More concerns in bottled water, via Chemistry World

Everyone remember BPA? The stuff your water bottle now proudly proclaims it doesn’t have? There’s a new suspect in town to get flustered over. Bis(2-ethylhexyl) (2E)-but-2-enedioate.

Mugshot of the perp.

Mugshot of the perp.

But the Chemistry World link doesn’t answer a pretty fundamental question: Where’s this molecule coming from? Even the study’s authors skirt around the question a bit. I’d wager it’s a plasticizer: a small molecule added to the plastic in the water bottles to help make it more malleable and processable. The long branched hydrocarbon sidechains are a pretty strong hint. They prevent the plastic molecules (who love to hang out with each other) from getting too tightly packed and cozy, which would end up giving you a brittle inflexible water bottle. (The authors suggest it’s the decomposition product of some other molecule, but it sure looks like a conventional plasticizer to me.)

Because these types of molecules haven’t traditionally been regulated, or even monitored terribly closely, it’s tough to say if its concentration is too little to be much concerned about or not. That’s another reason that the study is nice – we’ve now got some definitive sleuthing that this molecule is in 18 different bottled waters from 13 different companies from varying countries (did I mention that’s how widespread it is, cuz that’s how widespread it is). It’s not possible to say with certainty how this molecule affects your health (Chem World notes that this particular one is not known to produce both the anti-androgenic and anti-estrogenic activities of suspected molecules), BUT it certainly ain’t gonna help your body any.

Original study (open access, woohoo!) here: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0072472

Advertisements

How’s it put together? Blow it up to find out!

Ok, this is just way cool. Researcher Martin Pitzer and a German-Swiss-Canadian team want to know how molecules are put together spatially, so in true mad scientist fashion, they’re blowing ’em up (Chemistry World writeup here). More specifically, they track bits of exploding molecule to figure out the stereochemical arrangement of the molecule’s atomic components – that is, where all the molecule’s pieces sit relative to each other pre-explosion.

Brace yourself, because their method also has a requisite badass name: Coulomb Explosion Imaging.

If you’ve studied organic chemistry, stereochemistry is probably familiar (if perhaps also the subject of recurring nightmares). It’s the study of how the various atoms of a molecule are arranged around each other. A non symmetric molecule can have identical atomic structure as its neighbor, even identical connections between atoms, but those atoms may be sticking out in front, while its neighbor’s are sticking out back. The arrangement is not simply rotational. Instead, the atoms are bound together differently. Images of two molecules cannot be superimposed over each other, no matter how you arrange them in space.

Blasting these with lasers is not recommended. (From unina.it, which coincidentally has a very accessible overview of stereochemistry.)

Far and away, everyone’s favorite metaphor for stereochemistry is your hands. Both the left and the right have five fingers: a thumb, a pinky, a few in the middle. Their constituent parts are identical. But there’s no way to superimpose one over the other in the same orientation. They’re mirror images of each other. In chemistry terms, they have opposite stereochemistry.

So who cares? Your body does actually. You may have heard of thalidomide. The story is quite famous and rather horrifying. Thalidomide was a drug prescribed to pregnant women to help fight morning sickness. Until it started causing genetic defects. Whoops. The idea is that one stereochemical arrangement of thalidomide was safe, but the other messed you up badly. Same molecule, if you count the atoms. But the relative position of those atoms made a drastic difference (the mechanism actually is assumed to be more complicated than that, where your body can turn one arrangement into the other, so really neither is “safe”).

So what’s new now? Well, not surprisingly, studying stereochemistry is a big deal, particularly for the medicinal community. The problem is that actually figuring out how a molecule is arranged ain’t easy. The most common method is to X-ray a very pure, pristine crystalline sample. But large complicated molecules and proteins are fiendishly difficult to make into perfect crystals. Here’s where the German-Swiss-Canadian team comes in: instead of trying to make the cleanest most perfect crystalline samples, they blow them up. By blasting samples with a laser, the molecules get stripped of their electrons. And in a strong electric field – BOOM! They blow apart, and the pieces hit a detector. Depending where each fragment lands, Pitzer and his colleagues can do some CSI work and trace the atoms back to their original molecular arrangement. Voila! X-ray-free stereochemistry!

Little known fact: Darth Vader was actually an unsung hero of stereochemistry.

A caveat here is how hard it is to track all those busted molecular fragments.  The trigger-happy researchers were only working with a small molecule made of five atoms.  Tracking all the possible fragments from just those five seems to be pushing the bounds of what their detector can do.  So this doesn’t immediately solve the problem of stereochemistry in large complex molecules, but it’s immensely cool and impressive.

Full, pay-walled Science article here: Direct Determination of Absolute Molecular Stereochemistry in Gas Phase by Coulomb Explosion Imaging

Element 115 get!

So we’ve a new element!  Good old 115.  So fresh, it’s still got its placeholder name: ununpentium.  The news has already been broken for a few days now, so here’s what some old-fashioned thinking on the topic has come up with.

Image

Just look at that majesty!

Odd facts related to #115

  • We’ll start easy: 115 of course refers to it’s place in the periodic table, not order of discovery.
  • It’s only maybe the 115th element we’ve discovered, chronologically.
  • It could maybe be the 116th, depending if you trust the as-yet unverified but previous discovery claim for #113 (yep, we officially verified #115 before #113).
  • Or maybe it’s the 117th (#117 on the table also has a prior claim in play).

Wait, what, we’re looking for ’em out of order?

Finding elements, not too dissimilar from time travel (diagram from Noah Ilinsky)

  • It’s not quite like Looper, Periodic Table Edition, but sort of.  Some elements are more stable and easier to make, so you find them first.  Also the IUPAC (the guys who confirm discoveries), are particular sticklers for replication by other labs, as they should be, so sometimes you’ve got to wait for backup.
  • The new #115 for example, actually had a claim made on it a decade ago before being replicated now (fun fact: that claim was by the #114 folks).
  • Researchers get really territorial about these claims, particularly if they feel they’re snubbed.  Go read the Wiki edits for #113.  Downton Abbey‘s got nothing on that drama.

What are we really gonna call it?

What could we do with it?

  • It only exists for fractions of a second before it decays. (I can’t immediately find how long it stayed #115 before decaying into other elements, but it’s probably not too different than the other elements around it.  So a few hundred milliseconds?)
  • We can hold antimatter – frickin’ antimatter for a hundred thousand times longer than we can hold #115 (current number I found is about 20 minutes).
  • So…I dunno?
  • Some kind of disappearing magic trick?
  • Side note: An non-exhaustive Wikipedia search (so take it how you will) seems to show Californium (element #98) as the highest synthetic element with a non-fundamental-research use.