moleculeoftheday | October 9, 2006Indole-3-butyric acid is a member of a class of hormones known as auxins, which are responsible for all sorts of plant growth regulation. You may have seen it on the shelves at a garden store, sold as "rooting hormone" - among other things, it can help a cutting of a plant set down roots more readily.
moleculeoftheday | October 6, 2006Lactisole is a pretty simple compound, apparently first found in roasted coffee. I doubt it tastes like much; maybe soapy at high concentrations. However, at relatively low concentrations (0.1% by weight), it has the unique ability to suppress sweet flavors.
The estimable Harold McGee says that it can reduce sweetness by ca. two-thirds. Why would you want to do this? So your jams and jellies taste fruitier and less cloying, apparently. Neat, anyway.
moleculeoftheday | October 5, 2006Stevioside is an intense sweetener found in stevia, an herb that's known pretty much for expressing this sort of molecule:
Stevioside, shown above, is a glycoside (that is, a glucose derivative) of a terpene. Unlike a lot of other sweeteners, stevioside is actually a sugar derivative (for others, see here, here, and here). I'm not sure if the sugar in steviosides actually gets metabolised, but it doesn't really matter, since it's a few hundred-fold sweeter than sucrose (so you'd eat a lot less).
I've tried stevia extract and thought it tasted unpleasantly like licorice. The pure molecule…
moleculeoftheday | October 4, 2006Eugenol is a substance found in cloves. In addition to the distinct aroma of cloves, it's responsible for the numbness that clove oil can induce (dentists often swab your gums with it before giving you an injection of novocaine or lidocaine):
Sharp readers will notice the similarity to vanillin. The aromatic nucleus behind both these molecules is guaiacol.
Eugenol is one of those natural products that is sufficiently abundant it can be recovered by steam distillation (PDF).
moleculeoftheday | October 3, 2006Brass is an alloy of copper and zinc. Pennies, fortunately, have both, so you can actually use them to make some brass.
To get at the zinc (which makes up the creamy center of a penny), use a file to make some ridges in the edge of your penny. You can use electricity to oxidize the Zn metal on the inside to Zn (II), but it's easier to just use the reaction:
Zn + 2H+ -> Zn2+ + H2
That is, the zinc will reduce protons to hydrogen, becoming oxidized to zinc (II) cation on the way there. This is really easy. Aqueous acid is a source of protons, and any would work in theory, but I had the best…
moleculeoftheday | September 29, 2006Is a blogger and synthetic organic chemist in Barry Trost's group at Stanford. He has successfully e-panhandled his way to an iPod. He will not be blogging anymore starting in a couple days (presumably because it's dissertation time for him). This also means his blog will only be publicly accessible for another month. If you haven't yet, check out the blog of the guy who readers loved enough to toss a couple hundred bucks his way (an audience comprised largely of similarly impoverished grad students, I'll bet).
(He will also be destroying his old, broken ipod with assorted cleaning reagents…
moleculeoftheday | September 29, 2006Another member of the unusual collection of decent-smelling thiols (take a look at the previous entries on diallyl sulfide and ethyl thiolactate) is furfuryl mercaptan:
Furfuryl mercaptan smells of coffee. You'd expect it to smell awful, but it doesn't. Fragrance and flavor people talk about this stuff to no end in trade mags like Perfumer and Flavorist:(See here and here for the article refrenced below)
"... I have smelt
Corruption in the dish, incense in the latrine, the sewer in
the incense, the smell of sweet soap in
the woodpath..."
-- T.S. Eliot, "Murder In The Cathedral" (1934)
Eliot…
moleculeoftheday | September 28, 2006(Oops, this should have been published on Tuesday. I didn't click publish. Sorry!)
Certain bacteria, under certain conditions, will excrete plastic.
The one above is a polybutyrate, but many are possible.
This is neat, first of all, because it's bizzare. Can you imagine being able to excrete plastic?:
To produce PHB a culture of a micro-organism such as Alcaligenes eutrophus is placed in a suitable medium and fed appropriate nutrients so that it multiplies rapidly. Once the population has reached a substancial level, the 'diet' is changed to force the micro-organism to create PHB. Harvested…
moleculeoftheday | September 27, 2006Check out Khymos, a molecular gastronomy website, as I work my way through it too (thanks Jase!)
moleculeoftheday | September 27, 2006Inspired by Keith's comment on polylactic acid's tendency to deform under heat, and procrastination, I just did a quickie test of the heat-deformation characteristics of my polylactic acid bottle.
I took my PLA bottle and a cute little PET bottle I had lying around. I put some tap-hot water in the microwave and heated it up for awhile. After stirring to equilibrate the temperature, I measured it with my oh-so-cool noncontact thermometer, a Raytek Raynger ST-6, which I wouldn't own if it weren't for Jeffrey Steingarten's unintentional salesmanship (fortunately, by the time I got one, the model…
moleculeoftheday | September 25, 2006This weekend I came across Biota brand spring water, which is the normal expensive kind of spring water (the kind where they make a point of saying where in the earth it came from rather than obfuscating the "municipal source" text). It was pretty good - maybe even one of the better waters I've had.
I'm not here to talk water, though. What's unique about this is the bottle. Most water bottles are PET, a polyester of terephthalic acid and ethylene glycol. These bottles are made of PLA, or polylactic acid.
Esters are pretty labile, and will break down pretty easily into their components. The…
moleculeoftheday | September 22, 2006Inspired by the comments yesterday, here is a compound that was used in early human genetics: phenylthiocarbamide, or PTC:
PTC is one of those molecules with the puzzling properties of tasting bitter to some, and like nothing at all to others. This page gives a good overview:
To some people the chemical substance phenylthiocarbamide tastes intensely bitter while to others it is almost tasteless. The ability to taste this and a number of other chemically related substances is inherited. There are two genes, T for tasting and t for non-tasting. T is dominant in expression over t. This system…
moleculeoftheday | September 21, 2006This is one that will be familiar to anyone who works in chemistry, but I was a bit surprised to see it the first time I went into a lab.
Certain compounds, called esters, can be prepared from an acid and an alcohol (usually a carboxylic acid). They are ubiquitous in the flavor and fragrance industry (although they're not quite stable to water over the long-term, and once an ester is hydrolyzed, it liberates its component alcohol and acid, which are often pretty rank).
One classic organic lab is preparing some sweet-smelling esters from otherwise nasty-smelling carboxylic acids and esters (…
moleculeoftheday | September 19, 2006Yesterday's entry on crown ethers demonstrated a way to do reactions with a mixture of polar and nonpolar substrates. These crowns allowed for ions to be brought into the nonpolar solvent. Another approach is to just throw up your hands and mix oil and water, so to speak: reactions can occur with two phases.
Not very well, though.
One way to help this along is with phase transfer catalysts, usually quaternary ammonium salts. A QAC, ammonium compound, quat, or whatever you want to call it has four substitents on the nitrogen, (nitrogen usually carries 3) so it has a positive charge. This makes…
moleculeoftheday | September 18, 2006Crown ethers are an unusual series of molecules that have the ability to complex small cations, notably alkali metals such as sodium and potassium. These cyclic molecules, upon complexing a cation, can allow a salt to go into organic solvent that otherwise wouldn't. This makes reactions that are otherwise impossible accessible.
A good example is how 18-crown-6 (shown below, an 18-membered ring with 6 oxygens/ether linkages) can help potassium permanganate (a beautiful purple oxidizing agent based on manganese (VII)) go into organic solvent. Normally, you can only get permanganate into very…
moleculeoftheday | September 14, 2006These are great: ferrofluids are stable suspensions of ferromagnetic particles. Typically, the liquid is something organic and nonvolatile, and the magnetic particles are iron oxides (such as Fe2O3 or Fe3O4).
Why so neat? Look here. Magnets, moved around near a ferrofluid, can create beautiful patterns that are a direct effect of the field lines.
Image courtesy Flickr User Steve Jurvetson.
It's tricky stuff to make: generating liquid colloids is hard enough, but making one that's stable for any appreciable length of time is even harder. Over time, the particles tend to settle and aggregate.…
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 | September 12, 2006Yesterday's mention of tyramine, and the comment, reminded me of inhibitors in general, and one in particular: harmine. Harmine belongs to a class of MAOIs known as the beta-carbolines.
MAOIs are problematic because they inhibit the metabolism of certain (toxic in the absence of gastrointestinal MAO) chemicals such as tyramine. Certain MAO enzymes, active in the gut, process these chemicals (ingested through foods such as cheese and wine, as mentioned yesterday). Oral MAOI-class antidepressants act as inhibitors of this enzyme. They aren't used much these days, because of newer…