I am looking for a cheap OTC way to make semicarbazide (without hydrazine) Sodium hypochloride can react with urea to form chlorourea. Chlorourea then
react with ammonia to give semicarbazide. I was thinking to produce sodium hypochloride from sodium chloride with electrolysis.
Any thoughts ?
Need semicarbazide to form formylcarbazide with formic acid, a precursor to NTO
[Edited on 5-1-2024 by underground]Niklas - 5-1-2024 at 04:03
I was thinking to produce sodium hypochloride from sodium chloride with electrolysis.
Why would you wanna make sodium hypochlorite? It’s literally one of the most otc reagents out there, the synthesis wouldn’t even be worth the
effort considering how cheap it is underground - 5-1-2024 at 06:15
Store bought bleach has low concentration
[Edited on 5-1-2024 by underground]dettoo456 - 5-1-2024 at 19:15
Semicarbazide can be produced via the normal Hydrazine synthesis by adding an excess of urea and jacking up the temperature, but carbodihydrazide,
hydrazodicarbonamide, and azodicarbonamide are formed as by-products. There are a couple of Chinese patents that outline the processes. In industry,
isolation of hydrazine for Semicarbazide and carbodihydrazide synthesis seems unpopular, so that’s why they try to bypass it.
They do isolate the chlorourea sodium salt but the process then requires anhydrous NH3.
If you use the ketazine process, you could potentially just react the MEK solution directly with urea at high temp without the need to hydrolyze. underground - 6-1-2024 at 01:24
So methyl ethyl ketazine and urea will yield semicarbazide and MEK ? I have seen the procedure of MEKetazine from nurdrage. Is there any reported
synthesis of Semicarbazide from MEKetazine ?dettoo456 - 6-1-2024 at 07:25
I don’t know if it’d work for sure, it’s just speculation. The main issue would be hydrolysis of the ketazine to MEK and aqueous Hydrazine. If
HCl won’t hinder the reaction then it should work but in all of the Semicarbazide syntheses I’ve seen, acid is only added after the synth
(refluxing for 3hrs) to crash out the Semicarbazide HCl salt.
Could semicarbazide be made directly from the hydrazine sinthesis from bleach and urea? Without making Hydrazine Sulphate. I was thinking to make an
automatic machine which you will feed it bleach/NaOH solution and urea/gelatin solution and urea solution to produce semicarbazide. I may even go a
step further and make it directly produce triazolone by feeding it formic acid in addition.
My plan it to make an automatic machine that you will feed it the nesesary chemicals to directly produce NTO
NTO only require Urea NaOH Bleach Gelatin Formic acid and 65% Nitric acid which is quite attractive
[Edited on 8-1-2024 by underground]clearly_not_atara - 8-1-2024 at 11:50
Quote:
They do isolate the chlorourea sodium salt but the process then requires anhydrous NH3.
This sounds less ominous than the other possibilities though. Ammonia is toxic in high concentration but it's not a serious carcinogen or pollutant if
you have decent containment.dettoo456 - 8-1-2024 at 17:54
Yea it’s not too bad of a reagent in general but hard to procure unless you’re in the agriculture business, and even then you wouldn’t likely be
able to buy in <500kg amounts.
@underground I do not think that would work, at least not the triazolone cyclization step. Semicarbazide could potentially be produced directly from a
solution of urea, hydrazine, NaOH, and Na2CO3, but without careful monitoring and real-time monitoring of hydrazine and urea concentrations in
solution, you’d yield a mess of products. And even then, isolation would be far too improbable. The only way you could potentially get close is
through the Peroxide Process, since excess heat could drive off excess O2 and NH3, and then urea could be added to the aqueous Hydrazine solution to
form Semicarbazide. Even with the peroxide process though, MEK is required as it forms an oxaziridine intermediate and eventually the azine.
Is semicarbazide bicarbonate insoluble in water ? If it is insoluble in water then it could be made directly from hydrazine synthesis by adding urea
then add sodium bicarbonate to ppt out just like aminoguanidine bicarbonatedettoo456 - 9-1-2024 at 14:12
I believe it might be but then again, I do not know how readily Semicarbazide forms salts - especially weakly bonded salts like bicarbonate. If it
could work, CO2 would need to be bubbled in instead of just adding NaHCO3 I’d think.
The main products left in solution before acid addition (in a normal prep of hydrazine sulfate) would be NaCl, NaOH, N2H4, Na2CO3, gelatin, and maybe
a little excess urea. So you’d need to assume the sodium salts and gelatin would be inert throughout refluxing with added urea for maybe 1.5hrs with
the aqueous Hydrazine. I guess in that case you’d need to neutralize the NaOH and Na2CO3 but not the Hydrazine before adding Urea to react to form
Semicarbazide.
I think the best option is through formation of the MEKazine with just NH4OH and NaOCl, crack the azole somehow (maybe strong base like NH3 would do
it) and add Urea and reflux.
The reagents arent expensive though, so I’d recommend experimenting if you have time and if you are really interested in yielding lots of
Semicarbazideunderground - 10-1-2024 at 00:19
Does the ph have to be neutral for the semicarbazide formation ?dettoo456 - 10-1-2024 at 07:33
It needs to be neutral at the least, but most likely basic, since you’d be aminating the urea amide. I haven’t studied the physical chemistry of
animations with hydrazine, so don’t quote me on anything.
I also found out that Purolite C160 (a solid acidic resin) can be used to partially hydrolyze MEKazine without forming a hydrazine salt. So NH4OH and
NaClO can be reacted in the normal way with MEK, the MEKazine separated and fed through a pressurized bed with acidic resin, then the remaining liquid
fed to a reactor to reflux with Urea to yield Semicarbazide.
That isn’t 1-pot but feasibly a flow compatible prep. You just need some peristaltic pumps and pressure rated glassware. underground - 10-1-2024 at 08:32
If that is the case, since a) i can not find MEK and b) it is more expensive than H2SO4, i may just go with Hydrazine Sulphate , then reflux HS with
urea 1:1 molar mass while slowly NaOH is added.
[Edited on 10-1-2024 by underground]kmno4 - 10-1-2024 at 15:25
urea -> -> nitrourea - reduction -> desired compound
It works and no N2H4 is needed.
[Edited on 11-1-2024 by kmno4]underground - 11-1-2024 at 07:38
Any info for the procedure ?
P.S. i jave seen somewhere (dont remember where) that NU can be reduced to semicarbazide with electrolysis
[Edited on 11-1-2024 by underground]EF2000 - 11-1-2024 at 09:14
First procedure even says that the product is "sufficiently pure for use in the preparation of semicarbazide". Second one also lists alternative
pathways in Discussion section, with refs.
Attachment: The electrolytic reduction of nitrourea.pdf (341kB) This file has been downloaded 160 timesunderground - 11-1-2024 at 22:55
Interesting. Seems nitrourea can be reduced to semicarbazide with iron electrodes and ammonium chloride electrolyte. Yields seems to be close to 60% ,
not that great but still better than dealing with hydrazine and the starting materials are cheap. Urea and ammonium nitrate (fertilizers) with HCL
yield urea nitrate and ammonium chloride which both can be used for semicarbazide production. Seems a viable way to produce semicarbazide.
I search a bit for the solubility of Semicarbazide sulphate and i coudnt find anything. Any idea how much is in water? Was thinking to ppt out
SemicSulph in stead of benzaldehyde.
Also is there any info about how much is the solubility of Semicarbazide formate ?
