Junior Qualifying Examinations

So at Reed you have to pass a junior qualifying examination before you can register for your senior thesis. As an interdisciplinary major, I had to take both biology and chemistry. Biology was an open note/book/internet exam basically based on my coursework. I wrote an essay about haploinsufficiency in Marfan's syndrome fibrillin-1 gene and the elastin gene in Williams' syndrome and another essay where I wrote about the growth hormone axis and how nutrition (both being malnourished and obese) affected this axis. I also did some quantitative questions like calculating Tms of DNA strands and making buffers. I should hear back about it soon, although I'm afraid I might have gotten a conditional pass from messing up calculating TRIS on that buffer question, eeek. It's not a big deal if that happens, I just need to fix what I got wrong.

The chemistry qual was an oral exam where I was given this paper and had to learn as much as I could about it in 48 hours. Then they asked me questions, specifically about the paper, but really probing my organic chemistry knowledge as a whole. I had two options, an organic option and a biochem option, and I decided to go with the organic option. The biochem option was interesting too, it was on nicotine binding in the brain and how it is different from its inhibitory effects on your muscles (if it did hit the receptor in your muscles you'd be dead). But ultimately I felt more comfortable with the sort of questions they would ask in an organic qual, especially since my advanced synthetic final last semester was in the exact same format. Luckily, my organic paper was a synthetic paper and not a mechanistic paper--because for some reason the long lists of data tables with numbered compounds in mechanistic organic papers followed by colums of de's and ee's result in my eyes glazing over a lot of the time.

I think it overall went well. A lot of the questions were definitional--what is the kinetic enolate vs. thermodynamic enolate, what is an allene functional group, what is "latent stereochemistry". The main places I got tripped up on were mechanisms. I had this divinyl oxy-anion cyclopropyl Cope rearrangement mediated by a Brook rearrangement, and I started off drawing the reaction in a different perspective than I had in my notes which kind of threw me. The paper went to great pains to discuss why this enolate attacked from the more sterically hindered side (because it was reversible and resulted in the more stable transition state for the subsequent Cope) but to demonstrate it only showed what didn't happen due to steric repulsions--so there was no picture to look at what did happen. Which I knew, but it's just sort of difficult to pull all of that together visually on the board with weird bicyclic systems and the boat transition state and so forth. It went ok, I just had a moment where I was like "wait Connie..."

The other place I got tripped up due to nerves was the mechanism for oxidizing an enolate with a Davis oxaziridine. Again, it was ultimately ok, just a little bit of nerves. Also drawing 7 and 8 membered rings on the whiteboard was tricky!

The spectroscopy portion was easy since they had already assigned the peaks in my paper and my profs didn't ask me anything too difficult. Just like, why methyl groups attached to silyl groups were more upfield than methyls attached to carbons and whether this one set of diastereotopic methylnes were chemically equivalent or not, and why they had different J-values coupling to a neighboring proton that sort of thing.

It also struck me last night that wow, college has crammed a lot of chemistry into my head in the past 2 years.

So I should be hearing back about whether I passed, conditionally passed, or failed those shortly.

Molecular computing: logic gate

This is pretty neat: it's a molecular logic gate. It senses pH, sodium concentration, and zinc concentration, and if all three are present, it fluoresces. I just found the concept to be pretty clever. The molecule looks like this:

J. Am. Chem. Soc., 2006, 128 (15), pp 4950–4951

DOI: 10.1021/ja058295+

There's so much to chemistry

Basically what this semester seems to be boiling down to is physical and inorganic chemistry are waaaaayyyy different from organic. Jesus christ.

I've been fussing around trying to calculate the numerical radii for the radial nodes of a 3s and 3p orbital for frickin' ever.

I feel like my rather shitty math background has been a constant handicap. Due to the fact that the math department at Reed only teaches theoretical math geared towards math majors, and due to the fact that Rao (the math head) determined my semester of calc I at UIC as equivalent to Reed math 111 (calculus), I have managed to skate through Reed college only taking probability & statistics. Because of this wacky math system, math 112 is more introduction to proof writing than a calc II course, and I was told that unless I was really into theoretical math it wasn't going to be fun and it certainly wasn't going to be useful. I never took calculus in high school and I didn't want to push physics to my junior year (thank god I didn't).

Due to this situation the chemistry and (especially) the physics department pick up some of the slack. Yesterday I learned how to take a second partial derivative with respect to two different variables. Having never taken a multi class, I picked up the concept of a partial derivative and how to do it in intro physics when learning about the wave equation. I had never seen the notation for a double partial derivative before. I'm a little shake on integral tricks too.

I'm usually ok with this fact, and I've kind of accepted that I'm more prone to think about the world in descriptive terms. This doesn't mean that I'm not down for a few computations, but I'd rather plug it into a modelling program or mathematica. I'm good with scooting around arrows, stability rationalizations in the style that organic chemists do it, and basically things that operate in pictures and words with small amounts of algebra and maybe a derivative or two. I love to learn about biophysics and I think the techniques that are out there are quite fantastic, but my understanding of them is all in pictures and words. Same goes with NMR. My feeling for the physical world is one where math is a tool, but I'm not interpreting it through it. I see math is a way to get better pictures in my head. This is at a stark contrast to the way physicists--and for that matter, even physical chemists--seem to view it--as if they interpret physical phenomena through math.

I'm re-learning about the quantum numbers for inorganic (I learned it in intro chem once but forgot) and there's always something in the book like "you can solve the Schrodinger equation for hydrogen and hydrogen-like nuclei, but we're not going to go into it in here" and sometimes it makes me feel bad about not taking quantum. It's like, even though I did quite well in my synth class, I feel like I don't have quite the feeling for what is all behind it as some people. I know that what I learned in intro physics I generally rarely use beyond bits and pieces here and there, but it was good for backing up my general physical intuition and understanding for how things work. Conservation of energy, waves, momentum, acceleration, electric and magnetic fields, these are all fundamental things that I need to understand as any sort of scientist--and are even helpful conceptually for biology. Ploughing through it all, I can't really do those problems anymore but I left with a better conceptual understanding of the physical world. Dan reminded me the other day that physical chemistry does this for other types of chemistry, i.e. the pictorial representations of stability rationalizations are quantifiable (well, sometimes) and that's where the theoretical basis for these qualitative observations come from even if we don't always have the computational power and models to find them quantitatively. It doesn't mean I have to want to be a physical chemist, but I do realize the power in other chemical approaches and understand why I need to learn about them.

I think a lot of my issue with math is a lack of confidence from being "bad" at it for so long. I mean, calculus is a tool like algebra and not like WHOA COMPLICATED OMG MAGIC!

On the up side, speaking of nice, fuzzy picture-based synthetic organic chemistry, Pat gave me a little project to mess around in the lab with. He gave me a couple compounds he'd like to make and test the pKas. I need to go play with Sci-Finder to see if they have been made before. This is good; they're small molecules and models for the types of compounds the lab as a whole works with, but in the past the research I did with him was more guided like "here's this idea I got, I'd like you to try it out" instead of asking me to find preps that I might be able to run. I also know more chemistry and know how to use Sci-Finder better than I did when I worked for him last summer, though.

First day back

As predicted, my chemistry courses are pushing me out of my comfort zone. Inorganic and stat therm are totally different types of chemistry from what I'm used to dealing with. Even adv. mech is pushing me out of my comfort zone with some tough Diels-Alder structures. I'm ok at seeing them retrosynthetically (I think probably from reading Totally Synthetic)--but for some reason the product picking and remembering the endo rule is harder for me to put together since I don't have much experience with dealing with pericyclic reactions. I also realized that I don't know where anything is on the periodic table besides...uh..most of the first two rows. I don't know what Maggie is going to think on my pre-quiz. If only I could take solely organic chemistry classes...

I had a minor flip out about not being mathematically prepared enough for stat therm after working through some calculus review Dan gave us. Also not knowing how to do double partial dervitives with respect to different variables. He sat me down and showed me how to do it and assured me that the calculus would not be my problem--it would be the algebra and the concepts and that I had a decent grasp, even of partial derivitives. I also had an involved conversation with Alan about various things, including things posted the other day, and about how he and his wife coordinated their careers.

I feel so much more at home in the chemistry department than in the biology department like 99% of the time.