Sciencemadness Discussion Board - Perchloric acid failed synthesis. HELP REQUIRED!

Perchloric acid failed synthesis. HELP REQUIRED!

Achilles - 19-9-2023 at 10:14

i need help. i tried distilling perchloric acid by mixing KClO4 and 70% H2SO4, i was hoping to distill 70% HClO4.

i go on details, at first water came over then a few acidic droplets and a lot of smoke chlorine-like smell and strong oxidizer gas. it was able to re light up a glowing charcoal or piece of paper, as i said chlorine smell seemed a white smoke not green/yellow. it was insoluble in water had struggle to react even in the sodium hydroxide solution trap. as i kept distilling solids accumulated on the condenser and on the distillate but i didn’t see any heavy bubbling/splashing that brought any there. i read here that the synthesis that i tried with potassium perchlorate doesnt work but it works with sodium. i am interested on the reasons of why potassium ion makes a different reaction and what the products actually were.

other question

can it work with HCl and KClO4?
i tried distilling it again with sulfuric acid at vacuum but the vapors broke it (now fixed).
i dont have ammonium perchlorate just potassium perchlorate. how can i prepare perchloric acid with it?

B(a)P - 19-9-2023 at 14:19

You will not be able to distill perchloric acid in this way at atmospheric pressure as the perchloric acid will decompose, which is what you likely observed in your first attempt. This is a potentially dangerous situation.
When you say that you tried 'distilling it again with sulfuric acid at vacuum but the vapors broke it', do you mean it broke your vacuum pump?
Distilling at constant vacuum is your key to success with this reaction. Did you have a trap in place when you were distilling under vacuum?
What mass of KClO₄, H₂SO₄ and water did you use?
Note that you need to make sure your glassware is very clean before distilling perchloric acid.

dettoo456 - 19-9-2023 at 20:40

B(a)P is right, but I’d advise to just avoid the distillation entirely. No one in their right mind would need HClO4 above azeotropic level and distilling an oxidizing acid over sulfuric without prerequisite safety knowledge is a straight shot to the hospital.

If you can get ahold of/make KClO4 then you can surely procure sodium perchlorate. Take that and run metathesis to the Ca(ClO4)2 and just mix it with your sulfuric acid and filter (glass frit). It’s way easier and safer than distillation especially if you don’t have much experience - no offense.

EF2000 - 19-9-2023 at 22:08

And if you can procure sodium perchlorate, you can make ammonium perchlorate from it, 'cause AP is less soluble.
And that opens way to another method: HClO4 ........(from NH4ClO4). No distillation, but requires some heating, and be prepared to some noxious gases.
So maybe try dettoo456's more safe proposal first, but save AP process for later, it's pretty efficient.

Achilles - 19-9-2023 at 22:34

Quote: Originally posted by B(a)P

You will not be able to distill perchloric acid in this way at atmospheric pressure as the perchloric acid will decompose, which is what you likely observed in your first attempt. This is a potentially dangerous situation.
When you say that you tried 'distilling it again with sulfuric acid at vacuum but the vapors broke it', do you mean it broke your vacuum pump?
Distilling at constant vacuum is your key to success with this reaction. Did you have a trap in place when you were distilling under vacuum?
What mass of KClO₄, H₂SO₄ and water did you use?
Note that you need to make sure your glassware is very clean before distilling perchloric acid.

i dont remember excatly but i used an excess of KClO4 and i used %70 H2SO4 by mass.
yes the vapors broke the pump

Achilles - 19-9-2023 at 22:36

Quote: Originally posted by EF2000

And if you can procure sodium perchlorate, you can make ammonium perchlorate from it, 'cause AP is less soluble.
And that opens way to another method: HClO4 ........(from NH4ClO4). No distillation, but requires some heating, and be prepared to some noxious gases.
So maybe try dettoo456's more safe proposal first, but save AP process for later, it's pretty efficient.

i bought KClO4 so to make ammonium perchlorate id need ammonium sulfate i was just wondering if i could do it with KClO4

Laboratory of Liptakov - 19-9-2023 at 22:37

Achilles........I recommend abandoning experiments with vacuum distillation and concentrating on the production of NaClO4. Which gives you a relatively easy path to HClO4. And thus to all other perchlorates. There is plenty of study material on this topic. Others may add some links. I am attaching a proven method for making the NaClO4 from NaClO3.
https://www.youtube.com/watch?v=1Ylt2ZKJlME

Achilles - 19-9-2023 at 22:39

so in short.. or i do vacuum distillation or AP and HNO3/HCl right?
thats sad i needed it and i dont have a cold trap to put before the vacuum pump so i gotta make ammonium perchlorate...

EF2000 - 20-9-2023 at 00:22

Also, if you need perchloric acid really bad and don't have problems with funding (read as: your pocket allowance is mine*10x), chemcraft.su has it in stock. Pure, 60%, but rather pricy.
Last time I checked they don't have any problems with delivery (kind of easy to cross reverse Iron Curtain, when you're based in Koningsberg). Only problem is BTC as only payment option.
(Not an advertisment, of course)

woelen - 20-9-2023 at 01:21

If you want to do anything else than pyrotechnics with your perchlorate, then KClO4 is the worst perchlorate to have. It is only very sparingly soluble in cold water and hence cannot be used with other salts to make other perchlorates. it always precipitates out first.

Try to obtain NaClO4 and mix a concentrated solution of that with conc. HCl. NaCl will precipitate and you are left with quite pure HClO4.
Next, boil off water, until the temperature reaches 150 C or so. This drives off all chloride as HCl and lots of water. On cooling down a little NaClO4 may precipitate. After this step you'll have acid of better than 50% concentration and only with a tiny amount of sodium ions left.

If you are in the EU, then you cannot get NaClO4. In that case, try to get NH4ClO4, which is not forbidden in the EU. From that you can make a solution of NaClO4 with NaOH and then proceed as above. I also tried the reaction of NH4ClO4 with aqua regia, but that reaction was not succesful in my attempt.

[Edited on 20-9-23 by woelen]

BromicAcid - 20-9-2023 at 18:25

That reaction between ammonium perchlorate and aqua regia always seemed a little hellacious, it's cited frequently but I've wondered if it's carried through literature from a single citation as a curiosity rather than something anyone else has tried.

Elemental Phosphorus - 20-9-2023 at 21:57

Quote: Originally posted by BromicAcid

That reaction between ammonium perchlorate and aqua regia always seemed a little hellacious, it's cited frequently but I've wondered if it's carried through literature from a single citation as a curiosity rather than something anyone else has tried.

I have done it and it worked pretty well. Lots of nitrogen dioxide fumes and whatnot but it worked well. The product was very acidic and reacted nicely with potassium hydroxide solution to produce a precipitate.

I have a video I made of the synthesis somewhere, I can post some parts of it if desired.

Edit: Actually the good Doctor himself has already made a video - and from the looks of it, it's better filmed than mine.
https://www.youtube.com/watch?v=KXpGlgj9_uw

[Edited on 21-9-2023 by Elemental Phosphorus]

woelen - 20-9-2023 at 22:43

Quote: Originally posted by Elemental Phosphorus

[...]The product was very acidic and reacted nicely with potassium hydroxide solution to produce a precipitate. [...]

That does not mean anything. It only tells that your liquid contained perchlorate ions, and that is not surprising, because you added NH4ClO4.

In my attempt I had the same situation, but on prolonged heating of the NH4ClO4/HCl/HNO3 mix I finally boiled off most liquid and on cooling down crystals appeared. These crystals were crystals of NH4ClO4, and I had simply boiled off all HCl and HNO3 (and made a lot of NO/NO2/ONCl/Cl2 in the process). I'm quite sure that my product contained some HClO4, but most of it still was NH4ClO4.

EF2000 - 20-9-2023 at 23:47

Quote: Originally posted by Elemental Phosphorus

The product was very acidic and reacted nicely with potassium hydroxide solution to produce a precipitate.
[Edited on 21-9-2023 by Elemental Phosphorus]

Quote: Originally posted by woelen

That does not mean anything. It only tells that your liquid contained perchlorate ions, and that is not surprising, because you added NH4ClO4.

Maybe it can be used as something like "perchlorating mixture" for making hexamine diperchlorate and stuff like that?

Achilles - 21-9-2023 at 02:14

Quote: Originally posted by Laboratory of Liptakov

Achilles........I recommend abandoning experiments with vacuum distillation and concentrating on the production of NaClO4. Which gives you a relatively easy path to HClO4. And thus to all other perchlorates. There is plenty of study material on this topic. Others may add some links. I am attaching a proven method for making the NaClO4 from NaClO3.
https://www.youtube.com/watch?v=1Ylt2ZKJlME

I know but aside that I was wondering why this reaction has struggle to take place with potassium ion, I wanted to know the mechanism that bring it to have different products

woelen - 21-9-2023 at 04:40

The crystal lattice of KClO4 is quite strong, you need quite some energy to separate the ions from each other. More so than in NaClO4 and NH4ClO4. That's why you need more heat to dissolve the KClO4 in H2SO4 and have it react to form HClO4 (the formation of that first requires the breakdown of KClO4 in its constituting ions). This higher heat leads to more decomposition of HClO4, formed in the reaction, and it makes the distillation process more dangerous.

I personally would not like to do any distillation of (nearly) anhydrous HClO4. The azeotrope (70% HClO4) is quite stable and also remarkably inert (except for its strongly acidic properties), but anhydrous HClO4 is really dangerous stuff and even looking angrily at it may make it bite back in the form of an explosion!

Metacelsus - 21-9-2023 at 04:44

Back in the day (~2014) I did a vacuum distillation of HClO4, from NaClO4 and 70% H2SO4. I was targeting the azeotrope but I didn't have quite enough water so I actually ended up making hydronium perchlorate in my condenser, which started to clog it up! (Remarkably, it's a solid hydronium salt.) Afterwards I carefully diluted it down to the azeotrope (and gave some to plante1999, who wanted it).

My main conclusion is that distillation of HClO4 is quite tricky. It's just another dumb thing I did in high school, and I'm glad I survived.

Elemental Phosphorus - 21-9-2023 at 07:43

Quote: Originally posted by woelen

Quote: Originally posted by Elemental Phosphorus

[...]The product was very acidic and reacted nicely with potassium hydroxide solution to produce a precipitate. [...]

Of course you are right, and I had considered that, but I saw only minimal crystal formation upon cooling to 0C, and there was still perchlorate formed with KOH after removing those crystals.(presumably crystals of NH4ClO4.)

I won't be at my lab for the next couple weeks but if desired when I am back I can do some more rigorous tests.

Perhaps boiling down 5mL of liquid and then measuring the weight (if any) of NH4ClO4 left behind and then combining 5mL of solution with an excess of KClO4, filtering off any soluble salts, and measuring the molar quantity of KClO4 could show the concentration of perchloric acid, if the quantity of solid left behind is minimal or none, and the molar quantity of KClO4 formed is much greater, then I'll know that it's mostly perchloric acid.)

[Edited on 21-9-2023 by Elemental Phosphorus]