Sciencemadness Discussion Board

ETN synth lab report

Justin - 16-5-2010 at 06:34

Hi, i was very interested in synthing ETN but nervous about the problems i had heard. Here is how i did mine.
Took my 93% H2SO4 from the chem supply and heated it too 250C for 3 hours, this should bump it up to 98%. i follow a recommendation from the ETN synth probs thread. I used:
50 mL 98% H2SO4
30g 325 mesh KNO3
7.5g 100% ethyritol

1. Cooled H2SO4 to -5C then slowly added KNO3 keeping temp under 20C. After it was all added i mixed well.
2. Addition of ethryitol slowly in 1g increments over 15min.
3. Stirred every 2-5min and kept temp between 12C-20C
4. Nitrated for one hour after all ethryitol was added
5. Dumped into 500mL cold dH2O
6. Vacuum filtered
7. Added to about 50mL MeOH at 55C
8. Rapidly cooled in the freezer to -10C
9. Brown color was noted, idk what causes this
10. Vacuum filtered and washed with 1000mL dH20
My Yield was 13g, i doubled the ratios and followed the same technique and got 26g, i just got done with a 60g erythritol nitration and looks like a good yeild just waiting for it too dry. I got a pic of the yeild from the 60g nitration, just waiting for it too dry to get a mass for it, looks like atleast 100g though but idk. I just dont know how to resize it so i can post it.

medx - 16-5-2010 at 10:49

It seems very easy. How did you heat acid? Are you sure when you heated 93%H2SO4 it increase %98? If so, i think it is possible to use battery acid, too.

Justin - 16-5-2010 at 19:23

First off the yeild from the nitration of 60g erythritol turned out to be only 50g! in the ETN synth prob thread there is a reference to the 60g limit, so its probably best to keep it between 7.5 and 30g erythritol. I heated almost 2L of 93% H2SO4 in a 2L RBF with a heating mantle, i have not done a titration yet to determine the exact percentage, however the acid started out very nicely clear for H2SO4, i was told it was 93% from the chem supply guy, ive heard that heating it to 250-300C will drive off excess water, then i plugged the flask with cork stoppers to prevent any absorbption of H2O and let it cool to room temp. Im very disappointed in the 60g nitration, everything seemed consistant until i quadrupled the amount of ethryitol from 15g to 60g. Maybe a 30g rxn would be optimal when using KNO3 although i havent tried yet. I have 1/2kg of erythritol and am recieving 10kg of NH4NO3 so ill do some tests with NH4NO3 also. However using KNO3 gave some good yields when using amounts around 15g. I have about a gallon of clear 70%HNO3 sitting around so i may purify some of it to do a straight HNO3/H2SO4 rxn. Of course if i get around to purifying my HNO3 it'll go into some RDX cuz that kg of hexamine has been lacking attention lol.

Justin - 16-5-2010 at 19:38

I would question the purity of battery acid and the time it would take to purify it, most likely some soluble sulfates in it which would affect the yeild i would think, however, i can get a gallon of very clear 93% H2SO4 for around $15 so its no problem for me. Check around for a chem supply place, although ACS grade is best all i can get my hands on is tech grade and im not about to pay outrageous shipping and prices for some ACS grade stuff. I would atleast try and reduce the water out of battery acid H2SO4, just make sure not to get it above 300C and watch out for the SOx fumes when it gets that hot. I took my thermometer out when it was that hot and it was billowing SOx fumes off of the glass thermometer, as long as theres not much airflow in the heating vessel fumes wont be a prob, but if you got a breeze blowing through it there's gonna be some seriously choking SOx fumes coming off that thing!!!!! i'd love to hear your results however

medx - 17-5-2010 at 22:03

Is your erythritol lab grade?
For battery acid, I tried to purify it four times. At the last of them It’s normal concentration was about 32-3%. I heated it on electrical heater about one and half hours. Through process I took heater between 100 C and 150 C and temperature of acid was about 100 – 120 C. At the end volume of acid decreased one of third of initial volume. I measured it’s density. It was 1.789gr/cm3. According to this my last acid’s concentration is bout 85%. This is the best result that I can reach until now. I didn’t understand why I can not get 98% H2SO4.

Justin - 18-5-2010 at 01:51

No my erythritol is not reagent grade, its just food grade. Thats the highest temp you can reach? You really need to get it above 200C to drive off as much water as possible, maybe try a longer heating time if you can only get it too 100-120C, but H2SO4 holds onto water really well so you may not be able to get above your reported 85% with the temps that your operating at. Hotter and longer is all i can tell ya, or go find some drain cleaner at a hardware store thats H2SO4, its 93% already. I suppose your going to use it in a energetic material synthesis?

grndpndr - 19-5-2010 at 20:06


According to references ive found 85% is about best youll do at 120c and youll lose alot of sulfuric acid doing it.93.3% max can be expected @338c and ambient pressure but expect considerable loss of sulfuric acid vapors along with the water.A higher % sulfuric acid than that takes more than simple heating to achieve.Alls not lost though you can adjust your synthesis to compensate.

In fact above 70% concentration you will begin to lose sulfuric acid vapors along with water.No free lunch.On the positive side
ive collected used battery electrolyte decanted clear electrolyte after lead etc settled boiled the now clear electroltye until a voluminous white'fog' emanated.The resulting acid worked very well for a similar synthesis.

[Edited on 20-5-2010 by grndpndr]

medx - 19-5-2010 at 23:06

Yes, I am planning to use it in energetic materials synthesis. If I supply erythritol ETN will be one of them.
I used higher temperature and longer time in some experiments. But their result was worse. After white fumes finished color of acid is changed toward gray. After this point I think acid decomposed. My battery acid was clear. It hasn’t used in battery before.

quicksilver - 20-5-2010 at 06:46

The "black" material in many store bought H2SO4 is generally aluminum (salts, etc) from anodizing - as a great amount of H2SO4 is used in anodizing and scrubbing baths for hot-rolled steel, or pickling metal generally. Then sold off instead of disposed as toxics. The money saved is tremendous. Sulfuric acid may be a largest level single chemical produced in the world. Sub-boil (270C+ or just below 290) will allow the blackened material to layer & solidify, leaving a greater amount of clean water-white 96+% acid to be decanted. It would be common to get 98% from such a thing. The material called Olium is H2SO4 with free SO3 & depending on the amount, accounts for the level of "fuming" sulfuric acid; those grades go as high as 80% free SO3. but due to it's charring nature on wood & sugar is not the best choice for explosive synthesis. Too long (or too high a ratio) of exposure periods w/ sugars will oxidize a percentage prior to nitration, therefore be responsible for poor yields. A higher level of common H2SO4 in some synthesis is the culprit for poor yields; oxidizing the sugar effortlessly. The "sweet spot" for reduction of water in the common "cooking down" of sulfuric acid seems to be 240C. *
This is a great example of how multiplication of a ratio, when scaling up doesn't always produce a yield similar to that of a synthesis at a different weight range. The most remarkable example (using a solid polyol) is manitol. MHN provides yield at single gram levels (perhaps 2-6) but scaling up throws the whole issue into disarray with a great deal of penta or tri-nitrates (some of which may be water soluble). Additionally I have heard of people not allowing the solid alkali nitrates to completely dissolve into solution with the H2SO4 & that's almost a guarantee of a poor yield full of by-products.

* Sourced from Merck notes 1992

grndpndr - 20-5-2010 at 15:03

Quicksilver says 240c to concentrate H2SO4 then thats what Id use.I dont have a therm thats appropriate for temps that high but as I recall
the electrolyte lost approx 2/3 original volume. when a very dense
white fuming began(at approx 85%,quite different from water vapor) I let it continue for a time to ensure I had concentrated the SA as far as heat alone could do it.No problems whatever with the synthesis using the concentrated electrolyte realizing 93% or an improvised tech grade H2SO4 adjusting synthesis to suit.

In lieu of electrolyte theres some very good drain cleaner available Ive had luck with in the past.called Liquid Fire Its Specific gravity is 1.835 according to the MSDS. light yellow color, viscosity of light motor oil.





[Edited on 21-5-2010 by grndpndr]

quicksilver - 21-5-2010 at 06:17

You MAY find that different sources for the H2SO4 have different levels of impurities. I have seen Liquid Fire with a lot of black material and "Rooto" brand with a fairly clear make-up. Given that most all of this H2SO4 is surplus acid, if you find a source that has less solids or obvious impurities; buy that source obviously. But brand loyalty may yield disappointment. Also remember that clarity in & of itself may not be an indicator of purity. But "cooking down" the acid to get a higher strength may help ascertain what's cookin'. If used for pickling steel, the only impurity may be a small amount (trace percentage below 1%) of ferric sulfate or whatever. That may not be as annoying as blackened aluminum or zinc oxide.

gnitseretni - 21-5-2010 at 07:32

I've been using Liquid Fire for years now. I noticed it has changed colors over the years. I remember when I first got Liquid Fire the stuff was black as night. Now it's... light brown or yellow-ish, either way it's a LOT clearer.

Justin - 21-5-2010 at 21:18

Ya even thinking that my cooked down 93% H2SO4 was 98% didnt hurt my ETN synth at all, it kinda got alittle darker brown when i cooked it. Im gonna check the density of the cooked versus uncooked and see if there is any difference. Im very lucky to have a chem supply place that sells a gal of 93% H2SO4 for $15 and a gal of 70% HNO3 for $25. Im wanting to concentrate some of my HNO3, it started out clear and now its kinda yellow so i brought it inside to slow buildup of NOx. Of course the bottle is clear glass so that doesnt help even though i keep it in the dark. I have a dist setup but my vac pump broke, it was a diaphram pump that sucked in some water and i think it broke the diaphram. Would throwing in a certain amount of my H2SO4 with the HNO3 to suck up some water and then distilling the HNO3 at atmospheric pressure work very well without alot of oxidation of the HNO3?? It would be nice to have conc HNO3 for certain synths. Also would using anhydrous MgSO4 work to absorb some water from my 93% H2SO4??

grndpndr - 22-5-2010 at 07:58

Quote: Originally posted by quicksilver  
You MAY find that different sources for the H2SO4 have different levels of impurities. I have seen Liquid Fire with a lot of black material and "Rooto" brand with a fairly clear make-up. Given that most all of this H2SO4 is surplus acid, if you find a source that has less solids or obvious impurities; buy that source obviously. But brand loyalty may yield disappointment. Also remember that clarity in & of itself may not be an indicator of purity. But "cooking down" the acid to get a higher strength may help ascertain what's cookin'. If used for pickling steel, the only impurity may be a small amount (trace percentage below 1%) of ferric sulfate or whatever. That may not be as annoying as blackened aluminum or zinc oxide.


Funny what geography reveals.Locally the Rooto is pich black.
Liquid fire,at least the lot/store ive been sourcing it from is exavctly as I said a light wieght motor oil color/viscosity.I like the fact current MSDS claims 1.835 sp. G! 96%-97% LF. Frankly dont believe ill do 93% H2SO4 any good heating it to 240c.Im still convinced from all the sources ive been able to find 93.3% is the best concentration youll get by heating a sample no matter how long or temp.SA has a bitch affinity for water.A more agressive dessicant likely work to increase H2SO4 concentration.

Im sure what Quicksiler says in regard to purity regardless of appearance might have a dreat deal to do with ultimate purity.
For instance heating sorces or dark black drain cleaner might reveal clear acid as the impurity settles to the bottom of the beaker removed by careful decanting!
By the way Ill check my LF drain cleaners lot #s to try to detremine consistency.

[Edited on 22-5-2010 by grndpndr]

Rain - 31-5-2010 at 12:42

When I mixed my black sulphuric acid with Ammonium nitrate, the mixture turned clear as water after a few days in a sealed container.So where could the black gunk have gone?Nitrated, oxidised?There is no NOx visible either.

[Edited on 31-5-2010 by Rain]

hissingnoise - 1-6-2010 at 11:45

I haven't yet seen black H2SO4 draincleaner nor have I any desire to. . .
If oxidation of an organic occurred, the CO2 produced would be expected to pressurise a sealed container.
It does though, seem that the dark impurity interfered with the formation of HNO3 from NH4NO3.
In any case on mixing a NH4NO3/H2SO4 mixture a HNO3 mist (can quickly fill a room) is produced.
I did have DC with an amber colour at one time but what I find on the shelves now is practically water-white.
A matter of luck, possibly. . .

quicksilver - 2-6-2010 at 06:20

The H2SO4 sold as drain cleaner is generally a surplus acid from a variety of industrial sources. It can come from steel pickling or aluminum anodizing plants on a very large scale. The "black" may be a sediment impurity or a dye. I have seen both.
Sulfuric acid, being perhaps the largest single "plant production chemical" in the world is so abundant that it is often sold off after use to contain cost. Thousands of tons are simply too much to dispose of when the acid can be continually be a viable product for alternative uses.

quicksilver - 2-6-2010 at 07:14

Quote: Originally posted by Justin  
.....and a gal of 70% HNO3 for $25. Im wanting to concentrate some of my HNO3, it started out clear and now its kinda yellow so i brought it inside to slow buildup of NOx. Of course the bottle is clear glass so that doesnt help even though i keep it in the dark. I have a dist setup but my vac pump broke, it was a diaphram pump that sucked in some water and i think it broke the diaphram. Would throwing in a certain amount of my H2SO4 with the HNO3 to suck up some water and then distilling the HNO3 at atmospheric pressure work very well without alot of oxidation of the HNO3?? It would be nice to have conc HNO3 for certain synths. Also would using anhydrous MgSO4 work to absorb some water from my 93% H2SO4??




I have experimented with distillation of HNO3 (70%) using a variety of methods. I have found that unless you have a serious chem-lab vacuum, it's best to use some cheap gadget because the acid will decimate almost everything you can imagine.
However, I only noticed a real difference when the vacuum level was substantial. I had a chance to borrow a very high quality unit that pulled at what amounted to 3 atHg (thats strong enough to break cheap glass). Otherwise the main differences were to find a seriously well made condenser (like a LARGE spiral Liebig), maintain temp at 80C and to keep the receiving flask quite cold.
I measured the difference between using a solid nitrate and H2SO4 in my distillation & using HNO3 both with & without sulfuric acid.
It's my opinion that one can achieve the same level of 1.51 acid with a solid nitrate & sulfuric vs. HNO3, either alone or w/ sulfuric. Basically I would keep the HNO3 (@ 70%) and distill a solid nitrate. For the return it just makes more sense.


EDIT:
Years ago I tried all sorts of things like your anhydrous MgSO4: nothing really worked like maintaining temp and having a REALLY quality condenser.
The lemon yellow acid is fine! A half gram or Urea will make that water white in a few minutes if you care about color. The big issue is that very acid fumes of NOx will be pulled into a vacuum and anything but a unit MADE for acid resistance will get wasted! In fact (I don't have my notes so I can't quote figures) no vacuum at all but having a really fantastic condenser made a serious difference between a good vacuum and a very elementary condenser.
IF I remember correctly, the best you can hope to achieve will be close to 600ml from one liter of HNO3 but you can get that with no problem with sulfuric & a solid nitrate!
If you raise the temp, or you have a small condenser, you'll pull acid faster but when that drip stops, it stops!. If you work slow at 80C you'll get the best yield; especially if the condenser really traps your distillation.

[Edited on 2-6-2010 by quicksilver]

Justin - 3-6-2010 at 02:08

Thank you very much for your advice, I'll follow your recommendation and leave my HNO3 alone and if the need arises I'll just distill highly conc. HNO3 from a solid nitrate and H2SO4.

maxidastier - 12-8-2010 at 07:05

I am distilling my own 99% HNO3 from cheap 53% HNO3.
It's far more cheaper than wasting H2SO4 with potassium nitrate or so, because you can reuse the H2SO4!

I have simple destillation setup: 2x 500 ml round bottom flask, liebig 40cm and water aspirator.

First step: mix 125 ml HNO3 53%/65% and 250 ml H2SO4 92-98% and distill at atmospheric pressure at 85°C
The distilled HNO3 should be over 80% now.

Second step: now take that HNO3 and mix with same amount H2SO4 (fresh, not the one u used before)
connect you water aspirator or whatever and distill at low pressure around 80°C.
Lowered pressure is needed to obtain WHITE FUMING NITRIC ACID (as far as you intend to produce HE's this would be better than RFNA ;)

You should finally get around 60 ml of 98-100% HNO3, white fuming!

Now you can concentrate all you H2SO4, that contains now the water of the HNO3 and reuse it.

IMO a better and cheaper way to get 99% HNO3.

Microtek - 12-8-2010 at 08:47

I use a very similar method as it also makes sense for me to recycle the sulfuric. In the end it comes down to the relative cost of dilute nitric vs sulfuric and nitrate.
Incidentally, a vacuum source is not necessary - instead you can do a slow distillation a atmospheric pressure and then bubble dried air through the RFNA at ca. 50 C to get high quality WFNA (better than 99% if you are careful and work meticulously).

maxidastier - 14-8-2010 at 05:58

What can I use to bubble dry air through it?

[Edited on 14-8-2010 by maxidastier]

Microtek - 14-8-2010 at 12:59

I used an aquarium pump to pump air through a coloumn filled with CaCl2 scales and then through the acid. You can quite easily tell if the air is dry enough, because moist air will cause dense off-white fumes to billow from the acid while dry air will mostly strip the NOx, giving a much smaller volume of brown gas.
The operation is much more efficient if you use something with many small perforations at the end of the air tube to split up the air stream, rather than just putting the end of the tube into the acid.

Another ETN synth lab report

UndermineBriarEverglade - 27-8-2024 at 10:36

Adding my report since this thread is the one linked in the topical compendium for ETN. This is the second time I've run this synthesis and I got much better yield than my last attempt. The biggest problem is that so much sulfuric acid is required to keep the mixture stirrable and I'm not recovering it.

I first ran the reaction with erythritol as the limiting factor:



Then, I realized I should focus on efficiently using my KNO3 since erythritol is so cheap and accessible. I added another 3.5g erythritol (so 1:6.5 mol KNO3). I've seen excess nitrate recommended to avoid undernitration, but partial nitrates should dissolve in water. I think next time I will start with 8:1, and add erythritol until 4:1.

  1. In ice bath, dissolved KNO3 in H2SO4. Max temp 40C.
  2. Slowly (36 minutes) added 16.5g erythritol. Max temp 20C. I had to add more sulfuric acid after almost every increment of erythritol to keep it stirrable.
  3. Continued heavy overhead stirring for 80 minutes. The mixture fell to 15C.
  4. Removed from ice bath and let temperature rise to ambient (29C). By this point the mixture was a thick batter that barely flowed.
  5. Crashed into water and filtered to get bulk ETN.
  6. Dumped once more into water, stirred, and filtered.
  7. In the filter, poured over a 5% by weight sodium bicarbonate solution. No apparent bubbling.
  8. Dissolved the 56g of wet crystals in about 60mL of acetone.
  9. The acetone solution separated into two layers. I discarded the top layer which was dark brown, strongly basic on pH paper, and did not precipitate in water. I believe it was potassium hydroxide that had been trapped within the crystals.
  10. I filtered the remaining solution, then crashed it into water.
  11. Dissolved the crystals in acetone. Two layers formed as before. I discarded the top layer, which was clear and did not precipitate in water.
  12. I crashed the remaining solution into a 5% by weight urea solution, then filtered.
  13. Yield 46g of damp crystals (112% :o)


The crystals smell of acetone and must be very wet. I might have also added more than 16.5g erythritol. I knocked over my pre-measured container during the addition, swept up and weighed the lost erythritol, and added that much clean erythritol. So I may have measured extra mass of dust.

When crashing I poured gently into lightly stirred water. This yielded clumpy, crunchy crystals that were much faster to filter than the fluffy plates from fast pouring into heavily stirred water. I plan to melt-cast it so crystal size is unimportant as long as they're clean. But based on the amount of KOH that was released in the first recrystallization, I might have made them too large.

UndermineBriarEverglade - 4-9-2024 at 09:46

When melt-casting, a significant amount of water (smelling of acetone) evaporated from the ETN. So my overall yield was 83%.