Stinky
omnibrain | March 4, 2010Here's a snippet of some of the relevant text from the article describing the model below:
show attribute/state-oriented functions.
Type7. [Useful Attribute/State]: 2.3) Change of structure or object
directly make a useful "attribute" including "ability".
Type8. [Attribute/State]à Interactionà [Useful State]: 2.4) Change of
structure or object makes interaction between its "attribute/state" and the
other "attribute/state" which makes up a useful "state".
show
And now for the actual model:
Any guesses? Head past the break for the big reveal. Trust me - you'll be surprised.
Got it yet?
No?…
moleculeoftheday | September 9, 2008Yesterday, I discussed octenol, a lipid degradation product that's all over your skin. Ever wonder why a cut on your hand smells "like metal," or your hands smell "like metal" after handling some?
Metal ions are great at shuttling electrons around, and that's just what they're doing here. The iron ions in blood (or metal oxides on the metal surface) catalyze the oxidation of the same lipids that degrade to octenol to something a little more oxidized (that is, octenone) - the oxidizing equivalents just come from the air. Octenone is where that metal smell comes from!
Of course, you need skin…
moleculeoftheday | August 21, 2008Short alkanoic acids stink. Apparently hexanoic acid smells of goats:
Hexanoic acid, as Dylan Stiles (L:tender P:button) memorably mentioned, smells of goats. Goats! Alkanoic acids smell of vinegar, cheese, vomit, poo, and, apparently, goats.
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 | March 3, 2008Butyric acid has been covered obliquely before - it's part of the nice-smelling amyl butyrate (which is eau de Juicy Fruit, pretty much). On its own, though, it's a foul vomit-smelling liquid (the Wikipedia article, however, notes that some intrepid chemist tasted it and reported it had a sweetish ethereal taste).
You may have gotten from the headline, though, that this particular organic compound has made the news lately because anti-whaling vigilantes threw over a gallon onto the deck of the Nisshin Maru, a Japanese whaling vessel. I can only imagine what it'd be like if I dropped a 4L…
moleculeoftheday | November 29, 2007DDQ is a benzoquinone derivative with some electron-withdrawing substituents, making it a bit more potent:
It's a bit more soluble than stuff like KMnO4, but not by much - it's a nightmare to work with.
moleculeoftheday | September 24, 2007Pyridine is simply benzene with a nitrogen substituted for one of the CHs:
Such a simple change has myriad effects. The addition of the electronegative nitrogen makes pyridine a good base (it's commonly used in reactions that generate protons to mop up the acid as you go). The same change makes it miscible with water (benzene is only about 0.2% soluble).
Most importantly, however, pyridine stinks. Even at high dilution. It's not a normal piercing chemical scent, either, it has a distinct biological richness that the nitrogenous heterocycles seem to deliver on especially well (witness the…
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 | 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 | July 3, 2007At the blog's previous location awhile back, I covered an oligoamine; spermine - which helps to compact DNA in cells. Spermine isn't volatile enough to smell much, but a shorter amine, putrescine, is.
Honestly I don't get the low MW amine thing. Pyridine smells pretty awful to me, but triethylamine and the like are just a bit ripe to me. Putrescine, apparently, occurs in decomposing flesh - it's the decarboxylation product of hte amino acid lysine.
Back Thursday.
moleculeoftheday | February 23, 2007Ammonium carbonate is analogous to the other bicarbonate and carbonate salts you see - baking soda. In the presence of acid; or just sufficient heat, it will offgas ammonia and carbon dioxide, hopefully leaving pleasing bubbles in whatever you're making.
Whatever you're making better not have much moisture, though. Ammonia loves water, and any residual water will hold onto enough to give whatever food you're making a profound stench. This pretty much limits you to crackers; ammonium carbonate-leavened banana bread will not be pleasant.
The salt has been around for a long time but has been…
moleculeoftheday | January 26, 2007Piperidine is a useful little heterocycle - Walter Gilbert won a Nobel Prize, due in part to his development of a method of sequencing DNA (which uses piperidine as a base). It also has some use in peptide synthesis. Piperidine is also a very useful thing to hang off a drug, because it adds some lipophilic bits (the ring is mostly paraffinic carbon, after all), as well as an amine. These are often two very useful things to have in a drug molecule.
There are also some less-savory uses of piperidine.
Piperidine derivatives are found in fire ant venom. It is also a precursor to PCP and has been…
moleculeoftheday | November 13, 2006Para-dichlorobenzene is the principal molecule found in mothballs. We used to use naphthalene, but these days, we've switched. I suspect neither may be particularly healthy, and I suspect that you wouldn't have much luck getting such a product on the market these days, but mothballs have been around for ages.
moleculeoftheday | October 20, 2006Pyridines and thiols are two of the stinkiest kinds of compounds you can come across in chemistry. You'd think if you put them together in a molecule, you'd have something nasty. Oddly, you don't:
Bafflingly, thiopyridine is apparently odorless. You'll notice I've drawn two structures here - this is a phenomenon called tautomerism, a special case of isomerism. This might play a role in the special non-stinkiness. Think of thiopyridine as a mixture of these two structures.
For more discussions on organo-stank, see this entry at Derek Lowe's blog. If you've never been, take a look; it's one of…
moleculeoftheday | September 13, 2006The lablels on bottles of chemicals with warnings always make me smile. One often-joked about example is the bottles of chemicals labeled "Flammable (US) / Highly Flammable (Europe)," which makes you feel smug if you're on my side of the pond. Another is "STENCH!". There's really no other way to say it, and it's definitely something you want to know before you open one of these chemicals, forcing the regulatory/safety people to come out and say "Uh, this smells bad. I mean really bad." Seeing this next to "LACHRYMATOR! TOXIC! RISK OF IRREVERSIBLE EFFECTS!" always made me smile. (That…
moleculeoftheday | August 16, 2006If you take a look at wine bottles today, you'll note that the sealing devices are all over the place. Traditionally, cork was used, and that's still the dominant seal, but you'll also see synthetic foam-type corks, as well as screw-caps. Cork was originally used in wine because it was a relatively cheap airtight seal. It was the best available at the time. It worked pretty well, too; wines with the capacity to age will last many years if stored sideways (ensuring the cork doesn't shrink, allowing air in). However, there is a sinister side to corks.
Some corks are contaminated with chemicals…