Sciencemadness Discussion Board - Nitric Acid From Oxalic Acid

Nitric Acid From Oxalic Acid

Chem Science - 4-8-2018 at 19:29

Hello everyone !
So Here we go again, the typical amateur problems of Acid being Expensive enuf to make one go make it by conventional methods or finding new ones. Here is one that i thought it could work well, its not that awesome, but it works

FUNDAMENT
Its well known that Calcium Oxalate is very insoluble in water, and in general Oxalic acid and Nitrate salts like calcium nitrate are cheap and easily available. So the reaction that in my minde pup-up was

Ca(NO3)2 + (COOH)2 = Ca(COO)2 + 2HNO3

Now these reaction is in equilibrium and the insolubility of the Calcium Oxalate Should make it go to the Right, some thing to have in mind is that the solubility of Calcium Oxalate increases with pH, so i was alredy thinking on doing these in a somhat large volume of water. To save you time, my best Yield was 32% in Azeotropic nitric acid, but it can be 50% !! Keep reading and you'll see why. Theoretical yield is 450ml of acid azeotrope and these was one of my big inspirations on doing it, SUPER CHEAP

METHOD

So we prepare 2 solutions and mix theme together,
SOLUTION 1) 100g Oxalic acid dihydrate and 1/2 Liter of water. Heat these up until all dissolves
SOLUTION 2) 390,5g Calcium nitrate and 450ml water, stirr these up untill disolve.
With the 2 solution clear, Mix theme together and let these cool to rome temperature, and then put it on the fridge. A large amount of Calcium oxalate will precipitate off, After cool, filter the calcium oxalate and do what you can with it ( I just trow it away) in these setep it's important to get as mouch solution as posible, because here is our dilute nitric acid I got around 1150cc. now these is fractionally distilled to remove 80% of the water ( or until you see NO2 gas formation ) at these point tur off the heat and leti it cool in the fridge. Some Calcium oxalate and oxalic acid comes off here, it's important to do this step, because these excess salts react at High-temps in redox reactions producing CO2 and NO2 that destroys the Nitric acid Once these is done, put it back on Fractional distillation and get your Azeotropic Nitric acid boiling at 120 - 121 degrees My final yield was 32% almous 100 ml .. Now i said it can be 50% these is because my fractional distillation apparatus is not a big one and i eventually lose 100 ml ( I titrate the hole 80% of the distillate to see these because the yield was low and make my wonder, and these was the first place to lok at) So if you have a good Fractional distillation apparatus you can get 200 ml of Nitric acid. Another mistake i did was on telling when to stop the first part of the distillation, temperature was not god indicator on my overloded aparatus, so i used the NO2 gas to see these ( Not the best way i think )Also maybe using more Oxalic acid can help since i Used Stoichiometric amounts, these reaction has the down side that it takes work, i did these some 3 times, and didin't hade the inspiration to try other conditions at the moment. but so far i think these mthod is good and it did get me some good acid, with no Oxalate contamination. The Acid i got had a Density of 1,35g/ml and wass a red colour ( NO2 contamination ) but i reacted it with very pure copper metal, and the solution wass cristal clear, so i suspect no oxalates are contaminating it.

Okay so these is all, Hope these is useful. See you next time !!

[Edited on 5-8-2018 by Chem Science]

j_sum1 - 4-8-2018 at 19:57

This is a nice method. Useful for those who have limited access to sulfuric acid. Oxalic acid is pretty easy to get around here although nitrate salts are a bit of a trick. It might be worthwhile giving this a go.

RogueRose - 5-8-2018 at 00:23

189 to 191 °C (372 to 376 °F; 462 to 464 K)
101.5 °C (214.7 °F; 374.6 K) dihydrate

decomposes (anhydrous)
132 °C (270 °F; 405 K) (tetrahydrate)

I'm wondering if you have tried doing this without water or at least with much less water as most of the calcium nitrate's are the tetra hydrate, which is about 44% water by weight and the dihydrate of oxalic acid is 40% by weight and both decompose are realatively low temps

melting points are about as follows:
~102C (215F)for Oxilic acid dihydrate
~189-191C (372-376) for the anhydrous oxalic acid
~132C (~270F) for Cal Nitrate tetrahydrate decomposition temp

In your example of 100g and 390g there is a total of 212g of water in the salts/acids, if the calcium was the tetrahydrate.

I was looking at the same process a little while ago and trying to compare it to using sodium bisulfate as the acid and I was told to do the distillation with the cal nitrate and bisulfate dry, though I haven't had time to do it yet. Have you looked at this method? It supposedly can yield much higher acid percentages, higher than azeotropic from what I remember, though I'm not sure.

I am curious if the water generated by the oxalic acid decomposing (looses 2 water molecules) at about 102C, is enough to mix/dissolve the nitrate & oxalic acid or if that would occur more towards 370+F when the nitrate looses it's water. Since HNO3 boils around 170-180F it would seem that as soon as the HNO3 is made from the acid/salt mixing, it should boil off pretty quickly.

I'd like to have a little more accurate thermometers/thermocouples to measure where the reactions are taking place and see where I start to get HNO3 coming over.

AJKOER - 5-8-2018 at 06:21

Having researched and experimented (and reported those experiments on SM in a thread, see http://www.sciencemadness.org/talk/viewthread.php?tid=18963#...), I discovered a possible major concern. You have to avoid an excess of H2C2O4 that can react with any produced oxidizing acid (like HOCl, HClO2, HClO3, ..) or concentrated acid (like conc H2SO4, see https://www.quora.com/What-happens-when-gas-obtained-by-heat... ). The most obvious example of what I'm talking about presented in the literature is the recommended procedure for the generation of chlorine dioxide by the action of H2C2O4 on KClO3. The problem, or blessing in the current case, is that with chloric acid formation (from oxalic acid acting on a chlorate), the resulting chloric acid can further react with an excess of oxalic acid producing volumes of carbon dioxide gas. In the case of ClO2, this dilutive effect reduces the explosion danger of ClO2. Less favorable circumstances can result in the dangerous ejection of acid and gases.

Example of cited reaction (see page 6 at https://www.grandcircuitinc.com/sites/default/files/Howard%2... and also https://books.google.com/books?id=pu3HBQAAQBAJ&pg=PA279&... ):

2 HClO3 + H2C2O4 --> 2 ClO2 + 2 CO2 + 2 H2O

where in the current context:

2 KClO3 + H2C2O4 --> K2C2O4 (s) + 2 HClO3
-------------------------------------------------------

Another case where I do not recommend the use of H2C2O4, is in a reaction with aqueous NaOCl + NaCl (found in chlorine bleach) as an accidental excess of oxalic acid is potentially dangerous.

The reaction does produce chlorine gas but, beware, the reaction due to the accompanying CO2 gas and reaction heat, I deem as potentially at times with excess H2C2O4, being just too energetic to be a safe path to toxic chlorine gas.

For associated reactions and more comments see my discussion at http://www.sciencemadness.org/talk/viewthread.php?tid=20109 . Aqueous reactions presented there suggest that 1 mole (90 grams) of H2C2O4 can produce 3 moles of gas (over 67 liters not adjusting for any elevation of volume due to heating over RT). So, 0.1 mole of oxalic acid (around 5 cc) could quickly create in excess of 7 liters of a hot mix of 2/3 CO2 & 1/3 Cl2 gases. Use of solid hypochlorites with H2C2O4 is described as explosive.

[Edited on 5-8-2018 by AJKOER]

Chem Science - 6-8-2018 at 03:50

Hi RogueRose .Yes, i did try using Oxalic acid Dihydrate and Calcium Nitrate powders and distilling. But the acid is very contaminated with oxalic acid, and decomposition occurs, But the acid is strong !! Mabe another distillation will remove the oxalic acid.I did try alsou try using sodium bisulfate and calcium nitrate, the acid was pure, concentrated but yield is low and i'm not comfortable with dry distillation, i got 36% Yield with Bisulfate.The rock of sulfates is no very difficult to dissolve but i have break a flask with it. After the test, i did some calculations on stoichiometry and thought about the water of crystallization problems,but to be honest, i took me 2 days of work per experiment, and i was very idiot at the time to optimize on paper and theory before going to the lab to play.

[Edited on 6-8-2018 by Chem Science]

Chem Science - 6-8-2018 at 03:59

Hi AJKOER Thanks for the links !! Oxalic acid has its concerns, as an acid its not a good idea for reaction with acid incompatible chemicals like bleach, even if it's a weak acid. Thank You for the links and tips

Im reading your posts

symboom - 6-8-2018 at 14:07

So a win for oxalic acid
I have so far seen by percipitation
Oxalic acid and magnesium sulfate forms sulfuric acid proven
Oxalic acid and calcium chloride forms HCl?
Oxalic acid and calcium nitrate forms nitric acid proven
Sugar is oxidized to oxalic acid by nitric acid proven

This is a processs that can be repeated with sulfuric acid
Sulfuric acid and Calcium nitrate forming nitric acid and
Calcium sulfate

Could be possible
Urea sulfate and nitric acid forms sulfuric acid and insouble urea nitrate
Urea chloride and nitric acid forms urea nitrate and HCl acid

Alot of these reactions would not expect to work due to oxalic acid is considered a weaker acid but due to percipitation it drives the reaction forward

I think its simular to lithium reducing cesium chloride to ceasium metal in this case it is driven forward due to ceasium metal having a lower boiling point than lithium

This find is quite interesting

[Edited on 6-8-2018 by symboom]

Chem Science - 9-8-2018 at 05:35

Hi symboom
Well i did try with calcium chloride and oxalic acid, i did get a bunch of precipitate, but after distillation my Yield was horrible, and the acid was poorly concentrated. Maybe after all the Nitric acid work i was a little tired and did something wrong somewhere.

symboom - 9-8-2018 at 18:00

Hmm that is interesting removing the hydrochoric acid by boiling it off hydrochloric acid and leaving behind oxalate salt. i would try it again with a transition metal salt transition metals like copper chloride or iron chloride or aluminum chloride. Also know as acid salts. My guess is transition metals give up chloride ions quickly Although i sure it in theroy should have worked unless the is an intermediate that is effecting it.

[Edited on 10-8-2018 by symboom]

[Edited on 10-8-2018 by symboom]

Chem Science - 11-8-2018 at 17:02

Once i get some new equipment to do better distillations i will give it a try to

artemov - 26-8-2018 at 03:10

Quote: Originally posted by Chem Science

Ca(NO3)2 + (COOH)2 = Ca(COO)2 + 2HNO3
SOLUTION 1) 100g Oxalic acid dihydrate and 1/2 Liter of water
SOLUTION 2) 390,5g Calcium nitrate and 450ml water
... Also maybe using more Oxalic acid can help since i Used Stoichiometric amounts ...

... these is fractionally distilled to remove 80% of the water ( or until you see NO2 gas formation ) at these point tur off the heat and leti it cool in the fridge. Some Calcium oxalate and oxalic acid comes off here, it's important to do this step, because these excess salts react at High-temps in redox reactions producing CO2 and NO2 that destroys the Nitric acid ...
[Edited on 5-8-2018 by Chem Science]

Hi. I'm also trying to make nitric and sulphuric acid via this method (using calcium nitrate and calcium sulphate respectively).

Just want to verify, is 100g of oxalic acid and 390.5g of calcium nitrate tetrahydrate stochiometric amount?

Also, what do you mean by "some Calcium oxalate and oxalic acid comes off here"? Are you saying they will precipitate out of the solution upon cooling in the fridge?

For sulphuric acid, do you have any suggestion on how this method can be done, since calcium sulphate is very insoluble?

I dun have a distillation kit yet, can I just boil nitric acid (and sulphuric acid) in an open beaker to concentrate them some how?

Cheers.

[Edited on 26-8-2018 by artemov]

JJay - 26-8-2018 at 05:04

It's unlikely to work well with calcium sulfate. Oxalic acid is typically a dihydrate, but it can be anhydrous. If I'm doing the math correctly, you should use more oxalic acid:

100/(90+36)*(164+18*4)=187 g calcium nitrate tetrahydrate for the dihydrate
100/(90)*(164+18*4)=262 g calcium nitrate tetrahydrate for the anhydrous acid

I'd suggest making dilute nitric acid and then fractionally distilling.

CobaltChloride - 26-8-2018 at 06:34

If you want to make sulfuric acid, I'd say the easiest method of making it is by reacting H2O2 and SO2. Just bubble SO2 into aqueous hydrogen peroxide until the peroxide solution starts smelling of SO2. The SO2 can be made by either burning sulfur (chemplayer has a video on this method but I can't find it) or by reacting metabisulfite from the brewing store with any acid.

Boiling the resulting soon until it starts fuming should make pretty concentrated H2SO4.

j_sum1 - 26-8-2018 at 07:22

Quote: Originally posted by CobaltChloride

IThe SO2 can be made by either burning sulfur (chemplayer has a video on this method but I can't find it) or by reacting metabisulfite from the brewing store with any acid.

Not Chemplayer. Nurdrage.
https://youtu.be/2gXByJkg0iY?t=3m24s

CobaltChloride - 26-8-2018 at 09:38

Quote: Originally posted by j_sum1

Quote: Originally posted by CobaltChloride

IThe SO2 can be made by either burning sulfur (chemplayer has a video on this method but I can't find it) or by reacting metabisulfite from the brewing store with any acid.

Not Chemplayer. Nurdrage.
https://youtu.be/2gXByJkg0iY?t=3m24s

There's also this chemplayer video where they do the exact same thing I described: https://smvideo.djr.pw/watch/120/sulfuric-acid-from-sulfur-u...

It seems we're both right

AJKOER - 26-8-2018 at 14:08

Quote: Originally posted by CobaltChloride

If you want to make sulfuric acid, I'd say the easiest method of making it is by reacting H2O2 and SO2. Just bubble SO2 into aqueous hydrogen peroxide until the peroxide solution starts smelling of SO2. The SO2 can be made by either burning sulfur (chemplayer has a video on this method but I can't find it) or by reacting metabisulfite from the brewing store with any acid.

Boiling the resulting soon until it starts fuming should make pretty concentrated H2SO4.

Actually, I am not too excited about using H2O2 to prepare not too strong H2SO4, and paths employing H2C2O4 probably do better in producing a more concentrated acid.

However, I do find very interesting the below path to the powerful sulfate radical anion!

But, one will need a UV Lamp and N2O (Laughing Gas, now sold in Walmart in CO2 like cartridges) in addition to the SO2.

The chemistry involves radical creation from the uv photolysis of aqueous N2O. Expected reactions:

SO2 + H2O = H+ + HSO3-

N2O + uv --> N2 + •O-

•O- + H2O --> •OH + OH- (except at very high pH, where the reaction moves to the right)

HSO3- + •OH --> •SO3- + H2O

•SO3- + N2O = SO3 + •O- + N2 k = 3.5 x 10^7 /M/s (a bit slow, source: Reaction 3.3 at https://srd.nist.gov/NSRDS/NSRDS-NBS-65.pdf which also documents many radical reactions cited)

And with more water:

SO3 + H2O = H+ + HSO4-

•O- + H2O --> •OH + OH-

HSO4- + •OH --> H2O + •SO4-

Net reaction:

SO2 + 2 N2O (aq) + uv ---> 2 N2 (g) + •SO4- (aq)

This method lends itself naturally to small quantities, but if you have a weather balloon, I stand corrected

.

Note, my link above is to a large (4 megs) file, which per Table 2, contains many examples of inorganic and organic reaction rates involving the sulfate radical anion (which is a very short lived radical).

Note 2: In practice N2O can be employed with conventional visible light photocatalyst, like TiO2 (see, for example, https://pdfs.semanticscholar.org/7be8/607ceeed1afa18c2a5e504... ), which produces, among other products with light, solvated electrons. The latter react with N2O as follows:

N2O + e-(aq) --> N2 + •O-
•O- + H2O --> •OH + OH-

So, the once only uv sensitive N2O, can now be effective in sunlight in the presence of TiO2 (or other visible light photocatalysts). Reference: see, for example, https://www.researchgate.net/publication/255990890_Photocata... .

[Edited on 27-8-2018 by AJKOER]

Keras - 27-8-2018 at 05:18

Quote: Originally posted by Chem Science

Hello everyone !

Its well known that Calcium Oxalate is very insoluble in water, and in general Oxalic acid and Nitrate salts like calcium nitrate are cheap and easily available. So the reaction that in my minde pup-up was

Ca(NO3)2 + (COOH)2 = Ca(COO)2 + 2HNO3

Frankly, I’m surprised this reaction actually works. I wouldn't expect a weak acid (even oxalic acid with pK_a ~ 1) to be able to react and form a strong acid like nitric acid.

Fantasma4500 - 14-3-2022 at 09:21

has anyone yet considered melting NaNO3 with oxalic acid to produce RFNA? or could this whole mixture end up prone to blowing up as the oxalic acid is organic?
1kg of oxalic acid should theoretically yield about 1.4L 70% HNO3, about 22 moles of HNO3, 70% being 15.4M

this thread deserves more attention with the tightening grip on sulfuric acid.

Texium - 14-3-2022 at 11:04

Doesn't seem like a very safe or workable idea. Oxalic acid can be oxidized to CO₂ and CO relatively easily, and at high temperatures (but still well below its melting point) it will sublime. It can decompose in the vapor phase to CO₂ and formic acid, even in the absence of an oxidizing agent (see attached reference). Presumably this would be accelerated in an oxidizing environment. Heating oxalic acid dry with an oxidizer, seems like a recipe for thermal runaway at worst, or at best the oxalic acid and its decomposition products would be oxidized by the produced nitric acid, eating into your yield and the concentration of your acid.

Here's a paper on the vapor-phase decomposition of oxalic acid:
Attachment: j100789a032.pdf (303kB)
This file has been downloaded 230 times

Tsjerk - 14-3-2022 at 12:01

Melting or even heating oxalic acid with a nitrate will oxidize the oxalic acid, but you could very well first make a aqueous solution of nitric acid, filter the calcium oxalate and then distill.

Texium - 14-3-2022 at 12:45

Quote: Originally posted by Tsjerk

Melting or even heating oxalic acid with a nitrate will oxidize the oxalic acid, but you could very well first make a aqueous solution of nitric acid, filter the calcium oxalate and then distill.

Yeah, that is what the OP did and showed to work. My reply was just directed to Antiswat’s proposal of dry distilling sodium nitrate with oxalic acid.

I have a feeling the yield could be improved by using an excess of the calcium nitrate, to ensure full precipitation of the calcium oxalate. That way you’ll have very little oxalate or excess oxalic acid left in solution after you filter, and your distillation should go smoothly. Leftover calcium nitrate solution could be re-used for the next batch.

Fantasma4500 - 15-3-2022 at 03:37

how about, if one were to take stoichiometric amount
heat it up just a fair bit, and keep it at that for maybe a week
and then add in DCM, or maybe reflux it with DCM and eventually pull out the DCM?
DCM can be used to extract WFNA, and since its possible to still get some paint thinners and the like with DCM, DCM is kinda OTC

i believe first up we would wanna try to heat up oxalic acid with pure nitric acid to see what that does
oxalic acid is produced FROM nitric acid reacting with.. sugar, iirc?
so it cant be super reactive, thats my take.

if nitric acid was to react it would go something like this

HNO3 + H2C2O4 = H2O + CO2 + CO

with HNO3 below 70% this should be less likely to occur- but this is where DCM might come in handy, as it could immediatedly seperate the two
and DCM, could maybe be used as example. afaik it doesnt react with WFNA

as for nitric and oxalic acid, i might try it as i have a small 29/32 flask and a 29/32 hose adapter, i can try to see if it produces any gas upon heating it with about 70% nitric- after trying a small sample size, heated generously, it should pop down below 70% as the oxalic acid is likely hydrate- thereafter if nothing happens i could add some conc sulfuric acid to oxalic acid to see how prone to anhydrous acid it is, if that does nothing then i could add some nitrate in and heat it a bit.

Fantasma4500 - 21-3-2022 at 10:04

alright i tested out the following:

HNO3 70% + oxalic acid, no reaction. heating just causes HNO3 to evaporate

98% H2SO4 + oxalic acid, no immediate reaction
heating causes H2SO4 fumes and some bubbling. SO3?

98% H2SO4 + KNO3 + oxalic acid, no immediate reaction, heating causes HNO3 to evaporate

oxalic acid + a bit of water + KNO3, barely produces any nitric acid
i tried to scale it up and redo it but couldnt get it to form any nitric acid whatsoever

not sure if molten nitrate with oxalic acid would work, oxalic acid is nasty stuff, i dont feel safe handling such a strong oxidizer with a potential fuel

Sulaiman - 21-3-2022 at 19:50

Quote: Originally posted by Chem Science

... and the acid was poorly concentrated.

Was it just that HCl azeotrope is c20%?