Sciencemadness Discussion Board

perchloric acid

Ramiel - 31-8-2002 at 22:49

Robinson reported a detonation of 3 g of a Perchlorate salt of a rhodium-polyamine complex undergoing an evaporation step in a rotary evaporator. A violent explosion destroyed the evaporator, smashed a lab jack, cracked the bench top, and chipped walls over 15 feet away. Fortunately, this happened in an empty laboratory.

If that isn't energetic, then what is!

by the way, would this reaction work?
KNO3 + HClO4 <==>> HNO3 + KClO4

IodineForLunch - 1-9-2002 at 10:43

Yes, that reaction will work, but it will tend towards the nitric acid & ptoassium perchlorate side, because potassium perchlorate is less soluble than potassium nitrate.

Who the fuck is Robinson?

David Hansen

vulture - 1-9-2002 at 11:37

Well, I can imagine Rhodium complexes do not have strong bonds. Also, Rhodium, being a noble metal, would like to return to it's elemental state when heated.
Add to that a perchlorate group which is eager to oxidize the partially radicalized (because the Rhodium decomplexes) amines and you've got a nice bang!

Not a smart move, heating perchlorate esters.

vulture - 1-9-2002 at 11:40

Not a smart move, heating perchlorate esters.

That should say: Not a smart move, heating organic perchlorate compounds.

Ramiel - 2-9-2002 at 05:56


Also, Rhodium, being a noble metal,

If Rhodium is noble, then how does it display metallic properties?

ps. So, it does work, and it is an equilibrium reaction, tending towards the KClO4 side...
Now theoretically one might obtain a good yeild by extracting th precipitate KClO4 as it formed.

Now to get rid of the HClO4... it reacts with silver I believe, so a little chunk of that would absorb the excess, but it is expensive, any other method(s) for getting rid of the excess KNO3 and HClO4?

vulture - 3-9-2002 at 01:34


Rhodium is a metal, look it up?

And what are you babbling about in the last paragraphs of your posts?

vulture - 3-9-2002 at 01:39

Wow sorry. Missed something there.:(

Why would you want to get rid of the HClO4? HClO4 is a very strong acid, it easily reacts with KOH, etc....

Rhodium conducts electricity, has a very high melting point and it is a Platinum metal. It's in group 8b of the Periodic table.

Ramiel - 3-9-2002 at 02:11

I got confused; you were talking about it being a noble metal. Please remember that in year twelve chemistry, we still treat metals like Au and Rh as reactive, But now I understand (my chem teacher is 1337)

This has veered a little off the topic, but;

Why would you want to get rid of the HClO4?

because I want to make KClO4 - which is the product of the forward reaction. Although HNO3 is a by-product, but I'd like to keep it if possible.


it easily reacts with KOH

So does HNO3.

Madog - 3-9-2002 at 05:58

what do you plan to do with the KClO4? just use it as an oxidiser? if you want it for HE mixes just make NH4ClO4. it is far superior

HClO4 + NH4OH = NH4ClO4 + H2O

and if you want to make HEs why dont you make something a little more exotic? if you are crazy you can go for organic perchlorates. these interest me.

Ramiel - 5-9-2002 at 00:59

I've heard it makes a "/\/\4D" oxidizer for flash mixtures.

Oh, and I've been looking at "RDx"

vulture - 5-9-2002 at 07:48

The problem with making organic perchlorates is that there are some very unstable intermediate compounds or byproducts. Also, temperature control is EXTREMELY important because perchloric acid will ignite anything flammable.

So you better stay well below the flashpoint of your organic.

PHILOU Zrealone - 9-9-2002 at 16:04

As explained elsewere transition metals often forms complexes with pi electron donor ligands (complexants)...amines, amonia, urea, hydrazine, ethylene diamine...the counteranion can be a strong oxydiser like Cr2O7(2-), SO5(2-), NO2(-), NO3(-), ClO4(-), IO3(-), MnO4(-), ....the fact it is a complex lower strongly the activation energy and this explains why
Cu powder and KMnO4 can sensitise AN!
TACuN and other are sensitive HE...some complexes are so unstable that they are touchy sensitive even in solution; it is the case of Ni(NH2-NH2)3(ClO4)2 that explodes in diluted solution when agitated!

Ni(NH2-NH2)3(NO2)2 is one of the best primaries I have ever made:
VOD = 7km/s, quite unsensitive to shock very sensitive to flame, unsoluble in water!
The sole problem is that you need pure NH2-NH2 hydrate!Deflagrate in the open or in tiny amounts and detonates strongly when confined.


IodineForLunch - 9-10-2002 at 15:55

Philou, how did you prepare Ni(N2H4)3(NO2)2?

David Hansen

PHILOU Zrealone - 5-3-2003 at 02:32

Ni(NH2-NH2)3(NO3)2 is fairly easy to do:
Make a mix of saturated Ni(NO3)2 in water add twice the amount of ethanol; you get a green solution.
Make a saturated solution of hydrazine hydrate in ethanol (50/50)!

Then allow the first one to fall drop by drop in the other under magnetic agitation...until no more precipitate forms!

You will see deep blue flocks form those will break under the agitation and turn pale pink; then when reaction is ended (it heats a little during complexation) filtrate the will be estonished how much there will be!
Wash it under cold distillated water first (insoluble in water), filtrate; then wash with ethanol, filtrate and dry in open air get a white pinkish powder/or like cley blocks.

You can grind them smoothly to make it loos!

This stuff is powerful and deflagrate when in the air in large amount ( over 2g); when confined 0,5g will detonate in Al foil wrapped chunk trowed in an open fire... beware the fire ball can be 40 cm diameter and trow burning wooden pieces all over the place!

That's it man!
It is more powerful than other primaries, but if in tiny amounts the detonation rate is irregular!
I have solved that problem; it is one of my discoveries, and I'm very proud of it.... I use Ag2C2.2HNO3!
The two detonating substance are very unsoluble, don't react at ambiant T and they both provide the best of them to the mix!

Ag2C2.2HNO3 easy to make, easy detonation even unconfined, powerfull and fast!

Ni(NH2-NH2)3(NO3)2 easy to make, detonate only when confined or in large amount, much more powerfull, brisant and faster!

About the rest of the answers, I have many things to say:

Making organic perchlorates is easy especially amines perchlorates (as soon as you are dilluted enough no risk due to heat when neutralising); beware of transition metals that may form complexes upon contact!

Making complexated perchlorate is much more dangerous; some detonate while solution is agitated!

Making organic ester perchlorate is foolish too: they inflame or detonate spontaneously at 20°C and are all very sensitive!

Rhodium belongs to the platinium familly of noble metal; but noble means rare and hard to oxydise; it doesn't mean unreactive like the noble gases..rhodium was named because of the color of its salts...thus it makes salts much more easily than Au or Pt does!
The whole familly also has the property to complexate ligands!I have worked many times with Ruthenium for my study endwork!

KNO3 + HClO4 --> KClO4 + HNO3 (heat at 90°C on water bath and collect the condensed HNO3).

The reaction is favourised by many more factors:
*HClO4 is 4 000 000 times more acidic than HNO3 thus NO3(-) is the same time much basic than ClO4(-)
*KClO4 is less soluble than KNO3
*HNO3 is more volatile (much lower BP) than HClO4.

Rotary evaporator are used to draw off solvant under reduced pressure and normal temperatures...For sensitive compounds it is the best; but if the stuff cristallised in the flask, and that he did this cristals might frictionnate each other in the flask while rotating...maybe he did heat it too strongly...those complexes of noble metals are quite heat sensitive and decomplexate or react when over heated (over 40°C).

The guy probably never made any small test on the stuff prior to experiment to evaluate risk or didn't knew about explosivity of perchlorate complexes (what means he asn't informed before acting).

Polverone - 5-3-2003 at 12:09

Ag2C2.2HNO3 easy to make, easy detonation even unconfined, powerfull and fast!

Is this as simple as it sounds - i.e. combining Ag2C2 and HNO3 in a 1:2 ratio? What about sensitivity to heat, impact, friction, static, etc.? Can you prepare Cu2C2.2HNO3 similarly, and does it behave similarly?

Microtek - 6-3-2003 at 11:00

Silveracetylide-nitrate can be made by bubbling acetylene through a solution of silver in nitric acid ( where Ag2C2 is made by bubbling C2H2 through AgNO3 in ammoniacal solution ).

rikkitikkitavi - 6-3-2003 at 11:14

all carbides reacts with acids yielding
hydroxide and C2H2, some takes strong acids (Cu2C2, Ag2C2) some it only needs water...


a_bab - 6-3-2003 at 11:29

Actually these which are before the H in the activity series (na, Ca, etc) are decomposed by the water with the formation of acetylene, and ethane. Al4C3 i.e. needs HCl because to disolve the Al2O3 formed in the reaction with the water in order to give ethene. These carbides are stable in temperature. Carbides after the H are unstable in elevated temps (explosives) but stable in water.

Philou, have you ever cosidered to write a book (I mean a small file) about your experience in the field ? I bet it'll be the best one. And it's pitty if you don't write one.

PHILOU Zrealone - 23-3-2003 at 15:30

Ag2C2.xHNO3 only forms when C2H2 is bubbled into neutral or slightly acidic AgNO3 solution!
H-C#C-H + 2AgNO3 --> Ag2C2 + 2HNO3
And HNO3 is trapped/complexed in the solid precipitate that flocculates!
It seems very unprobable HNO3 can be added to a precipitate of Ag2C2 in an efficienter way than when it does in precipitation process!
The amoniacal process is harder and leaves residual Ag-NH2 (hell of the mirror makers) that explodes in solution; this not only increases sensitivity to heat, impact and light! Density is about the same but VOD of nitrated complex is about twice the one of the one from ammonia! Thus there is no reason to make Ag2C2 instead of Ag2C2.xHNO3

This gives me an idea!
C2H2 + AgClO4 --> Ag2C2.xHClO4
For sure this must be a little more powerfull and maybe a bit more sensitive!

Cu2C2 is not a stable carbide it fast disproportionnates in water to give CuC2 + Cu that has about the same colour and no explosivity! I don't think a similar nitrate complex exists...but I haven't ever tried! The fact is that you need to make CuCl in ammonia to allow the making of Cu2C2; CuNO3 doesn't exist long enough in water to react!

Hg2C2 is also a powerfull explosive of similar properties as Ag2C2 plus the fact that Hg can be gaseous product (high volatility).

Al4C3 reacts with water to provide CH4 not C2H2! Na2C2, K2C2, Li2C2, BaC2, CaC2 and SrC2 provides C2H2!
Fe4C3 is stable and responsible of the hardness of iron steel!

To write a book is hard work and I have the project to do so for nearly 10 years; but I need to gather info's and make more experiments to have something really complete and professionnal! One of the major investissement I have to do is to buy a portable power G4 (60 gigas, DVD and CD writer) this would allow me to go to the library and make a good data base about all articles about HE from my digital cam without passing by the long and expensive photoprinting of all books/articles!
Also to have articles is a thing; to read them, understand their meaning and the application of them is another; then summarize and integrate that in the good chapter and make a complete master piece!

PHILOU Zrealone - 23-3-2003 at 15:36

I forgot to tell that the guy that had that accident maybe forgot that the ammonia complexes of those noble metals, not only are heat sensitive but also light sensitive! They display very dark colour and catch nearly all light that passes trough them to convert it into Infrared.Light induces ligand splitting and destabilisation of those complexes!


dann2 - 25-6-2009 at 10:11

Attached is some info. on Perchloric acid from the Bereau of Mines taken from
Happy reading.

Attachment: Perk. acid (1.2MB)
This file has been downloaded 612 times

dann2 - 25-1-2012 at 19:27

Can anyone tell me if I were to make some Perchloric acid from HCl (conc) + Sodium Perchlorate with a small amount of Chlorate contamination would the Chlorate present much of a hazard.
Would I not just get some ClO2 going off.
It will be in a well ventilated area, do not intend to concentrate or store the Perchloric acid (will dilute once made to 20% or so).
The Chlorate contamination is approx. 0.003% (1 gram per liter of concentrated Sodium Perchlorate solution or one gram in 500 grams approx.


Pulverulescent - 26-1-2012 at 04:40

Can anyone tell me if I were to make some Perchloric acid from HCl (conc) + Sodium Perchlorate with a small amount of Chlorate contamination would the Chlorate present much of a hazard.

It's been a while but using a large excess of HCl will decompose any NaClO<sub>3</sub> in the perchlorate . . .
The fumes will be orange coloured and the reaction vigorous!
I know from experience that inhaling the fumes is less than pleasant.
But the small amounts of chlorate contaminant you have shouldn't be a problem!
The reaction itself is exothermic enough to ignite sugar/chlorate mixtures!
Distill off the HCl and stop when dense white vapour appears in the flask and you're done.
The minute quantity of NaClO<sub>4</sub> remaining in the acid can be disregarded!
Distillation of the HClO<sub>4</sub> you'll have shouldn't be attempted for obvious reasons!

Chill the solution after the addition to precipitate all the NaCl; the longer you leave it, the better, and then filter . . .


[Edited on 26-1-2012 by Pulverulescent]

dann2 - 29-1-2012 at 10:18

Thanks for that.
I got around to doing it.

Added 750ml conc. HCl acid to 500ml of a saturated solution of Sodium Perchlorate of density 1.62
(about 520 grams Na Perchlorate). Temperature of solutions was around 8C.
Thats around 4.25 moles of Na Perchlorate which is 4.25 moles Perchloric acid = 426 grams (100%
acid) = 592 grams of 72% acid = 365ml of acid (density = 1.62 approx. read from graph) to be expected .
I ended up with 352 grams of 72% acid.

The Perchlorate contained about 2 grams Chlorate. The solutions warmed very slightly when mixed
and I obtained an immediate fine ppt of Sodium Chloride. The solution was yellowish. Let it sit for
about three hours and put in freezer for another three hours and filtered through a 15cm paper filter.
Obtained about 900ml of a yellowish liquid. Would have got more if I had suction filtered as
there was a large volume of wet NaCl.
Placed into a one liter beaker and boiled (outside) using a flame and a sand bath. At the beginning
the fumes were of HCl acid. When the volume was around 480ml the fumes were quite mild, temperature
around 130C. The colour of the liquid was still yellow but I think it was the sand underneath the beaker
that was making it look more yellow than it actually was . Boiled on until there was white fumes coming and
then boiled some more. I guess I boiled too much as I ended up with only 220ml. The temperature reading
on the thermometer was 170C.

The colour of the Perchloric acid was very slightly yellow at this stage but the HCl acid had a yellow tinge to it.

I let it cool and added 250ml water to it. The density of the acid is now 1.35g/cc. A concentration of
about 46% according to a graph. The acid looked much clearer the next day, very little if any yellow.

From Russion Journal:
Colourless perchloric acid, i.e. an acid containing no
lower oxides of chlorine, does not explode out of contact
with reductants, and is therefore safe when handled carefully.

Tested for Chloride using Silver Nitrate and there was none.
There is no sigh of any Na Perchlorate coming out of the acid when I checked two days later.

fumes.jpg - 47kB

Adas - 29-1-2012 at 12:24

Dann, very nice, are you gonna make some organic perchlorate salt? If yes, try Biuret Perchlorate, in small quantity. It may be interesting.

Pulverulescent - 29-1-2012 at 13:07

Dann, very nice, are you gonna make some organic perchlorate salt? If yes, try Biuret Perchlorate, in small quantity. It may be interesting.

Too interesting sometimes ─ don't forget ─ organic perchlorates have a real baaad reputation!


Adas - 29-1-2012 at 13:26

Yeah, that's why I mentioned to do it in small quantity :)

dann2 - 29-1-2012 at 14:17

Actually I am putting it into a Perchlorate cell to keep pH down. Here is little need to keep pH down AFAIK but just doing it anyways.


Pulverulescent - 29-1-2012 at 14:34

Actually I am putting it into a Perchlorate cell to keep pH down.
'Not quite sure what you mean there, dann2 . . . ?
70% HClO<sub>4</sub> is easily storable in Merck safebreak bottles!


dann2 - 30-1-2012 at 13:42

I am storing it in a plastic bottle. It's around 50% stuff, as I diluted the 72% stuff I made with water.
I am putting small amounts of the Perchloric acid into a Perchlorate cell that I am running to lower the pH of the cell.
HCl acid puts a Perchlorate cell CRAZY.
I don't think there is any benifit in running a Perchlorate cell at a low pH anyways buts thats another story.
They seem to drift to a high pH of there own accord. Will post in Technochem. some more blow by blow details.

Pulverulescent - 31-1-2012 at 12:33

I am putting small amounts of the Perchloric acid into a Perchlorate cell that I am running to lower the pH of the cell.

You're putting one of the strongest, most highly oxidising acids into a perchlorate cell!
You gotta' be kidding me! (:D)


Adas - 31-1-2012 at 13:02

I also don't understand why he is trying to lower the pH. The pH itself rises up in time, because NaOH is formed and not all chlorine reacts with it.

Pulverulescent - 31-1-2012 at 13:24

I've only ever made fuck all NaClO<sub>4</sub> even though I have the Pt/Ir wires for years!
I remember thinking it'd be nice to go directly from chloride to perchlorate!
But the fairly moderate conductivity of the alloy soon made me reconsider and I quickly lost all interest . . .
But now that I've just kicked a 33 year long, several joints a night, dope habit I'm a'rearin' to go!
I'll get out ye olde gouging rods (assuming I can still find them), make some chlorate, separate by fractioning and then add that all-important extra O! (:D)
The chlorate is the hard part, what with filtering, adjusting pH, getting adequate current and fractioning/filtering again!
I used to have some NH<sub>4</sub>ClO<sub>4</sub> lying around from time immemorial too ─ finding that'll be fun as the biro-ink on all my labels has, long ago, succumbed to the passage of time! (:o)


Adas - 31-1-2012 at 13:59

I was making NaClO3/NaClO4 once using 5A, I let it run for like a month with graphite electrodes (which have been eaten fast), but the (per)chlorate seemed to be fairly stable to friction when mixed with sugar. It also contained a lot of contaminants, for sure (NaOH, NaHCO3.....).

I think you don't really have to do any recrystallization and all the crap, just keep the temp high enough to destroy NaClO and create NaClO3, then NaClO4.

Pulverulescent - 31-1-2012 at 16:12

I was making NaClO3/NaClO4 once using 5A, I let it run for like a month with graphite electrodes (which have been eaten fast), but the (per)chlorate seemed to be fairly stable to friction when mixed with sugar. It also contained a lot of contaminants, for sure (NaOH, NaHCO3.....).

I think you don't really have to do any recrystallization and all the crap, just keep the temp high enough to destroy NaClO and create NaClO3, then NaClO4.

5 Amps, eh?
'Small wonder you had to do such a looong run! (:D)
And while graphite will produce perchlorate, the amounts would be negligible, at best!
It is, of course, best not to have chloride in a perchlorate-cell if using Pt, and having Pt as cathode is advantageous to avoid loss of metal during a run!
Polarities should be switched occasionally to replace the Pt transferred from anode to cathode . . .
And graphite anodes that erode quickly are cheap, polymer-bound graphite powder types!
For the very best results you need the compressed, thermally-bound variety of gouging rod!
They're hardwearing and produce no contaminant other than fast settling, graphite sludge!


dann2 - 1-2-2012 at 11:27

AAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHH Another 'making Perchlorate using Graphite' dude

Stating that you had a cell run at 5 amps is a bit like saying you had a mechanically propelled vehicle that did 5 miles to the gallon.
(You need to mention was the vechicle a mope head, small car, large car, truck, bulldozer, a ship....)

If the cell is small it will finish in no-time-a-tall-a-tall.

Going back to the Perchloric acid. It has been used to lower pH in Perk. cells in some of the studies in Journals etc.
How else would you lower it?
HCl is out unless there is very little Chloride in the cell, because once you start adding Chloride (via the HCl ) Chlorine starts to creep out of the cell and this is inclined to raise pH. HCl acid does lower pH if there is little or no Chloride there already and you just add enough HCl acid to do the job.
You could use Sulphuric acid I suppose but then you are starting to contaminate with Sulphate.

Just to note: I am not argueing that it is necessary or even desirable to controll the pH of Perchlorate cells.
I was just having a look to see how to do it since I read that high pH (allegedly) dissolved LD Anodes. I cannot say I have observed any LD dissolution due to high pH.

Dann 2

[Edited on 1-2-2012 by dann2]

Pulverulescent - 2-2-2012 at 02:25

NaClO<sub>3</sub> is a neutral salt!
Ideally, the perchlorate-cell should contain no chloride, therefore no alkaline drift will occur.
The chlorate is oxidised by the nascent oxygen produced at the anode . . .


Failure while method looks promising

woelen - 2-2-2012 at 06:48

I purchased some ammonium perchlorate, hoping to be able to make perchloric acid, according to the method, mentioned in the attached file. I tried several times, but the experiment is a total failure each time.

I took ammonium perchlorate, nitric acid (65%) and hydrochloric acid (30 ... 35%), in the quantities as mentioned in the attached document, but scaled down a factor 50. The acids are general lab grade and are clear colorless liquids, not the usual yellow stuff from a hardware store. The ammonium perchlorate is from a seller, geared towards pyrotechnics. It is a coarse crystalline solid which dissolves completely and gives perfectly clear solutions in distilled water. Normally one has to ballmill this coarse material when used for pyrotechnics, but for my use in chemical experiments it is perfectly OK.

When heating the mix, the solid ammonium perchlorate dissolves with difficulty. At a certain point in time, a lot of gas is produced (first, a lot of orange gas is produced, probably a mix of NOx and ONCl from the aqua regia formed), but lateron the gas mix becomes colorless. The liquid goes from colorless, when cold and just mixed, to yellow/orange, when heated and lateron it becomes colorless again. I kept on heating and had the liquid boiling for a long time and in the meantime producing nasty dense fumes. But finally, the clear liquid more or less solidified and a white crystalline mess was produced. At that point I stopped heating and quit the experiment. I have the idea that I just boiled off water and acid.

I expected that after some time I would end up with a clear liquid, which remains clear without any solid matter in it. I have to conclude that this method of making perchloric acid does not work very well, at least not in my setup. Are there any other people who have experience with this method? It sounds very good. Coarse ammonium perchlorate without anticaking agents can be obtained fairly easily where I live and it would be a great source of the hard to obtain perchloric acid if this method works. Any suggestions from other people are welcome. Simply heating a mix for a while does not work, you just boil off most of the acid. Probably part of the ammonium is destroyed (you get a lot of colorless gas), but only a part. Maybe the colorless gas was only in small amounts. Due to the boiling it may look much more impressive than it actually was (small bubbles of gas can act as starting points for formation of large gas bubbles from boiling liquid).

Attachment: The preparation of Perchloric acid.pdf (431kB)
This file has been downloaded 505 times

Pulverulescent - 2-2-2012 at 13:47

─ woelen, I believe you'd have had better results using the sodium salt!
A large excess of HCl is needed though.
Precipitating NaCl at low temperature should work well.
You can then recover unreacted HCl, leaving only slightly NaClO<sub>4</sub> contaminated acid. (:))
Distilling at almost any pressure is fairly loaded . . .


woelen - 2-2-2012 at 23:42

Yes, I know of the NaClO4-method, but I have NH4ClO4, not NaClO4 (the latter is harder to obtain, it is a much less common reagent). The principle behind the NaClO4-method is simply precipitating out the sodium ions and then boiling off excess HCl. The principle behind the NH4ClO4 method is destruction of NH4(+) ions by means of the combination HNO3/HCl and then boiling off excess HNO3/HCl. In theory this should work nicely according to the attached paper, but in practice it is a lot harder. NH4(+) is not that easily oxidized by the HNO3/HCl combo.

Pulverulescent - 3-2-2012 at 01:02

Yes, I know of the NaClO4-method, but I have NH4ClO4, not NaClO4 (the latter is harder to obtain, it is a much less common reagent).

I'm surprised woelen, as the sodium salt is the basic product!
I bought some years ago from Lennox; reasonable price 99% purity.
You could, though, see black flecks of PbO<sub>2</sub>!
Times have changed!


woelen - 3-2-2012 at 01:45

NaClO4 may be the basic product, but in commerce the only two perchlorates which are easy to obtain are KClO4 and NH4ClO4, because of their use in pyrotechnics. I have the strange situation that I can easily obtain pyro-related chemicals where I live, but I am not allowed to use these chemicals for pyrotechnics purposes (over here in NL pyrotechnics is totally forbidden, in any form, unless you have a special license, e.g. for industrial purposes). Perchloric acid and NaClO4 on the other hand are special purpose reagents and these are not easy to obtain. I have a small quantity of HClO4, but it would be great if I can make more of this on demand from chemicals which I can easily obtain.

Pulverulescent - 3-2-2012 at 02:13

─ woelen, have you considered the electrolytic route, at all?
The only real expense is the Pt/LD anode for the perchlorate-cell . . .


woelen - 3-2-2012 at 02:59

I made chlorates by electrolytic means, using an MMO anode, but making perchlorates is beyond my reach at the moment. I am considering making a PbO2 coating on MMO, but I feel uncomfortable about risking one of my precious MMO anodes for this experiment. So, for the time being I'll continue research in the direction of oxidizing ammonium ions with volatile oxidizers, which can be boiled away.

dann2 - 3-2-2012 at 12:58

You could always make Sodium Perchlorate via Ammonium Perchlorate + Sodium Carbonate. Mix and boil and all the Ammonia and Carbonate will go away (at least I think it will?)
Then it's acid via the normal route.


woelen - 3-2-2012 at 13:20

Dann2, thanks for your hint! Stupid me, that I did not think of such a way myself :(.

Instead of Na2CO3 I'll use NaOH. The latter can be purchased over here at better than 99% purity (the rest being water and NaCl). With this I can indeed make NaClO4 and through that I can precipitate NaCl and make nearly pure HClO4 with only small amounts of NaClO4 left. I'll try this next weekend.

Probably I need to use a slight excess of NaOH, in order to be sure that all NH3 is driven off. A slight excess of Na(+) ions will be precipitated with 37% HCl.

quicksilver - 3-2-2012 at 13:21

I have also made chlorate from MMO / Ti via electrolytic tank. The problem with Perchlorates is that the actual "pay-off" is generally not worth the investment. There IS a thread discussing the application of PbO2 via a "baked on surfacing but remember that oven may become lead contaminated so that even with a low-cost technique you would have to sacrifice an oven. The other concepts of using a epoxy coat PbO2 doesn't expose enough PbO2 and pulling the PBO barriers from a lead-acid battery doesn't function well as the barrier is a thin plastic that simply can't stand up to much current.

Generally speaking current levels would need to be at least 3amp @ 5Vdc for any volume. I imagine you could get it lower but it would take a seriously long time to form up from your salt solution. This is a very nice site set up by some foks who have been working with electrolytic tanks for a long time:

There is a great deal of information there that comes from industrial sources. Perchlorates CAN be made via such a tank but the issue of if it's really worth the level of commitment is questionable. I have gone as far as a sealed 5gal bucket and some various anodes / cathodes with two serious commercial power supplies and unless you can get the items for surplus or at a heavy discount; it can get very expensive.

woelen - 3-2-2012 at 13:35

I agree with quicksilver. For me it is fairly easy to obtain KClO4 (app. EUR 10 per kg) and NH4ClO4 at a price tag of around EUR 25 per kg. One kg goes a long way for me, because I do no pyrotechnics (and then KClO4 is not interesting at all). All the investments of electrodes, huge power supplies, a suitable tank which can withstand the corrosive conditions of a hot cell and all the hassle are not something which makes me feel happy. Making a chlorate cell is a nice experiment for the home chemist and can be done at very moderate cost, but a perchlorate cell is another matter. Only if you are planning to make a LOT of perchlorate for pyrotechnics purposes, then it may be worth the effort. Another reason may be if you absolutely cannot buy any perchlorates.

Pulverulescent - 3-2-2012 at 15:15

Dann2, thanks for your hint! Stupid me, that I did not think of such a way myself.

Facepalm here too . . . (:D)


Rosco Bodine - 7-2-2012 at 03:01

Maybe try a half scale experiment in the same two liter flask and use a cold finger or a reflux condenser. There must be a loss of the volatile acid reactants rather than the loss of volatile byproducts which would explain why the reaction desired is not proceeding and you are being left unreacted starting solid material because
it didn't have the required contact time and reaction conditions.

caterpillar - 7-2-2012 at 20:16

What I know- may be, this info will be useful for someone. In my country there was no way to go and by perchlorates. I got Mg(ClO4)2, known as "anhydron". One bottle I simple stole from an open shelf, the next was a present. I made NH4CLO4 and KClO4, and used them as oxidizers in solid rocket propellant. But, one of my friends made chlorates. NaCl ->NaClO3->KClO3. It was rather simple, he used 300 Amps, graphite anod and steel katod. 250 gr NaCl + 5 gr Na2Cr2O7+ 5gr HCl per 1 liter. But, as I read, NaClO4 requires Pt anod. There is anlternative, really, PbO2 on graphite anod, But in this case NaF must be added to solution of NaClO3 instead of bichromate and HCl. And chlorides must not present in perchloric cell. BTW: I read about an explosion, that occured when one wise boy wanted to dry (CH3)3PO4 by mean of Mg(ClO4)2. Surely, he got some metylperchlorate.

dann2 - 2-4-2012 at 15:12


If I add Barium Perchlorate (anhydrous solid) to concentrated Sulphuric acid will I end up with 100% Perchloric acid. The Barium will precipitate as insoluble Barium Sulphate?
Barium Sulphate is insoluble in water but perhaps things are a bit more complicated in Sulphuric acid +/or Perchloric acid.
I suppose you could argue that 100% Perchloric acid is not a very wise goal.
Just wondering. Have Ba Perchlorate. Have conc H2SO4. The next step seems simple enough. I await further instruction.............

caterpillar - 2-4-2012 at 19:38

DO NOT DO IT!!! Most likely you'll get explosion. Conc H2SO4 + salt of HClO4 produces not only conc HClO4, but Cl2O7 too. This compound can explode after contact with trace amounts of reducing materials (and without serious reasons too). Ridiculous, but Mn2O7 has similar properties. Put some drops of conc H2SO4 on KMnO4 and result will be similar as if salt of perchloric acid is used instead.

woelen - 3-4-2012 at 00:17

Safer alternative is to dissolve Ba(ClO4)2 in water and slowly add 30% sulphuric acid to this solution. You get a precipitate of BaSO4 and after filtration you end up with a solution of HClO4 in water. Before filtering I first would boil the liquid with precipitate of BaSO4. This makes the precipitate somewhat coarser and easier to filter, but I still expect it to be a messy and slow procedure.

You can boil down the filtered solution safely. Put a thermometer in the liquid and boil away water until the temperature rises well above 100 C. Your liquid then will be well over 50% of HClO4. Up to 70% concentration this acid is remarkably inert and you do not have to fear explosion or violent decomposition.

You, however, have to very precisely adjust the amounts of barium perchlorate and sulphuric acid such that their stoichiometric ratio exactly matches the reaction for formation of BaSO4. I think that for most practical purposes you can better have a slight excess of H2SO4 than an excess of Ba(ClO4)2. Barium ions most likely are more disturbing than sulfate ions in most experiments with the acid.