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DBL%20Hendrix%20small.png College chemistry, 1983

Derek Lowe The 2002 Model

Dbl%20new%20portrait%20B%26W.png After 10 years of blogging. . .

Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases. To contact Derek email him directly: derekb.lowe@gmail.com Twitter: Dereklowe

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January 16, 2007

How Not to Do It: Sophomore Organic Edition

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Posted by Derek

I had a lot of long days when I was a teaching assistant. One semester I had three lab sections of sophomore organic chemistry to TA, and sometimes after the first lab of the week I knew that I was in for a rough ride.

Such was the case when we took the students through the good ol' Grignard reaction, as I mentioned here. The problem wasn't the reaction (I have to admit that I can't remember what we had everyone quench the reagent with, actually). The problem was the ether. We didn't have nearly enough fume hood space for all these reactions, so out on the bench tops they were. Two dozen steam baths hissing and gurgling, two dozen round-bottom flasks belching out ether vapors. By the third run-through of the week, I was teaching the lab section from out in the hall, trying to avoid another whiff of the damn stuff so I wouldn't have to run back in and puke in the sink.

The isoamyl acetate synthesis was another one in that vein. That's banana ester, the source of all the cheap, penetrating, one-note artificial banana flavor in the world. It's a pretty dramatic demonstration, in its way, because isoamyl alcohol and acetic acid (the starting materials) smell nothing like bananas, believe me. The workup was extraction with saturated sodium bicarbonate, a perfectly reasonable thing to do since there's an acid catalyst in the reaction.

But you do have to remember to vent the separatory funnel, oh yes. Close the stopcock, pour everything in, put in the stopper, shake it around - but never forget that shaking acid around with bicarb makes plenty of fizzy carbon dioxide. Especially don't forget about it until you've shaken the thing for, like, a minute and a half. And then open the stopcock. While it's pointed at your lab partner. This poor girl comes up to me with this huge stain all over the front of her dress, smelling like a shipwrecked banana boat, saying "I think I need to go back to the dorm and change".

The other thing that I can't help remembering is the day we had everyone do an oxidation with nitric acid, glucose to gluconic acid, I believe. Now, no one does that any more, at least since Emil Fischer keeled over from tasting his own compounds (a fact his Wikipedia article neglects to mention; I should edit that in there). And I'm not sure why that experiment was even in the lab curriculum. We did manage to get everyone into the fume hoods for it, though, thank God, except for one lunatic. He hauled his beaker of hot nitric goodness over to me, stuck it under my nose, and asked "Is this done yet?" I was coughing for three days. No matter where I end up over the next few months, at least no one's going to do that to me.

Comments (19) + TrackBacks (0) | Category: How Not to Do It


COMMENTS

1. Trevor on January 16, 2007 11:15 PM writes...

I had the pleasure of taking the organic chem lab last year, with many of the same reactions mentioned. There were plenty of fume hoods in our labs, but many didn't bother using them for the most noxious of chemicals. I was in a make-up lab at the end of the semester, and a kid thought it would be a good idea to do a mix at an open bench where the chemicals were instead of at his bench with the fume hood. He hit the floor after he inhaled the noxious fumes, and got up with a pounding headache and asking the TA repeatedly if he was going to die.

I never did figure out what it was he was mixing, but I got a whiff from a couple rows over and decided to exit the lab for a bit.

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2. carbazole on January 16, 2007 11:17 PM writes...

As a first-time TA last year, I got to babysit premeds through second semester organic chemistry lab. I started out the semester by telling them that my number 1 concern was that everyone make it out alive, my second concern was everyone retaining the use of all their digits. I knew it was going to be a long semester when we went to pull TLC spotters, and one student proceeded to hook her bunsen burner up to the water line as opposed to the gas line. The fountain of water spewing forth caught my attention, and I informed her that I'd be watching her for the rest of the semester.

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3. milkshake on January 16, 2007 11:29 PM writes...

Hehe this reminds me our freshmen organic labs - We had a good variety as everybody had a different procedure. The linear aldehyde C-12 that was made there is the actual artifical coconut flavor so we we all smelling like coconuts. A colleague across the bay made us cry with benzyl iodide, acetic anhydride caramel was dripping from the celing (after a guy mixed glucose with acetanhydride and added perchloric acid at last) there some were burning droplets of sodium overhead (when beautiful Teresa Narcisa was making sodium methoxide and hit the cooling bath instead)and one prompt evacuation when a half-liter bottle of thionyl chloride got knocked over and spilled over the floor.

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4. Jumbo on January 16, 2007 11:32 PM writes...

My most vivid memory from org chem lab (too many years ago to relate) was a day when we were using elemental sodium for some reaction or another (witness I didn't pursue a career in chemistry but rather became a biologist - yech!). Alledgedly the reaction was done, but another student (I swear, it wasn't me!!), decided to quench it by putting the reaction vessel under the faucet. All of you chemists don't need to have pointed out what happened next: A geyser of flame emitted from the sink drain all the way to the ceiling 20 ft above the floor. What really is fixed in my mind is the TA's reaction. Nonchalantly striding up to the sink, he looked at the panicked student and said: "Doused it with water, didn't we?" and turned to find an extinguisher. Calmness under hysterical circumstances - one of the best lessons I learned in college.

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5. Petros on January 17, 2007 2:59 AM writes...

Reminds me of a couple of things

At school (high school in the US), a class of about 15 each performed the reduction of nitrobezene to aniline,. One fume hood so on the bench top. The HCl fumes were horrendous.

And at CAmbridge U in the first year practicals one student decided to boil up some bezene over abunsen burner fortuantely in a hood.

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6. agogmagog on January 17, 2007 4:51 AM writes...


I have also experienced the Bunsen burner water cannon trick. My stand out memory is the student doing thermal gravimetric analysis on a hydrated salt. Heat to 400oC in the furnace. He switches it off, opens the door and immediately tries to pick up hot ceramic with bare fingers. Ouch! I offer said student a pair of tongs and watch in disbelief as he deftly picks up the crucible using the tongs and places it on his bare palm. Ouch again and sample on the floor. There is always one more fool than you counted on.

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7. GATC on January 17, 2007 9:52 AM writes...

Oh the memories......... Interestingly just a couple of months ago I received a box of old high school and college junk from my parent's attic. In there were my bound lab notebooks from college; general, organic, and analytical chemistry; very interesting reading 25 years later. This post takes me right back to organic. Being a lowly biology major, organic was the big time, and to top things off, we had a genuine east German organic chemistry postdoc as a TA (this was early 1980s before reunification). That guy could get water to crystallize at room temperature!

The two situations that are burned into my memory are the Grignard and several amines dished up as unknowns at the end of the second semester. I seem to remember a water pump running on the Grignard apparatus with so much ether going down the drain that even unused sinks in the lab were bubbling with fumes. It is a wonder that the sewage plant didn't wind up exploding.

The amines came into play when on a dare, a room mate and I decided to pull a week-long drunk just for fun. Drink heavily at night, but don't miss any class. It worked fine until we landed in organic lab and our set of unknowns included various amines. It was the first any only time I had to leave the lab due to nausea.

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8. Harry on January 17, 2007 10:16 AM writes...

LOL- takes me back, it does.

The time- 1975. The place- Sophomore Organic lab. The reaction- nitration of benzene.

We'd all run this reaction and were supposed to be distilling it in this little mini-lab still to get the unreacted benzene out. This little distilling head had a side port for taking off the distillate- just a plain glass tube sticking out the side with a stopper on it so you could stick a test tube on for a receiver.

Well- I was merrily distilling off benzene over a bunsen burner (no namby-pamby steam baths for us), when I glance over at the next pair (two nice-looking young ladies).

To my horror, I see that they don't have a test tube on the still. They'd merely set a 50 ml beaker on the bench top to catch the drops as they fell about an inch from the flame in the burner.

I reached over to yank the burner out from under the still just as the still, and beaker caught fire. Black smoke wafts gently up from the beaker as the TA runs over with a fire extinguisher.

Fortunately, the beaker only had a few ml in it, the still stopped as soon as I got the flame out from under it, and no one was hurt, except for the feelings of the two girls, who were treated to a prime rant by the TA.

Good times... good times. LOL

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9. Tim Mayer on January 17, 2007 11:19 AM writes...

My fave has to be the time a student in my organic lab tried to heat a beaker full of benzene with a bunsen burner. After the TA extinguished the column of fire, he asked the student what was in the beaker. On being told it was benzene, the TA turned to the lab and said:
"I hope everyone noted the characteristic sooty, yellow flame."

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10. James on January 17, 2007 11:56 AM writes...

Why is it that anytime you get synthetic chemists around a table (beer optional) you proceed to gat an unending stream of disasters.

A personal favourite: Undergrad is doing a distillation to separate dimethoxypentane from pentanone. Heats the hell out of his flask and then complains that the vapours won't come over. I wonder over, look at his setup and ask him what he thinks about heating a closed system. He gives a textbook answer, and I pass on the wisdom that he shoul let the flask cool, release any pressure gently, then add a sidearm with a vent and continue.

Guess what happens next. No cooling, stopper removed, explosion of superheated liquids straight onto heating mantle - towering inferno. Calm in the face of danger, I yelp like a scared little girl, slam down the sash and let "Firetrace" do the business.

Undergrads, can't kill them, but they can kill you.

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11. DrSnowboard on January 17, 2007 12:17 PM writes...

Aaah, the memories.
Making MeMgI used to be an Imperial lab. Explicitly written in large letters was 'ADD THE METHYL IODIDE DROPWISE, TAKING CARE THAT THE REACTION HAS COMMENCED'. At least a fifth of the class got a taciturn 'try again next week' from us demonstrators as they injected it in one go and got a geyser hitting the top of the (thank god) hood.
they probably watch a video now.

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12. Dr. Carbon on January 17, 2007 12:17 PM writes...

At UT Knoxville the organic students were performing a recrystallization of home-made dimedone. During the pre-lab chat, I gave them the usual advice; maximum amount of compound in a minimum amount of hot solvent, cool slowly then chill in an icebath, scratch the flask to induce crystallization. So, an hour into the lab I look down the row of benches to observe EVERY student holding up a RB flask and scratching the OUTSIDE of the flask with an index finger. Once gaining their attention with uncontrolled laughter, I explained that although the flask may enjoy their scratching technique, the compound inside was unaware of such carrying-on.

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13. Phil-Z on January 17, 2007 5:50 PM writes...

Since most BS bench chemists are drawn from the same pool as the kids featured in the stories above you still need to watch them for a few months when they're new. Try to stay away from drug companies that have a high turnover of lab techs or you'll spend all your time defending youself from the newbies!
I watched a kid add NaH to a flask without drying the flask first. When his error was pointed out he grabbed a propane torch and was about to flame dry the flask with the NaH still inside.
I think I've mentioned this before but I caught a new PhD weighing out about an oz of a volitile sensitizer on a balance outside the hood.
Avoid newbies.

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14. srp on January 17, 2007 7:26 PM writes...

I read Oliver Sachs's Uncle Tungsten where he describes playing with all kinds of chemical stuff as a kid, making bangs and booms, with little supervision and much facilitation from his relatives. (Great book, by the way.) And I wonder if there isn't a self-selection issue here, where the 11-year old who's motivated is likely to be safer than the 19-year old who's taking a lab because it's required.

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15. joel on January 17, 2007 11:38 PM writes...

My lab partner in college was a kleptomaniac by nature with a penchant for alkali metals. I think he liked the zzipp sound. Anyway, one day he deposited a golf ball size piece of Na in a half-full 1L beaker of water to see what would happen.

Everything you would normally expect happened, until he picked up the beaker and heard/felt this loud report. There was minimal smoke and no bystanders, but we were puzzled about the wereabouts of the unreacted Na until we located it on the ceiling in the form of a ~1.5 inch pancake.

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16. Jordan on January 18, 2007 8:43 PM writes...

3rd-year undergrad synthesis lab, mid-90s. Students are making phenylmagnesium bromide in ether in an N2 atmosphere. Rather than connecting the top of the reflux condenser to the nitrogen source in a "T"-configuration with the bubbler, someone hooks up the N2 so that it is forced to flow into the flask, over the reaction mixture, then out another neck to the bubbler. Student leaves apparatus unattended for ~30 mins while the N2 blows vigorously over his ethereal Grignard. At the end he gets a nice tarry syrup. Instructor tells him it's no good and to start again, so he takes his tarry syrup and pours it... down the drain.

The rest of us got our tracheas nicely decorated with magnesium hydroxide that afternoon.

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17. mike on February 1, 2007 4:25 PM writes...

heh.. I can still remember a friend of mine taking a tablespoon of lithium powder and mixing it with water [in a hood] up to that time I was unaware that you can set an entire fume hood on fire...

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18. Aldehyde on March 18, 2008 10:54 PM writes...

Undergrads... *shudder*
I was a TA in undergrad labs for 4 years and yet lived to tell the tale...
The reaction I hated most (and that was removed from the list pretty quickly) was when the students had to extract a reaction with half-conc sulphuric acid. I can't remember the other contents, but it always bubbled and fizzed, so I told them to pour the mixture into the sep funnel, stopper it, turn it around and vent it inmediatly. Do not shake it first... Ah, well, as things go, one was bound to forget that, pressure built up, she couldn't hold the stopper in place and drenched herself with half the contents of the funnel. I sent her to the bathrooms and found her another labcoat, so she could proceed with the rest of her mixture. Telling her again (all in a very calm manner), how to do it properly, I let her proceed. As soon as I had turned my back on her she drenched herself and her colleague in the rest of the contents of the sep funnel.
I think I then yelled something along the lines of 'too stupid to live' and left her to clean herself up (again).

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19. Robert on April 10, 2014 10:39 PM writes...

#10, in a situation where a term has different meanings in different fields, you need to be SURE that the student understands the meaning from the CORRECT field (especially when they've already shown themselves to be clueless - in this case, by heating a closed system). I wouldn't have been surprised if the student in question had "corrected" the problem by somehow connecting a gas-operated (instead of the normal recoil-operated) autoloading pistol to the aparatus. After all, it is a sidearm with a vent (in the barrel, to send gas to the loading mechanism).

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