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Author: Subject: From KCLO4 to NH4CLO4/NaCLO4/HCLO4
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[*] posted on 5-2-2019 at 06:18
From KCLO4 to NH4CLO4/NaCLO4/HCLO4


Is there any way to convert KCLO4 to either NH4CLO4/NaCLO4/HCLO4 w/o distilation ?
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Pok
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[*] posted on 5-2-2019 at 07:18


I made perchloric acid by salt metathesis from KClO4: description.

The process is quite complicated, because I had to avoid the crystallization of ammonium perchlorate due to legal regulations in my country (it's considered an explosive here).

You can simply add a hot ammonium tartrate solution to a hot solution of KClO4 with tartaric acid. Let it cool, filter off the cream of tartar. The filtrate contains about 75 % ammonium perchlorate, the rest (25 %) of the perchlorate will remain in the precipitate. This also can be recycled (dissolve the cream of tartar with Na2CO3 solution, the KClO4 will remain and can be reused). The crude ammonium perchlorate has to be recrystallized.




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[*] posted on 5-2-2019 at 14:48


Quote: Originally posted by Pok  
I made perchloric acid by salt metathesis from KClO4: description.

The process is quite complicated, because I had to avoid the crystallization of ammonium perchlorate due to legal regulations in my country (it's considered an explosive here).


You can simply add a hot ammonium tartrate solution to a hot solution of KClO4 with tartaric acid. Let it cool, filter off the cream of tartar. The filtrate contains about 75 % ammonium perchlorate, the rest (25 %) of the perchlorate will remain in the precipitate. This also can be recycled (dissolve the cream of tartar with Na2CO3 solution, the KClO4 will remain and can be reused). The crude ammonium perchlorate has to be recrystallized.


Wow really helpfull, i guess the same is working with sodium tartrate to produce NaCLO4 right?
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[*] posted on 5-2-2019 at 18:09


Yes, but NaClO4 is much more soluble than NH4ClO4 and thus more difficult to recrystallize.



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[*] posted on 6-2-2019 at 01:12


IIRC sodium bitartrate actually has a much higher solubility than ammonium bitartrate. Wiki claims that the resulting sodium perchlorate can be converted to perchloric acid by reaction with hydrochloric acid precipitating NaCl, although I’m guessing the yield isn’t great.



[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 6-2-2019 at 01:43


It is said that the yields are good enough, there is a patend on this subject, try to google it. This is the actual reason why i want to convert it to sodium salt. From sodium salt you can convert it to anything including HCLO4. Looks to be a good way to obtain any CLO4 salt you want w/o distilation and eletrolysis of difficult to separate salts like NaCl. Looks promising
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[*] posted on 7-2-2019 at 04:53


NaClO4 indeed can be converted to HClO4 quite well.
Dissolve the NaClO4 in an as little as possible amount of water. It is VERY soluble, so you can make really concentrated solutions.
Next, pour the solution of NaClO4 in fuming concentrated HCl. Use quite an excess amount of HCl (e.g. for one mole of perchlorate ion take 1.5 to 2 moles of HCl, no need to be accurate with this). You get a lot of white precipitate. This is NaCl. NaCl is only very sparingly soluble in conc. HCl. For this reason it is best to take as concentrated HCl as possible. If you have acess to 36% or 37% acid, use that. If you have 30% acid, take some of that acid, heat this and pass the produced HCl=gas through some other 30% acid to make it even more concentrated.

When the solutions of NaClO4 and HCl are mixed, decant the liquid from the precipitate. If you have a glass fritte, then you can recover nearly all of your liquid. Using a paper filter is not wise with all this strong acid in it. The collected liquid is a mix of HCl and HClO4. Boil down this liquid to drive off excess HCl. Boil until you reach a temperature of 150 C or so. At that temperature nearly all HCl will be gone, but you still are safely far from the boiling point of azeotropic HClO4. The remaining liquid will be quite pure HClO4 (50% or so). It still may contain some NaClO4, but the amount is low.

Try to use as pure as possible starting products. Especially the HCl is quite critical. Hardware store grade HCl usually has a pale yellow color. This concentrates into your end product and hence your HClO4 will be a piss-like liquid, while the pure acid is colorless. You can use reagent grade HCl, or use the 30% stuff from the hardware store and drive off HCl from that and dissolve in distilled water to make nice colorless acid. Adding a lot of CaCl2 to the acid will help driving off more HCl.




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