Sciencemadness Discussion Board

Diisopropyl amine using isopropyl amine

DisappearingAct - 27-1-2019 at 08:52

Hi all

I want to ask if its possible to make diisopropyl amine from isopropyl amine HCl and isopropyl bromide.

I know by using isopropyl amine this is feasible however I am having huge issues with cooling any isopropyl amine generated (from glyphosate weed killer).

Can I use isopropyl amine HCl or perhaps some other salt or perhaps create the isopropyl amine in situ ?

Much appreciated for any help.

Corrosive Joeseph - 27-1-2019 at 21:03

You might like this -

Diisopropylamine via Isopropylamine alkylation - https://www.sciencemadness.org/whisper/viewthread.php?tid=14...

Can I ask, how are you obtaining your isopropylamine from your herbicide. This is on my to-do list.


/CJ

Elrik - 27-1-2019 at 21:45

You should just be able to combine your isopropylamine•HCl and isopropyl bromide in dry isopropanol with an excess of powdered anhydrous potassium carbonate. A catalytic quantity of potassium iodide may help, as would magnetic stirring while maintaining it at a gentle 35º reflux with ice water going through the condenser.
The above linked synth got poor yields, I wonder if this is from a lack of potassium carbonate. He probably assumed the product would be a stronger base than isopropylamine and would mop up any HBr, but steric hindrance may have prevented that? So use lots of K2CO3

Do you plan to fractionally distill the product to isolate the diisopropylamine? If your having trouble cooling then your likely to have lots of isopropylamine left over since you wont be able to reflux for long.

Are you making hünig's base? Because if isopropylamine distillation is giving you that much trouble, methyl iodide will be just as bad, but far more toxic.

DisappearingAct - 27-1-2019 at 23:20

Corrosive Joeseph, I extracted the isopropyl amine in similar methods to both Magpie and Scr0t. I can confirm surfactants dont cause much issues unless excessive stirring and heat is applied. Since both methods work, I think adding the base to the weedkiller directly (both cooled first) followed by distillation is easier. (Yes technically I didnt managed to collect any product but I could smell it for sure)

Elrik, I think I'll try out your method when I get the chance. I hope this isnt a really dumb question but if I were mix potassium carbonate and isopropyl amine hcl I should be able to detect the isopropyl amine or would this necessarily only happen in the full reaction to make diisopropyl amine. Lastly I need ethyl bromide to make hunigs base but I see that might also represent an issue with my cooling system. Thanks for the safety note :D

Elrik - 28-1-2019 at 12:08

Yeah, sorry, I meant to say ethyl bromide. Same boiling point as isopropylamine, basically.
If you really cant get conditions cold enough there you could attempt ethyl iodide as it boils at 72º. I've read that the bromide actually gives better yield of hünig's base, so you'll want to review the issues involved if you go the iodide route. Perhaps ethyl iodide with catalytic potassium bromide.

Corrosive Joeseph - 29-1-2019 at 01:34

Quote: Originally posted by DisappearingAct  
Corrosive Joeseph, I extracted the isopropyl amine in similar methods to both Magpie and Scr0t. I can confirm surfactants dont cause much issues unless excessive stirring and heat is applied. Since both methods work, I think adding the base to the weedkiller directly (both cooled first) followed by distillation is easier. (Yes technically I didnt managed to collect any product but I could smell it for sure)


Huh, You extracted the isopropylamine, but didn't collect any product.............? Did you add enough base to free the amine...........?

I have yet to try it (soon though), and somebody tells me seal the system (hose pipe off the vacuum adapter out the window), distill through a fractionating column real slow, and collect in a cooled receiver, sitting in ice water.............. I think Scr0t mentions drying over NaOH and distilling again.


/CJ