Rhodanide
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Cyclization of Diaminoglyoxime to Diaminofurazan, unsure of synthesis.
Hi all,
I've successfully made what I presume to be Glyoxime and am looking to continue on to eventually make Diaminoazoxyfurazan. According to Axt's old post
about Furazans and the related compounds, Diaminoglyoxime must be heated with aqueous KOH in a sealed steel reactor. Uhh, what? Not only do I
not have a steel reactor available to me, but putting potentially energetic compounds in a steel vessel and heating it on an oil bath seems like
something I'd like to avoid. What I want to know is, if the whole steel reactor is necessary, and can I just get by with using normal glassware at
normal atmospheric pressure? Or even better, is there a different pathway to cyclize DAG to DAF? Please let me know. If I could I'd ask Axt himself,
but who knows where that guy has been all these years.
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Rhodanide
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I'd also be happy with a synthesis of just Furazan from Glyoxime. I can't find an easy synth anywhere really.
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Dornier 335A
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Diaminofurazan is not an energetic material, and an aqueous solution is definitely not an explosive hazard.
According to Axt's paper, the reaction needs to be performed at 180°C. The vapour pressure of water at that temperature is 10 bar, so you understand
why steel is used and not regular glassware.
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Microtek
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I've done this synthesis in the past using the classical procedure. As Dornier says, the cyclization happens at a reasonable rate only around
170-180C. If the reaction medium is water, then obviously the pressure needs to be quite high, hence the autoclave.
I have read a paper that uses ethylene glycol instead of water and is therefore able to conduct the reaction at normal atmospheric pressure. I have
tried that procedure once, but had a thermal runaway and moved on to other projects without exploring further.
I think you should look into the ethylene glycol mediated procedure if you wish to avoid the pressure vessel. However, a pressure vessel can be
constructed fairly easily from a steel water pipe with caps screwed on both ends. If the threads are lubricated with a sufficient amount of silicone
sealant, the silicone quickly polymerizes as the temperature rises, and the caps can still be screwed off after the reaction. You need to be quite
sure of your temperature control, since the pressure rises quickly if you go much beyond 180C.
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Praxichys
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Depending on the scale you're running at, pipes can be incredibly strong. At 200°C, water has a vapor pressure around 210 psi, and at 300°C about
1250 psi. There are a variety of pressure relief fittings using stainless burst discs available which could leave you with a mess instead of a bomb if
something goes wrong. However, sch 80 stainless pipe is quite strong, handling the vapor pressure and temperature of water at 316°C/1600psi up to 2"
diameter. Remember that burst pressure is much higher than working pressure since working pressure is designed to also handle transients brought about
by fluid flow at the working pressure.
https://www.mcmaster.com/burst-discs
https://www.engineeringtoolbox.com/stainless-steel-pipes-pre...
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Microtek
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Yes, as far as I could tell, I was pretty far from any potential catastrophic failures, and I had mapped the behaviour of the kitchen oven to make
sure it didn't overshoot. It was still a nerve wracking experience.
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