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Is evaporate down before freezing for recrystallization pointless?

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DoorSeeker

Rising Star
Does anyone know whether it is valuable to evaporate down your naphtha before freezing when doing a recrystallization? I think theory would answer this question. How much dmt can naphtha hold when at something like 0 degrees F? I see huge ranges for how much naphtha to use for a recrystallization. Everything from just enough drops to dissolve everything (which can easily be just a few ml per gram of dmt) to 50 ml per gram. Here's the real question, if I did recrystallizaton at 5ml per gram of dmt or 50 ml per gram of dmt would the difference be negligible? I'm trying to figure this out because if you use too little you are leaving a decent amount of dmt behind because the small amount left over to keep from pouring out the gunk at the bottom is still highly concentrated but if you use too much you risk not having all the dmt precipitate out... well maybe. That's what I'm trying to figure out.

If anyone knows how much dmt naphtha holds at freezing this should answer the question. I've seen the numbers before but I can't seem to find them again. Thanks. :)
 
As a general rule, rexes are done with a minimal amount of boiling solvent.

NEVER heat flammable materials over direct flame. Set up a water bath, oil bath, or sand bath to do the heating. And just to be safe, don't heat the bath over a flame.

I'd recommend using n-heptane over naptha if you've already acquired freebase status. If you've used a minimal amount of solvent, the recrystallization will begin as soon as the saturated solvent is removed from the heat source.

The way I've had great success is to do your pulls with naptha(assuming that is what you are using)
freeze precip
Do the following as quickly as possible to avoid any dmt from being redissolved:
collect precipitate
dry

Then:
redissolve in minimal amount of boiling heptane
freeze for 24-48hrs
Do all of the following as quickly as possible to avoid any dmt from being redissolved:
pour off the heptane
collect precipitate
dry

Heptane allows quite a spread of different colored precipitate to form, I usually get orange, yellow, and white out of it. Each with their own character.

Picture 1 is the starting material freeze precipitated from naptha that has already been used for two prior pulls.
Picture 2 is the yellow "fraction" from a heptane rex.
Picture 3 is the white "fraction" from a heptane rex.

There is also some that I called "orange" but it already disappeared.
 

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Hi BioTron, a question and two comments:

How do you obtain or separate the "fractions" from recrystallizations?

Most people here a have a hard time already to obtain reasonably clean naphtha. Advising pure heptane is perhaps not a practical general suggestion here.

Finally, and this comment is really the reason for writing this response, you are advising to dissolve dmt freebase in boiling solvent. While I agree with you that this would theoretically be the optimal procedure, I do not agree that it is in the practical context of this forum. Or at least, not unless accompanied by clear warnings about the risks associated with doing so and recommendations for safe procedures that minimize the dangers.

You see, many people who read this forum are not experts or experienced with the handling of chemicals and are likely to make naive mistakes. For example, an instruction to boil a flammable solvent may lead people to use an open pan on a kitchen gas stove to boil the flammable solvent. This is an accident waiting to happen and when it happens, the lives of many people could be endangered. Clearly, a pre-heated (to keep open flames away from the solvent) hot water bath must be used to hest the solvent and the solvent must be kept in a closed container (eg. a glass jar with closed lid).
 
The more naphtha you use, the cleaner your precipitate will be since it will hold onto more of the impurities, but it will also hold on to some small portion of DMT as well.
This really is a trade off with purity and yield. I don't have any hard numbers for you, but for reX the sweet spot for me is about 300mL/g. If I suspect that there is any significant amount of spice left in solution, I'll evaporate to make sure. This often yields a small nugget of dark orange tar that can be run through another A/B cycle to remove the gunk.
I don't find evaporation before reX to be any real help since this just allows more gunk to precipitate out with your spice. (lower purity)
 
Right, I am in the FAQ section. I'll keep that more in mind, I'm not quite used to addressing people with little experience working with hazardous chemicals. I feel like I got caught with my hand in the cookie jar, lol.

High quality heptane is available as Bestine brand rubber cement thinner.

Always use a type of water/oil bath or a steam bath(I actually prefer sand) to heat anything flammable.

AS to separation of the so-called "fractions". I like to do my recrystallizations in a very tall skinny vessel like a test tube or one of those tall form shot glasses. From heptane, I've always had the white crystals stick to the sides of the tube and the yellow crystals form further down, the further down the tube you go the darker the crystal formation until at the very bottom of the tube, there is usually a little mass of brown/dk orange.
 
*Off topic

BioTron said:
High quality heptane is available as Bestine brand rubber cement thinner.

I was under the impression that Union Rubber, the makers of Bestine, went out of business?
 
syberdelic said:
The more naphtha you use, the cleaner your precipitate will be since it will hold onto more of the impurities, but it will also hold on to some small portion of DMT as well.
This really is a trade off with purity and yield. I don't have any hard numbers for you, but for reX the sweet spot for me is about 300mL/g. If I suspect that there is any significant amount of spice left in solution, I'll evaporate to make sure. This often yields a small nugget of dark orange tar that can be run through another A/B cycle to remove the gunk.
I don't find evaporation before reX to be any real help since this just allows more gunk to precipitate out with your spice. (lower purity)

Interesting info about more naphtha holding more impurities. I never realized that. Thanks.

300ml/g though for a re-x?! That seems like a huge amount. You'd be using around a litre if you had just a few grams. Most people do it in a little shot glass. You do this purely for purity's sake and find it to be noticeably better quality? Is this better than just doing 2 recrystallizations with 30 - 50ml/g?
 
The Grateful One said:
*Off topic

BioTron said:
High quality heptane is available as Bestine brand rubber cement thinner.

I was under the impression that Union Rubber, the makers of Bestine, went out of business?

I have searched everywhere and then some for heptane/Bestine and cannot find it for my life. I gave up. I thought they went out of business too.
 
The Grateful One said:
*Off topic

BioTron said:
High quality heptane is available as Bestine brand rubber cement thinner.

I was under the impression that Union Rubber, the makers of Bestine, went out of business?


That very well may be the case, I haven't used that source in quite some time. I just did a search on google and found several sources selling this chemical. If you find the chemsavers brand, It is good, I've used it before. I also found a site selling hexane. It took less than 5 min.
 
BioTron said:
I'm not quite used to addressing people with little experience working with hazardous chemicals. I feel like I got caught with my hand in the cookie jar, lol.
You should not assume any knowledge or experience regarding hazardous chemicals in the readers of this forum. Even though some may be knowledgeable, others will not be. We have a responsibility to all readers, including the ones lacking in expert skills.

You seems to be having some interest and some skills in matters of chemistry, which in itself makes you a welcome addition to the forum, IMHO. Though keep in mind that whereas knowledge is often equated with power, a little knowledge can be a dangerous thing. I assume that you have read the Health and Safety and Attitude pages and have taken them to heart. Safety and responsibility are highly valued skills on this forum.

BioTron said:
AS to separation of the so-called "fractions". I like to do my recrystallizations in a very tall skinny vessel like a test tube or one of those tall form shot glasses. From heptane, I've always had the white crystals stick to the sides of the tube and the yellow crystals form further down, the further down the tube you go the darker the crystal formation until at the very bottom of the tube, there is usually a little mass of brown/dk orange.
When you dissolve dmt freebase in a minimal amount of boiling heptane, the dmt will start to fall out of solution when the heptane starts to cool. But, this initial dmt precipitate will not crystallize, because it is too hot. At temperatures just below the boiling point of heptane, dmt is in the liquid phase. In order to crystallize dmt, the temperature must be below its melting point, which is listed to be between 40 (wikipedia) and 45-46 or 57-58 (dmt-nexus wiki).

So the dmt that precipitates first from boiling heptane, has the form of agglomerates in the liquid phase, that will solidify and slowly and partially crystallize when the solution has cooled down to below the melting point of dmt. Only then will the precipitating dmt accumulate into new and onto existing crystals.

If you want to get the best crystals from a boiling alkane as recrystallization solvent, use pentane, not heptane. Otherwise keep the temperature below dmt's melting point.
 
I have read those pages and agree with the philosophy, and being a little more thorough on topics of safety should be addressed, especially in this sub-forum. I completely agree that a little knowledge is just enough to cause some catastrophic events to occur.

The "fractions" I get from heptane are all relatively free of oils that cause excessive clumping at room temperature, that is the main objective I try to accomplish with recrystallization. Forming those nice white crystals is almost an obsession of mine as well. Those, along with the ease and speed of reclaiming the used heptane by distillations, are the main reasons why I like using heptane after freeze precipitating the pulls of naptha.

I have been considering using hexane to see if it improved the yield of white crystals. Given the indifference of price, I'll probably give pentane and hexane a try alongside heptane(with a reduced temperature for both hexane and heptane) and see how the each fare on producing the crop of crystals I'm trying to achieve. Per Shulgin, crystals from boiling hexane(BP 68C) have a melting point from 67-68C, whereas product obtained from recrystallization from Diethyl-ether have a MP of 47C and are said to be off-white. This seems to indicate that either the purity is increased(and the MP right along with it), or the crystalline structure of DMT is polymorphic depending on conditions.

I'll have to try recrystallization of the darker "fraction" in heptane that is below the lowest MP and see what happens.

Thanks for the help, both with being more thorough about what I'm posting and the chemistry.
 
BioTron said:
The Grateful One said:
*Off topic

BioTron said:
High quality heptane is available as Bestine brand rubber cement thinner.

I was under the impression that Union Rubber, the makers of Bestine, went out of business?


That very well may be the case, I haven't used that source in quite some time. I just did a search on google and found several sources selling this chemical. If you find the chemsavers brand, It is good, I've used it before. I also found a site selling hexane. It took less than 5 min.

I am well aware of how to search on google, but thanks for the tip on the chemsaver brand. However, I was not looking for a new source of heptane (or solvents in general) because I have plenty of Bestine, Naphtha, and d-Limonene to work with. I was more curious about the Bestine brand itself since it was becoming increasingly difficult to find since late last year. All the art and hardware stores in my area stopped selling it or were "temporarily out of stock" for months on end. Many websites are also out of stock for the moment. It turns out that the "Best Test" and "Bestine" brand were bought out by another company called "Speedball Art Products" and should be widely available again sometime in June:

 
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