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Topic: Difficult separation of two aryl halides  (Read 4071 times)

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Offline democanarchis

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Difficult separation of two aryl halides
« on: May 13, 2010, 03:42:55 PM »
I'm having a bit of a headache trying to separate two compounds. One is the product from a sandmeyer reaction, a 1-bromo-2-chloronaphthalene. The second is the 1-bromonaphthalene which is generated in a side reaction. The compound can only be purified by running a column in neat heptane, and I have no access to reverse phase or prep hplc. I have about 600mg of the products in a 3:1 ratio.

The compounds co-elute on every mobile phase i've tried. The main 1,2 halogenated product has a MP of 46 and the minor a MP of 6 degrees C, but as a mixture are an oil. Their respective boiling points are too close to do a short path distillation, and there isn't enough material to do a conventional distillation.

Any suggestions? 

Offline MissPhosgene

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Re: Difficult separation of two aryl halides
« Reply #1 on: May 13, 2010, 09:36:17 PM »
Do you have access to a prep gc?
Stereograms of the 32 crystallographic point groups: little bike wheels of cold, hard, pure rationality.

Offline demoninatutu

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Re: Difficult separation of two aryl halides
« Reply #2 on: June 23, 2010, 01:14:05 AM »
If you're using the Sandmeyer reaction to substitute chlorine, why are there bromine side products?

Given that the main product has a melting point of 46 degrees, have you considered a recrystallistation?

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