Wednesday, July 26, 2006

The tastiest distillation there is

Today I purified my product using the lab's Kugelrohr distillation apparatus. Unlike many of the concepts one comes across in the field of chemical synthesis, Kugelrohr distillation isn't named for anyone. Kugelrohr translates to "ball tube" or "ball pipe" in German. It's my favorite way of purifying solids with low melting points. The idea is that by applying a vacuum to a flask (round bottomed, ie ball-shaped) with the impure, oily solid in it, you lower the boiling temperature. If the boiling points of what you want to separate are different enough, the pure product distills over into a receiver flask (also ball-shaped) chilled with ice water.
There are other setups for distilling things, but the Kugelrohr setup is infinitely easier to handle when dealing with solids, IMHO.
Rotating or swiveling the flask gives you a more even boil, and in the early days of this technology this was accomplished using a windshield wiper motor connected to a tube or pipe.
See this reference:

Graeve, R.; Wahl, G. H. J. Chem. Ed. 1964, 41, 279.

Today you can buy a swanktastic Kugelrohr apparatus from Sigma-Aldrich and other fine retailers. The apparatus comes with a hot air oven to warm the impure sample and get it boiling. Just be careful not to heat your sample too much, or you'll char it.

Random thoughts:
Is there any etymological relationship to the tasty treat we call kugel?
I think one of the coolest-sounding named reactions (lots of organic chem. reactions are named after someone) is the Chichibabin reaction. My opinion changes often on this matter.



At 2:49 PM, Anonymous Harriet said...

Kugel in German actually means 'sphere', so can be applied to any round object, including your tasty treat.

At 1:53 PM, Anonymous Davis said...

Kugelrohr is German for "ball rod" or "sphere tube".


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