Converting alkylamines like DMAA/DMBA/DMHA to free base?

[Soulfake]

I have some "AMP-Citrate" (Dimethylbutylamine, an alkylamine stimulant similar to DMAA) as well as DMHA HCL (Dimethylhexylamine).

Now I wanted to convert the DMBA-Citrate and/or the DMHA-HCL into the free, liquid amine base which I guess should smell quite like washing-powder, others experience this flavor as "fishy", I always found it just "chemically fresh". When I was walking near a car-washing station there was a really strong smell, at first I thought maybe a ton of amphetamine paste fell out of a truck container until I saw the car wash station.

Is it possible to convert the alkylamines with household stuff like baking soda / sodium bicarbonate or do I need anything from the chem store? Another question that comes to my mind right now is why for example cocaine base / crack is made with baking soda but forms the free base and not a carbonate? How do you know if the compound you neutralize with baking soda will be a base or a carbonate salt? If I would get DMBA/DMHA-Carbonate how could I transfer this further into the base or should I start with a different compound than baking soda?

 

[Soulfake]

It has to do with the pKa value (googlable). I believe with something like cocaine, the carbonate will form in trace amounts however due to the nature of carbonate (CO3)2- would need two cocaine+ not to mention that in aqueous solution ... So in reality the HCO3 as a weak base is mostly attracted to the strong acid H+ of the cocaine HCl, forming H2CO3 which in aqueous solution quickly becomes H2O+CO2 and evaporates (to an extent as there's an equilibrium to be maintained, with that though its on the order of .000000..1 : 1. Not sure about the amine bases although google pka values and you should be able to find your answer eventually

Thanks for the quick reply! The values are:

Dimethylbutylmine: pKa/pKb 11.07 (pKb)

2-Aminoisoheptane/Dimethylhexylamine: pka: 10.42 (self calculated with MarvinSketch, not sure if it´s right because it somehow doesn´t matter how I change the chain lenght, it´s always 10.42, also with DMBA)

I would be interested in Phenibut too, it´s Pka is: ACD Acidic: 4.1 pKa/ ACD Basic 10.51 pKa

So will those yield some carbonate salts or free bases with sodium bicarbonate? I´m still trying to understand all that pka/pks, ph etc. stuff but I don´t get it and have no time to spend hours on learning those chemistry formulas as I have really much other stuff to study for the next year.

 

[adder]

The length of chain has negligible to no impact on the pKa of amines for higher homologues, what has the most impact on the pKa is electronic and steric properties of the alkyl substituent(s) on the nitrogen atom and how many there are. Longer alkyl groups do not differ much with their electron-donating properties.

The pKa of the conjugate acid of NaHCO3 is ~10 which is enough to freebase amines, keep in mind acid-base reactions are equilibrium reactions, so by carrying out a few consecutive extractions with an organic solvent on the basified aqueous solution of your amine salt you push the equilibrium towards freebase amine and eventually get all the amine out of the aqueous solution.

You can calculate the equilibrium of an acid-base reaction by comparing the pKa values of two acids on the left-hand and right-hand side of the reaction scheme. E.g.:

             CH3NO2 + HO(-) <-----> (-)CH2NO2 + H2O
pKa =         10                                 14

14 - 10 = 4 which means that the concentration of (-)CH2NO2 will be 10^4 times higher than that of CH3NO2.

 

[Soulfake]

Ok so yesterday I wanted to make a quick test if it will turn into base or carbonate so I took about 10mg DMHA hcl and 10mg DMBA citrate, then I added about 10mg Sodium bicarbonate and 1 drop water. It had a strong reaction but I couldn't recognize any smell. I heated the spoon to make the reaction faster and more efficient which resulted in a bubbling/cooking liquid, for a very short moment (1 breath) it gave an ammonia-like smell (the stingy type, not the smelly) and then just dried up to a white powder. Maybe I heated it slightly too fast.

But there was no sign of a reaction into the free base as I couldn't smell any familiar amine type aroma, what did I wrong? Or is this a sign that it will only react into the carbonate-salt of each drug anyways even if I calculate the exact amounts of needed Sodium Bicarbonate, heat etc.?

 

[adder]

If you want to freebase those amines and isolate them, you don't need to calculate anything, you have to dissolve the amine salt in water, then saturate the solution with NaHCO3, the solution should become cloudy, then extract the amine into an organic solvent immiscible with water, dry the solution with a drying agent, filter it and evaporate the solvent.

Like I wrote in my previous post, the acid-base reaction is an equilibrium reaction. It can be irreversible only when there is a very big difference in the pKa of the acid and the conjugate acid of the base and the reaction does not proceed in reverse, this is essentially limited to deprotonation with organolithium bases such as n-butyllithium or lithium diisopropylamide and sodium hydride. Anyway, considering the pKa of protonated alkylamine is ~10 and the pKa of the conjugate acid of HCO3(-) is ~6, the equilibrium constant for the reaction is therefore 10^-4 which means when the equilibrium is reached the aminium/amine ratio is 10^4 for the stoichiometric reaction. Thus, you will not fully convert the aminium into the amine by adding stoichiometric or close to stoichiometric amount of NaHCO3, but by carrying out several consecutive extractions on the solution of the aminium salt saturated with NaHCO3, you will be able to get all the amine out of the aqueous solution.

 

[Coolwhip]

Are you trying to truly create freebase? Or just change the base a la crack?

 

[adder]

If it is the latter, it will not work like it does for cocaine. Cocaine has a much higher molecular weight and it is a solid in its freebase form (crack cocaine). DMHA and DMBA are liquids.

 

[Soulfake]

thanks adder, I think now I got it
Which other/stronger base instead of Sodium Bicarbonate could I use for the reaction? Would Sodium Hydroxide work better?

edit: Can I use petroleum ether (or is it called petroleum naphta in english? The stuff consisting mainly of Hexane and Pentane) as a solvent to extract the base?

@Coolwhip I just want to convert it into the free volatile base, not something similar to smokable Crack (I guess you would have to smoke quite a big amount of such alkylamines to get any effects and as they are mainly norepinephrine releasers and inhibitors I guess it would be quite heavy on the heart and not that pleasurable at all, although I don´t have experience with smoking stimulants)

 

[adder]

NaOH would be preferred here, but you could use Na2CO3 or Na3PO4 (or analogous potassium salts) which are more basic than NaHCO3 as well. Petroleum ether can be used to extract simple alkylamines. As for the name, I think petroleum ether is the most common one for the hexane fraction.