Sciencemadness Discussion Board

Nitroguanidine reduction product

Hey Buddy - 15-12-2022 at 10:33

I asked this in SQ/QA but no answer yet, I'm going to destory this today if I cant identify it. --I was recently attempting to reduce NQ via electrolysis. I used a copper anode which is a basic mistake, forgetting it produces this red substance. I am unable to ID from literature, I have been searching Thiel, Lieber, Kurzer but cant seem to find where this substance is mentioned. I know I have read it somewhere before, but now that its relevant I cant recall. I think its a Tetrazine but want to be sure of ID before disposal. If it's a tetrazine it might be a simple precursor for an energetic tetrazine complex, in which case I may just roll with it. Thanks.

_MG_9243.jpg - 261kB

Microtek - 16-12-2022 at 03:02

I have no idea what that is, but I would suggest you begin by isolating it and then testing it for Cu-ions.

Boffis - 16-12-2022 at 05:50

Under rather specific conditions with conventional reducing agents it is possible to reduce some nitro guanides and ureides to what are effectively 1,2-disubstituted hydrazine and some of these are readily oxidized to stable azo-guanyl compounds which are deep yellow to orange red. I still have a crop of such material prepared more than a decade ago waiting to be investigated. It is sparingly soluble in most solvents making it difficult to purify but if I recall it was prepared by the reduction of nitroguanidne with zinc. I will check my note books when I get home in a weeks time if you like. For references on these compounds check out von Richter's chemistry books.

Hey Buddy - 16-12-2022 at 08:09

Quote: Originally posted by Microtek  
I have no idea what that is, but I would suggest you begin by isolating it and then testing it for Cu-ions.


I threw it out, but it can be replicated later. If anyone is interested in how it was made: Anolyte 10% H2SO4 / copper anode. Catholyte 30% (NH4)2SO4 + NQ mixed in undissolved / lead cathode. No temp control, ~5 amps, unknown surface area of electrodes. It turns red very slowly at first then becomes more exponential. I let it run for about 12 hours and it was white NQ floating in sulfate solution at first then arterial-blood-red after a night.

[Edited on 16-12-2022 by Hey Buddy]

Boffis - 16-12-2022 at 09:53

Is the stuff floating in the red liquor actually red or just the solution? I checked out Richter vol 1 pages 504-505 and 516 there are several possibilities but H2N-CO-N=N-CO-NH2 is described as a sparingly soluble orange red solid. The only mention of colour for the guanyl derivatives is the nitrate salt of H2N-CNH-N=N-CNH-NH2 a sort of azobiguanyl which is yellow but the free base may not be.

Hey Buddy - 17-12-2022 at 11:59

Quote: Originally posted by Boffis  
Is the stuff floating in the red liquor actually red or just the solution?


I think the material is red when it is converted to completion but it begins as white NQ and then becomes tan then orange then red. I didnt continue the conversion because it was in error.

I also forgot to mention for anyone reading that I used a diaphragm for the copper anode. Clay flower pot with the H2SO4 anolyte inside and the NH42SO4/NQ on the outside with a stir bar.

Hey Buddy - 20-10-2023 at 14:46

I stumbled across the old article my brain was remembering about possible identities of this material. Then found the Thiele reference. There is a 1953 paper of lieber. Synthesis of Sym-diaminotetrazine. I suspect that this red product may be a 3,6-diamino 1,2,4,5 tetrazine or a derivative of it. A red/violet product from the action of potassium hydroxide on aminoguanidine HCl.-Lieber.
Also, Thiele obtained a red crystal from attempting to isolate free aminoguanidine by precipitation of the sulfate with barium hydroxide. I dont know whats going on but if it is forming a tetrazine, NQ could be reducing to aminoguanidine and then cyclizing to tetrazine. Boffis' suggestion also seems plausible...

just found these articles today and wanted to update this in case anyone wanted to know of possible easy route to tetrazines.




[Edited on 21-10-2023 by Hey Buddy]

Diachrynic - 20-10-2023 at 21:21

The red color of aminoguanidine self-condensation/oxidation was initially ascribed to the formation of diaminotetrazine by Ponzio and Gastaldi in 1913. After the compound had been made by Lin and Lieber in 1954 (the paper you mentioned!) it was established that the red product is not just diaminotetrazine:
Quote:
In conclusion, it is pertinent to mention that the properties manifested by VIIa [3,6-diamino-1,2,4,5-tetrazine] are distinctly different from those originally attributed to this structure by Ponzio and Gastaldi. The structure of the Ponzio product will be the subject of a future communication.


No follow-up communication ever came as far as I know. However, in 2014 the structure was determined by another group, and it is in fact not a tetrazine.
B. Tasso, G.Pirisino, F. Novelli, D. Garzon, R. Fruttero, F. Sparatore, A. Sironi, Tetrahedron 2014, 70, 43, 8056–8061. https://doi.org/10.1016/j.tet.2014.08.037
Attachment: tasso2014_aminoguanidine_self_condensation.pdf (675kB)
This file has been downloaded 176 times
Quote:
The structure of 3,6-diamino-1,2,4,5-tetrazine was assigned to the red-violet compound that was obtained by treating aminoguanidine hydrochloride with KOH by Ponzio and Gastaldi in 1913. At present, one century later, through a chemical and spectroscopic study, the structure of 1,1,4,10,10-pentaamino-2,3,5,6,8,9-hexaazadeca-1,3,5,7,9-pentaene was attributed to that compound.

EF2000 - 21-10-2023 at 01:47

Since there at least some aminoguanidine is present, can it be copper aminoguanidine sulfate complex?
Cu(AG)2(ClO4)2 is said to be violet here: Z. anorg. allg. Chem. (attached it too)
But as seen in attached picture (found somewhere on SM wiki and cropped), nickel sulfate complexes differ in color from nickel perchlorate ones. Maybe it's also true for copper. Kinda similiar orange, isn't it?

Nickel_aminoguanidine_sulfate_and_nitrate(cropped).jpg - 957kB

Attachment: Synthesis, Structural and Energetic Properties of Copper(II) Perchlorate Complex with Aminoguanidine.pdf (1MB)
This file has been downloaded 274 times

[Edited on 21-10-2023 by EF2000]

[Edited on 21-10-2023 by EF2000]

Diachrynic - 21-10-2023 at 03:11

The copper aminoguanidine complexes look nothing like the picture in the OP. All of them are some shade of blue or purple. Not red like nickel, that's just a common color for square planar complexes.
I wouldn't exclude Cu2O in part for the red color in the OP though.

(Also thanks, that's my picture :P)

EF2000 - 21-10-2023 at 03:37

Quote: Originally posted by Hey Buddy  

I also forgot to mention for anyone reading that I used a diaphragm for the copper anode. Clay flower pot with the H2SO4 anolyte inside and the NH42SO4/NQ on the outside with a stir bar.

Alright, copper complex excluded. My second attempt: what about iron? If the pot in question is made from red clay, iron could leach out. The color is pretty rusty
(Also, great picture, Diachrynic:))

[Edited on 21-10-2023 by EF2000]

Hey Buddy - 21-10-2023 at 15:59

Quote:
Quote: Originally posted by Diachrynic  
At present, one century later, through a chemical and spectroscopic study, the structure of 1,1,4,10,10-pentaamino-2,3,5,6,8,9-hexaazadeca-1,3,5,7,9-pentaene was attributed to that compound.


I wonder if that is the molecule. Very strange one. Begging to be cyclized. Maybe some oxalic acid. I dont suspect a metal interaction. I think it's simply the metal electronic character and maybe combination of anode/cathode that produces the red molecule. Electrolytic energetics are really creepy.

[Edited on 22-10-2023 by Hey Buddy]