How to make KClO4 ?

[skatebiker]

Years ago I managed to make rather pure KClO3 (http://KClO3.velp.info) but I read on several sites on the internet that perchlorate is more stable and thus safer, but harder to make. See e.g. http://en.wikipedia.org/wiki/KClO4 .

Does anyone have experience ?

[YT2095]

you`ll need to use Pt electrodes, it is possible with carbon, but they shred too easily and the yield isn`t good, the electrolyte must be 100% chloride free too.

[skatebiker]

Of course, Pt electrodes are better as the solution will not contain carbon electrode debris. I think a Pt wire of 0.5mm diameter a few times wound in a coil suffices.

But the problem is more the way of oxidation from chlorate to perchlorate which temperature is needed ? And does a little bit K2Cr2O7 help for a better result ?

[woelen]

http://www.wfvisser.dds.nl/EN/kclox_EN.html

[TATER]

I have been viewing various pyrotechnic websites and noticed prices for kclo4 (potassium perchlorate)are very highly priced .is there an easier way?

[John Cuthber]

If there were, lots of us would be making it, undercutting the other suppliers and making money.

[TATER]

very good point. the reason that it is so expensive is because the process involved in producing kclo4,kclo3 is toxic

[woelen]

very good point. the reason that it is so expensive is because the process involved in producing kclo4,kclo3 is toxic

No, that is not the reason of high prices. Many industrial processes use extremely toxic and corrosive chemicals in intermediate stages.

 

The real reason for high prices are manyfold, including:

1) Difficult processes, expensive equipment, energy intensive.

2) Profit stacked on profit stacked on profit .... Comapny A makes 100000 kilos of a chem, and sells this to a bulk reseller. The bulk reseller splits the chems in drums of 25 to 100 kilo. The company, buying these drums splits up in packages of a kilo or so, and the final outlet sells quantities of 500 grams or even less. All these things require transportation, handling, and each party wants its profits.

3) High purity demands. The labs (and also the individuals) usually obtain the chemically very pure material, which is much more expensive to make than the raw material. E.g. an extra recrystallize-step may be needed, and that adds a lot to the cost.

[TATER]

ok i thught that the residue left behind was toxic. plus chlorine gas is produced

[Okcchemist]

An old post, but the easiest way to make KClO4 is to neutralize some perchloric acid with KOH. Take care to use an ice bath to keep the temperature down and add a stoichiometric quantity of aqueous KOH SLOWLY to the HClO4 in a beaker or flask with gentle swirling. (outside or in a fume hood) The product will precipitate out. After the reaction is completed, decant the liquid layer then wash the product several times with water until it tests about neutral on pH paper or a meter. This cleanup step works very well because any excess HClO4 or KOH is readily soluable in water while KClO4 is only very slightly soluable in water. Air dry the product and it's ready for use.

[Theophrastus]

An old post, but the easiest way to make KClO4 is to neutralize some perchloric acid with KOH.

 

Yes, the basic process is valid, however you should also note that perchloric acid, is generally made in the lab by adding a strong acid like [ce] H2SO4 [/ce] to a perchlorate salt, like sodium or potassium perchlorate, under controlled conditions. Thus, it could be seen as a case of one step forward, one step back. (The alternative method is further oxidising of hypochlorous acid ("aqueous solution of chlorine"), but while it's simple in theory, I believe it's a lot trickier in implementation)

 

Regardless, I don't really see why someone would want to play with perchloric acid; it's some pretty nasty stuff. And if you do choose to attempt the process, (Having some perchloric acid handy) I once again recommend use of a fume hood, or well ventilated conditions, and keeping your acid, dead clear of any organic compounds; being a strong oxidiser as well as acid, the results of contact with organics, is evidently explosive.) I would also recommend use of an ice bath, to control the temperature, adding the acid bit by bit, in small quantities, as well as an excess of sodium hydroxide in the procedure, to completely rid oneself of acid.

Edited August 27, 2009 by Theophrastus

[Okcchemist]

There are several different ways to make KClO4, so one generally uses whatever is available to work with. Safety, and one's experience level in chemistry are other important factors in determining how to proceed. Commercially made perchloric acid is common in the labs that I have worked in. As a chemist of many years experience, I have no problem working with HClO4, I have for years. Amatuers should not attempt it. Having no idea what skill level I am addressing here, I merely pointed out the obvious, that the simple acid/base neutralization works very well. Your safety recommendations are well advised and should be used in all cases.

 

Since United Nuclear sells KClO4 again, ($26.00 a pound) making it would be a waste of time here in the U.S.

Edited September 11, 2009 by Okcchemist