Archive for the ‘general chemistry’ Category:
Cargo cult science in the Gulf, news at 11
by Chemjobber on Jul 20 2010 (16651 Views)
Credit: WKRG/Mediaite
The Gulf oil tragedy has already shown the ignorance of some reporters about chemistry. However, a Mobile TV station and their chemist has taken it to new heights when they blamed the oil spill for (likely) bad glassware.
WKRG is a local TV news station in Mobile, Alabama; they sent intrepid reporter Jessica Taloney to collect samples of local beach water. (See video of story below.) They asked a local lab to analyze the samples for oil and grease; the lab owner and analytical chemist, Bob Naman, suggested that the level of oil and grease should be pretty close to 5 ppm.
Of course, all the samples showed the presence of oil and grease, with amounts up to 200 ppm. While these results are not particularly surprising, the result of one sample was not obtainable because the chemist claimed that the sample exploded during the extraction. Rather than blame the broken separatory funnel on a star crack or a lack of venting, the chemist said that “We think that it most likely happened due to the presence of methanol, or methane gas, or the presence of the dispersant Corexit.”
No. This is just wrong. Having actually shaken separatory funnels full of mixtures of water and flammable solvents (including methanol!) on a daily or weekly basis for about 10 years now, I have yet to see any of them explode. Surfactants like Corexit are not known for being particularly explosive, especially at room temperature.
I think it is far more likely to be coincidental; in addition, wouldn’t a true explosion have left much less of the funnel? Heaven help us. (When the reporter obtained another sample from the same area 4 days later, the oil and grease concentrations were at the 1 ppm level. Not explosive enough? (That’s a joke, non-chemists.))
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Common Student Difficulties in Organic Chemistry
by Jeremy on Jul 13 2010 (11612 Views)
While cleaning out my newly assigned “war room” (the setting where I’ll strategize on how best to torture students this fall), I came across some fairly interesting documents that were buried in far corners of crowded file cabinets. They’re nothing personal or discriminating (sorry TMZ), but I saw them as material I could use in upcoming classes.
One of the several I found, titled “Common Student Difficulties in Organic Chemistry,” caught my attention more than the others. The document, which appears to have been assembled using a typewriter (for the unfamiliar, you can find information about typewriters here), lists problems students encounter while navigating through the dreaded “O Chem”. In any case, at the bottom of the page, in bold, is the following message:
If you start to get into trouble in this course review this sheet. Knowing what has gone wrong allows you to fix it.
This closing interested me from a historical perspective. Did enough students bomb the course to warrant this document’s assembly? Did the professor discover this or a similar list at an ACS meeting and felt it was prudent to include it in his/her course? Did the document actually help students better understand the course material?
Although I can speculate until the cows come home, I’m throwing it out to you, the blogosphere. Do you agree with this list? Would you change anything on it? I’m curious to see what the blogger generation thinks (FYI, I believe this list was developed in the 1980′s).
- Lack of organization
- Difficulty in keeping up with lecture while taking notes
- Failure to finish exams
- Inability to manipulate three-dimensional structures on paper
- Too little drill – lack of repetitive practice
- Falling behind
- Poor problem analysis
- Inability to see and mentally manipulate three-dimensional objects
- Insufficient energy and/or motivation for the challenges of this course
Your Academic Lineage
by Jeremy on Jul 05 2010 (7571 Views)Over dinner the other night, my uncle and I started comparing and contrasting our academic experiences. He’s a fascinating person who earned a bachelor’s degree in computer science in the late 1970’s.
After discussing the finer points of Moore’s Law, and how he agonized over purchasing a 20 MB hard drive in the 1980’s for $400, the substance of the conversation switched. “Have you ever researched your Ph.D. lineage,” he asked.
“I’ve gone as far back as Breslow,” I replied, completely forgetting that he probably didn’t know this “Breslow” character.
It turns out that several of his doctoral computer buddies had recently taken on this task, many of them somehow descending (academically) from Charles Babbage.
Our discussion prompted me to further examine my background. I soon discovered that there are several University websites that provide chemistry academic lineage for their faculty members. Being an organic chemist, I was interested to learn that E.J. Corey worked for John Sheehan (I admit it…I’m nerdly). In any case, here are some websites I found interesting:
- UT Austin is a really good site to start exploring. Here, I was able to learn that my roots (through Eric Anslyn) purportedly go through Breslow and Ira Remsen (1870), all the way back to Torbern Bergman (1758).
- My personal favorite website is the lineage posted by North Dakota State University. Apart from deriving academic lineage all the way back to Nicolo da Lonigo (1453), they’ve complied all of the data/information into a colorful map that would no doubt look good on a faculty member’s wall.
- Some other sites: UMass Amherst, Illinois, UConn, Kentucky, and Michigan State.
Science as Art
by azmanam on Jun 04 2010 (12560 Views)
Princeton University’s Art of Science contest has produced a gallery of pretty spectacular images of science in action.
This is the fourth Art of Science competition hosted by Princeton University. The 2010 competition drew more than 115 submissions from 20 departments. The exhibit includes work by undergraduates, faculty, research staff, graduate students, and alumni.
The 45 works chosen for the 2010 Art of Science exhibition represent this year’s theme of “energy” which we interpret in the broadest sense. These extraordinary images are not art for art’s sake. Rather, they were produced during the course of scientific research. Entries were chosen for their aesthetic excellence as well as scientific or technical interest.
Interestingly, first second and third prize were determined according to the golden ratio, with first prize earning $250, second prize earning $154.51, and third prize earning $95.49.
Be sure to check out all the images, many of them are quite striking. Clicking on the images gives a caption explaining what you’re looking at.
Art from molecular models
by Chemjobber on Apr 28 2010 (8761 Views)
"Heme", by Alexander Kobulnicky
In my travels here and about online, I recently found the paintings of Alexander Kobulnicky. He paints molecular models of, well, molecules, ranging from the life-giving (“Heme”, to the left) to the fun-related (THC, if that’s your thing) to the life-taking (CO.) The background of the artwork is most noteworthy — Mr. Kobulnicky paints what comes to mind with each different molecule. I think that thorazine is the one with the best background, although psilocybin comes in a close second.
Each painting comes with a little description of the relevant chemistry and an interesting structural note to make a chemist’s heart warm: “These molecules are rendered as space-filling models, in a natural, low-energy conformation, and displayed from an angle that shows off as much of their structure as possible.”
While I’m not quite to the art-collecting stage of my life yet, I have to say that I’m pretty enthusiastic about owning one of these someday.
Counterfeit drugs: an opportunity for innovative chemical thinking?
by Chemjobber on Apr 11 2010 (6189 Views)
Can you tell the difference? Left is authentic sample. Right is fake.
A recent article [1] in “Trends in Pharmaceutical Sciences” illustrates the interesting problem of counterfeit pharmaceuticals, especially fake anti-malarials. In the long term, I suspect that as pharmaceutical prices trend upwards, folks at the margins will be looking for ways to cut costs. Doubtless that some will be taken in by the global trade in fake or substandard pharmaceuticals, possibly even in the US.
One village in Burma was definitely taken in [2]: a young man with malaria was treated with what was thought to be arteminisin, the natural product that is an effective means of treating the disease. After he died of malaria, experts discovered that the packages had fake authentication holograms and the tablets failed a colorimetric test. MS results indicated that the main ingredient was acetaminophen and HPLC indicated that the levels of arteminisin was only 20% of the claimed dosage.
The authors ([1], Newton et al.) argue for more support for governmental medicinal regulatory agencies in developing countries; they also push for more inspections of GMP facilities. While I think both of these strategies will bear long-term fruit, there is potential room for innovation from the chemistry front.
Presented with this problem (questionable organic starting materials), the typical university-equipped chemist would perform a number of tests (NMR, MS) to determine the identity of the unknown material. The articles I looked at also mentioned colorimetric tests and TLC, both relatively low-tech analytical chemistry techniques. I like TLC as a potential answer for part of this problem; you’d want something that didn’t rely on silica gel plates, a UV light or complicated stains. You’d want something that worked with paper chromatography and very common chemicals (H2SO4?)
This might be the first foray into a chemical version of “appropriate technology”, which attempts to improve the lives of people in developing countries using materials that are available and sustainable. What do you all think?
References:
1. Newton, P.N., Green, M.D., Fernandex, F.M. “Impact of poor-quality medicines in the ‘developing’ world.” Trends in Pharmacological Sciences, 2010, 31 (3), 99-101.
If Jim Henson Taught Chemistry
by TheChemist on Oct 22 2009 (3006 Views)I’ve had a few people tell me about this video, and saw it on BoingBoing as well. It’s creative, if not terribly informative, I guess I don’t know what I should expect from something like this. I do know I thought that at least one fuzzy member of the cast might be of help when cleaning glassware.
Meth and mirror images: errors in Nick Reding’s “Methland”
by Chemjobber on Oct 20 2009 (5794 Views)
I recently picked up Nick Reding’s book Methland, which is about the blight of a small Iowa town due to methamphetamine use. I was interested in it because I had heard about it from NPR; I was interested in what Reding had to say about the chemistry of meth synthesis. What I found was pretty amusing.
I should pause to say that Reding was not focused on the chemistry at all — rather, his thesis was that meth was a mere symptom of the devastating effects of global economic forces on a small Iowa town. It’s well written and pretty gripping stuff.
I’m sure I’m not the only chemist who can get distracted by chemical explanations that’s just obviously wrong. But some of the explanations were just terribly, terribly wrong:
“Mirror imaging is a process whereby a chemical’s molecular structure is reversed, moving, for example, electrons from the bottom of a certain ring to the top, and vice versa. Pseudoephedrine, ephedrine, and methamphetamine are already near mirror images of one another. To make meth from ephedrine, it is necessary to remove a single oxygen atom from the outer electron ring. Thus ephedrine and methamphetamine not only look the same under a mass spectrometer, but both dilate the alveoli in the lungs and shrink blood vessels in the nose-hence ephedrine’s use as a decongestant while raising blood pressure and releasing adrenaline. The key difference is that meth, unlike ephedrine, prompts wide-scale releases of the neurotransmitters dopamine and epinephrine.
What the 1997 tests at the University of North Texas showed was that, at least in lab animals, mirror-image pseudoephedrine was equally as effective as regular pseudoephedrine as a decongestant. Unlike regular pseudo, however, the mirror-image version didn’t cause any side effects to the central nervous system, such as high blood pressure and a racing heart: the common “buzz” that one associates with cold medicine. Better yet for Warner-Lambert, mirror-image pseudoephedrine could only be synthesized into mirror-image methamphetamine, which, according to the Oregonian, had no stimulant effects and could not then be made into regular meth.” (quote thanks to Mike the Mad Biologist.)
Where to begin? First of all, “mirror imaging” is not a term; the word you’re looking for is, of course, enantiomers. The explanation about electrons is not correct; you can’t move electrons willy-nilly around rings. The comparison of ephedrine and methamphetamine as mirror images is wrong — they’re not even structural isomers. To make meth from ephedrine, you don’t “remove a single oxygen atom from the outer electron ring” (that sounds like something you do on the planet Zefu), you remove an oxygen and a hydrogen from a side chain by reduction. Ephedrine and methamphetamine most certainly DO NOT look the same under a mass spectrometer; I imagine it’s quite easy to distinguish the peaks from one another. Did Reding’s editor basically make a pass on the science stuff?
Reding’s book relies heavily on a series of articles on the meth epidemic written by Steve Suo of the Portland Oregonian. (If you look in Suo’s articles, you’ll see that Reding basically reworded the somewhat-more-correct chemistry explanation from Suo’s article.) Reding and Suo’s larger point is that (-)-pseudoephedrine does not generate CNS-active methamphetamine, and that Warner-Lambert (and subsequently, Pfizer) were not interested enough in the larger public health issues to spend the money to push (-)-psuedoephedrine through the FDA approval process when the enantiomer they had was already quite lucrative.
So now that we’ve had a laugh about bad chemistry explanations, a question for everyone: how easy is it to get (-)-pseudoephedrine? The companies in India contacted by Suo said that they could supply ton quantities, no problem. I’m skeptical, but not that skeptical. Anyone out there know about this?
Wolfram|Alpha as a resource for chemistry basics
by mitch on Aug 17 2009 (1655 Views)In honor of the ACS national meeting in DC, the WolframAlpha blog featured how to use their engine for chemistry. I won’t steal all their thunder so link is below.
Link: Wolfram|Alpha Chemistry 101
Mitch
