Sciencemadness Discussion Board

ETN recrystalization issues

Turner - 20-6-2014 at 21:41

I have had good success with this material in the past, but today I synthesized aarger amount roughly 80 grams and recrystalized with 800ml of denatured alchohol which turned out to be roughly half and half Ethanol/methanol both of which are suitable recryst solvents. The solution of ETN was very brown/yellow even though it was thoroughly washed and neutralized. After slow crystalizatioh and filtration I had a brownish product which after drying turned even more brown Almost having a burnt appearance. I have Always acheived white pure ETN when I recrystalized from ethanol. I noticed a brown/purple coloration upon the Addition of AN to clear sulfuric acid. Any ideas what this could be?

hissingnoise - 21-6-2014 at 00:54

Any ideas what this could be?

Phenolics and the various other contaminants commonly found in gas liquor ammonia?

Turner - 21-6-2014 at 05:34

Later I will post a picture. It has a very brown color. I think I will try another recrystallization.

hissingnoise - 21-6-2014 at 05:52

The aryl contaminants oxidise to tarry substances which are difficult to remove!

Distilling your acid will give much cleaner products and in higher yields . . .

Turner - 21-6-2014 at 05:56

My left-over solvent from recryst was very dark yellow, so it carried away some if this impurity I suppose. I will try another recrystalization out of interest though.

My sulfuric acid is very clear, and 95%+

hissingnoise - 21-6-2014 at 11:24

My sulfuric acid is very clear, and 95%+.

Then all you really need is alkali nitrate . . . and some glass . . .

Turner - 23-6-2014 at 06:39

Second recrystalization with 100ml of hot acetone, to dissolve 66g of impure ETN, all of the brown tarry substance didn't dissolve and was filtered out, the remaining ETN solution which was fairly clear and only slightly yellow was crashed into ice water precipitating the ETN.

Icefall - 4-6-2015 at 14:38

Sorry for opening such an old topic; but I seem to have the very same issue as Turner had and I can't find any information about this. I have had previous success with ETN and I am very satisfied with it in the role of a sensitive base explosive. Today I used last few grams of ETN I had, and decided to make a larger amount this time - I started from 15g erythritol (I have made only 3g batches so far). After nitration, quite some amount of ETN was obtained, which was very difficult to handle, with broken filtration papers etc. When I measured pH of the outcoming filtrates, they were still very acidic, even after a 500mls of 5% bicarb wash. So I decided to use ammonia (p.a. grade 25-27% NH4OH); after a single wash inside a beaker with concentrated ammonia, followed by dilution, filtering and final washing with water, the filtrate was found to be finally neutral. The crystals were placed into a 400mls beaker, and 200mls of 96% EtOH were added, with another 100mls EtOH prepared for further additon. This beaker was placed into a water bath, preheated to 55°C, with temperature monitoring. As it started to warm up, the crystals immediately began to dissolve considerably (nothing out of the common), but I noticed a faint yellow colour inside the solution. First I thought it was only an optical illusion, but at 40°C I took the beaker out of the water bath and noticed that the liquid was really getting yellow, without a sign of the contamination source. Because there were absolutely no fumes coming of the solution (NO/NO2) I put it back and applied more heat until 48°C, when the liquid phase started to become orange. I immediately took it out and ran a few meters away (nitric esters+red color=makes one scared). As the solution cooled it turn into a nice bright red color (like arterial blood); around 3/4 of the whole ETN was dissolved, with some larger chunks (which have stared to melt) settled on bottom of the glass beaker. I decided to pour some water in it, in an attempt to improve stability of the unknown stuff; it became paler and ETN started to precipitate out -

Is it possible that ETN gets hydrolysed by strong bases such as concentrated NH4OH? I heard that people had used ammonia successfully for ETN neutralisation, although there was never a word mentioned about concentration....What would products of such an alkaline hydrolysis hydrolysis look like ? The only thing I know about products of alkaline hydrolysis of nitric esters, is that they are often unpredictable and contain a mix of organic acids or the former alcohol.

*Sorry, I'm having issues with the IMG format...

Hennig Brand - 4-6-2015 at 16:34

If the washing stage, with only water, is effectively done there is almost no residual acidity left on the surface of the crystals. Simply pouring water over a clump of crude ETN in a filter paper does a very poor job of washing in my experience. What I have found effective is to rinse the ETN after synthesis in the filter which removes a good deal of acidity, then blot it well to remove as much of the acidic water as possible before placing the still slightly ETN in a vessel with fresh water and using strong mechanical agitation before filtering again. Rising after synthesis and then strong agitation in clean water, if done properly, seems to almost make a wash in bicarb solution unnecessary, though I still do it of course. For highest purity, and well formed crystals, recrystallization from a suitable solvent is of course needed as well.

Regarding the yellow color during recrystallization, this link will take you to where I discussed some of my experiences with it a while back and some likely explanations.

[Edited on 5-6-2015 by Hennig Brand]

dangerous amateur - 5-6-2015 at 07:22

When I recrystalize ETN in ethanol it allways gets a little yellow too.
Even when I recrystalize for the second time.

I think some of the yellow tint comes from the ethanol. Denaturing agent or something.

kecskesajt - 5-6-2015 at 10:48

When I purified using denatured alcohol it always turned snow like,white.After 6 month storage its white and has no NOx smell.Purified using 90% EtOH and 10% Acetone.

[Edited on 5-6-2015 by kecskesajt]

PHILOU Zrealone - 6-6-2015 at 08:00

Quote: Originally posted by dangerous amateur  
When I recrystalize ETN in ethanol it allways gets a little yellow too.
Even when I recrystalize for the second time.

I think some of the yellow tint comes from the ethanol. Denaturing agent or something.

It is a bad idea to recrystalize from "unpure" solvent like denaturated ethanol. The denaturant is not always wel defined and often in 1-15% content.

Not counting the colourizers.

[Edited on 6-6-2015 by PHILOU Zrealone]

Turner - 6-6-2015 at 19:02

If I recall correctly you can use the so called "green" or "earth friendly" denatured alcohol, it has a 95% ethanol content which is higher than other ones, this is always what I used until I needed to buy a gallon of it and only could get a gallon of regular "denatured alcohol" which had some methanol and other crap. The best over the counter bet would be everclear 190 proof although expensive and I wasn't 21.

I recrystallized ETN when I made a large batch which had some brownish impurity, I recrystallized it with ethanol and it had the same brown color when precipitated and dried, I decided to dissolve all 70 grams {roughly} in warm acetone, which only required something like 80-120ml to dissolve all. The brown stuff did not dissolve, I filtered it out and was left with a slightly yellowish solution (see pics) The resulting powder was snow white, but when melt casted had a slight yellow tint like the solution which was expected.

DSCN3605.jpg - 97kB

DSCN3604.jpg - 103kB

and the cast

DSCN3631.jpg - 92kB

It would seem that multiple recrystallizations can be done for higher purity, but in previous times, the product I made using only one recrystalization process did not at all noticeably change in it's color or impact sensitivity after 1 year in storage.

[Edited on 7-6-2015 by Turner]

Icefall - 22-6-2015 at 05:10

Well, I repeated the synthesis this time with only 6g erythritol and without NH3, everything went fine...The product was washed inside filter paper, contents transferred to a beaker with d-water, agitated, filtered, transferred to a beaker with NaHCO3 7.5% solution, agitated, filtered, transferred to d-water, agitated, filtered, recrystallized from warm ethanol. Pretty much the same stuff I normally get - snow white flakes, around 10g yield (67% theory)...
Oh, and about the solvent - my ethanol comes from pharmacy, so called Spiritus cum benzino 96% (Latin - Ethanol with gasoline). It comes for a reasonable price, and is denatured only with gasoline (1 liter of 96% EtOH contains 1 mL gasoline). I always sprinkle a bit of NaHCO3 into the ethanol, dissolve as much as I can and decant the solvent, leaving any undissolved bicarbonate behind - this EtOH 96% + 4% water + dissolved bicarb neutralizes any trace amounts of acid stuck inside the crystals. I'm sure there are no significant impurities inside my solvent, which would cause a whole batch of ETN turn orange-red :mad:

kecskesajt - 22-6-2015 at 07:27

Use denatured alcohol as paint strippers.It cheaper and wont cause any thing.

I'm the only one around here who dont have problems with coloration.I always ended up with fluffy/glass crystaline ETN no matter how stitty reagent I used.

BTW, 100th post :P

joseph6355 - 15-5-2018 at 09:24

Quote: Originally posted by Turner  
Second recrystalization with 100ml of hot acetone, to dissolve 66g of impure ETN, all of the brown tarry substance didn't dissolve and was filtered out, the remaining ETN solution which was fairly clear and only slightly yellow was crashed into ice water precipitating the ETN.

Can you dissolve 66g of ETN in 100 ml of boiling Acetone? Are you sure?

DrManhattan - 16-5-2018 at 03:56

Store bought methylated spirits in my area contains 90% ethanol, 4.9% water, and 0.1% Denatonium in order to make it unbearably bitter in case you want to drink it. Would the denatonium (bitrex) affect the re crystallization of ETN? Methanol is a little pricey and hard to find in my area, about $20 for 1L.

Tsjerk - 16-5-2018 at 04:12

Are you sure there is 0.1% denatonium in there? That sounds a bit overkill.

DrManhattan - 16-5-2018 at 04:46

That information came from the company itself as the msds only states 95% ethanol and 5% water so i emailed them asking what else is added. With this particular brand they do not add any toxic additives so maybe the 0.1% bitrex is in there to dissuade people from consuming it.

Tsjerk - 16-5-2018 at 04:53

Well, simple distillation with a little bit of sulfuric acid should get rid of about anything except MEK and methanol.

LearnedAmateur - 16-5-2018 at 06:07

I don’t think that the denatonium will affect it due to the low concentration, it’ll probably stay in solution but if you want to avoid it altogether then you should be able to distill the spirits first - DB melts at like double the temperature required to do so, and I presume would decompose at even higher temperatures although I don’t have an exact figure to share.