erythritol tetranitrate recrystallization

routes to neutrality

Quote: Originally posted by prometheus1970

plus water is not miscible with alcohol.

Quote: Originally posted by DougTheMapper

It's probably not the best way to do it but it's certainly feasible.

Recrystallization in Methanol and Sensitivity

In my experience, methanol is the most attainable and economic recrystallizing agent- 20L @ $40. Quicksilver mentioned in his legendary ETN lab diary that methanol is as viable of a recrystallizing/deacidifying agent as ethanol.

I have used it myself, and was certain that methanol has to be warmed up to about 50C. However, I noticed time and time again ETN gained a much different structure, crystals being much finer and the unshaven flakes being extra "fluffy" and light. This always resulted in more sensitivity in impact tests......15-20cm hammer fall would always provide a report. Usually, it requires more acceleration, but it went off from a rather regular fall, if I recall correctly. As a result, I have been recrystallizing ETN in regular temperature methanol, just using excess of it where ETN dissolves without much effort and generously adding sodium bicarbonate to the mix. Am I cheating my ETN of being acid-free by doing that? So far, ETN has been stored for 2 months without any change in color or sensitivity.

I've also had an experienced friend tell me that long recrystallization in methanol produces long ETN needles, with similar properties to primary explosives.


Disclaimer: Roscoe, if you think this belongs in ETN recrystallization, please, merge them, but I think this needs its own thread at least to get the discussion started.



[Edited on 16-12-2010 by holmes1880]

Quote: Originally posted by crazedguy

"Much like PETN, ETN is known for having a very long shelf life. Studies that directly observed the crystalline structure saw no signs of decomposition after four years of storage at room temperature." Wiki

I think, I know the ETN/methanol video you're talking about. http://www.youtube.com/watch?v=EEYtr1tU66E There is really only one, by "tooelitetodetermine". I think he just came up with that method on his own, although my first googbook search gave me a simple recrystallization method I use today. As dangerous as it might seem, I think he was rather safe.

Well, give me the worst case scenario of ETN getting past 70C.....it goes liquid and it's mixed with methanol, reducing its sensitivity. Or do you mean like the flask cracking and all that ETN going on the hot stove......

Don't give it a second thought.

An excellent example is that long discussions go on about the use of acronyms, etc in communications clarity. I'm not sure if it's even important to many others. I had been average / mediocre in everything I did academically & it rarely bothered me that most everyone I've interacted with were brighter, more studious, or generally more successful than I was. Frankly I believe that intellectually, I have less going for me than the majority. But I have a large penis and THAT is important.

Yellow liquid precipitation

First time nitration of 7.5 g erythritol with 50ml H2SO4 (96%) and 30 g KNO3.
SA and KNO mixed till clear liquid, chilled in icewater bath to <10°C, sugar added while stirring over 30' period. Continued stirring for 20', then left overnight in same water bath.

Mixture was solid next day, adding dH2O produced red nitric fumes, possibly from stuff stuck to the sides and on stirring rod, stopped after swirling. poured in coffee filter, 2 more washes.

Didn't have as much dH2O as I would have liked, and next actions were not so smart.
First step was neutralising the acid; Added dH2O, than NaOH, 4 mol/l while stirring. Mix got warmer and got foam on top. Fourth addition went passed neutral straight to pH 13 or 14...
Best option I could think of was adding some of the previous water wash. That got it acid again, then added small amounts of NaOH till pH around 6.

Filtered, left on stack of coffee filters to absorp most of the water, then put in beaker and added methanol.
Without quantitative solubility data to go on, and having added a considerable amount of methanol, I turned to acetone. When that didn't have any effect I of course realised I was trying to dissolve salts, not ETN.

Cooled the solution, fitered out the salts, then let evaporate for a night to reduce the volume.

Added icecold dH2O, filtered, got a bunch of white semi-transparent flakes. However, on the bottom of the flask was a yellowy mass with crystals in, as if the crystals had half melted.
Dissolved the contents of the flask in a little methanol, then slowly added cold water while swirling contents. When the water turned white from the crystals precipitating, a yellow liquid formed at the bottom.
First thought was Ooow shit, NG!

Separated yellow liquid whith eye-dropper.

A tiny amount of the fluid was absorbed in a strip of filter paper. Burnt with yellow flame and some crackles...

put it in a test tube and added water, white crystals formed at the contact surface, separating the two liquids. at the bottom there are some tiny solids floating around.

First theory was: impurities in chemicals, glassware, tools or solvents. Did I spill some glycerin somewhere? Maybe reaction mixture warmed up and developed hotspots after I left it.

Been doing some serious reading last few hours. Flunked chemistry 20 years ago, so it's a steep learning curve.
Came across a pdf:
"The alkaline hydrolysis of nitrate esters" by R.T.M. Fraser

Given the rapid hydrolysis of NG in alkaline medium (k = 0.24 /(M.s) ), and the similarity between NG and ETN a plausible scenario?
That leaves the question of what the liquid is. I know it didn't solidify after a few minutes in ice water, it's soluble in methanol and aceton, not soluble in water.

Don't want to take the risk of examining it further, will dispose of it in a safe way. A lot more learning to do before I experiment with HE again.

@quicksilver:
Thanx for the tip.

@SB15: I know, I had some written notes on the reaction itself but couldn't find the ones about neutralizing and recrystallizing. So I improvised, based on experience with some other reactions. Should have gone back to check. (don't have a pc there).
With less sensitive chemicals one can overshoot neutral with few consequences, and simply boil off excess solvent. Realised a bit late that that wasn't an option ...

Lot's of mistakes, I know. But no point in posting if I embellish the truth.

For those interested: The pdf I mentioned: The Alkaline Hydrolysis of Nitrate Esters
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD675917&Locatio...

Recrystallisation with Ethanol

I took a pic of acetone only recrystalised ETN at 10X


[Edited on 12-7-2013 by Motherload]

Where I live there is no difference

But i had nothing in mind to use two different words for it.

Invest in a decent fractionating distillation setup and have your own supply of EtOH.....that's the way I do it. No problems with solvent shortage, not to mention the endless supply for creating all kinds of barbaric herbal infusions for oral intake

Quote: Originally posted by Rogeryermaw

i nitrated about 9.5 grams of erythritol this morning. using 30 ml of >90% nitric acid (distilled last weekend) in 60 ml of 98% sulfuric acid cooled in ice bath and slow addition of the erythritol. i let the reaction proceed for 40 minutes keeping temp between 10C and 20C. after the 40 minutes i let the mixture slowly heat up until NOx fumes began to appear. when the reaction mixture reached about 58C i cooled the beaker and then crashed. the etn was already formed and the increased temp fused the mass of crystals as it cooled in water. broke up the mass, neutralized with conc. NaHCO3 and dried. crushed the slightly yellowish mass into powder, neutralized again and dissolved in the minimum amount of methanol. heating over a hot water bath, i reduced the solution beyond the saturation point, and, disturbing the liquid, it became a thick slush of etn crystals slightly wet with methanol. i emptied this mass into a buchner funnel, washed again with a final 15 ml portion of water and dried with vacuum filtration. all traces of yellow are gone. final product is snow white and like corn starch in consistency. final mass weighed in at 10.4 grams not including the portions removed for testing and losses from cleaning and recrystallization. a 100 mg mass pressed tightly into heavy foil confinement detonates with great force on heating. ears rang for 15 minutes...

Ah, I see...the causes for things always tend to be unnervingly trivial Since you have highly concentrated nitric at hand, why not use a nitric acid only route for obtaining of ETN and skip the sulfuric component entirely. I trust it will give a far superior yield similar to the case with PETN. Also I would advise against repeating the high temperature synthesis method that you practiced....there must be a better way to obtain a decent yield with mixed acid method if you choose to use this one. A different ratio of acids is a starting point. Perhaps the failed syntheses from the past were due to using too concentrated acids? With PETN nitration there is an established undestanding that a certain amount of water in the nitration mix is essential to the reaction mechanism and without it (in case of highly concentrated acids) the reaction rate drops dramatically.

Please find the articles attached:


Attachment: ETN Paper accepted PEP.pdf (806kB)
This file has been downloaded 1063 times

Attachment: Nitration of pentaerythritol by HNO3-H2SO4-H2O system .pdf (1.2MB)
This file has been downloaded 1046 times

<1 gram initiated by 3 mg lead styphnate fired electrically.

[Edited on 26-5-2014 by Rogeryermaw]

Quote: Originally posted by Rogeryermaw

ah but i had conc. HNO3 on hand and do not have lab grade at my disposal. i prefer to use it as is instead of diluting it.

5 gram charge primed with 500 mg 50/50 etn w/ lead styphnate. better quality anyway...

ya i'm barefoot..what?



[Edited on 26-5-2014 by Rogeryermaw]

Using 50 mL of acetone, I dissolved what I estimate to be 22 ish grams of dry ETN. The ETN was still wet after vacuum filtering when dissolved in the acetone and I made the mistake of not weighing it. I would estimate it was at least 30 grams of material including water. Can anyone explain what this separation is? Maybe the ETN saturated acetone separates from the water? I do not see how there could have been 50 mL of water in my vacuum dried ETN.

Quote: Originally posted by Brightthermite

Using 50 mL of acetone, I dissolved what I estimate to be 22 ish grams of dry ETN. The ETN was still wet after vacuum filtering when dissolved in the acetone and I made the mistake of not weighing it. I would estimate it was at least 30 grams of material including water. Can anyone explain what this separation is? Maybe the ETN saturated acetone separates from the water? I do not see how there could have been 50 mL of water in my vacuum dried ETN.

Quote: Originally posted by B(a)P

Quote: Originally posted by Brightthermite   Using 50 mL of acetone, I dissolved what I estimate to be 22 ish grams of dry ETN. The ETN was still wet after vacuum filtering when dissolved in the acetone and I made the mistake of not weighing it. I would estimate it was at least 30 grams of material including water. Can anyone explain what this separation is? Maybe the ETN saturated acetone separates from the water? I do not see how there could have been 50 mL of water in my vacuum dried ETN. You have added 50 ml of acetone to 22 g of ETN, how do you have a total volume of over 100 ml? Was anything else added? 50 ml of acetone plus 30 g of wet ETN should be less than 80 ml in volume..... Edit - maybe you had 60 g of wet ETN? [Edited on 17-8-2020 by B(a)P]

yes MeOH will work for recrystallization but you need to heat it to desolve the ETN.
I believe that 115ml of MeOH will desolve 10g of ETN at room temp.
i would reccomend heating up your MeOH to 35-45C and crash your ETN solution into a water bath that is 5c.

Quote: Originally posted by aromaticfanatic

Also a nice tip I discovered which may be a little risky is to dump your ETN in the acid mix into a smaller amount of water all at once with no stirring initially. It favors larger crystal size which filters wayyyy faster and makes it less likely for the filter paper to be eaten apart due to being in contact with acids for a long time.

Quote: Originally posted by Herr Haber

Quote: Originally posted by aromaticfanatic   Also a nice tip I discovered which may be a little risky is to dump your ETN in the acid mix into a smaller amount of water all at once with no stirring initially. It favors larger crystal size which filters wayyyy faster and makes it less likely for the filter paper to be eaten apart due to being in contact with acids for a long time. Dumping the nitration mixture in too little water seems a perfect way to lose product by local overheating. It does not promote larger crystal size as they are already formed when you drown it. Water will dilute the acid to the extent it wont be a problem for paper if you use enough of it !

Quote: Originally posted by aromaticfanatic

Yup the heating is a good idea. Just use a hot water bath and don't use a hot plate near it. Not worth risking the detonation if it catches fire. There is a thread on this exact thing happening. Don't be the person to make another post on that thread.

Quote: Originally posted by B(a)P

I have not tested it, but I always assumed you get a higher purity product by using more water in the initial drowning. If you use less water the acid is more concentrated. If the crystals are larger as you say, then surely they are holding onto more acid? In my opinion the less acid you are removing in your neutralisation/recrystallisation the better. @aromaticfanatic do you need more than one recrystallisation for your ETN?

Quote: Originally posted by aromaticfanatic

Quote: Originally posted by aromaticfanatic   Also a nice tip I discovered which may be a little risky is to dump your ETN in the acid mix into a smaller amount of water all at once with no stirring initially. It favors larger crystal size which filters wayyyy faster and makes it less likely for the filter paper to be eaten apart due to being in contact with acids for a long time. ? how would overheating be an issue? As long as nothing boils, you can just let it cool. With good stirring decomposition is negligible. In my experience I still got pretty good yields using this method. The crystal size is formed during dumping and you can change the crystal size using different conditions. It changes crystals size or at least density. In my experience the crystal size was definitely changed. The crystals were much larger during the small water amount dumping. In the large water dumping I got very fine crystals. Also you do use the water to make things less acidic but the main reason you dump the nitration mix in to water is to precipitate the ETN as it is much less soluble in water than in concentrated acids. Whenever I used the large crystal method, the initial dumping is just for crystal size. Afterwards I dump that water amount into larger amounts of water to dilute it for filtering. [Edited on 25-8-2020 by aromaticfanatic]

Quote: Originally posted by Herr Haber

Quote: Originally posted by aromaticfanatic   Quote: Originally posted by aromaticfanatic   Also a nice tip I discovered which may be a little risky is to dump your ETN in the acid mix into a smaller amount of water all at once with no stirring initially. It favors larger crystal size which filters wayyyy faster and makes it less likely for the filter paper to be eaten apart due to being in contact with acids for a long time. ? how would overheating be an issue? As long as nothing boils, you can just let it cool. With good stirring decomposition is negligible. In my experience I still got pretty good yields using this method. The crystal size is formed during dumping and you can change the crystal size using different conditions. It changes crystals size or at least density. In my experience the crystal size was definitely changed. The crystals were much larger during the small water amount dumping. In the large water dumping I got very fine crystals. Also you do use the water to make things less acidic but the main reason you dump the nitration mix in to water is to precipitate the ETN as it is much less soluble in water than in concentrated acids. Whenever I used the large crystal method, the initial dumping is just for crystal size. Afterwards I dump that water amount into larger amounts of water to dilute it for filtering. [Edited on 25-8-2020 by aromaticfanatic] So is it with or without stirring ? Because without stirring you are losing product for sure. I'm pretty sure these are crystals in the slurry prior to drowning. But since you are going to recrystallize in the next few minutes, why would you care about their size and shape at that point ? Just get your solvent and prefered base to neutralize the acids and get you the crystal size you're after, filter, dry, weight.

Quote: Originally posted by Brightthermite

No it's with stirring. And I thought the ETN is still soluble in the acids up to a point. I had ETN crystallize out once using KNO3 after the sulfate/metabisulfate salt kicked ETN out of solution all at once. It caused a large temperature spike. I've had no issues so far. I use cold water and stir the water right before addition and dump it. I've gotten 70% yields using NH4NO3 and drain cleaner. I was only able to reach a max of around 40% yield using lab grade 98% sulfuric acid (I also tried drain cleaner and there isn't much of a difference) and KNO3. I use the larger crystal size for quicker filtering which I mentioned earlier. If I dump into a large amount of water, it forms very fine crystals which clog up the filter and take ages to filter. The larger crystals filter much quicker. [/rquote] May I ask you method of synthesis and what kind of drain cleaner? My ETN using lab grade is light-years different in both color and performance.

You did nothing useful by letting the acetone evaporate except trap the acids again and the newly formed salts from the base which adds an extra unknown element in the behaviour of your product.
In this field, that's called playing with your life.

Dissolve in the solvent, crash in water where you have dissolved NaHCO3. "Tweaks" such as adding the base directly to the solvent with the leftover water from filtering the crude product should only be a last resort / reserved for a time when you have more experience. They add their own problems anyway.

If you're afraid there are still occluded acids you can just repeat the procedure. The solvent is easy to find & cheap, the product doesnt dissolve in water. These are ideal conditions for you to practice.
Think how your questions would apply to picric acid