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Bromine
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[*] posted on 16-9-2006 at 11:32
NH4NO2


Can be ammonium nitrite prepared by oxidizig concentrated ammonia solution by 30% hydrogen peroxide? This information i found somewere, i can't remember right now.:)



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[*] posted on 17-9-2006 at 09:38


Ammonium nitrite is unstable. If you add NaNO2 to a solution of NH4Cl, then bubbles of N2 are produced, especially when the liquid is heated a little. So, I expect the solid to be very unstable.

I expect that if you add concentrated H2O2 to concentrated ammonia solution, that the H2O2 will decompose quickly and that hardly any oxidation of ammonia occurs. Some oxidation may occur, but if this happens, then I expect haseous N2 and/or N2O to escape, or maybe some nitrate remains in solution, but I have strong doubts about all this.




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[*] posted on 17-9-2006 at 11:08


I read you can do it with NH3 and O3.



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AJKOER
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[*] posted on 19-11-2011 at 15:37


Quote: Originally posted by Bromine  
Can be ammonium nitrite prepared by oxidizig concentrated ammonia solution by 30% hydrogen peroxide? This information i found somewere, i can't remember right now.:)


Yes, Ammonium nitrite can be prepared by oxidizing an ammonia solution with hydrogen peroxide.

On an old thread on Sciencemadness no less (see http://sciencemadness.org/talk/viewthread.php?tid=11781 author: Formatik), apparently the required catalyst include any of NaOH, Na2CO3, Zn dust, Pt or Pd-H2.

Upon boiling (NH4OH + H2O2 + catalyst) the creation of NH4NO2 is apparently accomplished (a given reference is completely in German however). One can perform a demo by adding a mineral acid which results in the evolution of NO and NO2.

2 NH4NO2 + H2SO4 --> (NH4)2SO4 + 2 HNO2

2 HNO2 --> NO + NO2 + H2O

Note, NH4NO2 is unstable (a two hour half-life, decomposes 60 to70 C) and is considered a high explosive (solutions are also sensitive) with limited applications due to thermal and shock sensitivity.

Note, NH4NO2 is also considered to be acutely toxic.

Here is the complete quote by Formatik:

"The Ber. ref. from Hoppe-Seyler describes it. Namely, strong solutions of H2O2 with a few drops of NH4OH or solutions of ammonium carbonate (with or without NaOH or Na2CO3) can be let to stand 24 hours without any nitrite formation occurring. But upon longer standing, even with a small amount of hydroxide then nitrite forms. Nitrite also forms when a dilute solution of H2O2 is mixed with NH4OH and a little Na2CO3 and is evaporated over pure conc. H2SO4 with a bell jar.

H2O2 forms (even in very dilute solutions) nitrite very rapidly, if the H2O2 solution is mixed with a few drops of NH4OH and a little NaOH or Na2CO3, and this then boiled in a retort to a very small volume. They suggest this nitrite formation as a demonstration experiment because it is very quick to do, and then after acidification of the colorless liquid with H2SO4, the HNO2 can be nicely be proven to be present."

CAUTION: The reader may note that the suggested preparation of NH4NO2, and the MSDS described thermal detonation properties of NH4NO2 (if applicable to solutions also) appear to overlap. Hence, possible detonation may occur on following the described preparation route.


[Edited on 20-11-2011 by AJKOER]

[Edited on 20-11-2011 by AJKOER]
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[*] posted on 19-11-2011 at 16:47


see:
http://sciencemadness.org/talk/viewthread.php?tid=11781

Quote:

an interesting reaction from the literature of Marcellin Berthelot, dry ammonia gas reacts with the nitrogen dioxide and nitric oxide, at room temperature,

(2)NO2 + (2)NO + (4)NH3 --> (2)NH4NO2 + (2)H2O + (2)N2

Solid ammonium nitrite inside a tube explodes if heated on a water bath to between 60-70degC. And the substance gradually decomposes at room temperature, slower if cold, or faster in aqueous solutions, forming nitrogen gas.


Quote:

strong solutions of H2O2 with a few drops of NH4OH or solutions of ammonium carbonate (with or without NaOH or Na2CO3) can be let to stand 24 hours without any nitrite formation occurring. But upon longer standing, even with a small amount of hydroxide then nitrite forms. Nitrite also forms when a dilute solution of H2O2 is mixed with NH4OH and a little Na2CO3 and is evaporated over pure conc. H2SO4 with a bell jar.

H2O2 forms (even in very dilute solutions) nitrite very rapidly, if the H2O2 solution is mixed with a few drops of NH4OH and a little NaOH or Na2CO3, and this then boiled in a retort to a very small volume. They suggest this nitrite formation as a demonstration experiment because it is very quick to do, and then after acidification of the colorless liquid with H2SO4, the HNO2 can be nicely be proven to be present.
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[*] posted on 21-11-2011 at 00:05


Quote: Originally posted by AJKOER  
CAUTION: The reader may note that the suggested preparation of NH4NO2, and the MSDS described thermal detonation properties of NH4NO2 (if applicable to solutions also) appear to overlap. Hence, possible detonation may occur on following the described preparation route.


Ammonium nitrite in the aqueous phase is not thermally stable enough to survive being entirely boiled down. In fact, its decomposition in the aqueous boiling state by mixing aq. nitrite with an ammonium salt is an old method of preparing nitrogen gas.

Those were some good finds on forming it from hydrogen peroxide, but unfortunately I've not seen these qualitative experiments transformed into a workable synthesis. If I remember right, Gmelin has some good information references on its preparation using sodium nitrite as the starting point.
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