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Author: Subject: ETN synthesis problem
maxidastier
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[*] posted on 11-4-2010 at 04:51


I'm wondering how many solvable non-ETN material is in the mix.

I prepared some ETN with 20 g Ammonium Nitrate, 25 ml H2SO4 and 5 g of Erythritol.
After four hours of reaction I dumped the thick cream in around 150 ml of ice cold water.
Everything got cloudy, but I realized some stuff at the bottom, that only dissolved after stirring.

After filtrating it and drying a little bit, it was 37g! I thought, uh! This won't be all ETN, with only 5 g of Erythritol used.
Well, the next day I weight it again, more dry now, and it was still 32 g!
So I dumped it again into some cold water and neutralized with baking soda. It needed only some 0,5 gramms of it and it was then neutralized. Lots of ETN was smimming on the top.
I filtrated it and was shocked, that it had lost so much weight. First 32 g, now 20 g.
And I even hadn't recrystallized it.
But I did that an hour later, adding the stuff to some 50 ml of hot Methanol. It was so cloudy that I didn't see, if everything dissolved, but it should be most of it.
Well, after cooling it down in the freezer, filtrating it and drying it, I was REALLY shocked :o
Guess, what was left of ETN? 4 GRAMMS :mad:

I can't believe it yet, and I'm asking you: Was the rest of those 32 g some other stuff or what was my mistake?
Because 4 g ETN from 5 g Erythritol is more than a poor yield.

PS: I'm German, so don't blame me for my English..

[Edited on 11-4-2010 by maxidastier]

[Edited on 11-4-2010 by maxidastier]

[Edited on 11-4-2010 by maxidastier]
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quicksilver
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[*] posted on 11-4-2010 at 06:05


Quote: Originally posted by maxidastier  
I'm wondering how many solvable non-ETN material is in the mix.

I prepared some ETN with 20 g Ammonium Nitrate, 25 ml H2SO4 and 5 g of Erythritol.



It's a tough question because the ammonium nitrate (if from fertilizer) could have clay, dirt, & other nitrates.

The fact that you got a low yield is occasionally due to oxidation from too long a time exposed to nitration. Strange, yes - but it's happened too often not to be a factor. Proper time exposure is often a trial & error issue. Try one hour total & see if it happens that you don't get a better result.

However if the ammonium nitrate (or anything in the synthesis) has impurities then the reaction has a variable in it that cannot be responded to be an outside answer. Purification is in order, if you suspect that issue.



[Edited on 11-4-2010 by quicksilver]
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[*] posted on 11-4-2010 at 13:34


I had similar problems with ETN, initially there is a lot
of "solid material" formed from the nitration but a lot
is lost during the drowning. My AN seemed to be fairly pure,
there was no water insoluable material in it when I started. My thought was that the ETN contained a large amount of
di and tri nitrates which are fairly water soluable.
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[*] posted on 12-4-2010 at 08:55


It's really annoying now.
My forth synthesis with the same result:
5 g of Erythritol didn't give me expspected 9 g ETN, but only 4 grams again.

I followed your advice and only used a nitration time of one hour with stirring every 5 minutes.
I dumped it again in 200 ml ice cold water, filtrated it and then dumped it again in ice cold water to completely neutralize it with baking soda. It needed nearly 45 g of baking soda until CO2 bubbling stopped (is that normal?)
The last synthesis with longer nitration time needed only 5 g of baking soda to be completely neutralized...

Well, I dumped the stuff in some hot methanol until dissolved, discovering some material on the bottom that didn't dissolve (what was that?) So I first had to filtrate that again.
Then I cooled it down, very slowly.
The next morning everything was full of recrystallized ETN.
I thought, that had to be at least 8 grams, but again, I was shocked after filtrating it.

Again only 4 grams ETN from 5 g of Ertythritol?

What is wrong?
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maxidastier
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[*] posted on 12-4-2010 at 10:06


Recrystallization seems to be one key issue.
The nitration shouldn't even be so short.
One might only add so much boiling methanol until everything dissolves. NOT MORE! Otherwise much of the ETN won't get out of the mist anymore.
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[*] posted on 12-4-2010 at 10:49


AN, because of its hygroscopicity needs to be dried thoroughly before use and H2SO4 needs to be 98%.
AN can *look* dry while still retaining considerable moisture but if you want 10gms of nitrate from your 5gms of sugar, use mixed acid!

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[*] posted on 12-4-2010 at 11:58


You used 20g AN to 25 ml of Sulfuric? This seems to be a lot of AN. When I prepare a nitration bath using a nitrating salt for ETN (It seems to give me excellent yields using this method), I use 55g AN to 100 ml Sulfuric.

I have done dozens of ETN synthesis and this ratio seems to optimize my yields. I actually have a pile of ETN drying right now. I used 200 ml sulfuric to 110g AN. I added 35g Erythritol and have a yield of ~45-50g. Both chemicals used are ACS grade.

Maybe try similar ratios for your nitration bath and see if that makes a difference?

Also what maxidastier said with recrystallization; I had problems with adding too much ketone/alcohol which decreased the yield. Be cautious with adding it, making sure you don't use too much. The stuff you saw that didn't dissolve was probably un-nitrated erythritol or other impurities. Its a good thing to filter those out, another positive result of recrystallization.

Anyway, hope it works out. Good luck!

EDIT: Just so you guys know my ETN is legit ;)



[Edited on 12-4-2010 by rbick]




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[*] posted on 13-4-2010 at 07:51


Well, thankfully I kept that stuff that didn't dissolve in the methanol.
Although I couldn't believe that it would be useful later, it IS now!
It really is ETN, that didn't "want" to dissolve. It is no waste stuff, strange,
but I made some tests with that "stuff" with my hammer :D an it IS ETN. ;)
I'm wondering how it can be, that it didn't dissolve although I used TOO much of Methanol :o
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[*] posted on 13-4-2010 at 17:28


Maxidastier: I noticed something interesting today. Your problem motivated me to look back at lab notes and do an experimental ETN synthesis.

Looking back it seemed yields were lower when I kept the nitration at temperatures around 10*C but increased when I let the mix get around 20*C or even a little higher. Today, I made a nitration mixture with 100 ml 98% sulfuric and 60g purified AN. After dissolving all the AN, I put the nitration vessel into an ice bath and let it cool to 10*C.

Before I continue I forgot to mention something I read back on roguesci before it closed down: YOU HAVE TO READ THIS: http://pubs.acs.org/doi/abs/10.1021/ja01681a501

It talks about the dehydration of AN in Sulfuric Acid when it reaches a certain temperature, which means it produces more gas than nitric acid. Read it for details, its interesting.

So anyway; I added the erythritol to my nitration mix slowly over about 10 minutes maintaining 10*C. After adding all of it and letting it sit with occasional stirring for 15 minutes, I noticed the mixture wasn't that thick with ETN crystals. I removed the nitration vessel from the ice bath and let it get up to about 20*C. I then let it sit for an additional 15 minutes with stirring. In the 15 minutes, the mixture became thick with crystals, almost to the point of breaking my glass stirring rod. I filtered it and washed it with bicarb. I didn't recrystallize since I'll be dissolving it in NG and NM for some fun experiments, which I'll post later! :D

SO in conclusion: Could it be coincidence? Possibly, but try letting the temp get up to 20*C, maybe even a little higher and see what happens if you haven't already. Making ETN usually seems to result in a mild nitration without too much threat of runaway, but be careful anyway. Hope this helps.

[Edited on 14-4-2010 by rbick]




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[*] posted on 14-4-2010 at 02:50


You only had an nitration time about 20 mins?
Won't that result in a low yield?
Because I realized: A nitration time about 6 hours, mentioned in the pfd to be optimum, seems to nitrate everything, but maybe not only Erythritol.
Because at 6 hours I need very les bicarb to neutralized, while at a time about an hour, it takes much longer to neutralize...
Well, my syntheses yesterday was very warm, maybe to warm, because it got very yellow (NOx).
My last synthesis was at about 15°C but yield was only 6 g ETN from 5 g of Erythritol.
Is still don't know what's my mistake...
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[*] posted on 14-4-2010 at 04:40


Well jeez I don't know whats going on then :o! Since I had to let it warm up to 20*C and waited an additional 15 minutes, the nitration time after all of the erythritol addition was roughly an hour. The yield was pretty good. Haven't measured it yet but its appears to be over 20g from 15g of erythritol.

Read that article I put a link to. If your AN/Sulfuric nitration mix gets above a certain temp during AN addition, very little Nitric Acid is created. That might do it, who knows. Good luck.




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[*] posted on 14-4-2010 at 06:29


oh my god...One hour earlier I prepared a new synthesis and followed your tips with only 20 mins of nitration.
Damn it, why didn't you write that it was one hour, because that's also the way I normally do it...:(
Well, on that link I can't see an exact temp.
I kept my nitrate salt/ sulfuric mix at very low temp in ice bath, so I think it produced enough nitric acid.

But: This synthesis will be waste with only 20 minutes of nitrating :(
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[*] posted on 14-4-2010 at 07:45


When making PETN... a minute or so after all the PE has been added, I place the mixture in a hot bath(40-45C). It increases yield. Perhaps the same goes for ETN?
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[*] posted on 14-4-2010 at 07:46


A nitration time of only 20 mins seems not to lower the yield...
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[*] posted on 15-4-2010 at 05:56


No, i don'T think this goes for ETN. When I once let it get over 30C it got very yellow (maybe the NOx)
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[*] posted on 20-4-2010 at 10:21


30* is way too high and the yellow color is the ETN decomposing and the presence of NOx fumes. I would say max 20*C is a good idea.

Still having trouble with the synthesis? What grade chems are you using?




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[*] posted on 20-4-2010 at 15:04


I can only underline rbick's statement. 30 C is really pushing it. However I am also quite aware that yellow as a consistent color (no alterations) may have been an altogether diffing phenomenon if any TNP had been exposed to lab ware - such is the nature of the dye.
What's more, the measurement of time within nitrating must be "on the same page". Is that a total time allotted for addition or the time wherein all the polyol has been added and from that time to time of quench (or elimination of acid by other means)???

If the twenty minute time frame is from start of addition....it would seem rather short. However, from total time where all the material is exposed to HNO3 or mixed acid there is some interdependency on weight. If you are dealing with a few grams (5), it may suffice.
There appears to be some level of higher yield when ratios of acid increase, purity issues surface, & exposure is enhanced by continued stirring.

There are quite a few factors that are difficult to take into account when discussing a procedure that is not witnessed or exacting notes are unavailable.
There has been recorded a differing yield from nitration wherein polyols are dissolved in high strength nitric acid and sulfuric is added to that to precipitate yield. There are others that benefit from mixed acids as a continuum. Factors influencing nitration may be quite a few.

1. Time frame of addition
2. Weight of material
3. Ratio of acid(s) to nitrated material
4. The material itself
5. Type of nitration (nitric 1st then sulfuric, solid nitrates, mixed acids, etc)
6. Strength of nitric acid
7. Condition & type of nitrated material
8. Temperature of both material & acid (& alteration of temp)
9. Surface area of nitrated material
10. Speed of addition of nitrated material
11. Contamination of material, acid, or vessels

So you see that with at least ten areas of variance, there is a Hell of a lot of room for issues altering the result. The early plants and factories spent a GREAT deal of time on consistency alone. as the lack of consistency cost a great deal in profit, safety, & utility.


[Edited on 20-4-2010 by quicksilver]
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[*] posted on 21-4-2010 at 16:49


I have a quick question while we're on the subject -

I know ammonium nitrate seems to be the best nitrate salt to use in this synthesis in conjunction with sulfuric acid. However, sodium nitrate (and potassium nitrate) are much more readily available. Weight for weight, sodium nitrate contains almost exactly the same percentage of the nitrate group (you'd need about 7% more by weight than NH4NO3), not to mention that sodium sulfate has half about the solubility in water as ammonium sulfate, which could potentially keep the yield up.

Sodium nitrate is available for as little as $3 per pound from certain sources.

So why not use sodium nitrate?


[Edited on 22-4-2010 by DougTheMapper]
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[*] posted on 22-4-2010 at 06:20


- It will be fine provided you take certain steps. And this applies not just to NaNO3. The alkali nitrates will mostly function well in that capacity.
The issue generally is the FORM available. If using fertilizer grade materials there are often coatings of clay and other materials that make moving NaNO3 into a solution more difficult. IF you have a good supply of one or the other, it's often a great idea to re-crystallize the material to eliminate the impurities and make it easier to mix w/ H2SO4.

At minimum, crush the prills into a very fine powder prior to mixing into solution. You can also determine IF you have a source with impurities by working a solution of NaNO3 w/ water and determining if you see the clay. If so, [to not re-crystallize] will invite a poor synthesis.


[Edited on 22-4-2010 by quicksilver]
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[*] posted on 22-4-2010 at 10:02


Well, I used different ratios and different nitrates (KNO3 and NH4NO3)
My last synthesis was from http://n3chem.freehostia.com/?p=ETN, but it it was hard work with only the same yields as my other synths. I got 12 g ETN from 7,5g Erythritol. All my synths were like this.

Can one tell me the ratios with KNO3 and NH4NO3?
We need to try out different ways if making ETN, because ETN is a very good, strong HE, close to PETN but way easier (or not ;)) to make (if you don't get PE)
The best thing about it is that you can melt it easily and dump it into casings, reaching a very high density, resulting in perfect velocity!
I made tests with small amount of ETN in foil and hit it with a hammer. Made nice boom.
But then I made the same with molten ETN. Well, I would be deaf, if I didn't wear ear protection...:cool:
Perfect booster, too...

But synthesis and yield, well....
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[*] posted on 23-4-2010 at 10:06


Enclosed is the classic DuPont November 20th patent that all the fuss was made about (the law suit between DuPont & Nobel).
Herein is used the "dissolved in HNO3 and precipitate with H2SO4" model.
If you really want higher yield (a seriously higher yield) then you need to realize that scaling up or down does not always follow the multiplication of acids w/ nitrated materials path.

That being said, the collective experiments in several hobbyist notes came up with the 100/60/15 level of percentages as giving the best return for solid nitrate in sulfuric acid.
100gr H2SO4
60gr KNO3
15gr Erythritol

On a realistic basis this ratio was scaled up to 60gr Erythritol (as were the rest also scaled up, of course) & all seemed well until the 60gr limit was reached.
A question that had arisen time & again was: a discussion from several years back regarding the various solid nitrates & their effectiveness in synthesizing a mixed acid. I do recall the final observation made by several people & generally less NaNO3 was needed to do the job as KNO3 & HN4NO3 were about equal. If you have a further interest as to why; you can search for that discussion.



Attachment: ETN_du-pont.pdf (156kB)
This file has been downloaded 967 times

[Edited on 23-4-2010 by quicksilver]
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[*] posted on 26-4-2010 at 07:56


That .pdf is extremely interesting.

His process involves the dissolution of erythritol into sulfuric acid, then the introduction of this solution to nitric acid to nitrate the erythritol at as much as 60C!

He also claims that the majority of the heat given off occurs as the erythritol is dissolved in the sulfuric acid.

I see this as a way to achieve an excellent yield as the dissolved erythritol is essentially in the smallest physical form possible, allowing for more complete nitration as oppose to adding large "chunks" of the powder with a lower surface area.

Based on the .pdf, I propose two new ways of synthesis which both use the following materials:

5.5 parts conc. H2SO4
7 parts HNO3 equivalent of a nitrate salt
1 part Erythritol

Place the erythritol in a flask in an ice bath. Slowly add just enough sulfuric acid to completely dissolve the erythritol without exceeding 40C. In a separate flask, use the rest of the SA to dissolve the nitrate salt. Both solutions are brought to 40C and slowly mixed, maintaining above 40C but less than 60C. This is continuously agitated for 30 minutes, at which point the ETN has been formed as a liquid, eliminating the typical difficulty of stirring. (According to the .pdf, the ETN is formed as a liquid when the bath is 40-60C, but I believe the MP of ETN to be 61C, so this might require a bit more heat. I'm not sure what the presence of the acids will do.) This mixture is then chilled in an ice bath with rapid agitation to form fine ETN crystals. The acid is diluted with water, partially neutralized (as so not to destroy the filter), and the ETN is filtered from this solution. The filtrate is then neutralized, dissolved in hot acetone, and crashed into a large volume of water to achieve recrystallization.

Alternatively, large crystals can be obtained by evaporating the acetone and super fine crystals by rapid agitation while water is added to slowly to force it out of solution.

Thoughts?

-DTM

[EDIT] - I'd try it but I won't be back to the lab until the weekend.


[Edited on 26-4-2010 by DougTheMapper]
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[*] posted on 26-4-2010 at 14:26


Actually Doug acetone is TOO strong a solvent for ETN.
This is why ethanol and methanol had been used w/ success and could also control the crystal size without shaving concerns or other steps. Generally speaking, the 1.51 HNO3 solution of the desired nitration and using sulfuric to precipitate it out was very common back 100 years or so. It gave more temp control. You see you can start with cold HNO3 and as you add your target product, the rise in temp is much less than mixed acids.
Some time back hobbyist experiments included making one's mixed acids (using a solid nitrate or not) damn near freezing and adding the material in very uniform, time incremented amounts. The idea was to have a greater grasp of control [not only] over "run-a-ways" but to increase efficiency in that uniformity.

Most folks know that when the nitration of solid polyols reaches a certain point, the solution almost looks like porridge & is tough to continue to mix. By using the "HNO3 solution first" route, that issue is lessened to a greater degree. The question many ask is could that be used w/ 70% tech HNO3? Often, it will work, if the sulfuric is really reduced to 98% and not drain-cleaner grade. The wonderful thing there is that cooking down H2SO4 will give good results.
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[*] posted on 1-5-2010 at 02:07


@Dough: Well, it sounds interesting but:
I've read that at a certain temperature (little above 35°C) the formation of Erythritol Carbonate (or sth. like that, I don't know...) begins, which means: NO ETN!
Also, there are lots of brown NOx fumes even at 30°C and great loss of Nitric Acid.

As I see: At the beginning of the thread, everyone says: Don't let it get over 30°C...now we're at around 60°C-.- uh!

Well, I'm trying it right now, not with nitric acid, but with nitrate salt and hoping that my ammonium nitrate doesn't get dehydrated at 50°C as said someone before in the thread...
If it doesn't work out, I'll try KNO3. Hope this doesn't deyhdrate..?

Please try it out, when you're back to lab. I'm quite curious...

[Edited on 1-5-2010 by maxidastier]
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[*] posted on 1-5-2010 at 02:29


@quicksilver:
100gr H2SO4
60gr KNO3
15gr Erythritol

according to other descriptions, it has to be 100 ml H2SO4, so 200g!?
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