Lab is a unicorn

Being a Teaching Assistant is exhilarating and terrifying at the same time. I led my first experimental organic lab this week. It went as well as a first of anything can go. At one point we had 15 steam baths going, none in the hood. My boss walked in and said "Yevgeniy, it's like a sauna in here!" Then he claimed I was putting the students on a steam diet. I am going to a wedding so maybe I was. Next time, we will use hot plates. I might have scared the students with an explosion story that happened when I was in college. A lab partner heated some ether on a hot plate. The ether boiled onto the hot plate, and we are lucky that no one got hurt.

The first lab's goal was to recrystallize benzoic acid (left) in order to separate it from salicylic acid (right). This is a nice starting lab as it reinforces a couple of important concepts and lets one use a lot of different equipment. In fact, the process of recrystallization is often utilized by the pharmaceutical industry to insure purity of their active pharmaceutical ingredient (the key to the pills in our medicine cabinet). The idea behind recrystallization is the following:
more molecules of a certain type (the one to the left or right) dissolve in a hot solvent then in a cold one. If you dissolve a contaminated mix of stuff in as little hot solvent as possible, when the solution is cooled (and the solvent can longer contain the same number of molecules as before) the least soluble compound will crystallize out of solution. If two compounds have very different solubilities this process makes sense.

What happens if two compounds have very similar solubilities? Turns out, if one of the compounds dominates the contaminated mix then when the saturated solution is cooled, the dominant compound will form pure crystals. In chemistry like tends to aggregate with like.

Benzoic acid was an excellent choice for the lab as it is a medically relevant compound, a treatment for various fungal skin diseases.

Did you know that DNA methylation causes DNA condensation and transcriptional silencing. Turns out that adding a carbon with three hydrogens to a base (usually cytosine - as shown on the right, note the extra CH3 group in the second cytosine - or guanisine) blocks RNA polymerase from making RNA. This kind of modification is responsible for the silencing of one out of two X chromosomes in female mammals and what makes calico cats so crazy (see for yourself). The hair pattern is a result of random x-inactivation - all because of a carbon and three hydrogen.

A joke at every end:

What do you get when you cross an insomniac, an agnostic, and a dyslexic?
Someone who lies awake all night long wondering if there really is a Dog.