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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: Twitter: Dereklowe

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« Public Utility, You Say? | Main | Circular Mistakes »

October 12, 2004

A Day in the Life: Dichloromethane and Peanut Butter

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Posted by Derek

OK, I've got dry dichloromethane ready to go, right out of the Aldrich bottle. It's not like dichloromethane ever gets all that wet, not compared to something like THF. Stuff's a sponge. Man, I remember the days when we had to distill that fresh from sodium metal. And the fires! Now we just pay more money and it comes in a syringe-sealed bottle. What a deal. Beats calling the fire department once a month.

Bottled dry solvents! I'd have called that the height of decadent luxury back in grad school. Of course, a lot of stuff looked like the H. of D. L. at the time, have to keep that in mind - minimum wage would have been a real pay raise, considering the hours. . .took years before I could look at ramen noodles again, and that week where all I had in the place was a jar of peanut butter - smooth, too, worse luck. . .

Where was I? Dichloromethane. And my starting material, which was the right stuff two weeks ago and better not have changed into something else. Looks the same, anyway. I should take better care of this stuff. And thionyl chloride, hmmm - used to be a big bottle of it over here, but stuff moves around. I only do a fraction of the chemistry that goes on in this lab any more, and things get rearranged without me finding out about it.

Nope, not here. Must be some next door. . .what kind of research organization is this, anyway, that doesn't have thionyl chloride lying around? Sheesh. I spent half an hour the other day looking for a bottle of iodine. Everyone was supposed to have it, according to the Infallible Inventory System, but half the folks I asked had just loaned it out to someone - couldn't remember who - and the other half looked at me as if I'd asked them for Eye of Newt or something.

Ah, here we go, and the label's not even scorched off or anything. Must be good stuff. You've got to be either a serious chemist or an idiot to order an 800-mL bottle of reagents like this, though. Going to go bad by the time you get to the end of it, unless you've got a couple of big 250-mL chunk-style reactions to get through. Sure isn't one of 'em here. . .zero-point-three-five mL, right. You feel like a fool taking 0.35 mL out of an 800 mL bottle, but what the hey.

And a drop of DMF, to move things along, and that's that. I'm not sure that I'd trust a synthetic chemist who doesn't know the drop-of-DMF trick to speed up a thionyl chloride reaction. Something lacking in their education. . .probably didn't spend enough hours in the lab during grad school. Or maybe they didn't eat enough peanut butter. . .yeah. . .that must be it. . .

Comments (5) + TrackBacks (0) | Category: Life in the Drug Labs


1. Todd Romoff on October 12, 2004 10:35 PM writes...

OK, I didn't know about the DMF trick, and I've been doing this for 20 years. I did recently learn another trick - if you add 1 mg of copper(II) sulfate per 100 mL of methanol or ethanol, sodium will dissolve extremely fast, perhaps 10 times faster.

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2. The Novice Chemist on October 12, 2004 10:49 PM writes...

Okay, I didn't know that one either; but then again, I'm a little new to this. (Certainly newer than both Derek and Todd.)

Why does the DMF work?; I assume that you're doing some kind of chlorination. Does it act like DMAP somehow in a acetylation reaction? Inquiring minds want to know!

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3. Peter the Not-so-Great on October 13, 2004 12:57 AM writes...

Ah yes, solvent stills...I never started a fire with one when I was in grad school, but I came damn close to total disaster once. One weekend, I started to collect a large amount of solvent from a THF still, and promptly forgot about it; I even *left the lab* to run some errands and eat dinner (noone else was in the lab at the time).

When I came back a few hours later, the still pot had gone to dryness! I figure the only reason I didn't burn the entire building down was that I cranked up the nitrogen flow into the still when I started collecting. After getting over the panic phase, I let everything cool down, dismantled the still, *carefully* quenched the sodium in the still pot, and set up a fresh still. My supervisor never found out, either...

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4. Derek Lowe on October 13, 2004 9:43 AM writes...

The DMF forms a catalytic amount of a much more active chlorinating reagent, a Vilsmeier-looking thing, if I recall correctly.

And I had really never heard of that copper sulfate trick, oddly enough, even though I've been doing sodium/methanol reactions ever since my first research project as a undergrad back in 1981. I actually need to make some fresh sodium methoxide today, as fate would have it. I'm going to try it out and report back. . .

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5. Dawn B. on October 13, 2004 12:32 PM writes...

Too cute rambly post that is so much a "day in the life of."

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