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woelen
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Periodic acid -- properties and experiments
Although there is some information about this compound on sciencemadness, I think it is appropriate to create a dedicated thread about the properties
of this compound. Information about this compound is sparse. The only thing I could find is that it can be used to cleave -C(OH)-C(OH)- groups and
that it is a strong oxidizer.
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woelen
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As a start, I can give some nice experiments I did.
1) A solution of H5IO6 gives a white precipitate of KIO4 when a small amount of a solution of KOH is added. When more KOH is added, the precipitate
redissolves again. When dilute nitric acid is added, then a white compact crystalline precipitate is formed again.
This is quite interesting. It looks like being amphoteric. With a little amount of base, the IO4(-) ion seems to be formed, which gives a precipitate
with K(+) ions. At higher pH, IO6(..) based ions are formed?
The KIO4 can be separated very easily. Just rinsing with distilled water, decanting the liquid, having the liquid absorbed in tissue paper and then
drying. The KIO4 is an energetic material which burns fast with metal powder, and it sort of explodes with red P.
2) A mix of slightly crunched H5IO6 (30 mg) with powdered red P (7 mg) has the interesting property that it is self-igniting with a time delay. The
self ignition occurs when the mix is put in a pile. Just wait and at a certain moment it ignites. When the powdered mix is spread over a large area,
then it does not ignite.
The reaction between red P and H5IO6 is very fast, like flash powder. The mix does not seem very friction sensitive, I could not ignite it by
crunching/rubbing the mix.
3) The compound H5IO6 reacts with conc. HCl, giving loads of Cl2 and yellow ICl3, which remains in solution.
I did not try the cleaving method of di-ols. Does this mean that sugars like sorbitol (which contains OH groups on each C-atom) are completely broken
down? Under which conditions do such reactions occur?
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pantone159
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Checking some of my books...
Organic Chemistry, Brown and Foote, 3rd ed:
The mechanism for splitting glycols involves first forming a five-membered cyclic periodic ester, and electron redistribution then gives two C=O
groups. Glycols which cannot form such an intermediate (i.e. steric reasons) cannot undergo such a reaction.
This reaction is said to be useful in analyzing sugars, by analyzing the amount of periodic acid used and the products. Also, the periodic acid can
similarly attack a-hydroxyketones and a-hydroxyaldehydes.
Macroscale and Microscale Organic Experiments, Williamson, 2nd ed., has the following test for vicinal glycols:
Prepare periodic reagent by dissolving 0.25 g H5IO6 in 50 ml H2O.
To 2 ml of this reagent, add 1 drop (no more) of conc HNO3 and shake. Then add one drop or a small crystal of the unknown. Shake for 15 sec and add
1-2 drops of 0.3 M AgNO3 (aq). Instantaneous formation of a white ppt is a positive test.
This test gives positive results with a-hydroxy aldehydes, a-hydroxy ketones, a-hydroxy acids, a-amino alcohols, 1,2-diketones, as well as for the
1,2-glycols.
EDIT: Also, Solomons, 4th ed, states that lead tetraacetate brings about similar cleavage reactions. The lead compound works well in organic
solvents, while periodic acid works well in aqueous solutions, so the two are complementary.
The periodic reaction usually has quantitative yields.
EDIT2: I believe that sorbitol would indeed be broken down completely, the end carbons would become formaldehyde and the inner ones formic acid, so 1
mol sorbitol -> 2 mol formaldehyde + 4 mol formic acid.
[Edited on 7-4-2008 by pantone159]
[Edited on 7-4-2008 by pantone159]
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woelen
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Ammonium periodate
Today I made ammonium periodate. It is made very easily. If you make a solution of H5IO6 in a little water and then add some ammonia, then a compact
white crystalline precipitate is formed. This precipitate does not dissolve when much more ammonia is added, not even in 25% ammonia.
I let this precipitate dry above a heat radiator (50 C or so). A fine non-hygroscopic white powder is obtained. This compound is a remarkably powerful
explosive.
I put a very small amount in a thick-walled test tube, unconfined, and then heated the test tube above a small alcohol burner. The result is quite
impressive. At a certain point in time, the solid explodes with a remarkably loud report and iodine vapor is produced at once. I made a video of this
reaction, a small write-up on this will follow tonight or tomorrow.
What most surprises me is how easily this compound can be made from periodic acid. Apparently, periodates belong to a class of anions, which hardly
have any soluble compounds. Even the potassium and ammonium salts are almost completely insoluble in water. Only the meta-periodates are like this.
When NaOH is added, then the solid dissolves and ortho-periodates go into solution.
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Zinc
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Very interesting
I wish I have some periodic acid. Does anyone know where could it be obtained OTC or do I have to order it from some chem. company?
And could organic periodates be made (I know perchlorates can and they are very explosive)?
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sparkgap
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@woelen: If you want to test the polyol-cleaving property of periodic acid, even sucrose will suffice. 
@Zinc: AFAIK, periodic acid cannot be had OTC.
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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woelen
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Here follows the write-up on the preparation and explosive properties of ammonium periodate:
http://woelen.homescience.net/science/chem/exps/ammonium_per...
I'll try the cleavage reaction with sugar. I expect bubbles of CO2, first cleaving and then further oxidation to CO2. If not, then I at least should
smell formaldehyde and/or formic acid. Both chemicals have strong and distinct smells.
[Edited on 9-5-11 by woelen]
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chloric1
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Periodic acid can be quite expensive. If I recall, a certain ebay seller sells little 1 or 4 oz bottles along with iodides and few other chems. His
products are concerned with printing.
$62.99 for just25 grams JEEZ! Just search ebay for "iodide" and you will find the store.
[Edited on 4/12/2008 by chloric1]
Fellow molecular manipulator
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garage chemist
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Periodates are remarkably easy to make, much easier than perchlorates.
Check out Brauer, there's a detailed synthesis of NaIO4 in there in three steps from iodine.
The first one is HNO3-catalyzed oxidation of iodine with NaClO3, forming NaIO3 solution, second one production of sodium periodate by oxidation of the
iodate with chlorine in NaOH solution.
It is precipitated as the sparingly soluble salt Na3H2IO6, and in the last step this is reacted with HNO3 to form the easily soluble NaIO4 which is
isolated by fractional crystallization after concentration according to the procedure.
From NaIO4, ammonium periodate can be easily prepared without a doubt.
Making free crystalline periodic acid requires the barium salt Ba3(H2IO6)2, which is reacted with an excess of conc. HNO3 in which Ba(NO3)2 is
insoluble. The procedure is given in Brauer as well.
Everyone interested in periodate preparation check out those procedures in Brauer, they are very nice laboratory procedures that surely are a pleasure
to do and don't require any exotic chems!
Woelen, very interesting work with the ammonium periodate. I am surprised that this salt is explosive by simple heating, in contrast to ammonium
perchlorate, which only decomposes quite silently with a yellow flame when heated.
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woelen
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I also tried to make hydrazinium periodate, but this is not possible. As soon as H5IO6 is brought in contact with hydrazine, or one of its salts, then
an EXTREMELY violent reaction occurs. I have never seen a reaction between two aqueous solutions, which is so violent and hot, that iodine escapes
from the liquid as vapor.
This is a remarkable experiment in its own. If one has H5IO6 and hydrazine (or one of its salts) then make a solution of H5IO6 in a small amount of
water, make a solution of hydrazine or its salt (e.g. N2H4.2HCl) and then add the two solutions to each other. This results in the formation of a
thick plume of purple iodine vapor!
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YT2095
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sounds like wet chemistry version of Rocket fuel, almost Messerschmitt worthy 
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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Axt
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You can produce hexaiodobenzene (see attachment). Then attempt to <a href="http://www.sciencemadness.org/talk/viewthread.php?tid=4766">oxidise
to iodyl</a>, though I did do a lot of searching and never did I come across reference to iodyl groups ortho to each other.
Or see if it changes colour with temperature http://www.chemicalforums.com/index.php?topic=19644.0
Somewhat novel, it forms copper(III) periodate complexes as well.
Attachment: Periodination of Benzene.pdf (284kB)
This file has been downloaded 2255 times
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woelen
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This periodination of benzene looks very interesting. Unfortunately, benzene is VERY difficult to obtain in NL, it is one of the chemicals which is
banned completely. I do have toluene, what would you expect with toluene, under the conditions, as described in the article.
Thanks anyway for all this new info. A whole new world of iodine chemistry opens up to me , this old thread was buried too deep, so I have not seen it before. I especially like the benzene with the ICl2 groep on it. That really
is interesting chemistry!
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Axt
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Yep, I've attached the follow up article which includes pentaiodotoluene amoungst others.
Oh and I'm an idiot, I posted myself in the iodoxy thread that o-diiodylbenzene had been prepared, so yes theres an example of two iodyl moieties orto
to each other. The highest "iodylated" benzene i've seen is 1,3,5-triiodylbenzene, and was only mentioned as an "exotic initiator of the future" :/ No
reference nor indication that it has been made.
[Edited on 15-4-2008 by Axt]
Attachment: Direct Aromatic Periodination.pdf (440kB)
This file has been downloaded 1387 times
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UnintentionalChaos
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| Quote: |
Somewhat novel, it forms copper(III) periodate complexes as well. |
Attached a paper explaining somewhat vaguely this process.
Oxidation of Cu (II) by persulfate or hypochlorite in alkaline medium in the presence of periodate.
Attachment: Copper (III).pdf (157kB)
This file has been downloaded 1347 times
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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woelen
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@garage chemist: I have done the preparation of KIO4, based on a slightly modified procedure, as described in the reference you gave. This really
works nice. I have a lot of KIO3, and now I can easily make KIO4. I already had some, but only a very limited amount (it is soooo expensive). Making
the sodium salt also is easy for me, I have a lot of NaI and the periodate can directly be made from a boiling solution of NaI, NaOH through which Cl2
is bubbled.
A write-up with pictures will follow on the synthesis of KIO4.
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woelen
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Here follows the write-up of the synth of KIO4:
http://woelen.homescience.net/science/chem/exps/KIO4_synth/i...
Have fun and try it yourself, it really is easy.
[Edited on 9-5-11 by woelen]
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woelen
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| Quote: | Originally posted by woelen
I also tried to make hydrazinium periodate, but this is not possible. As soon as H5IO6 is brought in contact with hydrazine, or one of its salts, then
an EXTREMELY violent reaction occurs. I have never seen a reaction between two aqueous solutions, which is so violent and hot, that iodine escapes
from the liquid as vapor.
This is a remarkable experiment in its own. If one has H5IO6 and hydrazine (or one of its salts) then make a solution of H5IO6 in a small amount of
water, make a solution of hydrazine or its salt (e.g. N2H4.2HCl) and then add the two solutions to each other. This results in the formation of a
thick plume of purple iodine vapor! |
I did some further experimenting on this and under no condition, periodate and hydrazine can coexist. Not at high pH as free base, nor at low pH as
hydrazinium ion. In all cases there is a violent reaction. This reaction is fun in its own. I made a small webpage of this:
http://woelen.homescience.net/science/chem/exps/hydrazine_pe...
[Edited on 9-5-11 by woelen]
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Jor
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Very nice. I'm gonna make some KIO4 really soon! I have about 100g KIO3. I Also have hydrazine sulphate.
I'm gonna try this with potassium bromate. Should be really violent!
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Formatik
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| Quote: | Originally posted by woelen I did some further experimenting on this and under no condition, periodate and hydrazine can coexist. Not at high
pH as free base, nor at low pH as hydrazinium ion. In all cases there is a violent reaction. This reaction is fun in its own. I made a small webpage
of this:
http://woelen.homescience.net/science/chem/exps/hydrazine_pe... |
How about in liquid nitrogen, it still reacts violently?
Edit(woelen): Made link work again.
[Edited on 30-7-16 by woelen]
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JohnWW
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| Quote: | | Originally posted by JorI'm gonna make some KIO4 really soon! I have about 100g KIO3. I Also have hydrazine sulphate. I'm gonna try this with
potassium bromate. |
I presume you are going to try to make perbromate. Perbromates are very difficult to
prepare, being very strong oxidants, and were first obtained in any quantity only relatively recently, unlike perchlorates and periodates. Before
that, they were known only in small quantities through the decay of a short-lived Se isotope as selenate, which is itself oxidizing.
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Jor
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I know perbromates are very hard to make.
I ment that I was going to substitute a preiodate by a bromate in the experiment on woelen's site.
I always wondered why it is so impossible to make perbromate without F2 or XeF2 though. Things like ferrate(VI), manganese heptoxide, persulphate,
bismuthate, cerium(IV) etc. should be able to do the job in theory right? Because they are stronger oxidisers than perbromate. I can get all of these
chems (except ferrate, but it i possible to prepare barium ferrate >>> see versuchschemie), so i will try it some day.
Why is it so hard to make? Is it the Br going through oxidation state 6+ before achieving 7+? Maybe 6+ is so unstable that it will decompose
immidiately? I have no idea...
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Jor
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I mixed some a small amount of potassium bromate with a small amount of potassium permanganate on a petri dish. To this a large drop of conc.
sulphuric acid was added. Something was being oxidised, because the solution went brown. This must have been the bromate being oxidised. But yes, as
expected, there was a lot of bubbling. A saw a brown tint; indicates bromine. But there was also a lot of colorless gass : oxygen?
What exactly is happening here?
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ShadowWarrior4444
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| Quote: | Originally posted by Jor
I mixed some a small amount of potassium bromate with a small amount of potassium permanganate on a petri dish. To this a large drop of conc.
sulphuric acid was added. Something was being oxidised, because the solution went brown. This must have been the bromate being oxidised. But yes, as
expected, there was a lot of bubbling. A saw a brown tint; indicates bromine. But there was also a lot of colorless gass : oxygen?
What exactly is happening here? |
Perhaps the production of elemental bromine with the evolution of oxygen. Did you detect any characteristic scents?
| Quote: | | I can get all of these chems (except ferrate, but it i possible to prepare barium ferrate >>> see versuchschemie), so i will try it some day.
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Potassium ferrate is quite easy to prepare, and is used in 'Super-Iron' batteries. It is usually stabilized by the hypochlorite ion.
[Edited on 5-19-2008 by ShadowWarrior4444]
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Jor
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According to wiki, perbromic acid rapidly decomposes to bromic acid and oxygen, with the evolution of bromine vapor.
I read in a ACS-journal that bromate is not appreciably oxidised by persulphate at 100C. If my English is correct, this would mean
that some bromate is oxidised. Worth a try , if you do it for a long time, the boiling.
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