Post Tagged with: "C&EN"

Anti-Freeze and the Automotive Industry

My brother-in-law recently bought a new car with the intention of taking it with him into the Rocky Mountains in a few years.  Worried about sub-zero temperatures, he looked into modifying his coolant/anti-freeze system and learned about a new trend in the automotive industry.  An increasing number of suppliers have begun marketing propylene glycol as an alternative to the widely used ethylene glycol because propylene glycol has a lower freezing point than its two-carbon sibling.  A savvy chemist should instinctively think “freezing-point-depression,” a staple of freshman general chemistry lectures.  Mathematically, it’s identified by the following equation:

1

Wikipedia will inform you that freezing-point depression is a relation of the Clausius-Clapeyron equation and Raoult’s law.  Personally, I have not found use for either of these equations, and I’m not about to BS my way through the derivatives (pchem was not my strong point as an undergrad).  Anyhow, the above equation tells us that a pure compound’s freezing point will drop if you add another solvent to the solution.  For example, water typically freezes at 0 oC and propylene glycol freezes at 59 oC.  According to Sierra Anti-Freeze’s literature, a 2/3 mixture (by volume) of propylene glycol and water will start to crystallize at -4 oC, whereas a 3/2 mixture will begin crystallization at -54 oC.  In fact, the change in water’s freezing point is much larger with propylene glycol than with ethylene glycol. 

2Ethylene glycol is an interesting compound.  The majority of households know that anti-freeze (i.e. ethylene glycol) is highly toxic and that dogs like to drink it.  Upon ingestion mammals digest ethylene glycol by oxidizing it to oxalic acid (among other compounds), which has been linked to kidney failure.  Ethylene glycol purportedly tastes sweet to humans and dogs, which has prompted manufactuers to begin adding a bittering agent.  C&EN covered the issue a couple years back and from what I’ve recently read only Maine, Arizona, New Mexico, California and Oregon require bittering additives by law; Wisconsin’s right behind them.  For whatever it’s worth, the bittering agent (denatonium benzoate) is sold commercially as Bitrex or Aversion and is added to products such as rat poisons to prevent human consumption.  By comparison, propylene glycol is generally regarded as a safe, non-toxic chemical.

If propylene glycol is safer and appears more advantageous than ethylene glycol, why does the auto industry use it?  I couldn’t find an answer.  I did learn that some automobile manufacturers will actually void your warranty if you do not use their “approved” anti-freeze (usually ethylene glycol). Perhaps this issue will be addressed by the Obama-appointed US car czar in January. 
 

By December 28, 2008 12 comments general chemistry

32-electron chemistry

We all remember learning about octets and valence electrons in school. We may also remember the first time we saw an 18-electron transition metal complex. This week Dognon et al. discuss the possibility of 32-electron organometallic complexes.[JACS] In order to reach 32-electrons, f-orbital participation is essential. Below is a picture of a hypothetical organometallic complex with 28 carbons in a cage around an actinide element.

An@C28

 

Although these systems are not new, as the Smalley group made U@C28 in the gas-phase in ’92,[Science] Dognon et al. examine a series of these systems for different actinides. The major conclusion is that the plutonium system is theoretically predicted to have the largest bonding energy for its Pu4+@C28 complex. Since fullerenes and the intercalation of metals often only need heat to be synthesized, I wouldn’t be surprised if these complexes have already been made but missed as impurities and byproducts.

Link to paper: A Predicted Organometallic Series Following a 32-Electron Principle: An@C28 (An = Th, Pa+, U2+, Pu4+)

Update 1: Jyllian Kemsley also covered it at C&EN — Stable Caged Actinides Proposed(subscription)

Mitch


ACS PUBS Redesign Brings Chaos To the RSS Masses

The new ACS PUBS redesign is a great step forward for ACS. Unfortunately, it is causing havoc across the RSS landscape from looking at the recent blog postings at The Sceptical Chymist and Everyday Scientist. The root of the image problem seems to be the RSS feeds are calling .tif files even though they exist as .gif files in their respective folders (someone probably mistyped a ‘t’ for a ‘g’). Alas don’t fret, ChemFeeds is working just fine.  So if you want your graphical abstracts fix, head on over:

http://www.chemfeeds.com/

Edit 1: Actually the new ACS feeds seems to be causing greater than normal lag at ChemFeeds. Also, for some journals they are actually calling journal images from folders that have no images in them. So, although I’ve fixed them up as much as I can, I can’t create images in folders, but its better than nothing.

Edit 2: I’ve been going crazy looking over and pruning through their feeds that I generated this cool error shown below.

 

Edit 3: I just realized it says I’m from the University of Washington, I have no clue what is going wrong with their website now. As I’m connecting through Berkeley’s access.

Edit 4: Rachel has an update: About Those Feeds

Mitch

 

By November 19, 2008 13 comments chem 2.0

A Word on Research Misconduct

Dig out your dictionary and look up the word “hyperbole” (I know, it might be a while since you’ve last had English class)—exaggerated statement or claims not intended to be taken seriously.  I tend to hyperbolize a bit when I replay an incident that happened at the bar or in class, which I attribute to the fact that I’m a terrible storyteller.  I think we all do it to a certain extent.  I know I’ve once said something to the effect of, “It was the greatest movie, ever…in the history of humans.”  A hyperbole at its finest.

While most common vernacular is riddled with hyperboles, I’d argue that the majority of intellectual study makes an effort to stay away from gross exaggerations (with history being the exception).  In particular, science is the observation and study of the physical world, and it leaves no room for hyperboles.  Just facts.  For example, if you mix an aqueous solution of silver nitrate with an aqueous solution of sodium chloride it is a fact that a precipitate will form.  There are no equivocations about scientific facts.  Though, science sometimes falls short when making assumptions that connect two or more facts into one coherent theory or proposal.  Still, these assumptions, en route to a new theory, are usually reasonable if not simplistic (i.e. Occam’s razor).

What about bad data?  Of course, there are ways to make our raw data more “natural” without exaggerating.  In the event that we have to plot data points, for example, as scientists we can exclude data that “doesn’t belong.”  We call these anomalies “outliers” and there is statistical rationale as to why a stray might be “bounced” from the data set without any bias to the result.  But even in these cases, the data point is often so far away from the others that including it might be a detriment to a fact about Mother Nature.

What irritates me to no extent is a term I refer to as “hyperbolized research.”  We have all seen these situations before: yields that are bumped a good 5 to 10 to 50%, data that is fit just right, patent procedures that are not reproducible.  Why are these practices tolerated?  Contemporary science is themed “publish or perish,” which essentially means that if you are not producing enough results (nevermind quality) you will soon be unemployed.  I recall hearing stories about early 20th century scientists who studied science without the proverbial gun to their respective heads and still made great findings.  A lot of these experiments were groundbreaking, marvelous and truly beautiful.

It’s no surprise that this issue of “publish or perish” rears its ugly head in science.  Society is incredibly fast-paced, and science is certainly trying to keep up.  But, it’s really hard to do so with a tiny, bankrupt research group (where most if not all members are teaching) versus a behemoth firm with hundreds of years of experience and millions of dollars of materials to use. 

So, what do groups do to keep pace (or at least appease the boss)?  “How did you do with that reaction you couldn’t get to work last week?”  “Um…I got 98% yield with 95% ee.”  “Great, let’s write up a manuscript and submit to JACS.”  I’ve heard stories of “big name” research groups who’s members purposely inflate their yields to keep “the man” happy.  In these cases, researchers keep two sets of lab notebooks: the real one (usually under lock and key with the actual experimental results) and the boss’ one (usually kept in the open, so the boss can see how his researcher got a 90% yield on chemistry that is next to impossible to reproduce).  The bottom line is that papers get published, lectures are given and proposals are funded—criminality is rewarded.  How is this right?  Furthermore, how is it fair to another researcher who needs to repeat the results?

Have we not learned anything from the Bell Lab incident?  For those not familiar, Hendrik Schön was a groundbreaking physicist working for Bell Labs in the late 1990’s.  He was purportedly on par to win a Nobel Prize with his creation of an “organic molecular transistor.”  The papers describing this work were met with criticism in the scientific community and at some point (c. 2001), Bell Labs launched an internal investigatory committee to examine Schön’s work.  Their final report ultimately alleged 24 accounts of misconduct that were essentially fit into three categories: “Substitution of data,” “unrealistic precision of data,” “Results that contradict known physics.”  In the end, he was ultimately stripped of his doctoral degree.  But think about the repercussions of not investigating Schön’s findings.  Had Schön’s work not been policed, potentially millions of dollars would’ve been invested into falsified research.  While I’m aware that Bell Labs was recently closed, without insinuating anything, it makes me wonder if this Schön incident had any weight in the lab’s termination.

Rex Dalton covered the aftermath of this incident along with several other examples of research misconduct (Nature 2002, 420, 728-729).  He ultimately offered up the following observation:

“Science may be self-correcting, but sometimes it is a painfully slow process.”

Perhaps he’s right.  Sure, several papers are going to be questioned in the future.  And of those papers, a few might be blatant lies.  How much time is it going to take to correct these mistakes?  According to Corey: “Occasionally, blatantly wrong science is published, and to the credit of synthetic chemistry, the corrections usually come quickly and cleanly.”  Case in point?  The hexacyclinol incident that was excellently covered by C&EN and by a couple of fellow bloggers: Derek Lowe and Paul Docherty.  In this case, there was a rapid turn around (possibly due to public interest).  However, this case might be the exception.  It could be years before a questionable project is proven incorrect.

I know…you want me to provide a solution.  Maybe there isn’t an immediate, reasonable answer.  But, alas, here’s what I’ve uncovered: there are a few wonderful articles in J. Chem. Ed. about scientific misconduct, which both hover around the LBNL and Bell Lab incidents (see: J. Chem. Ed. 2002, 79, 1391; ibid. 2005, 82, 1521).  The authors’ messages (albeit bluntly or implied) were that ethics and empathy should be at the forefront in the early years of scientific training.  Some people cannot discern between right and wrong and teachers should do their jobs by teaching students about the rights and responsibilities of being a scientist.  While I did not receive formal training on scientific misconduct, I was given a lambasting for bordering on plagiarism my freshman year of college.   I learned my lesson early—you and your lab partner need to keep separate lab notebooks.  Perhaps this experience has formed me into the scientist that I am today (I’m anal-retentive about my lab notebook). 

I guess there is a remaining question still looming.  What sparked this rant about “doing the right thing”?  I’ve been repeating experiments for the past couple of months that were reported to be exceptionally clean (requiring no chromatography) and high yielding.  Most of these reactions have tanked—miserably—even with exceptional preparation and precision.  So, I’m painstakingly re-optimizing experimental procedures so someone else doesn’t have to.  It’s taking a while—much longer than it reasonably should.  But, hey, “sometimes (correcting science) is a painfully slow process.” 

By October 6, 2008 6 comments Uncategorized