• N&PD Moderators: Skorpio | thegreenhand

  • Neuroscience & Pharmacology Discussion Welcome Guest
    Posting Rules Bluelight Rules
    Recent Journal Articles Chemistry Mega-Thread
    FREE Chemistry Databases! Self-Education Guide

Gamma Butyrolactone purification

Status
Not open for further replies.
The temperature increasing leading to transition from liquid phase to gas phase (i.e. BP) doesn't necessarily have anything to do with reactive stability and "defense" against things like hydrolysis. Plenty of compounds hydrolyze at standard conditions that have nothing to do with phase changes.

There does seem to be some sort of azeotrope with GBL and water considering - I don't think - water cannot be distilled out of an aqueous GBL mixture, but that is still not the same as interactions determining the BP. Those would seem to be intramolecular vibrations affected by and affecting IR radiation. Per sort of single molecule there is some energy to lift it from one phase to another, to decohere it enough to start roaming around in the next state.
Certain interactions just make it all too 'sticky' to make that jump as a whole for the compound, but molecules are still as subjected to getting completely fubar'ed through heterogenous intermolecular activity.
 
Technically if you just burn the gbl over the normal gas stove, which will probably goes around 100-150C therefore, most of the impurities that has bp of 150C and below will be evaporated, isnt it?
 
As Transform said, it really depends on what kind of impurities are even expected to be in there? Unreacted 1,4-BDO - the industrial precursor - has a boiling point of iirc 235C so doesn't work...
Formaldehyde, shouldn't that just evaporate out at room temperature?
Propylene oxide same thing
Allyl alcohol, maybe yeah that can be boiled off.

Byproducts of 1,4-BDO synthesis? Phew who knows.
 
Because gbl can be contaminated if keep in a wrong plastic container, so i dont know if boiling can help evaporate the contaminated gbl
 
Contaminated with dissolved plastics... ehh well then we're back to distilling it again which is not an endeavor to take lightly of course, and also stop before you start burning whatever is dissolved in it or the GBL itself.
 
I'd imagine there would be more disolved plasticizer in "contaminated" GBL (e.g. dioctyl phthalate) than dissolved macropolymer.
 
Oh yeah you are probably right... that's likely worse though, phtalates, then again I don't know how bad dissolved plastics would be. Just a different sort of dietary fiber? :p A way to pimp your bezoar?
 
Phthalates seem to catch a lot of crap, but they were at one time considered inert enough to be used as inert carriers for all sorts of stuff. I've seen studies where they feed rats compounds dissolved in diethyl phthalate as a solvent!

Even "biologically safe" compounds like acetyl tributyl citrate can have unexpected activity: in the case of ATBC it is actually a CYP 3A inducer!
 
So convertion to GHB will make the GBL more potent? Because the impurities will not be converted only pure GBL right?
 
There are a few ways to consider your question, but I think they all still give the same answer:
- Per weight: conversions of GBL into GHB makes each molecule heavier which means that for the same weight you get less of them so less potency since they all end up as the same drug. (Apart from the fact that GBL is a liquid measure in ml and GHB is a salt like NaGHB that is a solid either weighed in grams or dissolved in water and measured in ml, but you cannot compare potency for a solution in water like that.
- Pharmacologically: There is little pharmacological difference between them, the only difference basically is the kinetics of GBL turning into GHB in your body and even that is usually negligible - well it is mostly when only potency - strength - is considered.
- The impurity thing: it doesn't matter whether there are impurities present and how much when we are talking about potency. You have some quantity of GBL present and converting that doesn't effectively change it.
 
Converting GBL into GHB actually makes it "appear" less potent because GBL is more rapidly absorbed and distributed around the body than GHB is, leading to a faster peak and therefore seemingly more intense effect.

The area under the bioavailibility curve for both drugs is about the same though, so GHB is not less strong overall, it's just less intense of a peak.

Assuming whatever impurity in your GBL was not a lactone, you could probably crystallize the GHB to purify it as its, I don't know, maybe calcium or magnesium salt? Presumably you aren't going to have access to barium hydroxide, whioch would work best.

If the impurities are volatile, liquid and/or water soluble, then you can probably even get away by forming the sodium GHB salt and then concentrating the reaction volume down over gentle flame until it thickens, then chill it down in the fridge or freezer, the NaGHB crystals should seperate from the water and everything else in the supernatant liquid. The sodium salt will tend to absorb water from the environment, the calcium and magnesium salts will not. (Check Rhodium for info on making the Ca and Mg salts).
 
Last edited:
My friend tried to boil the GBL in a beaker over a normal gas stove and the result is quite well, it seems like the GBL has became more potent than before, we dont know the reason behind can someone explain it, it starts to emit smoke reach 150C
 
Barium is too toxic and magnesium salt, although I may have mentioned that myself, is laxative (milk of magnesium etc)... so I think I'd opt for calcium. Seems inconvenient to crystallize a salt that you're not going to use as is.

Have you actually tried to separate the sodium salt from water? It likes to solidify as a highly hydrated wax, I'd say on account of being very hygroscopic. Are you saying lowering the temperature under STP makes enough of a difference for solubility to achieve some separation?

Maybe doing this stuff in alcohol is better considering it wouldn't stick nearly as much and also wouldn't freeze at -20C to form crystals, seems much more ideal to do such a purification?

bench2046 said:
My friend tried to boil the GBL in a beaker over a normal gas stove and the result is quite well, it seems like the GBL has became more potent than before, we dont know the reason behind can someone explain it, it starts to emit smoke reach 150C
Click to expand...

Lower boiling impurities were boiled off? among which maybe just water :) Well especially non-azeotropic impurities that is.
 
I dont know if its just water that is boiled off, my friend said the gbl were 10% lesser after boiled off and became more acidic, less plastic smell, but more potent
 
bench2046 said:
I dont know if its just water that is boiled off, my friend said the gbl were 10% lesser after boiled off and became more acidic, less plastic smell, but more potent
Click to expand...

so definitely your compound was more acidic, which is a good thing, you're referring to Lysergic acid diethylamide, right? :\
 
WSH said:
so definitely your compound was more acidic, which is a good thing, you're referring to Lysergic acid diethylamide, right? :\
Click to expand...
your comment doesn't make any sense, especially since LSD isn't actually an acid, chemistry-wise.

and if part of the GBL exists in the solution as GHB, an actual acid, boiling off some water will raise the ph.
 
GBL in the pure form is not an acid because it lacks the proton on the carboxylate group. It's a neutral lactone and only becomes an open chain acid in aqueous solutions.
 
Yes aqeous GBL considering the context: what does the pH do in aqueous GBL (not exactly, I mean generally speaking)? :)
I know you already mentioned it's open chain acid formation, but I thought formation of 'free acid' GHB was rather disfavored?

If you boil away the water in an aqueous GBL mixture will the pH actually rise? Then as the water is virtually gone pH measurement will become unreliable / impossible?
 
I would expect in aqueous environments that GHB can exist as a free acid, but strongly acidic environments probably encourage some formation of the lactone. Oral GHB and oral GBL behave differently in pharmacokinetics so obviously transient exposure to aqueous stomach acid at pH ~1 is not enough to cyclize it.

If you distill off water from aqueous GHB (not a salt), I'd expect it would lose water and hence raise the pH, eventually. But keep in mind that water's pH changes as it increases in temperature too!
 
Status
Not open for further replies.
Top