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Author: Subject: help make white fuming nitric acid.
Kiwichemicali
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[*] posted on 25-3-2012 at 00:52


Quote: Originally posted by quicksilver  

If it's a little yellow: simply add a half gram of Urea to every 500ml of nitric acid and it will clear it up water white.

[Edited on 30-9-2011 by quicksilver]


I've distilled Nitric Acid from Sulfuric Acid and Potassium Nitrate. The result is light yellow. However when I add Urea a vigorous reaction takes place en lots of NOx fumes escape.
Is the addition of Urea to fuming Nitric Acid always this violent?

Kiwi
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[*] posted on 25-3-2012 at 02:57


ISTR some fizzing but no NO<sub>2</sub> evolution.
Urea decomposes nitrous acid in solution to N<sub>2</sub> and water, diluting the acid.
Perhaps you used too much of it . . .
A better solution is bubbling dry air through your HNO<sub>3</sub> to oxidise NO<sub>2</sub>.




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AndersHoveland
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[*] posted on 25-3-2012 at 10:00


This is why I do not think urea is a good way to remove NO2 from nitric acid.

The most ideal way would be to pass dry air through an ozone generator. Then the ozone could oxidize the NO2 to nitric acid, increasing the concentration even further.
(the reaction of plain oxygen with NO2 only forms HNO3 up to a certain concentration, whereas O3 can even oxidize NO2 to N2O5, the acid anhydride of nitric acid.

[Edited on 25-3-2012 by AndersHoveland]
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Kiwichemicali
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[*] posted on 26-3-2012 at 08:18


Quote: Originally posted by AndersHoveland  
This is why I do not think urea is a good way to remove NO2 from nitric acid.

The most ideal way would be to pass dry air through an ozone generator. Then the ozone could oxidize the NO2 to nitric acid, increasing the concentration even further.
(the reaction of plain oxygen with NO2 only forms HNO3 up to a certain concentration, whereas O3 can even oxidize NO2 to N2O5, the acid anhydride of nitric acid.

[Edited on 25-3-2012 by AndersHoveland]


Any idea how much air needs to pass through 100ml? I tried pure O2 but gave up after a short time because I didn't see a result. I really have no idea what volume or how much time is needed.

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[*] posted on 26-3-2012 at 08:25


It's slow, takes patience ─ and warming the acid helps . . .



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[*] posted on 27-3-2012 at 01:06


Quote: Originally posted by Kiwichemicali  

Any idea how much air needs to pass through 100ml? I tried pure O2 but gave up after a short time because I didn't see a result. I really have no idea what volume or how much time is needed.


1 liter of gas contains 0.0446 moles of molecules under normal conditions. 100ml liters of water contains 5.556 moles. In the reaction of NO2, O2, and H2O, one mole of O2 makes the equivalent of 4 moles of HNO3, or when further concentrating the HNO3, 1 mole of O3 makes 2 moles of HNO3. You can do the calculations. A rough estimate is that 100 liters of gas contains the same number of molecules as 100ml of water. So that is a large quantity of gas, and the reaction will take long.
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[*] posted on 27-3-2012 at 21:31


Quote: Originally posted by KemiRockarFett  
Dry Ca(NO3)2 *4 H20 to Ca(NO3)2 and add H2SO4 , filter out the CaSO4 in a chermic filter. Done !

Another one is to take Ca(NO3)2 *4 H20 and add NaHSO4 and the nitric forms at 40 degrees C when the nitrate starts to melt in its own crystal water. CaSO4, NaNO3 and HNO3 will form.

what will be the concentration of HNO3 formed after filtering
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[*] posted on 17-4-2012 at 23:55


just a quick question if anyone can help,I was wondering if you can use 85% phosphoric acid to make nitric acid from a nitrate salt rather than sulphuric acid,I have both but my sulphuric is expensive and I get litres of the phosphoric for free and want to get some good use out of it.
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[*] posted on 18-4-2012 at 00:50


Quote: Originally posted by hames  
just a quick question if anyone can help,I was wondering if you can use 85% phosphoric acid to make nitric acid from a nitrate salt rather than sulphuric acid,I have both but my sulphuric is expensive and I get litres of the phosphoric for free and want to get some good use out of it.


Ca(NO3)2/other metal nitrates that forms insoluble/slightly soluble phosphates might work, but KNO3, NaNO3 and NH4NO3 definitely doesn't work. Try it with a bit of calcium nitrate and a bit of phosphoric acid first.



[Edited on 18-4-2012 by weiming1998]
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[*] posted on 18-4-2012 at 01:45


Quote: Originally posted by weiming1998  
Quote: Originally posted by hames  
just a quick question if anyone can help,I was wondering if you can use 85% phosphoric acid to make nitric acid from a nitrate salt rather than sulphuric acid,I have both but my sulphuric is expensive and I get litres of the phosphoric for free and want to get some good use out of it.


Ca(NO3)2/other metal nitrates that forms insoluble/slightly soluble phosphates might work, but KNO3, NaNO3 and NH4NO3 definitely doesn't work. Try it with a bit of calcium nitrate and a bit of phosphoric acid first.



[Edited on 18-4-2012 by weiming1998]
I would be distilling it afterwards so it shouldn't matter if the salts are soluble should it, I have an abundance of KNO3,I have no Ca(NO3)2 but I have Ba,Sr nitrates which might form insoluble phosphates.
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[*] posted on 21-4-2012 at 05:47


I was wondering whether anyone has prepared concentrated HNO3 from the action of Oxalic acid on a nitrate salt:

2 KNO3 + H2C2O4 ---> K2C2O4 + 2HNO3

Potassium oxalate may be soluble in dilute Nitric acid but insoluble in concentrated or in cold concentrated solutions. For feasibility per "A dictionary of chemistry and the allied branches of other sciences", Volume 4, by Henry Watts, page 251, to quote. Oxalate acid "is one of the strongest acids, decomposing dry chloride of sodium when heated, with evolution of hydrochloric acid, and converting chloride or nitrate of sodium in aqueous solution into acid oxalate.
The oxalates of the alkali-metals are soluble in water, the rest are for the most part insoluble in water, but soluble in dilute acids. "

Link:
http://books.google.com/books?pg=PA255&lpg=PA250&dq=...

An indirect approach may also be successful. Add copper turnings to a heated concentrated solution of H2C2O4 and KNO3. Collect the NOx gases, mix with air and dissolve in water.

If dilute HNO3 is presence:
3Cu(s) + 8HNO3(aq) ——> 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l)

If Conc HNO3:
Cu(s) + 4HNO3(aq) ——> Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l)


[Edited on 21-4-2012 by AJKOER]
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[*] posted on 21-4-2012 at 08:42


Oxalic acid isn't as "thirsty" as sulfuric acid. It's possible that some of the water could be retained but not as powerfully. What's more it's a powder so if you used it with a nitrate you would have to use water (from the HNO3 ?). Therefore you may have a 3rd adulterant chemical in a mixed acid wherein you simply wanted it for a clean nitration (or whatever). But if you tried it with HNO3; I don't believe you could do better than cooked and cleaned sulfuric (@ 98%), However it's a good question because to think along those lines MAY discover an acid that would preform better (than H2SO4). This is a very interesting "micro" experiment where weights and volumes after separation may be become a "hope note" that continues for quite some rime.



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[*] posted on 22-4-2012 at 23:31


I know phosphoric acid is used to make hydroiodic and hydrobromic acids because it doesn't oxidize them to their elements like sulphuric acid does.is there any reason this won't work for nitric acid? you would think at least the azeotrope would be formed.
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[*] posted on 25-4-2012 at 17:11


Nearly anhydrous nitric acid apparently can be made by carefully distilling nitric acid with dry phosphoric acid. It is important not to add the phosphoric acid all at once, as the heat can cause decomposition of some of the nitric acid. (Weber)
http://books.google.com/books?id=CrNXAAAAYAAJ&pg=PA342&a...
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[*] posted on 19-3-2013 at 15:03


For any of you thinking about dissolving N2O5 into nitric acid to raise the acid concentration, this may be of interest:

Nitric acid dissolves nitrogen pentoxide, and a definite compound, 2HNO3.N2O5, has been obtained which is liquid at ordinary temperatures but solidifies at 5° C.
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[*] posted on 21-3-2013 at 13:55


If you need WFNA for RDX production, you can successfully do without it. Distillation of KNO3 (NaNO3) + H2SO4 gives you yellow liquid, which most likely will burn hexamine, producing red fume of NO2 (I got it during my first experiments). But there is the simple way to resolve this problem. Dissolve NH4NO3 in HNO3 and use hexamine dinitrate instead of pure hexamine. Two birds with one stone- forget about nitrogen oxides and increase total yield. Read topic on RDX.



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Ral123
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[*] posted on 21-3-2013 at 23:31


I've never heard adding NH4NO3 helping increase yields of RDX toward WFNA. Why is nobody doing it?
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[*] posted on 22-3-2013 at 01:23


"There are more things, on the Earth, on the Heaven, Horatio..."

Organic Chemistry of Explosives by Jai Prakash Agrawal & Robert Hodgson.

This method is known as the K-process after its discoverer Koffler.

Like method 5.15.1.2 it
uses ammonium nitrate to compensate for the nitrogen deficiency in hexamine and works to
Equation (5.24) where two moles of RDX are produced per mole of hexamine. As observed
with method 5.15.1.2, the addition of ammonium nitrate to nitric acid appears to prevent
dangerous oxidation reactions from occurring. In fact, this nitrolysis reaction only occurs at
elevated temperature and so a constant temperature of 80 ◦
C is usually maintained throughout
the reaction. Yields of approximately 90% are attainable based on one mole of hexamine
producing two moles of RDX.

I can only add that if you use hexamine dinitrate, you save some cons HNO3 because part of acid is added as a part of hexamine dinitrate. And even without NH4NO3 using dinitrate prevents dangerous oxidization




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[*] posted on 24-3-2013 at 00:18


Quote: Originally posted by caterpillar  
As observed
with method 5.15.1.2, the addition of ammonium nitrate to nitric acid appears to prevent dangerous oxidation reactions from occurring.

Perhaps because the ammonium ions help absorb any undesirable NO2 that forms. Normally this is a slow reaction and requires boiling temperatures, however, so I am not completely sure.




I'm not saying let's go kill all the stupid people...I'm just saying lets remove all the warning labels and let the problem sort itself out.
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Ral123
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[*] posted on 24-3-2013 at 00:44


Ammonium nitrite is so unstable, ammonium chloride+sodium nitride yields nitrogen. I also have the opinion that with HDN the reaction goes more smoothly. I don't need to economise the hexamine witch is sold by the kilo quite cheap. The expensive here is the WFNA an all the solvents and distilled water for the HDN and washing and purifying the RDX.
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[*] posted on 24-3-2013 at 02:12


Well, that's just the same situation what I had, trying to prepare RDX. Conc HNO3 is the most valuable component here. This is why any way to replace some of HNO3 with diluted one (or even mixture of H2SO4 + KNO3 (NaNO3) is more than welcome. And this is the way to do it- one need DILUTED HNO3 to prepare hexamine dinitrate. Therefore, part of conc HNO3 can be replaced- it goes into reaction vessel as part of hexamine salt. Of course, this salt must be dry. Well, large excess of HNO3 is a must, but later diluted HNO3 may be used for preparation of hexamine dinitrate. On the other hand, I have such feeling, that using this method one can put more hexamine per a gram of HNO3 than usually (only hexamine and HNO3). And there is another way- Anders gave me link to it. A way, which lets one to use mixed acid instead of pure HNO3. I only suspect, that this method requires oleum, not only conc H2SO4. About which process is smoother. My own experience- reaction with hexamine dinitrate is milder out of question. Later, if you need to get more pure and stable RDX, you should perform oxidation of all linear nitramines. You must use reaction vessel, which can withstand fast heating (like pirex). The most civilized way to perform this op is to put slowly reaction mixture (70%) and water(30%) into same vessel. What you'll get is the typical runaway- mixture will boil. Do it in open air- NO2 will go away. But finally you'll get large crystals of RDX. Wash them with water.



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[*] posted on 25-2-2015 at 07:10


Does anyone know if one of these Dreschel bottles can be used like a cold trap to neutralize acid vapours when distilling Nitric acid under vacuum.
The one in the picture is mine and I am unsure if it can withstand the pressure of my Diaphragm pump? Has anyone used one for this purpose?



[Edited on 25-2-2015 by greenlight]

20150225_235532.jpg - 2.7MB

[Edited on 25-2-2015 by greenlight]
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[*] posted on 25-2-2015 at 09:02


Quote: Originally posted by hissingnoise  

If you need water-white HNO3 just add a small pinch of urea as a last resort.



Won't the resulting Urea nitration cause the release of more NOx, which might be redissolved?
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[*] posted on 25-2-2015 at 09:38


greenlight, I have used those before under about 50 torr, it didn't implode and was NOT vacuum rated. Really though nobody knows your glass better than yourself, so don't take my word for it. I suggest testing it under vacuum before you try the distillation. Losing that piece would suck, but it'd be better than losing it along with a bench or getting an acid burn if it implodes with fuming nitric acid in it.
How much vacuum can your diaphragm pull?
Are you going to neutralize the vapors with a basic solution or just condense them? I suggest the latter, but that's just because I use a real vacuum pump which is very expensive and could be ruined by acid vapors. A cold trap won't do a whole lot for WFNA at 50 torr.




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[*] posted on 25-2-2015 at 12:17


For low pressure distillation of corrosive substances like WFNA I would warmly reccommend the usage of a water jet vacuum pump. Preferably configured in to a pump driven recirculation system that drives the same water through the venturi jet in a loop. No need to dump hundreds of liters of water down the drain driving a jet pump off the tap directly. The scrubber systems will not save a mechanical vacuum pump from the harm of the corrosive acid or solvent vapours....at best they delay the inevitable death of the device. It is just a matter of time before the scrubbers saturate, the cooling of the vacuum trap fails or for some reason a huge amount of corrosive vapours is sucked through the system too quickly. Either way the harm will enter the pump and shut down the operation in a very uncomfortably short period of time. Unless you have a fully teflon coated pump system at your disposal, but these are rare and quite expensive. Hence a venturi type device is your best option, cheap, simple and quite insensitive towards most kind of corrosive environments.

Besides that the vacuum distillation for WFNA in amateur setup is a rather unnessesary complication and the benefits do not outweigh the added technical complications and dangers. There are very few purposes that I can think of for which a properly performed atmospheric pressure distillation will not yield a suitably pure WFNA (and heterocyclic nitramines are not among those purposes). Hence I would suggest to opt for the least technical complications and focus more on tuning the operating parameters of the system and carefully dividing the received fractions.

[Edited on 25-2-2015 by markx]




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