guy
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Decomposition of sulfamate
I searched google and found that salts of sulfamic acid produce NOx and SOx. Is this possible because I can't seem to balance the equations. When I
tried to balance it for copper sulfamate, the most sensible products are SO3, N2H4, and Cu. Any ideas?
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12AX7
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N2H4, heh...
Lemme see, sulfamate is NH2-SO3-H right? So that hydrolysis NH2SO3H + H2O makes NH4+ + HSO4-, ammonium bisulfate?
A salt like copper sulfamate is going to be something like Cu(NH2SO3)2, since sulfamate only gives one proton (hmm, Wikipedia says it can lose two
protons actually..). Decomposition might give...oh... I'm going to guess SO2, since the hydrogen sticking to the N is going to be kind of reducing.
Sulfate is sometimes a mild oxidizer...times like fire. Cu too. And SO2 isn't really strong enough to oxidize anything more. So, it might turn out
something like Cu(NH2SO3)2 = Cu + N2 + 2H2O + 2SO2. But the Cu may oxidize, so you could get hydrogen, or more likely ammonia out; or you could get
lower sulfur oxides, and some nitrogen oxides. I doubt much of something like N2O, which really tends to come from compounds with N-N bonds, or
something close to that anyway (like molten ammonium nitrate.. N atoms, with luggage (NH4 and NO3 stuffs), but close enough in a molten soup that
they'll work).
Er..but anyways...if the salt is hydrated, you might get other products with the steam. Copper oxide is still unlikely, it's pretty easy to reduce,
but N2 and H2O could do things I guess (of the sort like, say, 2N2 + 3H2O <--> 2NH3 + NO + NO2), if unlikely. More to the point, if you
decompose it in air, you'll get oxides of everything, which will include SO2, SO3, Cu, Cu2O and CuO, as well as NOx formed by oxygens combining with
the momentarily loose nitrogens when the stuff is burned.
Tim
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guy
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How is the hydrogen on the N reducing? If anything it should be oxidizing. I imagine that the N--S bond will break forming SO3, leaving NH2- group
which would reduce copper and react with the other NH2- group to form N2H4 which will probably decompose in the heat.
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chemoleo
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I am also not convinced about hydrazine that is being produced, no way, in such an oxidising environment. SO3 is oxidising, yes.
I figure something like this:
H2N-SO3-H --> NH3 + SO3 ---->> NO + SO2 +H2O; NO2 + SO2 +H2O,
You may balance this yourself 
I'd almost bet this is what's happening...any takers? As to the salt, at high heat, the same things, albeit at different proporitons, will be
produced.
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Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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unionised
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"I searched google and found that salts of sulfamic acid produce NOx and SOx."
Was this froma safety data sheet?
They often list NOx as a possible decomposition product of anything containing nitrogen. Ammonia, for example, is said to give NOx even though it
hasn't got any oxygen in it.
Since N2H4 isn't stable at high temperatures I can't see it being produced by pyrolysis of anything.
IIRC Sulphamates react with NOx to give N2 anyway so I think that you will get a mess.
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guy
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Well I decomposed some Ferric sulfamate today. I gave of white fumes of gas (but not like ammonium salt fumes, they quickly became colorless). The
gas smelled like SO2 but stronger and more bitter. The resulting mass was a black, crumbly powder. Any opinions?
Someone should try this too, someone with better analytical equiptment and skills.
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DeAdFX
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Mayve a mixture of SO2 and Ammonia. The black powder might be Fe3O4.
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guy
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I don't see how ammonia could have possibly be produced from a sulfamate. The nitrogen has to be oxidized somehow.
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unionised
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"I don't see how ammonia could have possibly be produced from a sulfamate. The nitrogen has to be oxidized somehow."
Why?
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guy
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Well to from ammonia, one of the hydrogen has to break of from another -NH2, and don't see why it would.
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unionised
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I assumed that, like a lot of sulphates, most sulphamates would be hydrated and you could get ammonia (at least as a salt) by hydrolysis.
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chloric1
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| Quote: | Originally posted by unionised
I assumed that, like a lot of sulphates, most sulphamates would be hydrated and you could get ammonia (at least as a salt) by hydrolysis.
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Sulfamates hydrolysise easily at low pH levels. Neutral or alkaline solutions are stable to boiling. In an attempt to prepare several hundred grams
of ammonium sulfamate for a guanidine experiment I found this out first hand. I used the store bought masonry etchant and the stuff i used was at
LEAST two years old. Not taking the extra time to purify by recrystallizing may have greatly reduced my yeild. As although ammonium sulfamate is
stated in the MERCK INDEX as being stable to boiling, I am sure the ammonium bisulfate impurity started a chain reaction hydrolysis reaction to the
sulfate. I have two batches of crystals that strngly resemble ammonium sulfate and one give a strong sulfate test with barium chloride and the other
only causes haziness. Ammonium sulfamate is one of the few sulfamates that will supposedly dissolve in alcohol. To what extent it will dissolve I
have no idea.
By the way dissolving the masonry etch in distilled water at 80 degrees C until saturation then cool slightly below 0C is by far the best purifying
method. You should get glistening platlets that have practically no hygroscopic tendicies(non-caking).
Fellow molecular manipulator
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