moleculeoftheday | September 12, 2007Electrons are reactive guys when they're on their own, and tricky to isolate. If you take a bit of fur and rub it on some amber, you end up with a surplus of electrons, but they won't hang around long (the reason I mention amber is because this is what the Greeks used - the word electron comes from the Greek for amber). This is kind of cheating, though, you just have a surface with surplus electrons. Actually isolating them is tricky. If you're a poor scientist like me and use a CRT you found by the Dumpster, your monitor has an electron gun, and you actually have some ephemeral isolated…
moleculeoftheday | September 11, 2007Tiron is a metal ligand and can be used in colorimetric metal assays.
Transition metal complexes tend to have the happy property of having their frontier orbitals separated by energy characteristic of photons of visible light - that is, they end up having pretty colors. I've never actually used it, but Merck claims complexes with different metals that span essentially the whole visible spectrum - iron gives blue, copper greenish-yellow, titanium orange, and molybdenum yellow.
For another example of a colorimetrically useful metal ligand, see my entry on that wonderfully named staple of…
moleculeoftheday | September 10, 2007Let's see if I can do better this week.
Tazarotene is a retinoid, or vitamin A analogue:
It's unusual because of its diarylacetylene moiety. Like most retinoids, it modulates some aspects of skin turnover and metabolism and finds use in dermatology.
moleculeoftheday | September 5, 2007See, you're ahead of the curve when you MoTD. A story about popcorn lung came out today, and just last week, ConAgra announced they were removing diacetyl from their buttered popcorn.
I could swear some sharp reader had pointed out the popcorn lung angle, but my entry mostly focuses on the smelliness. Check out the diacetyl entry from last year here.
Sorry for the sporadic posting, I have been going through gobs of measurements. Back to the regular schedule soon...
See also here and here.
moleculeoftheday | September 4, 2007Chorismate lies along a biosynthetic pathway in plants that leads to the aromatic amino acids.
A bit further up the pathway is shikimate, which is present in many organisms but especially abundant in star anise, and a precursor to Tamiflu (see also)
moleculeoftheday | August 30, 2007Mellitic anhydride is unusual - as mentioned in the argument over urea, it seems like it should be organic - it's a benzene derivative - but there's no hydrogen. This causes it to fail some peoples' tests for whether something's organic.
More bafflingly, mellitic acid's aluminum salt is a mineral! Mellite sure looks like a rock, huh?
moleculeoftheday | August 28, 2007Formaldehyde's funny stuff. It's naturally a gas. If you put too much of it in solution, it will polymerize and form a polyacetal, "paraformaldehyde," which is just -O-CH2- repeating over and over.
Because of this tendency towards polymerization, formaldehyde of commerce is sold with a little methanol added to keep it in solution. Interestingly, formaldehyde polymer is used as a plastic - and it's food approved! In some ways, it stands to reason - the stuff won't dissolve in much of anything so it's pretty chemically resistant. On the other hand, you can actually "crack" paraformaldehyde just…
moleculeoftheday | August 27, 2007Ellman reagent can be used to quantitate the amount of free thiol present in a protein or other molecule:
It reacts with the free thiol and releases a nitrocarboxythiophenolate, which is bright yellow. You can then quantitate it with a UV-vis.
moleculeoftheday | August 24, 2007Previously, I covered ethyl thiolactate, which is one of those oddly sweet smelling thiols (like grapefruit mercaptan). Ethyl lactate also smells nice.
Ethyl lactate is the ester of ethanol and lactic acid - Wikipedia claims it's biocompatible, because, after all, you have ethanol and lactate in you. The same is true of ethanol and acetic acid, though, and ethyl acetate is supposed to be moderately toxic. Maybe it's a hydrophobicity thing. Also, lactic acid is chiral, and you've only got one of the two running around.
Anyone have any ideas on those two?
moleculeoftheday | August 23, 2007Hydrazine, H2N-NH2 is the nitrogen analogue of hydrogen peroxide:
It's useful in the Gabriel synthesis of amines via phthalimide (or saccharin, oddly, but I'm not sure if hydrazinolysis works as well here).
In contrast to peroxide, hydrazine is a potent reducing agent and finds use in rocket fuel! Just last week, they used a hydrazine on the space shuttle.
It's also quite toxic - the famous chemist Emil Fisher used it and suffered from its toxicity, apparently. A classic use of a hydrazine is the use of 2,4-dinitrophenylhydrazine to derivatize carbonyl compounds (to which it adds avidly).…
moleculeoftheday | August 22, 2007This reagent is one of my favorite ones for replacing an alcohol with an iodine.
Eric Kool's lab has made good use of it to iodinate the 5'-OH after automated synthesis of a DNA strand.
moleculeoftheday | August 20, 2007I have alluded multiple times (see here and here) to the ubiquity of benzodiazepines in modern medicine. Xanax is one very popular one:
Xanax is just another benzodiazepine, but it's mostly used in antianxiety roles. Its triazole ring is unique; it's a heterocycle you don't see too often.
More importantly, Xanax is special enough to warrant HOLOGRAM ADS (Fair use image from Wikipedia, see contact link for removal requests):
moleculeoftheday | August 17, 2007AM404 is an active metabolite of acetaminophen:
Acetaminophen is an unusual painkiller - it isn't quite like ibuprofen or other NSAIDs. AM404 is its arachidonic acid conjugate, which has some cannabinoid activity (as well as COX activity).
Anyone who knows anything interesting about cannabinoids in analgesia (please, not people who say "you have to just smoke the plant," I'm much more interested in knowing what's doing the job), I'd love to hear from!
moleculeoftheday | August 16, 2007Carfentanil is an absurdly strong opiate - ca 10^4 times stronger than morphine.
It's so strong a ug will have effects on you, and it's really only good for tranquilizing lions and Jurassic Park dinosaurs. I spent one summer in a medchem lab synthesizing potential opiates and often wondered what would happen if i stumbled upon something like this. Technique aside, its not hard to take in a ug or two of something just by being near a powder (or getting a drop of an NMR sample in chloroform or DMSO on your glove!)
Fortunately, none of my stuff was anywhere close to a drug lead and I mostly ran…
moleculeoftheday | August 15, 2007Chloroauric acid is obtained by the oxidation of gold in the presence of chloride, as in aqua regia.
Chloroauric acid is central to one of the sweetest stories in science, ever: hiding Nobel prizes from the Nazis. From the old blog:
My very favorite story about aqua regia is this: during World War II, a Hungarian chemist living in Denmark, George de Hevesy, dissolved two fellow scientists' Nobel Prizes in aqua regia literally as the Nazis stormed into Copenhagen so they wouldn't be stolen (he assumed, correctly, that the Nazis would just leave the chemicals alone). After the war, he…
moleculeoftheday | August 14, 2007Clenbuterol is a phenethylamine, like adrenaline, tyramine, ecstasy, sudafed, wellbutrin, and methamphetamine. Don't let anyone ever tell you all these drugs are the same again.
Clenbuterol is a potent beta-adrenergic agonist with a long half-life. It's very long-lived and has found some use as an asthma medication. Like many other drugs in the class, it has some efficacy in weight loss - clen appears to be pretty good. Bodybuilders often use it illicitly; more recently, it's gotten a little attention outside the community. Like all beta-adrenergic agonists, it can increase blood pressure…
moleculeoftheday | August 10, 2007Nitrobenzene is a simple enough molecule. It smells just like benzaldehyde - it's really strikingly similar if you've smelled both. If you haven't, it's the artificial almond-cherry flavoring smell.
Nitrobenzene, like many nitroaromatics, is a bit toxic (although not as bad as plain benzene, purportedly!) Its nice (sort of) smell has resulted in its use as a solvent. It used to be ubiquitous in shoe polish.
It also has some mild oxidizing character to it - I once did a reaction that involved dissolving your reagent in straight nitrobenzene and heating - it was both oxidizer and solvent (…
moleculeoftheday | August 9, 20074-ethylphenol is a simple substituted phenol. It smells like band-aids.
You can find it in some wines or beers - rarely, this is intentional, and provides an interesting flavor at high dilution. Usually, though, it's because someone was homebrewing and contaminated the wort or must with Brettanomyces yeasts, which produce the stuff.
Interestingly, the related m-cresol is used as a preservative in medical insulin, which smells just like band-aids. The smell is defeinitely reminiscient of phenol - which I've smelled. Haven't smelled either of these two, though.
moleculeoftheday | August 8, 2007Methyl salicylate, much like aspirin (ASS to the Germans) is an analgesic drug.
It's structurally quite similar to aspirin, but less polar and doesn't ionize in water. This affords it some vapor pressure (it smells of wintergreen, and is actually used as a flavoring agent in low concentration!).
However, it's quite toxic, and it is only used as an analgesic in creams (as far as I know). Stuff like Ben-Gay. Earlier this year, a young athlete actually absorbed a lethal dose from topical methyl salicylate cream.
It looks like she was drastically overusing the stuff. Creams may seem like "lesser…
moleculeoftheday | August 7, 20075-nitro-2-propoxyaniline is a potent artificial sweetener:
It's banned in the States. Nitroaromatics tend to be tox liabilities. One toxic nitroaromatic with a very specific mechanism of action is 2,4-dinitrophenol.