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Problem with Freeze Precipitation.

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Crystalito

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A friend called me and described the situation.

A quantity (450 g) of MHRB purchased from a reputable vendor was used in an STB. Lots of base (NaOH) was used to be on the safe side,propably overbasified. Hexane (naptha, mentioning hexane and isomers) pulls were done, first a quantity of 400 ml naptha followed by two pulls of 200 ml naptha. The pulls unfortunatelly stayed in the extraction vessel for some days due to reasons not in my friends control. As a result brown red naptha pulls were procured.

When put in the freezer for 2-3 days nothing precipitated out of the solution. Initial volumes were reduced down to a small volume (a finger's width in a jar) and put in freezer again for more or less 5 days. Still nothing precipitated out.

It seems underbasification is not the problem, nor quality of MHRB. Also the solvent used is the correct one. Volumes where drastically reduced so my friend does not think they are a problem. The only "worrying" part is the color the naptha has acquired and ,of course, that it will not precipitate. I did not know what to respond to my friend, since i do not know if red brown naptha can be the cause of lack or precipitation (other people seem to precipitate fine from naptha that acquired heavy color from the pull). Also, what is the minimum temperature needed for precipitation? My friend's freezer is old but it reaches subzero temperature although she doesnt know exactly how cold it gets.

My friend keeps hearing about the relative ease of STB and freeze precipitation but she doesnt seem to be able to pull it off. Did anyone have something like that happen? What would be the preffered course of action?

Any help welcome, my friend is at a loss...
 
well, since you already have the naptha evaporated down, evap it all the way to see if there is any DMT in there.

This way you can start narrowing down where and if you have a problem.

If you do get some DMT you can clean it up. If nothing, change the parameters of the pulls. (amount, time, solvent, temp..)

if still nothing go back another step.

Don't through anything out, it's in there somewhere.




*edit* also sub zero is not cold enough.... -20c is.
 
if u had 800ml and now have 400ml that may still be too much. ive never used over 150
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From what i hear the pulls were not pooled together, and each individual pull was evaporated greatly. My friend says she can see some clouding of the hexane in the freezer , but certainly not crystals.

*edit* also sub zero is not cold enough.... -20c is.
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I tolde her to check this first, she will go after a freezer thermometer she told me. Do we know the exact temperature precipitation happens, or just because the majority of freezers can touch -20 C (or even lower) it was never looked into?



She tells me nothing has been thrown away, worst case senario would be evaporation and continuing from there. If anyone has any more light to shed please feel free to do so. I will update as i learn her news.
 
you can try either evaporating some more and sticking in the freezer again. If the solvent is getting cloudy but no precipitation, then its probably just not saturated enough (and/or the freezer isnt as cold as it should be.). By the way there is no 'temperature where precipitation happens', because precipitation is a matter of saturation, so it will depend both on temperature, amount of solvent and amount of dmt. There must be a curve one could graph, of how much dmt dissolves in how much naphtha at each specific temperature, which must go down with temperature, but AFAIK nobody ever tested enough to make this graph. I do know that somebody tested precipitating on a very cold (-80c) freezer and there was no significant difference in yield from the -20c one.

Alternatively, appart from evaporating some more of the solvent, you can try doing a small A/B on your red naphtha (re-salting 3x, basifying, extracting again), which should help with the colour. Im not sure if this red naphtha problem can indeed influence in precipitation or if they are two separate problems. In any case it wont hurt to do that. Indeed never throw anything away.

So you are sure the mimosa is good, yes? And appart from being left for a few days, was each naphtha pull properly mixed before pulling?
 
We talked over chat but i prefer answering here as well for documenting purposes and sake of continuity (some other people might be facing the same problems).

Its good to know that about temperature! I suspected it was a function of concentration...but as i always do i thought it wise to ask.

So you are sure the mimosa is good, yes? And appart from being left for a few days, was each naphtha pull properly mixed before pulling?
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Yes, from what she tells me (and i have checked the web address myslef to make sure its indeed what she tells me it is) she utilised a rather reliable vendor that is also a favorite of many people here , so no qualms about quality. On a related note : seems rather nice that people supplying bark so far have stayed true and we havent seen "bulking up" the weight by utilisation of...unscrupulous methods. Lets hope it stays this way and vendors of such materials are people with a genuine interest about them.

Yes, also the naptha was properly mixed. I made sure also to ask her, since i imagine someone could simply get bad results because the solvent was left just to rest on the aqueous phase. She told me though that she mixed it "hysterically" (thats the adjective she used).From what she told me she shook it like there was no tommorow. I asked her about emulsion issue and she said there was none, propably overbasification saved her.

I will update as i receive more of her news..She goes a bit slow since time is not on her side, so i suspect the pulls might also contain more hydrophobic compounds than a "standard" quick pull.So far she seems disappointed ,thinking it was a simple procedure with surefire results, and i remain baffled about the reaction of the material. I try to keep her positive,since the vedrict has not be reached yet. She told me that nevertheless she will keep pulling with hexane.
 
No matter how long the naphtha stays in contact with the basified solution it should not get a red/brown colour. People leave naphtha pulls in STBs for weeks and nothing is red.

But on the other hand there are quite some other people who report similar problems, even red crystals and thus is always with STBs. For my understanding naphtha should not get red/brown and if it does so I am willing to bet that there's something wrong with the bark.

How about this explanation: vendor's mimosa is adulterated (this may or may not be the fault of the vendor) -> something in the adulterant is unstable enough to break down after long exposure in very high pH (STB) to produce a naphtha-soluble chromophore -> naphtha gets red.
 
How about this explanation: vendor's mimosa is adulterated (this may or may not be the fault of the vendor) -> something in the adulterant is unstable enough to break down after long exposure in very high pH (STB) to produce a naphtha-soluble chromophore -> naphtha gets red.
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That would be worrying ,given that lately in the forum people mention red or even...brown naptha problems with STB. I wonder what their yields are, this could pinpoint if there is some adulteration going on.

I wonder how things will flow the coming months, if there will be more such occurences reported. So far, i do not know what to make of it.
 
It would be very helpful if people who get stuck with brown, red etc naphthas and/or reddish crystals to also report the vendor. Crystalito, would you like to make a mention of the vendor at the supplier's section?

If adulteration is to be blamed we should be able to track it down.
 
where is the naphtha from? does she have access to msds from it?
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Back for a bit leaving again tommorow.

The naptha is from the local supermarket. Me and my friend reside in a country where unfortunatelly the brands people mention in the forum simply do not exist, i think only zippo and swan lighterfluid exists here.

The naptha came in 400 ml bottles, for cleaning use. It was crystal clear in color and left no residue upon evaporation in bulk.The label says "hexane and hexane isomers" and the number it gave points to hexane when googled. Having used pure hexane in the past in labs, i bought also the same brand from the same supermarket as my friend and had a look at it, it smells like, evaporates like and looks like hexane in the lab, hence personaly i do not doubt its composition to the extend that i can judge that no major contaminants are present that could cause the red/brown phenomenon.

Unfortunatelly we do not have an MSDS the maker does not supply one.
 
endlessness said:
inf, there are several people reporting this 'red/dark naphtha problem around. Even with A/B extractions (check jbark's thread for example: A/B vs STB Comparison (pics) + FINAL TALLY! - Advanced/Enhanced chemistry - Welcome to the DMT-Nexus .. Though his A/B isnt a typical A/B as the material wasnt strained after the acid step).
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Yes, it is not typical A/B, it is far more towards the STB side than the A/B. In my opinion straining (or separation of water diffusible stuff from non-water diffusible ones) is what makes an A/B really different from STB. What is more, jbark used typical STB lye amounts in the pseudo-A/B. Reading through this thread I believe not much can knowledge can be gained - for once it is not a true A/B vs STB comparison as you did some time ago.

Back to the issue, yes, quite a few people come with the red naphtha issue and I am inclined to believe that there is some adulteration involved, that is why I think it would be good start for people to mention vendors as well. I do not imply whatsoever that vendors adulterate though!

A possible mechanism for the red naphtha would be a degradation by-product of something from the adulterant due to the very high STB pH that is soluble in the naphtha. This is not an issue with A/B.
 
i picked up from another thread that many ppl who get this red/orange dont let the cloud clear after adding naoh. is there anyway this could contrib? what is that gas?

i seem to have had worse problems since i did that. tho i also combined 200g of half pulled base liquid to 350g fresh bark liquid. i think it has too little water now tho.

its gotten worse since i started using less water.
 
I am also back with the temperatures. The freezer is -25 C , more than enough for freeze precipitation. Still, nothing has precipitated even after a week in there...

Next step will be evaporation...What is my friend supposed to see there?
 
well if nothing precipitated out of extraction with good bark at such temperatures, either:

A- It has xylene/aromatics mixed in (meaning it wont freeze precipitate, so you'll have to evaporate it all)

or

B- Its not saturated enough (so take it out of the freezer, evaporate till there's only, say, a fifth of the original volume left and try sticking in the freezer again. If after that, nothing precipitates in the first 12-24 hours, evap till the end and see if your friend is left with something
 
While the naptha in question doesnt seem to have aromatic hydrocarbons inside (at least its description and numbers dont mention anything), i will not take it for granded : who knows,the manufacturer might not mention it. Is there a "percentage" of aromatics that from that concentration and upwards the molecule in question will not precipitate? Is anything known on that field?

I will tell my friend to evaporate to be on the safe side, and propably try a re-x (or ...x in this case :) ) using another solvent. I dont know,zippo lighter fluid or swan lighter fluid, unless someone speaks against those solvents.

Is she supposed to see crystal formations during evaporation?

Once again thanks for all the help, and sorry for making a rather long thread, i hope in the future it might help other people in similar situations.
 
Once I used a solvent containing 3% xylene. It was quite peculiar, I had divided the first pulls mixed, and divided in two jars. One of the jars had nothing precipitated at all, the other had become of a red colour and had a small amounts of a red precipitation. Later on I evaporated and got a very beautiful red and white crystal formation, I will post pictures here later tonight.

So yeah, as low quantity as 3% will already somehow screw up freeze precip, but you might still get some crystal formation during evap. If its more xylene, its possible that evaporation will yield a goo that refuses to harden up.

Im not sure about zippo or swan, maybe others know. I guess your friend is not in USA so batches must change, but you could still check the links in the first post of this thread and see if it helps:


good luck to her
 
Thanks! Being more region specific,for elucidation's sake, she resides in southern Europe hence many times information concerning products in other continents unfortunatelly does not apply.
 
I was just informed by my friend that total evaporation of the pulls, yielded an oil and not a solid (crystals). She told me she will put it in the freezer for the moment being (propably easier to scrape up), but then, she is lost as what to do....

Re-crystalisation of some short?
 
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