Sciencemadness Discussion Board

tetrazine and diazotization

Chisholm - 4-4-2017 at 07:53

Attempts to isolate freebase aminoguanidine under most lab conditions result instead in the formation of 1,4-diaminotetrazine.

Is this compound explosive? Can it form salts with oxoacid anions that are explosive?
How does the freebase tetrazine react to nitrous acid? Does it polymerize by forming diazo-couplings, does it become a diazonium salt, or does it just fall apart?

PHILOU Zrealone - 4-4-2017 at 13:41

This comes from the tendency of carboaminohydrazide (R-C(=NH)-NH-NH2) to selfcondense and eliminate NH3 as a gas; then after isomerisation the oxygen of the air oxydizes the C-NH-NH-C sequence into C-N=N-C to complete aromatization into tetrazine.

In principle it must display a low basicity based onto similar structured molecule like melamine (pKa = 5) thus tetrazine must be close to the pKa of acetic acid (4-4,5) ; and second pKa function must be 3 pKa units lower (1-1,5) thus quite acidic.
For example melamine has 3 NH2 groups but when submitted to HC(NO3)2 only lead to a monosubstitued salt (with a power close to TNT...while one would expect disubsitued or even trisubsitued salts (melamine bis-nitroformiate and tris-nitroformiate) the last one would be a killer salt outperforming most HE...but it doesn't exist as such.

So here maybe a mono-nitroformiate or bis-nitroformiate (if possible) may be worth making and quite powerful.
H2N-C(N2)2C-NH2. HC(NO2)3
H2N-C(N2)2C-NH2. 2 HC(NO2)3

To ensure the protonation of second and third amino of the melamine one would need to use very strong acids like HNO3 or even better HClO4 even then the third protonation might be hard to acheive.
For tetrazine is would be easier since there is only two NH2 so the second protonation should be in reach of HNO3 and for sure of HClO4.

The resulting salts will be quite powerful and dense; the bis-perchlorate must be quite sensitive too.
H2N-C(N2)2C-NH2. HNO3
H2N-C(N2)2C-NH2. 2 HNO3
H2N-C(N2)2C-NH2. HClO4
H2N-C(N2)2C-NH2. 2 HClO4
All must be more powerful and denser than their aminoguanidine analogues (nitrate and perchlorate).

Those may be quite hygroscopic and hard to get anhydrous (or not with nitrates and perchlorates of amines hard to figure out without doing it).

I was asking myself the same question last year, so I have already a lot of ideas to share about it...must depend on the surrounding media and process...such diazonium must be quite reactive with the solvent (water)...
I was interested into the resulting putative polymeric energetic material :)

1°) (-(CN4C)-N=N-)n this must be colorfull and probably violet, red, brown or even black
Sadly the density will not be exceptionnal due to loss of H bondings vs its hydrazine brother (-(CN4C)-NH-NH-), but stil decent and the energy content wil be very good for this new carbo-nitrogen allotrope so maybe a very good energy fuel for binary mixes...must be a hell hot burning stuf. Organic electric conductor?

2°) By loss of N2 and radical fusion kind of polytetrazaphenyls
(-CN4C-)n...same blabal as above very good potential superfuel probably quite dark.

3°) By loss of N2 and reaction with water
HO-N=N-CN4C-N=N-OH --> 2 N2(g) + HO-CN4C-OH
This dihydrotetraazaquinon must be quite acidic (--> energetic salts?) and oxydable owing to keto-enol equilibrium (into the later reaction part of the N2 is left aside for convenience purpose)
HO-C-N=N-C-OH <==> O=C-NH-NH-C=O --O2--> O=C(-N=N-)2C=O (probably very unstable) + H2O

4°) Anion addition by N2 elimination...like common Sandmeyer reaction of diazoniums
--> Cl-CN4C-Cl
very interesting compound owing to the halide lability just like for trichlorotrinitrobenzene or cyanuric (tri)chloride (-C(Cl)=N-)3 possible interesting substitutions when submitted to N2H4, NaN3, AgNO2, CH3-NNa-NO2 or CH2(NO2Na)2 and maybe AgC(NO2)3...