Today in lab we made self-assembled thiolate monolayers on gold foil. I brought mine home. “What are they supposed to do?” asked my brother.
“Depending on the monolayer you use, it changes the surface properties of the object.”
“So what do these do?”
I got out a poly pipette and dripped a little water on each one. “See, the acid layer is hydrophilic, and the alkyl layer is hydrophobic, so the water on the acid layer spreads out a little more.”
Fortunately that was the last lab, so I don’t have to try to explain these things anymore.
In one month I will be finished with organic. In one week I will be finished with lab (*sob*). In four days I will be finished with that wretched professor who can’t explain a damn thing, and with the pretty lab instructor who likes to make things explode.
The best summary of this summer so far is “It makes my stomach hurt.” Tests every monday give me a stomachache. Two finals on thursday gives me a stomachache. Pretty lab instructor gives me a stomachache, and so does the fact that he’s leaving. Falling on the stairs and messing up my toe gives me a sore, bruised toenail, but also a stomachache.
That’s why the organic chemistry weight-loss plan works so well–because everything this summer makes me nervous–or, because I’m nervous and jumpy already, because it makes my stomach hurt.
I could really use a weekend that’s actually a weekend. Or even a night where I don’t dream about chemistry in any form.
The fact that I’m pretty damn bad at integrals didn’t stop me from taking calculus, and likewise the fact that I never acquired any programming skills beyond trivially amusing concatenations of loops and functions didn’t stop me from taking discrete math. And then I figured, what the hell, I’d take linear algebra, too, and once I shelved my book (always keep your textbooks!) I promtly forgot most of the nifty applications of matrices, because I had dropped out of school and when I came back I was a biology major.
But enough about me. Let’s talk about combinatorial synthesis.
Say you want to screen a group of chemicals for something–well, first you have to assemble a group of chemicals. If you’ve got a vague idea what you’re looking for, you can make exhaustive variations on a chemical theme and test each one. That’s how a lot of useful things are found. . You’ve probably got to react at least two compounds together to produce your thematic chemical. By assembling variants of those compounds and producing their chemical permutations, a large number of compounds can be produced.
Here’s the cool part: the canonical method would be to have an array with i chemicals of class 1 and j chemicals of class 2 and react each in a separate vessel, then test each separately, requiring i x j (x k x l) syntheses, workups, trials, etc. The use of combinatorial methods can eliminate a lot of that by producing and testing groups of compounds in a single go.
This is how we did it today: we had i aldehydes and j hydrazines, and we (presumably) tossed them together to make i x j hydrazones, but instead of reacting each combination separately, we organised vessels into two groups. Each in the first had a large aliquot of an aldehyde and a small one of each hydrazone; each in the second group had a large aliquot of a hydrazine and a small one of each aldehyde. So we’ve got four compounds in each vessel, but by keeping track of which tube has which reagents, a compound can be uniquely addressed by the combination of tubes that contain it.
But this really amuses me: if you ignore those annoying physical limitations (like competing and side reactions, workups, blah blah blah), you can extend the idea of combinatorial synthesis to N dimensions. You don’t need the entire dimensional space to locate a point, just the axes. So your number of reactions and tests will increase linearly with the number of classes of reagents, not exponentially. Or, if you prefer, and you have n classes of m reagents each on your hands, O(n*m), not O(m^n).
And fuck all, that’s cool.
In just five weeks, I’ve lost six pounds on the Ochem weight-loss plan! You, too, can reap the benefits of this program by following these simple rules: