moleculeoftheday | May 27, 2008I love stuff like this. A lot of people don't believe that water is blue until they see some really clean water. It really is, though, and the reason is simple yet fascinating. It is because water is blue - very faintly, it's a unique phenomenon because you don't see 10,000 gallon pools of methanol (etc.).
D2O, for example, is not blue.
To see some really brilliantly blue water, take a look at these incredible frozen wave glacier pictures.
Thanks for all the corrections; here is some moving water that does freeze.
moleculeoftheday | May 23, 2008In the news the last couple days: chloropicrin:
Chloropicrin is a pesticide. It's one of the older types that's just generally really, really toxic. It will easily hydrolyze to phosgene and nitrosyl chloride, one of the nasties aqua regia generates.
Just recently, a Japanese farmer swallowed some in a suicide attempt, which resulted in toxic, phosgene and nitrosyl chloride-containing vomit, poisoning those around him.
This brought to mind a story which still gets to me, that of Jason Altom, Elias Corey's student who commited suicide nearly ten years ago with cyanide:
Having accounted for the…
moleculeoftheday | May 19, 2008Mica is neat, you might remember it as the really flaky stuff you used during the minerals demo in grade school:
(Public domain wikipedia image)
The coolest thing about mica is that it makes a great substrate for AFM. If you take a sheet of mica and put it between two pieces of scotch tape, and pull them apart carefully, you will cleave the mica. This releases some ancient air that has been ensconced between the sheets for a few billion years (correct me if I'm off by a few orders of magnitude) and gives a perfectly atomically flat surface.
moleculeoftheday | May 15, 2008Hexamine is a nitrogenous analogue of adamantane.
The coolest thing about it is the exceptionally stable adamantyl-type system assembles on its own if you just mix ammonia and formaldehyde gas. It's got loads of uses, from little fuel tabs for stoves, to a component of explosive mixtures, to deodorant in China (anyone care to elaborate?)
moleculeoftheday | May 14, 2008Adamantane is a sort of triple-fused-cyclohexane structure:
I've previously covered its role as a functional group in a dermatological drug. The neatest thing about adamantane is that if you make polymers of it, you have carbons with four tetrahedral single bonds to other carbons, or a molecular diamond. Since part of why diamond is so unique is because it is in such a geometrically favored, fully valence-satisfied lattice, molecular diamonds are interesting in a lot of the ways diamonds are.
moleculeoftheday | May 9, 2008Previously I've mentioned triethylammonium acetate, and ammonium carbonate. These are salts formed by mixtures of volatile stuff - triethylamine, acetic acid, ammonia, and carbon dioxide. Awhile ago I made one I hadn't ever made before.
This one was triethylammonium bicarbonate, which is weird. You take triethylamine (about 100g), water (about 500mL), and a bunch of dry ice or a tank of CO2, and set something up to bubble gas in while it stirs. Oddly, the triethylamine won't go in at first (since when it's not charged, it's pretty nonpolar), so as you bubble in the carbon dioxide, you make…
moleculeoftheday | May 7, 2008Triacetin is the glycerol triester of acetic acid:
Since it's made of glycerol and acetic acid, it's kinda-sorta-almost edible, and the wiki informs me there is talk of feeding it to spacemen. Aside from its toxicity, it has an great liquid range (3-260C), especially for a nonpolar solvent and it makes a decent plasticizer. Puzzlingly (since it's basically food), it's used as an antifungal.
moleculeoftheday | May 5, 2008Automated solid-phase synthesis of biomolecules defines 20th century biology. I previously covered a protecting group that is ubiquitous in DNA synthesis, but the Nobel was actually awarded for peptide chemistry.
Fmoc is sort of to amino acids what DMT is to DNA. In amino acid synthesis, you take off stepwise protecting groups (fmoc) with base and release your peptide with acid, but in DNA, you take off stepwise groups (DMT) with acid and release your DNA with base.
Fmoc, like DMT, is useful because you can watch it come off because it's colored (well, Fmoc absorbs UV, DMT cation is kool-aid…
moleculeoftheday | May 1, 2008Chlorinated solvents are great solvents. The polarizability of chlorine, moderate electronegativity, moderate volatility, lack of acidic protons or reactivity - it all adds up to a great reaction medium. However, they usually are toxic.
Carbon tetrachloride, CCl4, used to find a lot of use, even in dry cleaning, but it's toxic, especially to the liver. Chloroform, CHCl3, is a little less toxic. And dichloromethane, CH2Cl2, is less toxic still.
A friend of mine used to joke that we'd use methyl chloride if only it weren't a gas.
moleculeoftheday | April 28, 2008Niacin is also known as Vitamin B3. Interestingly, it's also called "nicotinic acid," and the similarity of the name to "nicotine" isn't coincidental:
Take a look at nicotine and you'll see the structural similarity.
Interestingly, high doses of niacin have been noted to modulate cholesterol (hundreds of times the RDA). A few problems can occur, though - the most common is prostaglandin-mediated flushing of the face. The most serious are heart and liver problems.
Merck was going after a cholesterol drug that incorporated niacin, with a prostaglandin blocker to mitigate the side effects.…
moleculeoftheday | April 23, 2008Is paying $5/liter for Fiji water not cutting it? Trying to come up with a more environmentally abhorrent, gauche hydration accessory? How would you feel about $1,000/liter, along with some iffy health benefits?
Gerolsteiner? H2O? What are you, a subprime borrower? The Gulfstream+Carbon Credit set are drinking deuterium oxide. Evian facial spray? Do you drive a hybrid or something? Only D2O facial spray will do.
That's not all! Merely regioselectively deuterating say, guanine, may reduce its tendency to oxidize (assuming you don't synthesize any purine de novo)
If you thought it was difficult…
moleculeoftheday | April 20, 2008Oscillating reactions are neat; I should write up one of my favorites sometime... Here, electrons flow from iron metal to mercury (I) sulfate to chromium (VI) oxide. Listen to the video for a step-by step explanation...
moleculeoftheday | April 18, 2008A couple previous molecules of the day were in the news today: polylactide and lead chromate.
I previously covered the use of polylactide in plastic bottles. I also covered a big downside - it's not the sturdiest stuff. Today, Popular Science has a story about its use in plastic bags, which isn't that bad an idea strength-wise, but it is a bit of a bad idea in the sense that we need to wake up to the fact that we are running up against a wall in our ability to ability to produce enough corn to produce oil, staggering though our ability to produce it is.
Also, lead chromate, which apparently…
moleculeoftheday | April 16, 2008Phytic acid is an inositol derivative:
There was a time when phytate was mostly associated with disease states. All those phosphates make a fine metal binder, and people who lived on plants nigh-exclusively were often short on essential minerals.
We eat less plants these days, and phytate has shown itself to be capable of playing a number of different roles.
You could find worse ways to guess how prevalent diseases than to count drug commercials. By this technique, you might come to the conclusion that the bulk of the might of the American pharmaceutical industry is focused on herpes and…
moleculeoftheday | April 15, 2008Inositol is a sugar:
Most sugars are aldehydes and ketones, and they zip up into rings in solution on their own, forming rings with oxygens that look like substituted ethers. Inositol is a funny one - an enzyme has to do the work and make a cyclohexane, which won't fall apart without some metabolic heavy lifting.
Because the metabolism is a little inefficient, sugar alcohols like inositol have found some use as low-glycemic or slightly lower-calorie sweeteners (some are innately extra-sweet). It's a unique handle for an enzyme to grab, so its derivatves pop up throughout metabolism.
You may…
moleculeoftheday | April 10, 2008As you go down the group, the smells only get worse. You don't smell oxygen (you're soaking in it), sulfur compounds tend to be pretty stinky, selenium compounds are pretty rank, and purportedly, tellurium compounds are the worst.
Exposure to even elemental Te can result in your body producing myriad organotellurides (yep, this is where Telluride the town gets its name). As the estimable Derek Lowe points out, even selenium stinks something fierce. If you read through the comments, he mentions that tellurium-exposed individuals have had to go so far as to take leaves of absence to get over…
moleculeoftheday | April 9, 2008As far as I know, selenocysteine is the only reason you need selenium in your diet (which you almost certainly get enough of; the requirement is vanishingly small, <100 micrograms/day). It is a member of the same group as oxygen. As you go down a group, things change in subtle ways. Sulfur is a less-electronegative, bigger, more polarizable, more nucleophilic, stinkier oxygen. Similarly, selenium is all these things, but more so!
It is the nucleophilicity that is so important; it is found in the amino acid selenocysteine - that is, the selenium analogue of the sulfur amino acid cysteine (…
moleculeoftheday | April 3, 2008As Uncle Al mentioned, many antioxidants are ill-tolerated by the liver. However, it loves one antioxidant: silibinin.
Silibinin, found in Blessed Milk Thistle, is actually hepatoprotective - to the extent that it's used in toxic mushroom poisoning in hospitals in Europe!
moleculeoftheday | April 2, 2008Benzoyl peroxide is funny. As a commenter mentioned yesterday, it's used in skin care.
It's a potent oxidizer (and will quickly do a number on reducing agents like hydroquinone, which is the reason for the warning mentioned). Potent enough that it's an explosive. At 2.5-10% concentration, however, it's used in creams as an antimicrobial agent in the treatment of acne.
moleculeoftheday | April 1, 2008One of the most heavily trafficked entries on this site is that on TBHQ. While it's an antioxidant, it's a synthetic one, and some have suggested it might be toxic. Another antioxidant, ferulic acid, found in wheat, works on much the same principle and has found less blame.
Hydroquinone is, too, an antioxidant, but it exhibits some toxicity and potential carcenogenicity. The lesson that all "polyphenols" are not medicines and all "chemical antioxidants" are not toxins is well taken. The dose, the structure, and (perhaps most importantly) the metabolism make the poison.