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Author: Subject: Preparation of ionic nitrites
guy
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[*] posted on 17-8-2007 at 11:16


Yes Pb(NO2)2*H2O is yellow (reference: http://journals.iucr.org/c/issues/1985/10/00/a25000/a25000.p... )

I suppose this may be removed by addition of sulfate.

--------

I think PbO can be used as a catalyst for nitrate -> nitrite.

3PbO + KNO3 --> Pb3O4 + KNO2

Pb3O4 --500C--> 3PbO + 1/2 O2
------------------------------------
KNO3 --PbO/500C-->KNO2 + 1/2 O2

Is this plausible?



[Edited on 8/17/2007 by guy]
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[*] posted on 17-8-2007 at 14:22


What about 1/2 O2 + KNO2 = KNO3?

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[*] posted on 17-8-2007 at 14:58


Quote:
Originally posted by guy
Yes Pb(NO2)2*H2O is yellow (reference: http://journals.iucr.org/c/issues/1985/10/00/a25000/a25000.p... )
(cut)

That file, and indeed the whole site (of crystallography journals) requires a log-in name and password, i.e. it is censored!! Please give these to us, Guy.
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[*] posted on 17-8-2007 at 15:53


Quote:
Originally posted by JohnWW
Quote:
Originally posted by guy
Yes Pb(NO2)2*H2O is yellow (reference: http://journals.iucr.org/c/issues/1985/10/00/a25000/a25000.p... )
(cut)

That file, and indeed the whole site (of crystallography journals) requires a log-in name and password, i.e. it is censored!! Please give these to us, Guy.


Oh...Well I was accessing from my university so I didnt need to type in anything. Sorry!
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[*] posted on 17-8-2007 at 16:28


Quote:
Originally posted by 12AX7
What about 1/2 O2 + KNO2 = KNO3?

Tim


Oh yea you are right. darn.
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[*] posted on 23-8-2007 at 13:23


Quote:
Originally posted by Polverone
Quote:
Originally posted by Filemon
Quote:
Originally posted by guy
Na2CO3 and KNO3 does not make NH3.


I have also surprised. But smelled ammonia. You prove.

I would guess that your KNO3 is impure and contains some ammonium salt. Do you smell ammonia if you mix it with a small amount of NaOH or KOH and add a couple drops of water?


Not this impure one the KNO3 but Na2CO3. I don't know that impurity has but I have discovered that this quite impure one.
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[*] posted on 15-12-2007 at 05:55


Quote:
Originally posted by guy
Quote:
Originally posted by 12AX7
What about 1/2 O2 + KNO2 = KNO3?

Tim


Oh yea you are right. darn.


Hmm I don't think this would happen, because at higher temperatures KNO3 decomposes on its own to KNO2

I also made some experiments by pyrolysis of KNO3 without any reducing agent and got pretty bad results. The molten mass coloured greenish yellow but when adding some HCl to a solution of the product not much gas was produced.

I also noticed, the molten mass dissolved the glass layer of my crucible.

And I tried to separate the nitrite from the nitrate by dissolving the salts in ethyl alcohol. In some MSDS I've read, there is a difference in the solubility between the KNO2 and KNO3. So the KNO2 goes into the solution.
But i haven't got more detailed informations about this process and in my case the Nitrate doesn't disturbs, because at the moment i just need the nitrite for Gas production and some "Azo" syntheses.

Btw.: I'm about to modify the Mushpratt method in adding charcoal to molten KNO3, so I think the procedure is calmer.

[Edited on by JoPann]
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[*] posted on 27-5-2008 at 15:36


I once tried to make some nitrite through incomplete combustion of a mix of sugar and saltpeter. With HCl a simple test on the residue after 10g of random mix gave a voluminous amount of brown gas.

A week ago, I tried again, using three mixes. The first was 1:1, the second 1:2 (close to stoich) the third 1:3, which was hard as hell to get to burn due to the low amount of fuel.

This time I used a solution of KMnO4 on the extract and assuming the reaction went
H2O + 2KMnO4 + 3KNO2- ---> 2KOH + 2MnO2 + 3KNO2, the amount of KMnO4-soln to cause a permanent color change was measured by adding 1ml at a time.

Yields turned out to be very low, something like 1.5-2% based on original KNO3. YES it was a sloppy half-assed experiment but IMO the procedure does not show promise at all. I theorize strongly colored ClNO from the reaction with HCl tricked me into believing it was a generous amount of NOx.

Did an experiment today on the liquid alkali-nitrate reduction of carbon (60/30/5 KNO3 KOH C)
Water was added to homogenize (it turned into a goop) but the mix kept foaming even after being "dry" the first time. Was this CO2? Or just water from the KOH? Gradually it evolves slower, whatever it is.

Then all of a sudden a cloud of smoke rises, and within 2 seconds the (stainless steel!) beaker is rescued from the fire.

The cake was dissolved in 150ml of boiling water. 4ml of this was diluted to 50ml, and a 2mg/ml solution of KMnO4 was added two ml's at a time (stupid dripper)

Color change immediately, meaning a maximum of 0.3% of the intended 50g KNO2 is present. Only option here that could "save" this method would be if the smoke-evolution was some kind of runaway which destroyed all nitrite.

Time to aquire some lead, I guess.
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[*] posted on 16-3-2009 at 09:25


[I moved this to where is should be]

I have attempted performing the reduction of sodium nitrate using NaOH+S in nothing more then an informal test run. Mainly just to see what I would be getting into trying to reduce about and ounce and a half of nitrate.

All materials where pretty much eyeballed and a table spoon of each was mix and ground in a morter and pestle.
A small sample was taken out and put into a small stainless steal crucible and melted with a small hand torch with which it promptly ignited and sustained it self for a few seconds.

First thing to note as mentioned a few post above is that it is imperative to ball mill all this together else there is mini explosions that will splash molten melt everyware. Even grinding it as fine as possible it would still hit occasional "hot" spots and produce a small bang.

When it is gone to compleation there is a ring of redish substance and a dark grayish black solid lump.
HCl was driped on a piece of the lump I broke off and there was a puff of brown NO2 so that is a good sign I assume.


Question:Is there any substance that can be added to this mix to quell the pyrotechnics of it and still allow it to perform the reduction? It looks like it could be promising to me but the 7 inch high rapid flames comming of a small pile the size of a quarter makes me think that this performed on an ounce of nitrate could get ugly a little to quick for my liking.:o





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[*] posted on 19-3-2009 at 19:42


Sorry for the double post here but I can not edit any longer.


Ok Im on a little quest here to make some sodium nitrite and Iv noticed a wiki artical on ammonia nitrite that speaks of ammonia nitrites being produced thru the oxidation of ammonia with H2O2 or ozone.

Does anyone think that it would be feasable to produce sodium nitrite from the reaction of ammonia nitrite and NaOH?

Im thinking along the lines of feeding dry NH3 into my 35 percent H2O2 and gently boiling it down till I have a concentrated enough solution of nitrite and then reacting this with NaOH to yeild sodium nitrite and ammonia hydroxide.

Any one have any thoughts on this method before I have a go at it within the next few days? It would seem to me that it would yeild the purest of any nitrites discussed so far.





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[*] posted on 20-3-2009 at 02:38


That seems like a waste of good H2O2.. But other than that I don't see why it wouldn't work, if in fact H2O2 does oxidize NH3 at a reasonable rate. The yields might suck too, since NH4NO2 is so unstable.. I have doubts about whether it could even survive being boiled down from a dilute solution.

I think it would be more interesting and novel to build an ozone generator and mix dryish NH3 with the O3 stream to directly precipitate the NH4NO2. That might be an interesting route to HNO3 from only ammonia and electricity, if it worked well at all.. Hehehh, then decompose it to NO2 and run that back through the ozone stream to get some N2O5!
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[*] posted on 20-3-2009 at 06:46


As for wasting H2O2 this really isnt a concern of mind considering I can aquire this for about $20 for a quart of it very easyly yet nitrates and nitrites are becomming problematic.

Is there any reason that the NaOH and H2O2 can not be premixed and the NH3 feed into this solution to produce the more stable NaNO2 directly without having to boil the solution? I think that saturation of an H2O solution with NH3 would may be the best way to proceed then react the proper amount of H2O2 followed with the addition of Sodium hydroxide to form the sodium nitrite.

.Iv considered the use of O3 because I have a few table top homemade tesla coils and these will bail out ozone as theres no tommorow but then theres the issue of getting two gas generators to run perfectly to produce a solid. Im thinking it may be best to feed these into some sort of solvent to allow them to react there. Possibly some Alcohol or perhaps even H2O





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[*] posted on 21-3-2009 at 13:30


Starting small and improper as usual I attempted to add some 35% H2O2 to over the counter ammonia solution just to see if what I expected to happen would, It didn't.

First of all I expected to have the smell of ammonia disappear after the addition of H2O2 and the ammonia was oxidised to ammonia nitrite. Im not really sure but the smell may have subsided quite a bit but it is still noticeable and the solution took on almost a slight halogen smell like a dilute bleach smell.

Seeing as the faint NH3 smell could possibly be due to decomposition of the unstable nitrite I am going to attempt to scale it up and do it properly.

One concern I have at the moment is the so called NaOH I have is a mixture of NaOH/KOH which will make proper ratios impossible so until I obtain some pure NaOH I am not going to be able to do it the correct way.


Question: If oxidisers such as O3 and H2O2 work to oxidise the ammonia would it not be possible to use other oxidizers such as permagnates and the likes?

[edit] because after sitting over night the smell is greatly reduced.... but still there.

[Edited on 21-3-2009 by Sedit]





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[*] posted on 30-5-2009 at 14:19


I requested this paper sometime ago with no response so instead of wait I decided to just attempt a process that I felt may work so I did not have to hassle with hot lead and splattering PbO.

Quote:
Reduction rate of sodium nitrate by lead drops with wet-ballmilling

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, Sendai 980-77, JAPON

Localisation / Location
INIST-CNRS, Cote INIST : 21521, 35400006896014.0130

http://cat.inist.fr/?aModele=afficheN&cpsidt=2808050


If someone can get this for me it would be great.


Anyway it appears to work great although I never isolated yeilds because... well Im stupid and let it sit out to dry just to have it liquify on me.

I misplaces my lab notes and it was about a month ago yet I just tested it for NOx production and the flask was filled with a dense brown gas.

20 grams of NaNO3 where added to a ball mill with a 2x molar excess of lead shot smashed flat for more surface area. Also a small amount of course hardware store sand was added to assist in the removal of any PbO that will form on the lead surface and a little bit of h2o just enough to make a sludge.

I milled this for about two days which is more then likely over kill but with out the text I have no idea with out extensive runs how to optimise this. After I added hot water and filtered the mix (which I still hold the filtrate of and may be able to determine yeild based on PbO to Lead acetate and weigh). The filtered solution was slowly dried over a very gental heat and left out overnight to liquify again and lose some of it. :P

Either way when I just found the remains I set aside again as I was testing to see if NH3 feed into H2O2 formed nitrites(They do a little bit but thats another post all together) I droped a small amount into H2SO4 and a thick dark brown cloud came out only slightly less then when it was formed from molten lead. This slightly lighter color could also be due to its damp nature also.





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[*] posted on 24-8-2009 at 07:10


I tried the starch + diluted nitric acid and the sugar+KNO3 mehod as these ones seemed the most conveninet to make nitrites.
Maybe I missed something, but I failed in both cases, the yields were terrible or none at all.

In case of sugar+KNO3 I simply can't believe that someone could make a decent amount of nitrite, it seems that the product decomposes at that temperature and mainly K2CO3 forms. And you will definitely piss off the neighbours as a lot of fumes will be generated even with test tube quantities.

In case of starch+diluted nitric acid, it is hard to make 1:1 NO+NO2 gas mixture, so a lot of NO bubbling through the scrubber unused + I think you mainly generate CO2 which react with the NaOH giving carbonate instead of nitrite.

I dunno what to do next, sniffing lead vapors isn't something that my bone marrow would thak me... maybe the sulphur method.
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[*] posted on 29-8-2009 at 07:39


I had a go at the lead+NaNO3 method also. A coal fire in an old saucepan was used as heat source.

I first melted the NaNO3 and then added Pb according to

NaNO3 + Pb ---> NaNO2 + PbO

The Pb came in the form of 1mm lead shot. The reaction proceeded smoothly and quite some bubbling was observed.

n001.jpg - 69kB
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[*] posted on 29-8-2009 at 07:41


This is the end product. The mixture became thicker and thicker and in the end it was impossible to keep it thoroughly melted. I kept heating for another 30 minutes and let it cool down.

n006.jpg - 72kB
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[*] posted on 29-8-2009 at 08:08


Altough difficult to see in the image, quite a lot of lead remained unreacted. I extracted the fused mass with hot water, filtered and started boiling.

The filtrate was quite yellowish. A lot of unreacted lead was recovered tough.

First a huge amount of clear crystals formed which I filtered and tested with HCl. No reaction so this must be NaNO3 :mad:

The final yield was pathetic, maybe 80g of slightly yellowish crystals. They do fizzle and bubble a bit when thrown into HCl but its not nearly as intensive as with reagent grade NaNO2. Also the color is just slightly off-white whereas the reagent grade stuff is much more yellowish. I discarded it as I have no used for impure crap of unknown composition.

At least I could use the PbO to make Pb(NO3)2.

----

I wonder what I have done wrong here. Possible sources of error I have come up with so far:

-too low a temperature (not likely as the reaction proceeded very quickly in the beginning and then slowed down rapidly)

-NaNO2 oxidized to NaNO3 by O2 from air (maybe air must be excluded from the cooling mass and the filtrate as its boiled down). HOW PRONE IS NaNO2 TO AERIAL OXIDATION?

-Not enough stirring to react all Pb (quite possible - the mixture became very thick and unstirrable after the initial reaction subsided)

Anyways this is not a promising route to NaNO2 IMHO.

Possibly the easiest way to reasoably pure NaNO2 is to bubble NOx into a sodium peroxide solution/NaOH + H2O2 mixture.

ALSO a C+Ca(NO3)2 mixture might work well. Yields might be shitty but the CaCO3 formed is insoluble so at least the nitrite would be easy to isolate.
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[*] posted on 29-8-2009 at 08:55


This is the classic route to sodium nitrite, used for a long time and documented in many books on inorganic chemistry, including many lab methods and preparative chemistry books.
Quote:

INORGANIC CHEMICAL PREPARATIONS
BY
FELIX LENGFELD

SODIUM NITRITE
Hampe, A. 125, 336.
Melt 85 grammes sodium nitrate in a
small, flat, iron dish (sand-bath), and add
slowly 206 grammes granulated lead. Stir
until the lead is completely oxidized (30-50
minutes), and pour the molten mass upon
an iron or slate slab. Powder and wash
thoroughly with boiling water. Cool the
filtrate, pass in carbon dioxide for a few
minutes, heat to boiling, and filter hot.
Evaporate until crystals separate on cooling.
Unless the evaporation has been carried
too far, the crystals are almost pure sodium
nitrate. Pour off the solution, again evaporate
and cool, and repeat until the solid
shows a decided test for nitrite. Then
evaporate the mother liquor to dryness, and
extract repeatedly with boiling absolute
alcohol. Evaporate the alcohol and recrystallize
from water. To determine the
strength of the nitrite, dissolve a weighed
portion in considerable water, add the quantity
of potassium permanganate it would
require if pure, acidify with sulphuric acid,
and titrate the excess of permanganate.


Things that may have gone wrong include adding the lead too quickly which can chill the melt, failing to maintain the needed temperature, and the NaNO3 being too moist (it does absorb moisture) so the the melt contains too much water and is too cool to start with.

The reaction is somewhat exothermic, on a larger scale it sometimes glows where the lead is being added. The lead does need to be finely divided, or added slowly with good stirring. In a related preparation, barium nitrite is made from a boiling solution of barium nitrate with addition of powdered lead made by reacting a solution of lead acetate with magnesium ribbon.

Calcium nitrate tends to go all the way to the carbonate/oxide.


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[*] posted on 29-8-2009 at 09:08


I am confused Taoiseach. Personaly I feel that this is the most promising of all nitrite routes I have seen. Perhaps its about order or something. Opposed to how the text N_I quoted I find it best to melt an excess of Lead in a crucible and slowly add the nitrate with stirring. I have plans on performing this later tonight time permitting and as long as I can find some spectricide at my local stores.

When adding the nitrate to the lead it will quicly melt and turn the lead bright orange I stir this for a few minutes before adding another addition about a gram at a time. It is a little more extensive I assume but in the end addition to H2SO4 produces a dark cloud of NOx.

Perhaps you are evaporating the solution at to high of a temperature. I prefere to do it at a low temperature to prevent oxidation back to the nitrate.





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[*] posted on 29-8-2009 at 09:08


double post?????

[Edited on 29-8-2009 by Sedit]





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[*] posted on 29-8-2009 at 14:00


This procedure works, read my post on 4-th page in this thread.
NaNO2 is dirty cheap, about 4-5 dollars per 1 kg.
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[*] posted on 29-8-2009 at 14:20


What do you want to use the NaNO2 for? I suppose you could use it as a meat preservative, or for diazotization of aromatic amines (and thence formation of aromatic halides and phenols and nitriles, and aromatic diazo compounds including dyestuffs), or formation of nitrosylamines.
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[*] posted on 29-8-2009 at 14:55


I'm also confused. Obviously I did something wrong - but what?
I did everything as described in literature. Even passed CO2 thru the filtrate but no cloudiness appeared. I always wondered how plumbate complexes could possibly form as they require strongly alkaline conditions.

Maybe the mistake was that I let the melt cool down without covering it. It might have drawn air. Also I did not extract the mass with hot water but rather filled water into the soupcap and boiled it for quite some time. Maybe the PbO re-oxidized the NaNO2 or it was oxidized by air.

I could not find any information on how easily NaNO2 is oxidized to NaNO3. Does NaNO2 have to be protected from air?

@not_important

The NaNO3 was definetely dry as I first heated it for quite a while until a clear liquid was obtained.

Also the fact that obviously quite a lot of PbO was formed suggests that reduction did take place, so I start to believe the NaNO2 was re-oxidized/destroyed later.
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[*] posted on 29-8-2009 at 15:54


I remember that somebody asked for thermal stability of NaNO2 and NaNO3 in the air but I cannot find this post.
There is article about it (from Springer), but I do not have it at hand.
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