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Topic: Hexamethylenetetramine reactivity  (Read 3813 times)

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Offline Archer

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Hexamethylenetetramine reactivity
« on: December 24, 2013, 03:43:48 PM »
I am trying to add an amine to a molecule by reaction of Hexamethylenetetramine with my molecule which is an α-bromoketone.

I am following a literature procedure which seems simple enough, mix 50 mmol of each substance in 200 ml of chloroform, heat to 50°C for one hour and filter off the product.

50°C degrees for an hour made very little precipitate. Today I heated to reflux (60°C) for 7 hours and the precipitate collected was only about 8% of theoretical.

GC-MS of the filtrate shows is very clean, only the two starting materials present. So I can continue to heat and be patient.

This sluggish reaction is not ideal so I was hoping for any tips on how to speed things up a bit. I have considered a higher boiling solvent.
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Offline discodermolide

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Re: Hexamethylenetetramine reactivity
« Reply #1 on: December 24, 2013, 09:40:23 PM »
Perhaps use toluene and add some DMAP?
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Offline Archer

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Re: Hexamethylenetetramine reactivity
« Reply #2 on: December 25, 2013, 03:33:18 AM »
There are solubilty issues with toluene but DMAP is worth a try, although this my just irreversibly alkylate the DMAP. Otherwise I may have to recover my starting material and try Finklestein.

Thanks Discodermolide and Happy Christmas.
« Last Edit: December 25, 2013, 04:09:09 AM by Archer »
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Offline TheUnassuming

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Re: Hexamethylenetetramine reactivity
« Reply #3 on: December 28, 2013, 02:49:57 PM »
Definitely try adding some NaI. 
If that doesn't help, have you tried going through the azide?
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Offline zoork34

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Re: Hexamethylenetetramine reactivity
« Reply #4 on: January 16, 2014, 11:28:55 AM »
Another easy thing to try would be using a solvent that is more likely to precipitate a salt, like benzene. 

If that doesnt work, use acetonitrile or DMF, heat it up quite a bit (I'd try reflux for the acetonitrile, and maybe 70-90 C for the DMF).  Then, once it has cooled down, precipiate your product by dropping your reaction into some diethylether or THF. 

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