kakatea - 1-8-2011 at 16:21
Howdy!
I have quite naive question, but quite not-at-all-obvious for me: I have primary amine that is oil (2-methylbenzylamine, to be precise). I want to
make hydrochloride of that, hoping it'll be solid.
So, how do I exactly do the titration?
Do I dissolve amine in water, add HCl, wait for it to crystallize?
or do I dissolve amine in something organic, like chloroform, add HCl and happily collect the precipitate?
Thanks, and please don't laugh...
thea.
mario840 - 1-8-2011 at 21:43
Firstly you must calculate how many mols of HCl you will need , after that there are couple routes:
1) dissolve in small amount of water and start adding slight excess of of 38% HCl , then evaparote water you to start crystallize and move whole
solution to fridge (better yeild)
2) dissolve in organic solvent like toluen etc. and start "gassing" solution out with HCL (made from for example NaCL+H2SO4) , you got crystals and
don't need to evaporate solvent
kakatea - 2-8-2011 at 08:59
thank you!
Do I do the same for other salts? if I want salt of acid that's not gas, like acetate or sulfate, I can add glacial acetic acid to solution of amine
in toluene? I don't even know are they miscible...
mario840 - 2-8-2011 at 09:35
Yes this procedure is for all amines because they are basic and form salt with various acids, if you want acetate you can add carefully glacial acetic
acid or sulfuric acid, mostle amines in "freebase" form are misible with organics solvents , but you don't have to care that if acid don't, it doesn't
matter, the salt of amine are insoluble in organics solvent so they precipitates out in solution and easy to filter, rember if you don't sure that you
amine is free from water you dissolve it in for example toluene , than add some anhydrous MgSO4, NA2SO4 etc. wait couple hours, filter and than add
acid, water in organics solution will cost you some yield of product, be safe, bye !
Nicodem - 2-8-2011 at 10:32
There are several threads on the topic. I suggest you read them thoroughly. And no, it is not as simple and certainly not as general as mario840's
posts above might make it appear.
PS: Please open referenceless or beginner threads only in the appropriate forum section.