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Author: Subject: ETN synthesis issue
Chill
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[*] posted on 1-7-2013 at 20:26
ETN synthesis issue


In preparation for the 4th, I decided to try synthesizing erythritol tetranitrate. The following is my experience with the attempt, including a paraphrasing of my lab notes. Maybe someone can offer up some assistance.

The quantity and type of materials Is as follows

*100ml H2S04 (Battery Acid boiled close to azeotrope)
* 60g KNO3 (Spectracide Stump Remover)
* 15g Erythritol

I dissolved 60g agriculture grade KNO3 into 100ml of the H2S04. The yellowed (due to acid) solution was cooled down to ~18c, there was expected precipitation of KNO3 that led to a slushy mixture. White fumes indicated that my beaker contained nitric acid.

I started my addition of erythritol and mixed the slush very frequently. Every 5 minutes I added about half a gram of E and checked the temperature, it never went over 20 Celcius. After about half an hour I had finished adding erythritol and the concoction was very thick.

I waited a few minutes before adding some cold water to the solution in preparation for filtering. by now the solution was back to room temperature. I mixed the solution a bit and noticed that the slush was dissapearing.

I was left with nothing, all the slush that I assumed would contain some ETN was dissolved back in the acid. One can guess that this was because the slush was never ETN to begin with, but just precipitated KNO3.

I don't know where I went wrong, but I had obviously not created any ETN. Any feedback from the sciencemadness community would be greatly appreciated.
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Ral123
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[*] posted on 1-7-2013 at 21:46


KNO3 is the worst for that reaction, NaNO3 is better, NH4NO3 better, WFNA very nice. Also I ball mill my eritrithol with this: http://www.youtube.com/watch?v=58PBInYuJWU
Also, if the nitrate is cheap, you can recrystalise it.
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[*] posted on 1-7-2013 at 22:31


Quote: Originally posted by Ral123  
KNO3 is the worst for that reaction, NaNO3 is better, NH4NO3 better, WFNA very nice. Also I ball mill my eritrithol with this: http://www.youtube.com/watch?v=58PBInYuJWU
Also, if the nitrate is cheap, you can recrystalise it.


Interesting ball mill, personally I used the ol' pestle and mortar to grind up my sugar and potassium nitrate.

I do have quite a large load of medical grade NH4NO3, I'll have to try that eventually. I did not know that KNO3 was considered "shit tier" in ETN synthesis. I was thinking my problem might've been the crappy Sulfuric.

Stump remover KNO3 isn't exactly the cheapest ($3 a lb), but I don't know of any other local sources.
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[*] posted on 2-7-2013 at 05:22


I think ETN yeilds is mostly a matter of reagents.

You want decent H2SO4, I'd say at least 95%, and pure, dry AN, I don't know what medical grade is??? Erythritol should be powderd, I used mortar and pestle.

This sounds crazy, and probably wouldn't do it again, but I actually used a warm water bath to get the temp up to 25* C about.
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[*] posted on 2-7-2013 at 05:28


Greenhouse grade KNO3 can be had at most farm stores in the US. It's usually pure enough for pyrotechnic uses, but I would still do a recrystallization before I would use it for anything else.
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[*] posted on 2-7-2013 at 06:00


Quote: Originally posted by golfpro  
I think ETN yeilds is mostly a matter of reagents.

You want decent H2SO4, I'd say at least 95%, and pure, dry AN, I don't know what medical grade is??? Erythritol should be powderd, I used mortar and pestle.

This sounds crazy, and probably wouldn't do it again, but I actually used a warm water bath to get the temp up to 25* C about.


I believe my sulfuric was 95% if not very close, but I'd have to do titration to figure out for sure. All my reagents were powdered, so no worries there.

I don't think there is anything wrong with 25* C. As far as my knowledge goes, you can increase the temps just a little if the slurry gets to thick to stir. Infact, I remember reading people here getting higher yields with slightly higher temps around 20* C, which is why I attempted my first synthesis there. I can vouch for the ease of stirring at such temperatures.
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[*] posted on 2-7-2013 at 06:20


Dry your AN a few hours before it is used, it will get moist, and it clumps up.

You don't add water to acid solution pour the acid into a larger volume of cold water.
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[*] posted on 2-7-2013 at 06:33


Quote: Originally posted by hyfalcon  
Greenhouse grade KNO3 can be had at most farm stores in the US. It's usually pure enough for pyrotechnic uses, but I would still do a recrystallization before I would use it for anything else.


Not any farm stores near me as far as I can see. Spectracide is decently pure, and can be improved like you said. I should've done that in the first place, but I figured the nitrate wasn't the problem considering I had pretty heavy white fumes when adding it to H2S04.

Personally, I thought my misfortune was caused due to missing some important step. I read the dupont patent before attempting ETN just to be sure that I was going to do things properly, but since the result yielded no ETN, I have doubts that I had the technique down.

If you've had success with ETN, would you say that my process looks the way it should?
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[*] posted on 2-7-2013 at 06:40


Quote: Originally posted by golfpro  
Dry your AN a few hours before it is used, it will get moist, and it clumps up.

You don't add water to acid solution pour the acid into a larger volume of cold water.


Would adding cold water slowly like I did effect the yield though? What you are suggesting sounds more like a safety precaution. "Do what you outa, add acid to water."

I remember watching the acid change a very light (white) color temporarily when I DID add water. With the way things turned out, i'm not sure if that is a normally expected reaction.

[Edited on 7/2/2013 by Chill]
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[*] posted on 2-7-2013 at 17:40


Ok, my sulfuric acid is purplish 95% around, no I haven't done titration.. My yield was 12g ETN for 10g Erythritol. I probably could have let the nitration go a bit longer but I was anxious to see the stuff. I also probably left 1-3g out there in the filtration/recrystalization etc. PM me if you want to know exactly what I did, all I can say is find the pdf of quicksilver's procedure (at least I think it is), I would say that is the best one to go off of, I saw no temp rise (maybe half a degree C) during the whole time of adding Erythritol, infact it cooled a bit more than I wanted. Expect the worse, keep a nice bucket of cool water nearby.


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[*] posted on 4-7-2013 at 02:09



Quote:

boiled close to azeotrope


How do you know?
My guess would be your acid is not strong enough.

Whats the exact weight of your stuff per 100ml?
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[*] posted on 4-7-2013 at 12:33


I forgot to mention, the erythritol I'm using is the food grade sugar substitute that I bought at a health food store. Should this be recrystallized? I looked up a solubility graph and it looks like it's doable, but there will be some loss as I don't have the tools to reach -20*c.
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[*] posted on 4-7-2013 at 12:51


Most freezers will go below -20°C!



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[*] posted on 4-7-2013 at 17:31


Quote: Originally posted by Pulverulescent  
Most freezers will go below -20°C!


Maybe an empty freezer... I stuck a thermometer in my full freezer and it measured just a tad below 0*c. Around -2*c

[Edited on 7/5/2013 by Chill]
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[*] posted on 4-7-2013 at 22:24


Quote: Originally posted by dangerous amateur  

Quote:

boiled close to azeotrope


How do you know?
My guess would be your acid is not strong enough.

Whats the exact weight of your stuff per 100ml?


Alright, I finally got to weighing it. 50ml is 86g.

86x2=172g/mol which is damn close to 184g/mol (pure H2S04)
So my sulfuric acid is around 94% which should be alright for this experiment. Correct?
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[*] posted on 4-7-2013 at 23:31


H2SO4 is definately strong enough.
Are you sure that the spectracide is KNO3 ?
I have only made ETN with 68% HNO3 and boiled drain cleaner.
I can see ETN ppt even before I dunk it in water.

I wonder if one was to filter the ice cold KNO3 H2SO4 mix through sintered glass and remove pptd K2SO4 .... Would it help with stirring ?

Any one know solubility data on K2SO4 in HNO3 ?




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[*] posted on 4-7-2013 at 23:57


Quote: Originally posted by Motherload  
H2SO4 is definately strong enough.
Are you sure that the spectracide is KNO3 ?
I have only made ETN with 68% HNO3 and boiled drain cleaner.
I can see ETN ppt even before I dunk it in water.

I wonder if one was to filter the ice cold KNO3 H2SO4 mix through sintered glass and remove pptd K2SO4 .... Would it help with stirring ?

Any one know solubility data on K2SO4 in HNO3 ?


100% sure that spectracide is KNO3. I recrystallized it today and I'm going to try using it to make ETN tomorrow. If that doesn't work, I'm going to try using recrystallized ammonium nitrate.

Can I get a play-by-play of your method to compare it to my own? Doing just one step incorrectly could've screwed my yield up.

I believe I read somewhere that letting the erythritol nitrate for "too long" can lead it to have an extra hydroxyl group or something like that, and it causes it to be soluble in water, which would explain why I didn't see any yield.

I'll have to try looking for it again, it might be related.
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[*] posted on 5-7-2013 at 17:34


1 gm Erythritol for 4ml 68% HNO3 + 6ml 95% H2SO4
Erythritol was ground with mortar pestle.
Acid mix cooled to 10*C
Magnetic stirrer was used 240 rpm. And a thermometer dipped in the flask.
Flask was placed in cold water with a few ice cubes.
A 5 gal runnaway pail was near by.
The erythritol was trickled in with a powder trickler, I use for reloading ammunition, fairly constantly.
Temp was monitored and didn't exceed 18*C.
After the addition it was stirred for additional 20 mins.
The contents were poured into ice water, filtered and washed multiple times with water and neutralized with bicarbonate soln and re washed with water
Dried on a Teflon cookie tray and re crystallized.




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[*] posted on 5-7-2013 at 18:36


Quote: Originally posted by Motherload  
1 gm Erythritol for 4ml 68% HNO3 + 6ml 95% H2SO4
Erythritol was ground with mortar pestle.
Acid mix cooled to 10*C
Magnetic stirrer was used 240 rpm. And a thermometer dipped in the flask.
Flask was placed in cold water with a few ice cubes.
A 5 gal runnaway pail was near by.
The erythritol was trickled in with a powder trickler, I use for reloading ammunition, fairly constantly.
Temp was monitored and didn't exceed 18*C.
After the addition it was stirred for additional 20 mins.
The contents were poured into ice water, filtered and washed multiple times with water and neutralized with bicarbonate soln and re washed with water
Dried on a Teflon cookie tray and re crystallized.


I thought it was necessary (or heavily suggested) that you recrystallize the ETN in methanol or ethanol. You just washed yours?
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[*] posted on 5-7-2013 at 22:36


I said dried on a Teflon cookie tray and recrystalized.
Except I did it with acetone. It gave me a high density non fluffy crystals.

If you are going to use it as soon as the crude product has dried .... Recrystallization is unnesscesarry. But definately recrystalise if you are going to store it for even a week.

[Edited on 6-7-2013 by Motherload]




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[*] posted on 5-7-2013 at 22:39


Quote: Originally posted by Motherload  
I said dried on a Teflon cookie tray and re crystalized.
Except I did it with acetone. It gave me a high density non fluffy crystals.


Dammit, I was reading in such a rush that I missed that part, sorry about that.

Some threads suggested not using acetone because it is too good at dissolving ETN, and it becomes a PITA to get it back out of solution. Glad you were able to get it to work. I had a few bottle of pure methanol lying around collecting dust so I plan on using those.
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[*] posted on 5-7-2013 at 22:44


Acetone solution of ETN phase separates in water with bicarbonate and urea.
I evaporated/boiled off the acetone with stirring at 50*C.
Adding water alone with bicarbonate and urea won't ppt the ETN.

The only reason I figured this out is because I was out of methanol and you use way too much compared to acetone.

[Edited on 6-7-2013 by Motherload]




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[*] posted on 6-7-2013 at 07:18


I don't think there's anything wrong with fluffy crystals, except that if you have 20grams, it looks like a lot, you press it and 3 grams is a small amount
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[*] posted on 6-7-2013 at 08:12


Quote: Originally posted by Motherload  
Acetone solution of ETN phase separates in water with bicarbonate and urea.
I evaporated/boiled off the acetone with stirring at 50*C.
Adding water alone with bicarbonate and urea won't ppt the ETN.

The only reason I figured this out is because I was out of methanol and you use way too much compared to acetone.

[Edited on 6-7-2013 by Motherload]


Just wondering what does the urea do? The bicarbonate neutralizes the acid, but what does the urea do?
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[*] posted on 6-7-2013 at 11:53


Urea serves as a stabilizer which is necessary for every nitric esters longer shelf life.
There are other better stabilizers out there .... Urea is cheap and available.
You don't need if if you don't plan on storing it.




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