Sorry to punt again but I’m just getting home. Today’s molecule is carboxymethylcellulose. It is made from cellulose by its reaction with chloroacetic acid.

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Again, another artificial sweetener discovered by sloppy, sloppy chemists. God bless them (us?). It makes me wonder sometimes whether I’m working with a bench full of delicious chemicals that are just waiting for an accidental taste.

Aspartame was discovered in 1965 by James M. Schlatter, a chemist working for G.D. Searle & Company. Schlatter had synthesized aspartame in the course of producing an anti-ulcer drug candidate. He discovered its sweet taste serendipitously when he licked his finger, which had accidentally become contaminated with aspartame.

Here is the structure of aspartame. It is the methyl ester of a dipeptide of aspartic acid and phenylalanine. That’s it. It’s an incredibly simple structure:

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One thing they touch on in biology class but never really get into is the fact that DNA is wound up into a tight little structure in the nucleus of eukaryotic cells, as well as sperm. Just how the cell gets the DNA to cooperate isn’t really explained. DNA is a polyanion - that is, it has a repeating negative charge.

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The last, fastest spot on the chromatograph is FD&C Blue #1, or Brilliant Blue FCF:

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The next spot on our chromatograph is Red 40, or Allura Red AC. Here is its structure:

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When cannibis was first being studied, the active principle was isolated and found to be delta-9-tetrahydrocannabinol, shown below. Later on, studies showed that there were, in fact, endogeneous receptors that interacted with the compound. In abundance. We termed it the cannabinoid receptor, for lack of a better word. Endogeneous or not, the only thing we knew that would fit in it came from a drug of abuse!
This was baffling: Nature tends to be pretty parsimonious. A truly vestigial receptor class was unlikely. So did we evolve in the (continuous) presence of dope fields? Surely not. This was a strong indication that there was some sort of endogeneous cannabinoid. The search was on. Despite having known about marijuana for literal millenia, we didn’t find an endogenous ligand until 1992! This came out of Raphael Mechoulam’s lab - the same guy who isolated THC back in 1964! To be fair, even though THC was long-since discovered, we only knew about cannabinoid receptors as recently as 1988.

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Many people who come here from Gilead seem to peek at the Tamiflu page and take off. Gilead, you see, are actually the people who came up with Tamiflu, not Roche. They simply purchased the rights. After the whole bird flu thing pushed it into the public eye, Gilead and Roche had a brief spat, which was settled a few months later.

In general, this is the sort of thing Gilead make: small molecule antivirals. Let’s take a look at another Gilead drug, adefovir:

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You have probably heard of chromatography. This is a chemical technique for separating mixtures of compounds. Various “stationary phases” can be used to separate compounds based on different characteristics. Probably the most common is silica, which is just pure, clean sand (speaking a little loosely. It’s so pure you wouldn’t recognize it as sand. It’s a fine white powder and very homogeneous in size.) It separates compounds based on their polarity. It is the most common medium used by organic chemists because it’s relatively cheap and it works on a wide variety of substrates.

Biochemistry makes it trickier. First of all, everything’s dissolved in water, which is the most polar solvent most people will ever encounter. Silica chromatography with water just doesn’t work. It’s done with organic solvents like ethyl acetate and methylene chloride. Biomolecules, as a rule, don’t take well to being dissolved in anything but water. A lot of the time (especially with proteins), you’re worried about a specific three-dimensional structure. Organic molecules, as a rule, don’t really care. This is largely because most of them are too small to have enough freedom to fold into anything interesting. This is why I can show the daily molecule as a stick drawing and not have to worry about 3D structure.

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99 years ago, a Japanese researcher was looking into some puzzling stuff. A broth of kelp, when boiled down, yielded some brown crystals that tasted like, well, essence of savoriness. “Savory” is one of those flavors that is hard to pinpoint - for salty, sweet, sour, bitter, we have archetypes - sugar, sodium chloride, lemon juice, and alkaloids, which you don’t taste on their own very often. As Barry Sharpless noted, he won’t taste a compound with a nitrogen atom in it - these are the bulk of our alkaloids, many of which are psychotropic (not nearly all, though). The best everyday example of a bitter compound I can think of is tonic water, which is bitter due to the alkaloid quinine.

Anyway, savoriness, or “umami,” as he put it, is hard to pinpoint. Those crystals he found came close, which were those of the much-maligned monosodium glutamate, or MSG:

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Lead is one of the most familiar heavy metals to people. Disquieting is the fact that so many people haven’t handled it because of all the concern about its toxicity. Fishing weights are increasingly being replaced with heavy but less-toxic alternatives, like bismuth.

If you’ve never handled lead, please try it. I worry that it will go the way of mercury and you just won’t be able to get it in ten years. I can get all sorts of weird stuff in a chemistry building, but you don’t really have that luxury. It is soft and magic. If you have it in bar form you can bend it like Superman. It will make your week. Just wash your hands afterwards, and don’t store it in the butter dish.
Enter one of my heroes, Theodore Gray, with his Periodic Table Table. His entry on lead does the element more justice than I will. He also notes a few places you can get lead: hardware stores, fishing stores, and Wal-Mart. With lead’s wide use in plumbing, it probably won’t go away as quickly as I claim (the symbol for lead, Pb, comes from the latin plumbum. as you might expect, this is where the word plumbing comes from).

Lead is a lot like mercury - toxic, but not so terrible. You can handle lead pretty freely - for instance, I’d hold lead in my hands, not mercury. You can dent it with your fingernail. It’s surprisngly heavy, but not as heavy as gold or tungsten. Like mercury, the soluble compounds are much worse. One is Lead (II) acetate:

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