Fine-Tuning DXM extraction

[peruquet]

Hello Everyone,

Afaik,
An A/B extraction is based on :

A solvent (STEP 1)

An Alkali (STEP 1)

An Acidifier (STEP 2)


My monkey has to extract DXM from
a 150ml bottle of syrup containing 300mg of DXM
(excipients are sugar, benzoic acid, no guafainesin)


He has 80ml of Naphta on hand

My question is :

What is the OPTIMAL ammount of NAOH
to minimize emulsion and maximize Freebasing ? (Question 1)

What is the OPTIMAL ammount of Citric Acid
to convert to DXM citrate without getting
excess acid in the final drinkable glass-shot ? (Question 2)

 

[sekio]

What is the OPTIMAL ammount of NAOH
to minimize emulsion and maximize Freebasing ?

dxm hbr Molecular Weight: 370.3 g/mol
0.300g / 370.3 g/mol = 810 micromoles dxm hbr
so 810 micromol * 40.00 g/mol = 32 milligrams NaOH
(obviously you will use more due to the benzoic acid present)
I would prepare a 1 mol/L solution of NaOH and add 1mL at a time (=1000 micromol NaOH) until pH is >10

What is the OPTIMAL ammount of Citric Acid
to convert to DXM citrate without getting
excess acid in the final drinkable glass-shot ? (Question 2)

Molar mass: 192.124 g/mol * 810 micromol = ~156 milligrams
(or for 3 mol DXM : 1 mol citrate, use ~52mg)
at such low concentrations you can easily add a 2-3 fold excess without too much worry, as much as 500mg citric acid will not be any more than really sour

also: better to do multiple small extractions with naptha rather than doing one big one
and don't let any monkeys anywhere near any lab equipment or reagents

 

[peruquet]

Thank You Sekio
I am relieved

Other futile but epi-curious educational questions:

Why PH 10 ?
Isn't any PH above 7 going to deprotonize the Hydrobromide salts ?
Is it that 8 < PH < 10 makes the freebasing obsolete on the scale of hours ?

Also pure Naphta (which evaporates without residue) ..
.. is rare in my area these days,
but White Spirit is cheap and available


Unexperienced with WhiteSpirit A/B Tek on DXM hydrobromide
I am a little anxious
I do not know how WhiteSpirit compares to Naphta in terms of :
density, non-polarity, and other unthought-of parameters.

 

[sekio]

pH 10 is arbitrary, anything greater than 8 will work

white spirit is poorly defined as to exact composition but is likely a heavier cut of alkanes than naptha is, meaning it will take much longer to ervaporate

also doing an extraction on such a small amount of dxm is liable to have poor yields due to incomplete extractions at each stage if you aren;'t thorough

 

[peruquet]

also: better to do multiple small extractions with naptha rather than doing one big one

also doing an extraction on such a small amount of dxm is liable to have poor yields due to incomplete extractions at each stage if you aren;'t thorough

Then isn't better to do single-batch extractions
because the factor time T is likely greater when all syrup is processed at once ?
(time spent freebasing in NAOH, time spent converting to citrate in separatory funnel)

How do you define 'thorought' ?
There is no way to know for sure to tell if (nearly) all DXM has converted to freebase
The same can be said about citrate :
In other words, the instruction
' Shake the Naphta/NAOH-DXM solution for 5 minutes'
.. seems totally arbitrary, like a rule of thumb.

I don't know what is the curve of 'exposure-to-alkali/conversion'
For example (numbers are made up)
Maybe shaking for 35 minutes instead of 5 minutes increase yield from 75% to 82%
I don't know

There's ought to be a methodical way
of determining
a somewhat
preferred temperature when mixing
preferred time of exposure to NAOH
preferred time of exposure to citrate
preferred ammount of solvent


Perhaps all this inquiry is utterly useless in scale
if all the difference it makes is in the hundred mgs while extracting a few grams.
Once again,
I don't know


Thank Sekio for taking the time
to enlighten and en-knowledge

 

[sekio]

acid base reactions are very rapid, in my experience it takes no more than 60 seconds of vigorous mixing to convert between salt and freebase

There's ought to be a methodical way
of determining
a somewhat
preferred temperature when mixing
preferred time of exposure to NAOH
preferred time of exposure to citrate
preferred ammount of solvent

there is - perform a series of extractions, varying one variable at a time
unfortunately nobody has done an in depth study on extraction of dxm because there is no real academic reason to need to do such a thing
maybe you can be the first

 

[peruquet]

Oh please, I meant to ask ...

Would Turpentine work as a non-polar solvent
despite being chemically very different
from aliphatic hydrocarbon solvent like naphta ??

 

[sekio]

I wouldn't use turpentine as a solvent, it doesn't have a definite composition depending on which trees it was extracted from

Besides I don't think DXM freebase will have a good solubility in terpene hydrocarbons