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):
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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.
As reported in lecture this evening, the lab report for this experiment will be due at the “end” of Monday, Nov 16. FYI “end” means before I arrive on Tuesday morning.
I forgot one vital piece of information concerning the lab report: what information needs to be printed out in your NMR spectrum.
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I’m sure you are all familiar with the “placebo effect”, the ability of an inactive substance to produce biological effects. The usual explanation is that the placebo substance activates the patient’s “belief” that a treatment is being received and this belief, somehow, has restorative powers.
The placebo effect is too strong to ignore so when pharmaceutical companies test new drugs they divide the patients into two groups: one that receives the drug and one that receives a look-alike placebo. It isn’t enough for the candidate pill to do something, it must actually be better than the placebo in order to receive FDA approval. The truly amazing thing is that, according to this recent Wired article by Steve Silberman, it appears as if placebos are getting harder and harder to beat.
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The slides for last Friday’s lecture, which covered the last part of Chapter 7 – the stereochemistry of chemical reactions – can be viewed here.
Today’s lecture discussed how to name these classes of compounds: RX, ROH, RSH, ROR, RSR. An important point: the complexity of naming/drawing problems will be limited to compounds containing a single principal group.
Slides for today’s lecture are located here.
Those of you who check the online lab calendar have probably wondered what is an NMR workshop?
Simple. It’s classroom time devoted to studying Loudon, Chapter 13, Nuclear Magnetic Resonance (NMR) Spectroscopy.
The students in each lab session this week will spend 2.5-3 hours working on ChemActivities dealing with Nuclear Magnetic Resonance spectroscopy. This will prepare you to print out and interpret your NMR spectrum of isopentyl acetate in the final hour of the lab session. So, in short, we will be doing classroom work and computer work this week, but no wet lab work.
The Monday and Tuesday lab sections will meet in Rm. 105 at 1:10 PM. The Wednesday lab section will meet in Rm. 301 at 1:30 PM (there will be a Chem 101 conference finishing up around that time so we will wait in the hallway until they are finished). After the classroom work, each lab section will move to the computer lab (Rm. 203) during the final hour of the lab.
One or two students may also need to wrap up work on the synthesis of isopentyl acetate this week. I’d appreciate it if these students would remind me of their situation so the instructors and lab assistants can plan accordingly.
