Chem 201 - 202tag:blogs.reed.edu,2008-08-01:/chem201202//1252009-11-17T19:26:30ZOrganic Chemistry, 2009-2010Movable Type Open Source 4.2rc2-enLab schedule Th & next weektag:blogs.reed.edu,2009:/chem201202//125.4912009-11-17T19:20:09Z2009-11-17T19:26:30ZLab 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...Alan Shusterman 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 ]]>
Q&A session for Exam #3tag:blogs.reed.edu,2009:/chem201202//125.4902009-11-16T22:00:57Z2009-11-16T22:20:31ZI 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...Alan Shusterman
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. ]]>
Final exam '09 date/time settag:blogs.reed.edu,2009:/chem201202//125.4892009-11-14T01:10:07Z2009-11-14T01:12:34ZI 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...Alan Shustermanhere. ]]>
What does SN2 transition state look like?tag:blogs.reed.edu,2009:/chem201202//125.4872009-11-11T19:18:19Z2009-11-11T19:19:49ZThe images and data table for the three SN2 transition states shown in lecture today can be viewed here....Alan Shustermanhere. ]]>
Schedule changes: Exam #3, HW #6, Syllabustag:blogs.reed.edu,2009:/chem201202//125.4862009-11-09T22:47:27Z2009-11-09T23:08:27ZSince 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...Alan Shusterman 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. ]]>
SN2 kinetics and geometrytag:blogs.reed.edu,2009:/chem201202//125.4852009-11-09T18:10:30Z2009-11-09T22:24:52ZAlan Shustermanback side attack & HOMO-LUMO overlap (Oct 13, 2008).
There are also a couple of points that I want to add concerning reaction rates (kinetics): ]]>
Carefully read section 9.3, Reaction Rates. I couldn't find a convenient way to fit this material into lecture, but it is vitally important. Now for some specific points:
#1 - We usually compare competing reactions by comparing their rate constants.
Loudon says this is legitimate when the competing reactions are both
performed under "standard conditions" and he's right. It is also a fair comparison when
the rate laws for the competing reactions are the same, i.e., they
differ only in the numerical values of their respective rate constants. When this condition is satisfied,
we don't have to be limited to standard conditions.
#2 - The lifetime of a species is inversely related to the rate
constant for its disappearance. A large rate constant (for
disappearing) means a short life. This also means that the "time to
completion" for a chemical reaction is inversely related to the rate
constant for the reaction. A large rate constant means a short time to
completion.
#3 - The ratio between two rate constants is exponentially
related to the difference in their activation energies. See equations
9.22. Also compare data in different columns of Table 9.2. Reactions
that have "time to completion" of 12 minutes, 20 hours, and 83 days
have nearly the same free energies of activation. The exponential
relationship makes this possible.
#4 - (see
section 9.4B) Acid-base reactions happen much, much faster than SN2
reactions (and much, much faster than just about any other kind of
organic reaction). A mechanistic hypothesis can't be valid if it
requires favorable acid-base reactions to "wait" for other reactions. ]]>
URGENT - Change schedule for Exam #3 ???tag:blogs.reed.edu,2009:/chem201202//125.4842009-11-07T20:50:02Z2009-11-07T20:53:52ZI'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 #1Exam #3 would still be on Monday, November 16. However, if the exam were to be...Alan Shusterman 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. ]]>
Dining in a Looking-Glass Universetag:blogs.reed.edu,2009:/chem201202//125.4832009-11-07T01:59:34Z2009-11-07T02:16:06ZPity (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...Alan Shusterman 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).
]]>
Lecture slides - Fri Nov 6tag:blogs.reed.edu,2009:/chem201202//125.4822009-11-06T19:55:27Z2009-11-06T19:59:23ZSlides 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...Alan Shustermanhere.
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. ]]>
Lecture slides - Wed, Nov 4tag:blogs.reed.edu,2009:/chem201202//125.4812009-11-06T19:53:36Z2009-11-06T19:55:07ZI 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....Alan Shustermanhere. ]]>
Isopentyl acetate report - due date & extra infotag:blogs.reed.edu,2009:/chem201202//125.4802009-11-06T03:33:03Z2009-11-06T04:27:14ZAs 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...Alan Shusterman I forgot one vital piece of information concerning the lab report: what information needs to be printed out in your NMR spectrum. ]]>
Second, I would like to see that integrations were performed for all
peaks and peak picking was performed on a "need to pick" basis
(basically all patterns except for the singlet). If I can see these
data on the same spectrum as the -0.2 to 4.2 ppm so much the better.
As a practical matter, however, you might find it useful to look at the
complicated patterns around 1.5 and 1.7 ppm more closely than a
one-page printout allows. You can look at them on the computer screen
using SpinWorks. You might also find it helpful to print this region
out on a separate piece of paper. If you do this, adjust the horizontal
and vertical scales so that you can see signals clearly.
So, at most, two pieces of paper, the original one encompassing all 5 patterns + TMS, and (optionally) an expansion of the small, hard-to-see patterns.
Finally, you might derive some benefit from a post that I made last year regarding this lab report. See Reporting IR & NMR & GC data (posted Dec 6, 2008)]]>
Pharmaceutical Companies Develop Better Placebostag:blogs.reed.edu,2009:/chem201202//125.4792009-11-03T16:45:43Z2009-11-03T17:00:28ZI'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...Alan Shusterman 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. ]]>
"Last November, a new type of gene therapy for Parkinson's disease,
championed by the Michael J. Fox Foundation, was abruptly withdrawn
from Phase II trials after unexpectedly tanking against placebo. A
stem-cell startup called Osiris Therapeutics got a drubbing on Wall
Street in March, when it suspended trials of its pill for Crohn's
disease, an intestinal ailment, citing an "unusually high" response to
placebo. Two days later, Eli Lilly broke off testing of a much-touted
new drug for schizophrenia when volunteers showed double the expected
level of placebo response."
Notice that the problem is not simply failure to beat placebo, it is the increasing effectiveness of placebo treatments. Does this mean that it is getting easier to activate the belief network in the mind? Perhaps it means that the belief network is becoming more effective at activating healing responses in the body? Perhaps drug companies are developing better placebos?
Read the Wired article. And, if you would like a really truly amazing audio introduction to the placebo effect, listen to this podcast from The Radio Lab (May 18, 2007). ]]>
Lecture slides - Fri Oct 30tag:blogs.reed.edu,2009:/chem201202//125.4782009-11-03T02:41:47Z2009-11-03T02:43:25ZThe slides for last Friday's lecture, which covered the last part of Chapter 7 - the stereochemistry of chemical reactions - can be viewed here....Alan Shustermanhere. ]]>
Lecture slides - Mon Nov 2tag:blogs.reed.edu,2009:/chem201202//125.4772009-11-02T19:48:20Z2009-11-02T19:54:13ZToday'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....Alan Shusterman Slides for today's lecture are located here. ]]>
Lab this week - NMR Workshoptag:blogs.reed.edu,2009:/chem201202//125.4762009-11-02T06:51:32Z2009-11-02T07:00:09ZThose 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...Alan Shustermanlab 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. ]]>