Sciencemadness Discussion Board

Triethylamine complexes

ItalianChemist - 26-1-2011 at 05:40

Hi! I'm new and i excuse me for my english, but I'm Italian and I kwow it only a little...
I ask for somebody who knows synthesis of triethylamine complexes with Fe,Ni,Cu and Co.
And i'd like to know sythesis of trietilammonium hydrochloride and acetate.
Thanks to all.
Bye

Nicodem - 26-1-2011 at 06:38

Triethylammonium hydrochloride can be made by simply neutralizing a solution of triethylamine in a proper solvent (isopropanol, ethanol, methanol, diethyl ether) with conc. HCl(aq) followed by rotavaping the resulting mixture. You can additionally dry the residue and remove eventual excess of HCl by adding portions of water azeotrope forming solvents like isopropanol, propanol or acetonitrile and rotavaping again.

Triethylammonium acetate is not crystalline. It is a ionic liquid, so all you need to do is slowly add a stoichiometric amount of glacial acetic acid to triethylamine while cooling in an ice bath. The resulting liquid is triethylammonium acetate.

ItalianChemist - 26-1-2011 at 07:14

Thanks a lot! :)
I Will try this as soon as possible!
If i made triethylammonium hydrochloride it will precipitate?

ScienceSquirrel - 26-1-2011 at 11:56

You will find that triethylammonium chloride is pretty soluble in water, in alcohol / water mixtures, lower alcohols and other things beside.
It is quite hygroscopic and if left out in the air will attract sufficient water to dissolve.

Sedit - 26-1-2011 at 12:32

Perhaps as with a few other amines you could precipitate a saturated solution using acetone as long as the solubility of the amine hydrochloride is low enough.

ItalianChemist - 28-1-2011 at 13:49

Thanks to all!
I've just tried to neutralize a triethylamine solution in acetone with diluited hydrochloric acid, but i've obtained only a white solution with no precipitate!
Triethylamine smells like fish :S

Ozone - 28-1-2011 at 15:38

He meant to neutralize the triethylamine (TEA) in an appropriate solvent, e.g. to treat a given quantity of TEA, dissolved in, say, isopropanol, with a stoichiometric (1:1) quantity of mineral acid (e.g. HCl, calculated from, say, 37% w/w).

Which...it looks like you tried to do. Acetone is a poor solvent choice for use with acids because they can cause ketones (such as acetone) and aldehydes to condense.

My guess is that (most likely) a) insufficient acid was added and the acetone is co-solving the amine and/or (less likely if the acid was dilute) b) some of the acetone has condensed.

Hold your nose,
O3

Nicodem - 29-1-2011 at 06:21

ItalianChemist, I never talked about any precipitate and have no idea where did you got that misconception from. It seems obvious that you misread my post (you should try using machine translation if you have troubles with English - often it helps more than just guessing the meaning of the words). What I said is that you need to rotavap the resulting mixture and azeotropically dry the residue to get triethylamine hydrochloride. You also misread the post of ScienceSquirrel or else you would not use acetone and diluted hydrochloric acid (I wander what was the point of using acetone when you used diluted HCl anyway?).

Unless you used a very exact stochiometric ratio, your acetone solution will go bad due to excess of either of the reactants, so make sure you rotavap it in no more than few days (before it gets a reddish colouration). You will obtain an oily residue which will need to be azeotropically dried by the above described procedure in order to get it to crystallize.

ItalianChemist - 29-1-2011 at 07:17

Ops...:(
I will try again with a better procedure!
I would use it also for TCPO synthesis but I don't know if TEA is corrosive with plastic materials...