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Topic: I need help removing trace triethylamine from dry d-benzene  (Read 648 times)

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Offline melwiz

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I need help removing trace triethylamine from dry d-benzene
« on: August 17, 2019, 12:05:08 PM »
Hi, this is my first time on this forum but I'm getting desperate.

I just recently dried a pot of d-benzene twice with potassium. After running a blank nmr of my solvent, I found to my horror, a trace amount of triethylamine.

I have no idea how it could possibly have gotten in to the distillation setup, but now I'm much more concerned about getting rid of the triethylamine.

I tried digging through Armarego's Purification of Laboratory Chemicals, nothing really talks about removing triethylamine. I have considered Calcium chloride (the book mentioned it forms addition products with amines) and maybe P2O5 (which appears later as a drying agent for triethylamine :/).

So in essence, I'm in quite a pickle and very confused

Thank you very much for patiently reading to the end, I really hope someone could help me

Offline wildfyr

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Re: I need help removing trace triethylamine from dry d-benzene
« Reply #1 on: August 17, 2019, 09:34:07 PM »
Extract with weakly acidic aqueous solution
Then dry with sieves.

Offline melwiz

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Re: I need help removing trace triethylamine from dry d-benzene
« Reply #2 on: August 17, 2019, 10:18:03 PM »
Thank you so much for your suggestion, I guess there's no escaping acid extraction

My main concern now would just be the introduction of nmr invisible impurities during the extraction (maybe bits of acid or salts)

But I'll definitely give it a go, thank you so much!

Offline wildfyr

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Re: I need help removing trace triethylamine from dry d-benzene
« Reply #3 on: August 18, 2019, 07:41:57 AM »
Inorganic alts are pretty darn insoluble in benzene. You could do a second extraction with sodium bicarb to make sure there is no acid from the first wash. In fact I think I would suggest that, HCl does probably have a little benzene solubility. But bicarb has zero. Then do a brine wash and dry with sieves. I bet you'll be good to go. Don't bother with potassium, sieves are far superior as long as you've dried them correctly. Google "dry solvents with sieves" and a very famous paper by Lawton comes up showing how even things like ethanol go down to 7ppm water when put over sieves for a day.


Just wondering... Is it possible the TEA was from a dirty NMR tube or cap instead of the solvent bottle?

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