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NaOH residue in DCM pulls

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acacian

acacian

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Hey all,

recently made the change to DCM for testing Acacia.. I have adopted it in my extraction routine due to pulling a wide range of alkaloids and fast evapping... however.. A problem I have now encountered a couple times is residual NaOH seems to be making it into some of my extracts. My guess is that because DCM can hold a small amount of water that perhaps it is holding very basic water which is ending up in the final extract. Toluene/xylene I've not encountered this issue..

Could this be a result of using too much NaOH in my soup? I usually only use about 6g. After doing my initial pull - I am rinsing with slightly salty basic water a couple times before separating and evapping. I've carefully allowed the layers to separate properly before draining the solvent off - and the solvent has no visible polar layer floating in it. I am using analytical grade solvent.

Wondering if any DCM users could chime in here?
 
What makes you sure that the residue you have is naoh? Dichloromethane like any other fast evaporating solvent will form water condensation droplets on its surface especially when you blow air on it. Could the condensation formed be what you think is residual naoh?

Noah is strongly polar and will stay in the Polar layer. I use both chloroform and dichloromethane on a regular basis for extractions and I don't get this issue. I don't even wash my solvent after pulling.

Droplets of basic solution can pass into your pull and you won't notice it if it sticks to the sides of the container. When the DCM is evaporating those basic solution droplets will stick to the sides of the container while your extract will stick at the bottom of the container. If I notice any basic droplets on the surface of DCM I simply toutch the droplet with the tip of paper towel. It readily absorbs onto the paper towel.
 
Also when I pull the DCM from the extraction vessel I use a syringe with a needle. I let the syringe dribble when I get it out of the basic solution, wipe it on the sides of the jar then wipe the syringe with paper towel so that no drops of basic solution ends up in my DCM pull.
 
what makes me sure is the typical lye crystals forming which after drying don't dissolve in fresh dcm when poured onto them.. the dcm strips the often yellow colour leaving behind white NaOH looking crystal and they are very soluble in water. I also touched them and ran water over my finger and sure enough was slimy/soapy texture.. the white residue is on the bottom as well as the sides. I wouldn't have thought it would make it over into the solvent but it definitely is there an in abundance, despite several washes after the initial pull
 
The problem is, the density of DCM and solutions of NaOH of a certain concentration is similar enough that droplets of the latter remain suspended. Gravity alone won't separate things of the same density. This a major reason behind the notoriety of halogenated solvents for forming emulsions.

Washing the DCM pulls with brine or sodium bicarbonate solution should help remove much of the lye contamination. Extreme caution when performing the phase mixing will also help to minimise droplet formation.
 
downwardsfromzero said:
The problem is, the density of DCM and solutions of NaOH of a certain concentration is similar enough that droplets of the latter remain suspended. Gravity alone won't separate things of the same density. This a major reason behind the notoriety of halogenated solvents for forming emulsions.

Washing the DCM pulls with brine or sodium bicarbonate solution should help remove much of the lye contamination. Extreme caution when performing the phase mixing will also help to minimise droplet formation.
Click to expand...

How come this hasn't happened for me even though I used copious amount of naoh in small volumes of water? Dichloromethane still Sabi to the bottom and seperated nicely. It took longer time for DCM to seperate then chloroform but it still seperated well and haven't had the contamination issue.

You can do a mini a/b and pull with a non halogenated solvent I guess. I still wonder how this could have happened.
 
OK, I was clearly wrong to state that suggestion quite so definitively!

This makes the conundrum all the more interesting, though. One obvious difference here is that acacian has been testing acacia whereas sidi, if my inference is correct, you have been testing phalaris. A more exact and precise comparison of materials, methods and techniques now seems desirable - are you maybe shaking the extraction too hard, acacian?

Throwing some more ideas around: does the aqueous phase of an acacia extraction end up a bit more dense after adding base? If so, would this be because acacia extractions require more base, or are more concentrated?

Or perhaps acacia has more of a surfactant effect than phalaris - acacian's hunch that water may dissolve in DCM and carry NaOH with it kind of ties in with this; it also reminds me of phase transfer agents. The way this might be working is that one or more quaternary arylalkylammonium compounds carry hydroxide ions out of the aqueous phase along with a certain amount of hydration, which then solvates sodium ions and further hydroxide ions.

It's a pretty safe bet that these quaternary ammonium compounds are of widespread occurrence amongst the acacias. I wonder if they would cause similar problems in extracting from the cactus species where they are also found? Anyhow, this idea can be both tested experimentally and checked for precedent in the literature.
 
As far as acacia goes I used chloroform on an acuminate branch bark and phyllodes. It took longer than usual to separate but it did eventually. I never shake I just swirl the jar with a Spoon until the chloroform disperse into tiny droplets, let it seperate and repeat about 4 times and pull.

Speaking of phalaris i tried the leaf powder sublingually and was active 😁
 
Thanks for the replies guys. There's some helpful info there. downwardsfromzero your inference is correct I am working primarily with acacia and differebn't species with each gtest usually. I have been shaking solution more lately.. I will adopt my more gentle swirling again and see if that makes a difference. I don't have too much time right now but generally my method is as follows:

1. soak phyllodes or twig/stem in solution of water, ethanol and vinegar about 80:10:10m for 24 hrs and then boil material for about 45 mins. I then strain material and filter liquid meticulously several times before adding fresh liquid (same ratios roughly) and then boil material for another half hr to 45 mins.

2. Combine, reduce and filter again

3. Make basic with NaOH.. I have not been measuring amounts .. just adding it gradually until I see a reaction occur. Allow to sit and react/cool

4. 100ml DCM added and solution shaken in sep funnel and allowed to stand until separated

5. Solvent drained and washed with a salty basic solution (bout a tsp salt/NaOH) and left to separate

6. Solvent drained and slow evap in glass tray
 
Common way of cleaning a solvent is to just add drying agent in form of some dry salt and mixing it, probably calcium chloride would work based on quick internet search.

But I've never worked with DCM.
 
I edited my last post to include a couple more ideas so have another read, particularly the quaternary ammonium bit. [The edit took longer than expected, otherwise I would have just made another post.]

Phalaris powder active? No solvents required at all then, sidi!
 
..hi all...with DCM there is a quaternary ammonium salt byproduct that can form slowly in extended separating funnel exposure, in small amounts, but it is easily removed by cleaning the product with pure water...it's possible acacian there could be a minor contaminant in whatever source of NaOH, if it's not lab grade..this can vary..but also with acacias and other plants there can be very fine particulate matter (of different kinds) that requires either scientific grade filter papers, or decanting, to remove..patience is always the key with extraction

when i get more time i look forward to commenting more on recent Phalaris findings, and the good news there...
 
Ooh, good call, nen - the possibility of solvent reactivity slipped my mind yesterday! It would be a tad ironic if it were the tryptamines themselves that have been causing phase-transfer through in situ formation of the N-chloromethyl derivatives. On a similar note, it's worth remembering that chloroform has been observed to react with mescaline, in this instance to produce 2-chloromescaline (albeit not a qaternary compound.

It seems reasonable, while on this tangent, to imagine that trichocerine might form a similar quaternary ammonium compound, and also that N-chloromethylated primary and secondary amines (e.g. those of T, NMT, mescaline and N-methylmescaline) would be reactive alkylating agents and possibly genotoxic/carcinogenic. They might not survive the basic extraction conditions but it still seems worthy of caution - not to mention being the kind of question that Endlessness' or benzyme's labs might be best equipped to answer (or any other bright chemists out there!)
 
^..hey DFZ it's a fascinating world of compounds, these reaction by-products.. and always enjoy your hypothesising....some quarterny ammonium salts are among the most effective of known anti-covid agents..
Chlorinated DMT analogues are certainly of unknown toxicity..though interestingly this paper -
www.ncbi.nlm.nih.gov

Reaction of N,N-Dimethyltryptamine with Dichloromethane Under Common Experimental Conditions

A large number of clinically used drugs and experimental pharmaceuticals possess the N,N-dimethyltryptamine (DMT) structural core. Previous reports have described the reaction of this motif with dichloromethane (DCM), a common laboratory solvent used ...
www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
found that it wasn't that easy to form them in standard lab extraction or purification conditions...only by really extended exposure...

"..we became aware of reports detailing the reaction of DMT with dichloromethane (DCM) to form N-chloromethyl-N,N-dimethyltryptamine chloride (10) ...These findings have caused some chemists to question the appropriateness of using DCM in the synthesis, work-up, or purification of DMT derivatives, despite the fact that DCM possesses many desirable traits like being one of the only commercially available low boiling solvents that is nonflammable...

Here, we confirm that DMT does form (10) when stored in DCM for extended periods of time as previously reported. However, we find that under typical experimental conditions, the reaction of DMT with DCM does not negatively impact the reaction yield or increase the risk of contamination by (10). We conclude that DCM is a suitable solvent for the work-up and purification of DMT and related analogs..."

..so, unless exposing the alkaloids for many hours (and probably heat) it is unlikely to form these byproducts
 
Might add that the only toxic smoked extract I had came from an Extraction where chloroform stayed in the basic tea for many days.
 
How many days? I’ve had an extract sitting in DCM for about 4 days now as have been experiencing a difficult emulsion. I since found that out that some of the precipitates were ‘bottle necking’ in the sep funnel as the layers separate within seconds when transferred to a large bottle. Will evap tonight.. have been a little busy this week. Hoping it hasn’t formed dimethyltryptamine chloride :/
 
^..it's partly a function of temperature as well as time...if the DCM is very cold, at 4 days there is less than 1% chlorinated tryptamine (of the total alkaloid, which is probably not a problem), but it's still potentially there..at higher temperatures more can be formed in that time..in general, 1-2 days would be the maximum to leave it sitting with tryptamines to avoid the byproduct..if extended exposure is required, a different solvent should be used...DCM is particularly good for purification, crystalization and chromatographic partitioning
it would generally be advised to deal with emulsions as quickly as possible - pH change, some heat, adding more water, centrifuge etc..or just ignore the emulsion if it's small, it's probably not trapping much alkaloid.. Conclusion: 24 hours cold is recommended maximum continuous DCM exposure..that said, i have not personally seen issues with longer DCM exposure times, but the science suggests the above...i have seen issues with chloroform, as also noted by sidi
 
Thanks nen..

The issue here is not that i can choose between the DCM and an emulsion sitting above it and sacrificing a little yield.. the DCM just doesn't want to go to the bottom in a sep funnel shaped vessel.. I've never had this happen before.. whatever the precipitate is, it seems to want to compete for the bottom of the funnel.. whereas when putting in a large 5L bottle they separate instantaneously when they have an even surface. So what I am doing now to try and get around it, is meticulously filtering the liquid.. I've added some extra DCM and mixed thoroughly so am confident all the alkaloids which be in the NP layer and alkaloids shouldnt be lost in the caught particulates.

I'll then pour off as much as I can of the soup leaving mostly DCM and a small amount of soup.. yet whenever I transfer the bulk of solvent (with some soup in there too) to a smaller vessel, the precipitates start mixing at the bottom again. Its strange that when they are both "flat/even" in more spacious containers ewith a flat bottom, they separate with ease.. so I don't know that is is an emulsion per se.. but that the DCM is not falling to the bottom when these precipitates are bottle necking..

perhaps I'll upload some pics to show exactly what's going on..
 
That sounds like a classic case where filtration should sort out the issue. Particulates will deinitely increase the likelihood of separation problems since, again, it looks like there's an issue with the density range being a bit narrow.

Your observations regarding the shape of the container appear quite valuable. There's a thing called an aspirator jar, which is like a lab bottle with a sidearm spigot at the level of the base; perhaps something like that will help separate DCM in a tricky situation like yours. I can post a pic in a bit, once I've found the thing :D
 
Thanks downwardsfromzero :)

The apirirator jar sounds like a great tool to have in the arsenal! I will look into that further.

I am doing some meticulous filtering now and the solution seems to be clearing up. Will leave over night as coffee filters are taking a long time. Curious as to what the precipitate was that was competing for the bottom real estate in the sep funnel

Will let you guys know how I go..
 
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