You can download the complete final exam schedule here.

The images and data table for the three SN2 transition states shown in lecture today can be viewed here.

Since no strong objections were raised to the schedule changes that I had proposed, I have made the following changes for the upcoming exam, homework and classes (all of the appropriate online schedules have been updated to reflect these chanes):

Exam #3 - Thursday, Nov 19, in conference. Please attend conference at your normal time and location. Bring a model kit. Keep in mind that some students may have already taken the exam or will be taking the exam later than you, so please do not blurt out anything about the exam and do not discuss the exam publicly until 2 PM.

HW #6 - out late Monday, Nov 9; due Monday, Nov 16, noon; returned Wednesday, Nov 18, 9 AM.

Syllabus - I am gaining an extra lecture day on Monday, Nov 16 and this will affect the lecture schedule for the rest of the term. I will start lecturing on Chapter 10 on Monday, Nov 16. There will be two additional lectures on Chapter 10 on Wednesday, Nov 18 (note that these first two lectures are coming before exam #3) and on Friday, Nov 20. There will also be a lab lecture on Thursday, Nov 19.

First, if you would like to see the MO pictures that I used in class today, check out last year's post on back side attack & HOMO-LUMO overlap (Oct 13, 2008).

There are also a couple of points that I want to add concerning reaction rates (kinetics):

I've been looking over Chapter #9 and the schedule for the next two weeks and I'm kicking around two options in my mind.

Option #1
Exam #3 would still be on Monday, November 16. However, if the exam were to be held on this day, I would abbreviate the exam's coverage of chapter 9 topics slightly (and these topics would appear on the final exam instead). The "abbreviated" exam would not include sections 9.6-9.8, but would include 9.1-9.5 which is the bulk of the chapter.

Option #2
Exam #3 would be moved to Thursday, November 19, i.e., you would take the exam during your conference hour and in your conference room. The exam would cover all of Chapter 9 right through section 9.8. To support this, the next homework assignment would also cover all of chapter 9 and the due date would be extended. Monday, November 16 would just be a normal lecture (finishing chapter 9?, starting Chapter 10).

Frankly, option #2 is a much more sensible way to proceed (but it has never occurred to me before to use conference time in this way). I would like to follow option #2, but because this is a major schedule change, I would like to consult with the class first. Please let me know ASAP if you have any objections to option #2.

Pity (or envy) poor Alice. In one book she falls down a rabbit hole. When she gets to her feet, she finds bits of food that demand to be eaten ("Eat me!"). And in the next book she steps through a looking glass only to find everything reversed. What is a girl to do?

Well, one thing scientists have always thought is that Alice should not eat any food while she visits the looking-glass universe. All of the protein in Alice's body is built from single enantiomers of chiral amino acids. This means these proteins, including her digestive enzymes, exist as single enantiomers, and they wouldn't be able to digest the mirror-image proteins that get cooked in a looking-glass kitchen. Worse, if she did eat looking-glass food, she might get a terrible stomach ache, and would definitely starve. According to the traditional view, there just isn't any biological value in looking-glass amino acids. A new study, however, turns this view on its head. If you would like to read about this, check out "Expanding Functionality Within the Looking-Glass Universe" (News Perspective, Science, 18 September 2009, 325, 1505-1506).

Slides from today's lecture can be viewed here.

Correction: I was gently informed after lecture that I was wrong about the behavior of CH3CN (acetonitrile) and water. They do mix. I had said they don't. In fact, mixtures of these solvents are routinely used as a solvent mixture for HPLC, a form of chromatography that is closely related to the procedure we will be using in lab next week. My mistake.

I didn't use PowerPoint on Wednesday, but I did show potential maps of several simple molecules that represent the functional groups covered in chapter 8. Slides of these potential maps can be viewed here.