Question Seems an easy question but is not

[btcboss2022]

I have an alkali mixture of water and meth freebase.
I add solvent in that case Hexane and in the bottom layer appears something that hexane dont dissolve and later the water layer ok.
When I isolate this "impurity" I mix it with DCM and its dissolved.
So here is the dilemma this situation means:

1- Hexane is not enough good solvent for that kind of freebase.

2- DCM dissolves some organic impurities.

What you would do discard it or solve it in DCM evaporate solvent and use it?

Thanks.

 

[bblanco]

good one! lets see where they are....

 

[UWe9o12jkied91d]

Use TLC to determine level that isolated, purified freebase climbs to and use as a reference standard to compare against your "dirty freebase", this should make visible the impurity.Now that you have a reference for the impurity you can go down in the supply chain and identify the source of the impurity if any.Once source is identified you can go on with qualitative analyses.

 

[Osmosis Vanderwaal]

If you knew how it was made you would know the side reactions and have a good idea what it is. There is a list of impurities by synth route on the rhodium archive

 

[Acab1312]

(clearnet)

Impurities in Illicit Drug Preparations: Amphetamine and Methamphetamine - [www.rhodium.ws]

They are right, I personally can only recommend.

 

[Osmosis Vanderwaal]

Hexane no and dcm yes sounds polar or at least aprotic and large dipole moment

 

[btcboss2022]

O
Ok Thanks you all for your answers but I solved the mistery today.

This is what was happening:

Hexane is more hydrophobic than DCM so when the freebase is to mixed with water(not necessary an emulsion) Hexane dont dissolve it while DCM do it even water remaining but if you wait (Im talking about several hours) finally the small layer water remaining is separated and freebase dissolved in the hexane.
Obviously dont need to wait these hours just dry the mixture with anhydrous sodium sulfate, filter it and its done.
I just discovered this morning.
Im learning everyday to try to improve the processes.
No other way to do it than having problema, making mistakes and try solutions.

 

[HerrHaber]

Chlorinated solvents are notoriously forming emulsions with aqueous alkaline solutions such as DCM, chloroform and CCl4, I assume bromoform and its relatives have the same problem but they’re both expensive and considerably more toxic. The secret is in their shaking which should be gentle even if they need more time it’s still faster than with a vibrating dildo and patience. In this case salt isn’t the best choice.

 

[btcboss2022]

In that case happened with Hexane that is not chlorinated but thanks for the info its carefully noted now.

 

[HerrHaber]

It’s called pushing the boundaries of knowledge... don’t worry about the pace but rather focus on the climb.

 

[Mr Good Cat]

Interesting topic. I gonna to keep my eye.

I have my own stupid question: why do you prefer DCM against petroleum ether 40/60?

 

[btcboss2022]

The main reasons are price, accessibility to large quantities in discreet way and layer position of the solvent(DCM is to bottom layer normally)this is more comfortable to work in big scale.

 

[Mr Good Cat]

what hexane do u use? n-hexane cas 110-54-3 or iso mixture hexane cas 64742-49-0?
how do you estimate its solubility in gr of base per ml of hexane?

as i understand iso mixture hexane is a kind of petroleum ether with similar properties? in my case petroleum ether may be 10-15% more expensive. solubility difficult to say, may be i do something wrong, but completely dissolve base from heavy black compound it takes 3-4 ml per 1 gr of base. may be i really do something wrong and waste most part of ether to grab some side impurities.

dcm, probably yes, dissloves it more easy, but i don't like it to be honest don't know why.

 

[Mr Good Cat]

This time I did base extraction with iso hexane cas 64742-49-0. It was small amount 60 gr of chloride just to test the method. Expected base weight - 50.5 gr

I used isohexane cas 64742-49-0 in volume 160 ml to isolate most of base in 3 steps. Each step took around 40-60 minutes to separate layers.
At the same time isolated hexane-base liquid was kept in the flask in the freezer.

But when I got ready to separate leftovers, i noticed in the freezer some amount of water oily liquid separated from hexane.
I separated this oily substance and added to leftovers from main batch, then added some more hexane. After a while oily substance falls down below water layer. Not black, just brown, the same as main water liquid, just more dense and distinguishable .

I separated it and dissolved it with more water and hexane, but still not sure what it was - base or real impurities.

Final yeld around 48 gr of base.

 

[Mr Good Cat]

I did read on this topic of solubility of different solvents this morning. If I understand this topic correctly, solubility depends on vacuum permittivity. If solvent "A" is water, then solvent "B" will be soluble in solvent "A" as much as its vacuum permittivity is high.
Vacuum permittivity of petroleum ether and hexane is 1.9.
Vacuum permittivity of DCM is 9.1.

Some sources point that substances with vacuum permittivity in range 9-10 are mixable with water as much as 6-7%.

Probably, petroleum ether and hexane are much better in comparison with DCM, as some impurities soluble in water will be trapped in DCM together with water.

 

[Mr Good Cat]

Boss, I want to continue your topic on difficult questions of base extraction. Hahaha)))))

I did base extraction rescently. There were three steps of separation done, and I spent with them something as 4 ml per 1 gr of base of isohexane cas 107-83-5.

Still there was small layer of base + shit around 20-40 ml, so I did step 4.
I added something 200 ml more of isohexane to dissolve them. But at this step I got base layer slightly yellowish, that didn't happen on previous steps. Previous steps gave me pure transparent base layer.

It looks if more soluble base is over, isohexane starts dissolve less soluble water and shit in small volume.

 

[btcboss2022]

What you mean with this exactly?
"There were three steps of separation done"
"so I did step 4"
What PH has your mixture at this point?
"But at this step I got base layer slightly yellowish, that didn't happen on previous steps. Previous steps gave me pure transparent base layer."

 

[Mr Good Cat]

I separated base on separating funnel in 3 steps.
Each step I added isohexane in proportions equal 1.3 ml of hexane per 1 gr of base. Each step, here, I got pure transparent base/hexane liquid. And with these 3 steps I dissolved most (not all) base

As there was some dirty base left in water layer, I did separation one time more. I didn't check PH at this point. But as I added NaOH, PH was more than 12.

I think my mistake was I added isohexane too much, may be 2-3 times more than necessary. So I caught some water and shit. I don't think too much shit, but some.

This is how it looked in funnel on this last step.


Another name of this isohexane is 2-Methylpentane, it has the same vacuum permittivity 1.9.

 

[Mr Good Cat]

By the way, isohexane cas 107-83-5 is completely different from isohexane cas 64742-49-0. They have different boiling points. But more important cas 107-83-5 is extremely volatile: starting boiling point is 60c. But if heated up to 70c, you will evap utmost 90%.

 

[Mr Good Cat]

I found another interesting property of two different hexanes cas 64742-49-0 and cas 107-83-5.
Posted it here, if you are interested: http://bbzzzsvqcrqtki6umym6itiixfhn...64742-49-0-and-cas-107-83-5-differences.9422/