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BromicAcid
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There is always a steam distillation, that would give your perchloric acid at a lower temperature and with nearly zero risk of what just happened to
you. However sulfuric acid will come over too though considerably less then the amount of perchloric that will come over. So a second distillation
would be necessary, not to mention that your perchloric will be dilluted.
As for what happened with the perchloric monohydrate, shouldn't it have been a liquid considering the temperature of the inside walls of the
glass? Strange that you got anything like that considering the hygroscopicity of the monohydrate and the extreme difficulty in obtaining the
anhydrous form or anything greater then the monohydrate (involving distilling the dihydrate with 6x weight of 99%+
H<sub>2</sub>SO<sub>4</sub> . Very strange indeed.
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garage chemist
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Yes, it's strange, but I was kinda expecting something like that. KClO4 is too insuluble to react fast enough, and I'm just boiling away the
water of the H2SO4 first and then I have conc. H2SO4 with KClO4 and I get HClO4 of a dangerously high concentration which will clog the condenser as
the crystalline monohydrate.
I am aware of the procedure in "Brauer" and I take every measurement to PREVENT that the distillation goes like described there. It yields
the anhydrous HClO4! The receiver needs to be cooled to -40°C in order to minimize the explosion risk.
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chloric1
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Ammonium Perchlorate
Several years ago I made about 100 to 150ml of Aqua regia and then added ammonium perchlorate. You get a soup of nitrous acid, oxides, and chlorine.
The solution is black cherry colored and I let it set undesturbed for the night to eliminate risk for explosions. After the solution is clear or off
yellow, it is safe to distill off the excess nitrous-hydrochloric-chlorine solution and the 72 % constant boiling acid is in the flask. The file I am
attaching should elighten you all to the theories on the mechanism for this reaction. Mind you, my explorations where 7 years before I obtained this
file so the mounts of nitric and hydrochloric acid I used where quite excessive. This proceedure would definately be a cheaper as far as reagents are
concerned.
Attachment: The preparation of Perchloric acid.pdf (431kB)
This file has been downloaded 1421 times
Fellow molecular manipulator
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garage chemist
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Thanks for the instructions, but I have no access to ammonium perchlorate.
I want to use KClO4 as the starting material!
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jpsmith123
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Perchloric Acid By Electrolysis - Patent
Just in case anyone's interested, here's a patent I found regarding the production of HClO4 by electrolytic oxidation of HCl.
Regards,
Joe
Attachment: 1271633.pdf (294kB)
This file has been downloaded 1159 times
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Taaie-Neuskoek
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If one has BaCl2 ánd a working chlorate cell, it is pretty staight forward:
BaCl2 electrolyses --> Ba(ClO4)2, Ba(ClO4) + dil . H2SO4 --> BaSO4 (s) + HClO4.
From Mg(ClO4)2, which have on hand: Mg(ClO4)2 + Ba(OH)2 --> Ba(ClO4)2 + Mg(OH)2(s)
Via bariumperchlorate it looks rather easy, but the high toxicity of barium is a point to consider.
Never argue with idiots, they drag you down their level and beat you with experience.
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12AX7
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Explain this to me, you are writing in a perchloric acid thread that you are concerned about barium toxicity? I'm missing something here! LOL
Tim
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Taaie-Neuskoek
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You're left with a waste of Ba, which is toxic, even though the sulphate make it a lot safer due to it's insolubility.
Anyway, you're handling all the way very soluble barium salt's, which you have to filter, purify, etc... BaCl2 is considered as T by Merck,
I don't know about the perchlorate. I do have a bottle of HClO4 60%, so I am not that interested in making a lot of the stuff, but if I can find
some time and can make some Ba(OH)2 I might give it a shot to make a few ml.
Furthermore did I read that people were vacuum distilling perchloric acid, which is not advisable according to this site:
http://www-safety.deas.harvard.edu/advise/PerchloricAcid.htm...
I quote:
| Quote: |
Do not distill perchloric acid in a vacuum, because the unstable anhydride may be formed and cause a spontaneous explosion. Protect vacuum sources
from perchloric acid/perchlorate contamination. Vacuum pumps should be thoroughly flushed and refilled with Kel-F or Fluorolube.
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[Edited on 28-8-2005 by Taaie-Neuskoek]
Never argue with idiots, they drag you down their level and beat you with experience.
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garage chemist
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Now I have a very good perchlorate cell running with a platinum anode (0,5mm wire, 25cm long, coiled up, was really expensive but it was well worth
it!) and store- bought 45% sodium chlorate solution (liquid weedkiller from France, sold in 5L canisters) with added dichromate. It produces a sodium
perchlorate solution of about 520g/L concentration, with minor impurities like NaCl, Na2SO4 and Na2SO3 from the destruction of residual chlorate with
bisulfite.
I have successfully produced KClO4 (very good yield, over 90%) and NH4ClO4 (acceptable yield, ca. 60%) from this cell liquor.
This cell provides me with a never- ending supply of large amounts of KClO4 and NH4ClO4. The platinum wire was a very good investment. I live near to
France and can get the necessary chloride- free (very important! Don't use homemade NaClO3 solution!) NaClO3 solution easily.
Today I tried the production of HClO4 directly from NaClO4 and HCl by those instructions: http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
I used 50ml NaClO4 solution and 125ml HCl. I used a porous glass suction filter to filter the NaCl, which worked beautifully.
It went as described. I concentrated the HClO4 in a still and used a scrubber to get rid of the HCl offgas. When the volume was at about 25ml, the
temperature shot up to 209°C and the liquid became yellow. I had concentrated HClO4 at this moment.
But on cooling, an enormous amount of NaClO4 crystallized out. The crystals filled the entire liquid. Apparently my 520g/L NaClO4 solution wasn't
concentrated enough and too much water was left in the solution, which had the effect of higher NaCl solubility.
I vacuum distilled it with a boiling capillary and got 17ml oily liquid looking exactly like conc. H2SO4, being maybe a bit more viscous. I measured
the density as 1,68 and was very pleased when I looked up the literature value for 70% HClO4.
This procedure is a good pathway to HClO4, but one needs a really concentrated NaClO4 solution and also HCl of really 37% concentration, otherwise
vacuum distillation of the crude HClO4 is imperative because of the enormous amounts of crystallizing NaClO4 (this also lowers the yield). Maybe one
should boil down the NaClO4 solution completely and add that to the HCl in order to have a higher HCl concentration in the liquid and hence a lower
solubility of NaCl.
Also, having to use 125ml of conc. HCl in order to get 17ml HClO4 is rather uneconomic.
A possibility would also be to boil down my NaClO4 solution and vacuum distill that with dilute H2SO4. The high solubility of NaClO4 should effect a
complete reaction.
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BromicAcid
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Excelent to finally hear some sucess in this thread, maybe next time consider bubbling HCl gas into your solution of hydrochloric acid and sodium
perchlorate to help eek out some more of that sodium as sodium chloride.
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garage chemist
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That's a good idea, and would perhaps allow for less conc. HCl being used and therefore save time at the evaporation step.
However, if I succeed in directly distilling HClO4 from NaClO4 and dilute H2SO4, then I'm done with the research on HClO4 production since this
would be the most economic and cost- effective way.
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jpsmith123
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I'm glad to hear of your success, garage chemist.
I'm wondering, what current are you running in your 0.5 mm platinum wire?
I have two pieces of pt wire; one is rather thick, maybe about 1 mm diameter and about 60 cm long, while the other is 0.5 mm x 30 cm, similar to
yours. If my PbO2 electrode effort ultimately fails, I'm just going to end up doing a two stage process using some of this pt wire for the
perchlorate part.
(BTW there is a guy selling 0.5 mm x 30 mm platinum wire on ebay for $34.00 USD http://cgi.ebay.com/PLATINUM-WIRE-12-inches-99-9-PURE_W0QQit...).
| Quote: | Originally posted by garage chemist
Now I have a very good perchlorate cell running with a platinum anode (0,5mm wire, 25cm long, coiled up, was really expensive but it was well worth
it!) and store- bought 45% sodium chlorate solution (liquid weedkiller from France, sold in 5L canisters) with added dichromate. It produces a sodium
perchlorate solution of about 520g/L concentration, with minor impurities like NaCl, Na2SO4 and Na2SO3 from the destruction of residual chlorate with
bisulfite... |
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garage chemist
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My Pt anode can be used with a current of up to 3 Ampere, though I'm using 2 Ampere to limit heating of the cell (the efficiency drops sharply at
over 40°C). Cathode is a coil of thick copper wire. The cell volume is 250ml, and it is standing in a tub of cooling water.
It is stirred magnetically. Mixing of the electrolyte is very important in perchlorate cells, and the mixing from the hydrogen at the cathode is NOT
sufficient.
With 2 amperes and a 45% NaClO3 solution and 1g dichromate, the cell is done in 48 hours of non- stop running. The cell gasses start smelling like
ozone in the last few hours strongly, this indicates that mostly water is electrolyzed and a lot of oxygen is evolving at the anode.
The used NaClO3 solution must be chloride- free (test it with AgNO3 solution!), this is extremely important and failure to use absolutely chloride-
free solutions will result in severe corrosion of the Pt anode. Tap water already contains too much chloride.
I once runned the cell without dichromate, and the Pt got etched noticeably because the nascent hydrogen at the cathode reduced a small portion of the
chlorate to chloride. Dichromate prevents this by forming a diaphragm of hydrated Cr2O3 around the cathode. Also, dont make the cathode of too large a
surface.
Running a perchlorate cell is considerably more difficult than a chlorate cell. A lot of factors are important.
However, pH doesn't need to be adjusted.
The done cell liquor is strongly acidified with HCl and a spatula of Na2S2O5 is added. This turns the liquid green by reduction of the dichromate. If
on boiling the solution still smells like SO2, the chlorate is also destroyed. If necessary, add a bit more Na2S2O5 until it smells like SO2.
Then basify with NaOH solution, this will precipitate Cr2O3 and the above solution is clear and pure. It contains 520g/L NaClO4 and no chlorate.
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jpsmith123
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Thanks for the info.
I think I've read that persulfate works as well as dichromate to prevent reduction of chlorate, do you know anything about that?
Anyway, I'm wondering how practical it would be to produce NaClO4 by thermal decomposition of NaClO3, rather than by electrolysis?
If NaClO3 can be bought rather easily and cheaply, maybe it would be somewhat less troublesome to make NaClO4 by heating it and then purifying the
NaClO4 by recrystallization?
If I remember correctly, NaClO3 decomposes at about 300 degrees C, whereas NaClO4 decomposes around 500 degrees C, so all you'd have to do is
hold the temperature somewhere between, say, 300 to 400 degrees for a little while.
If I've done the math correctly, 100 grams of NaClO3 would provide a theoretical yield of about 86 grams of NaClO4, which should be fairly easy
to seperate because of the large difference in solubilities of the the products.
What do you think about that?
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garage chemist
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Look at this thread:
https://sciencemadness.org/talk/viewthread.php?tid=4077
The method is very time -and especially propane- consuming. Also quite some NaClO3 is left undecomposed, which has to be destroyed first with strong
HCl, then with Na2S2O5, which would give a very impure solution due to the large amount of chlorate to be destroyed.
But it works beautifully for preparation of KClO4.
Getting the right temperature (exactly 400°C) is difficult without an electronic thermometer and requires a lot of experience.
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JoPann
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hi
Iv'e just made some HClO4 in dissolving ClO2 into water (but I used a mix of ClO2 and CO2, which is safer).
After this step I put the mix of acids (HCl, HClO2, HClO3, HClO4) out into the sunlight for 2 days, to let the HClO2 and HClO3 reakt to HCl and HClO4.
Then I enriched the HClO4 in distilling off the HCl under vacuum, when the temperature began to rise i stopped heating, because i don't want
anhydrous perchloric acid.
I tested the final produkt with AgNO3 for Cl^-, and some was laft, but not much.
Then i neutralized it and calculated a concentration of 0,8mol/l (enough for me)
does anybody have suggestions for this kind of procedure?
king regards
[Edited on 10-9-2005 by JoPann]
[Edited on 11-9-2005 by JoPann]
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SAM4CH
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concentartion density table
I need a table of relations of concentration of perchloric acid and its Specific Gravity "like any aqueous solution"!!?
[Edited on 6-3-2006 by SAM4CH]
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mick
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A quick coment,
As an organic chemist by trade
Organic perchlorates, organic azides and organic nitrates should be treated with respect.
Take care
mick
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SAM4CH
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Can I reach 90-95% yield in preparing Ammonium perchlorate from concentrated solution of sodium perchlorate "250g/L" at 70-80º C by using ammonium
chloride, I read the yield will not be over 70%, but can we use an precipitating agent "e.g. commen ion, organic solvent,...etc" which can ppt. NaCl
and can not precipitate AP!!!!!!!!!!?
[Edited on 14-3-2006 by SAM4CH]
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Madandcrazy
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What will you prepared from,
Ammonim perchlorate from perchloric acid or
perchloric acid from ammonim perchlorate ?
Maybe perchloric acid from sodium perchlorate and HCl
and than ammonim perchlorate by NH4OH (NH3)
HCl and sodium perchlorate, by eletrolysis , or by
perchloric acid and sodium perchlorate.
Is the ammonium perchlorate staple and prepared by electrolysis ?
[Edited on 15-3-2006 by Madandcrazy]
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SAM4CH
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I am searching for the best method which can give largest yield, I have sodium perchlorate from electrolysis of NaCl and then I like to convert it to
pure ammonium perchlorate, my dream is having yield more than 85%.
Ammonium perchlorate from ammonium chloride by electrolysis is not in my planning because it is very dangerous method which can produce unstable
material "ammonium chlorate".!!?
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praseodym
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The reason you gave for not using the electrolysis of ammonium chloride is that there is a possibility of the production of ammonium chlorate which
you think is too unstable. However, isnt ammonium perchlorate itself a rather unstable compound since all perchlorates are powerful oxidising agents?
Furthermore, the ammonium chlorate can be converted to ammonium perchlorate simply by heating.
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woelen
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Electrolysis of NH4Cl definitely does not give NH4ClO3. The Cl2, formed at the anode, mainly forms NCl3 with ammonium ion. NCl3 is an exceedingly
dangerous chemical. It is very unstable and looking bad at it may be sufficient to let it explode .
Suppose you had some ammonium chlorate, then heating of this definitely causes the material to violently decompose or explode.
The ammonium ion cannot be simply thought of as an alternative for potassium ion or sodium ion in these cases. The ammonium ion is too good a reductor
to be compatible with Cl2 and ClO3(-).
So, summarizing: NH4Cl is useless for making chlorate and it is useless for making perchlorate.
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JohnWW
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Woelen is correct. The Cl produced at the anode would initially form chloro-substituted ammonium salts of chloramines (NH2Cl, NHCl2), which are less
basic than NH3, with HCl as byproduct, and finally NCl3, which is dangerously explosive without warning. The French chemist Dulong who discovered it
in the 19th century was seriously injured by it.
It would be safer to try electrolysis of a solution of an alkali metal chloride. This results in the formation of a strongly alkaline solution of
hypochlorite (being the industrial process for household bleach), and further electrolysis of this, with the liberated Cl2 being entrained in
solution, would result in chlorate and perchlorate.
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YT2095
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does anyone know the solubility of Ammonium perchlorate as compared to potassium chloride?
I have the KCl listed but not the NH4ClO4.
in a wet reaction I have NH4Cl and KClO4 dissolved together (only mg quantities), and there are crystals forming already as the soln evaporates
slowly.
My guess is that the NH4ClO4 is least soluble, as the crystals (although very tiny) don`t resemble KCl.
can anyone confirm this?
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