Liquid Carbon (liquidcarbon) wrote,
Liquid Carbon

Saturday Night Distillation.

  As one of those spoiled by flash chromatography (and solvent columns), I realized that I forgot when was the last time I distilled anything. After that insane month preceding the ACS meeting, I decided that my homecoming to the hood should commence from distilling furfurylamine, which I use quite a lot as a starting material. No matter what I do, this 250 mL bottle with orange liquid would never end, so I helped it. Not a desperate call for purification in this case, it usually works fine, giving 90+% yields, but it seemed like in a couple of cases the amides wouldn't crystallize because of this colored crap that dragged on from the amine — requiring a column to make it solid.

  I spent a good hour looking for the distillation equipment. I looked everywhere. The only possible apparatus good for about 150 mL was finally assembled, consisting exclusively of the parts occuring only once. It appears that nobody distills things on this scale in our lab. 1–2 L setups and Kugelrohr were much easier to find. I used house vacuum, since the subject boils a little bit too high at about 145 °C at 1 atm. It came out pale-yellow. I used a capillary to bleed in air and was lazy to set it up under nitrogen. But... I took NMR of my fractions. As far as I could tell, all of them contained satisfactorily pure furfurylamine. The brown residue was enriched in some crap, and most of the water came out in the first one. The latter was evidenced by a very broad peak (~0.15 ppm @ half-height) centered at 1.49, as opposed to moderately broad (~0.07) at 1.42 in the main fraction (all in chloroform, stored over calcined, powdered pot carb). And I'm definitely not the winner in "The most original and appropriate choice of an internal standard" nomination. For the absence of mesitylene, 2,4,6-collidine seemed like a good replacement. It is not. Yay long-range coupling.

  It seems like the main justification of these efforts is going to be the augmented aesthetic appeal of pale-yellow over bright-orange.

Tags: nmr, purifications

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