woelen - 6-2-2020 at 05:52
Several years ago, I purchased a full kilo of pyro-grade NH4ClO4 (it was cheap, beige/brownish material and still needs to be cleaned up).
While searching the internet for possible routes to high purity HClO4 from NH4ClO4, I stubled on this, a bachelor thesis from 1922:
https://thesis.library.caltech.edu/1619/
I think I have to share this find! You can freely download this as scanned PDF file. A nice read!
This gives me ideas for experiments which I can do with that old NH4ClO4.
[Edited on 6-2-20 by woelen]
Fery - 6-2-2020 at 09:03
Hi woelen, thx for sharing. Interesting method. I know the method using HNO3+HCl to convert NH4+ into N2O + Cl2 gases so leaving pure HClO4. Using NOx
to destroy NH4+ is very nice idea.
[Edited on 6-2-2020 by Fery]
Bezaleel - 6-2-2020 at 09:28
Thanks for sharing. It's really easy-reading. Their apparatus seems pretty complicated, and working with NO2 seems difficult to me. Do you consider to
try this yourself?
But yes, if you could employ it to make HClO4 from pyro-grade NH4ClO4, that would of course be great!
woelen - 6-2-2020 at 11:25
I indeed will try this.
Several years ago I purchased some cheap NH4ClO4 (the only common perchlorate which we can buy in these days for reasonable price). The stuff I
purchased is intended to be used in pyrotechnic compositions and for that purpose it need not be very pure. It contains brown insoluble matter, it was
packaged in an old-looking brown paper bag. I'll dissolve it in boiling hot water, filter the solution and then let the solution cool down and further
evaporate. In this way, I can get a nice white product, which may be a good starting point for making HClO4, free of sodium ions. I already tried that
on a small scale and it works quite well, although some patience is needed to evaporate all the water from it. A second recrystallization may be
needed to remove invisible (also soluble and white) impurities.
I can try the reaction with NO2 in my backyard. NO2 I can make from NaNO2 and dilute acid. I have plenty of NaNO2.
unionised - 6-2-2020 at 11:41
It's an interesting idea but I must be missing something.
Where did they get NH4ClO4 from (cheaply)?
It's pretty much useless if you need to use HClO4 to make the ammonium salt, to make the acid.
[Edited on 6-2-20 by unionised]
woelen - 6-2-2020 at 13:48
This is a 1922 thesis. At that time probably HClO4 was much more expensive industrially.
For me, HClO4 also is much more expensive (EUR 100 per 1000 grams of 70% acid) and generally, it is harder to obtain for most people. NH4ClO4 is appr.
EUR 35 per kilo for me. So, this may be interesting for the home chemist.
clearly_not_atara - 6-2-2020 at 15:34
If you make sodium perchlorate by electrolysis you should obtain a ppt of NH4ClO4 upon adding some ammonium salt
woelen - 7-2-2020 at 00:58
Making NH4ClO4 is not interesting for me, I have quite a lot of the stuff and I can purchase more of it, if I need to.
It is HClO4 which I would like to have in bigger quantitites.
I once tried the route through NaClO4 (made from NH4ClO4 and NaOH, by boiling off all resulting NH3) and concentrated HCl, such that NaCl is
precipitated. This works quite well, but the end product always contains a little NaClO4 (HCl can be driven off by boiling to 150 C or so). I find it
annoying to have some NaClO4 left in the acid. E.g. if I use it for making metal complexes such as Cu(en)2(ClO4)2, then I do not want slight
contamination of my product with NaClO4. Using NH4ClO4 directly in such experiments also is not an option. NH4ClO4 is much less soluble than NaClO4
and will lead to even more contamination of the end product.
[Edited on 7-2-20 by woelen]