Sciencemadness Discussion Board

Urea explorations

Polverone - 20-8-2002 at 14:59

Since I have 50 pounds of urea on hand and not much use for it, I have recently been experimenting with it.

The first of my experiments led (I believe) to the production of ethyl carbamate and I'm not sure what else. I dissolved urea in boiling alcohol. I let it cool after a few minutes of boiling and a thick mass of needlelike crystals formed - presumably unreacted urea. Then I heated the mixture again and also added some ammonium nitrate. The ammonium nitrate slowly dissolved. When I let the mixture cool again, no crystals formed. Even when I cooled it in the refrigerator, tried dropping in a seed crystal, and scraped the side of the jar, nothing formed. I'm guessing that I now have, more or less, ethyl carbamate and alcohol.

But what of the ammonium nitrate? I tried adding some of this non-crystal-forming liquid to hydrochloric acid and introducing zinc dust. With NH4NO3 and HCl this gives NO2 fumes as well as hydrogen. There were no visible fumes and no scent of NO2.

I know it's rather silly of me to just start trying things when I could look them up, but I love the hands on parts of chemistry and I was disconnected from the net at the time.

I also tried a few experiments with molten urea. Almost-anhydrous copper sulfate powder (copper sulfate that was at one point anhydrous but had been stored long enough to turn a very pale blue) gave a beautiful deep blue color when added to molten urea. It also caused the urea to vigorously expel ammonia. I wonder if the blue color was due to the well-known copper-ammonia complex. When I cleaned out the vessel the color faded as water washed over the material and it seemed to become a cloudy, boring light blue. With pale-colored ferric ammonium sulfate, the urea again bubbled and gave off ammonia and also yielded an intense brown-red color. With manganese chloride the urea gave off ammonia but did not provide any impressive colors. Yellow potassium chromate eventually gave a green color and - you guessed it - caused the urea to decompose, giving off ammonia (quite likely CO2 also, but I can't smell that).

I know that urease, alkalinity, and acidity all catalyze the decomposition of urea. Do all transition metals do the same?

Wouldn't it be nice...

Polverone - 30-8-2002 at 10:16

Urea actually decomposes from heat to form cyanic acid (which readily polymerizes to cyanuric acid) and ammonia; depending on the reaction conditions (pressure/temperature, etc.), ammelide, ammeline, and melamine may be produced as well (by successive substitution of OH by NH2 in cyanuric acid).

Hydrazine can be produced by the oxidation of urea with sodium hypochlorite. To quote "Engineering and Process Development", article "Properties, Production, and Uses of Hydrazine" by James E. Troyan:

"Urea, in place of ammonia, is oxidized with hypochlorite in the presence of a stoichiometric amount of caustic soda. Synthesis proceeds according to the equation NH2CONH2 + 2NaOH +2NaOCl --> N2H4.H2O + Na2CO3 + NaCl. Here the yield is 65-70% under optimum conditions."

PHILOU Zrealone - 10-4-2003 at 14:26

NH2-CO-NH2 + NH2-CO-NH2 -heat-> NH2-CO-NH-CO-NH2 (biuret)+ NH3
NH2-CO-NH-CO-NH2 + NH2-CO-NH2 -heat-> NH2-CO-NH-CO-NH-CO-NH2 + NH3
NH2-CO-NH-CO-NH-CO-NH2 -heat-> (-NH-CO-)3 + NH3

NH2-CO-NH2 -heat-> HN=C=O + NH3 <--> HO-C#N +NH3
3 HO-C#N (cyanic acid) -heat-> (-N=C(OH)-)3 (cyanuric acid)
3 HN=C=O (isocyanic acid) -heat-> (-NH-CO-)3 (isocyanuric acid)

(-N=C(OH)-)3 <--> (-NH-CO-)3
enol-ceton equilibrium!

By the way:
NH2-CO-NH2 provides a perchlorate and a nitrate that are both more sensitive and powerful than the related NH4 perchlorate/nitrate!
Their VOD and brisance is satisfactory but perchlorate is better on both levels!

I theorise that
NH2-CO-NH-CO-NH2 would make nice higher density dinitrate and diperchlorate with better OB!
Thus higher VOD, brisances and maybe better or equal sensitivities!

NH2-CO-NH-CO-NH2.2HClO4 (N3H7C2Cl2O10)
NH2-CO-NH2.HClO4 (N2H5CClO5)

(N3H7C2Cl2O10) > (N2H5CClO5) > NH4ClO4
(N5H7C2O8) > (N3H5CO4) > NH4NO3
:o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o


Theoretic - 25-6-2003 at 06:58

I think that, apart from reactions of urea with ammonium and transition-metal salts, this reaction would work as well:
Ca(OH)2 + CO(NH2)2 -> CaCO3 + 2NH3.
This could be a source of high-grade, ahhydrous ammonia.
Also, the nitrogen in urea could oxidize metals to amides, imides and nitrides.
3Zn + CO(NH2)2 -> Zn3N2 + CO + 2H2
2Zn + CO(NH2)2 -> 2ZnNH + CO + 2H2
Zn + CO(NH2)2 -> Zn(NH2)2 + CO +2H2
Would anyone try it?:o:o:o

Theoretic - 27-6-2003 at 04:25

Sorry again!
Not equations 1 and 2, but 2 and 3!

Theoretic - 6-7-2003 at 04:10

Could guaniddinium nitrate (C(NH2)3(NO3)) form from urea (CO(NH2)2) and AN (NH4NO3)?

Mephisto - 6-7-2003 at 05:50

The normal way to guanidine nitrate is from ammonium nitrate and dicyandiamide or calcium cyanamide. But guanidine salts can form from heating urea with ammonium salts. And I know for sure, that guanidine (the liquid) can be synthesized from urea and nitric acid. But I don’t know how to get practical guanidine nitrate from urea, without getting urea nitrate as result.

Iv4 - 7-7-2003 at 03:57

I can't get pure ammoniam nitrate but ammoniam sulfate and urea I can.Hopefully potasium nitrate too(to make the AN).

My resources are VERY limited(as in I dont have a proper scale..)but are there any tests I can do for ganendine still?

Spling and please keep in mind pure is only relativly pure(fertilzer grade)

[Edited on 7-7-2003 by Iv4]

Theoretic - 7-7-2003 at 06:23

Quote (oridinally posted by Mephisto):
"guanidine (the liquid) can be synthesized from urea and nitric acid"
How is that? If guanidinium ion is made via urea + NH4+, then surely guanidine would be made via urea + NH3! Also, every nitrogen atom in guanidine is reduced, in HNO3 the nitrogen atom is oxidized! :o:o:o

Iv4 - 7-7-2003 at 08:12

I think that(using ammonia)would form ammonium cyanide.Besides I'm gusing you'd need to heat it to a point which would make the ammonia evaporate.

Damn I'm sorry I was thinking about ammonia in water(sorry drunk and probably wont have time soon).

But let me get this strait Urea and an ammonian salt will form a guanendine salt.But I'm thinking that there should be cyanide formed here becaus it seems to react the same as any metal group in terms of cyanides,and sodium in that case would form sodium cyanide.Am I totaly of track?

[Edited on 7-7-2003 by Iv4]

Mephisto - 8-7-2003 at 10:51

Sorry, but I couldn’t answer earlier.

The U.S. patent 3,009,949 looks quite interesting.
Urea + ammonium meta phosphate + water + 71% nitric acid --> guanidine nitrate + ...

To see the scanned patent-pages you need a program like AlternaTIFF.

Theoretic - 8-7-2003 at 23:32

So I guess that guanidine can be made by combining urea and (NH4)2SO4 and using a base like Ca(OH)2 to precipitate the sulfate ion (I guess a little water is left)?

Mephisto - 9-7-2003 at 02:32

In the U.S. patent 2,590,257 there is a similar process described: (see example 3, page 1/2)

Therefore guanidine is made by combining urea and a sulfonamide (but which?!), dissolving the reaction-product in ethanol and using potassium hydroxide to precipitate the sulfate ion as potassium sulfate, getting an alcoholic solution of guanidine.

Note: I'm going on holiday next time, so I’ll can’t answer until ~ the 20th July.

Theoretic - 15-10-2003 at 06:45

No, cyanides don't form at temperatures that low.
So, since urea and ammonium salts form guanidinium salts, guanidinium nitrate (and guanidine nitrate by subsequent dehydration by conc. H2SO4) can be made (avoiding Megalomania's mind- bending precursors) as follows :cool: :
1) (NH4)2SO4+2CO(NH2)2=> 2C(NH2)3SO4+2H2O
2) C(NH2)3SO4+Ca(OH)2=>Ca(SO4)+NHC(NH2)2+2H2O
3) NHC(NH2)2+HNO3=>C(NH2)3NO3

polymerisations with urea

chemoleo - 16-10-2003 at 11:53

a further exploration is to mix urea with formaldehyde, and a white soft polymer is formed. Wonder what would happen with acetaldehyde, or ketones like acetone?

KABOOOM(pyrojustforfun) - 17-10-2003 at 19:43

to Theoretic if you got Qsulfate just dissolve it with stoichiometric amount of Ca(NO3)2 filter....
or if you just have KNO3/NaNO3 you can use them but need to add alcohol to precipitate the sufate. u know the rest...

KABOOOM(pyrojustforfun) - 22-10-2003 at 20:09

see US patents 4,535,185 & 5,041,662
they are kind of AN + urea => GN + H2O
there's a thread on E & W about it. look for <i>Guanidine nitrate...</i> the thread starter is Mr cool (Nick F)

to chemoleo: I <i>think</i> aceatldehyde forms insoluble polymers with urea in acidic conditions like how CH<sub>2</sub>O does. I also <font color=purple size=4>guess</font> aqueous soloutions of urea and aldehydes / ketones in mold PH conditions are equilibrating systems like this:
RCOR&#039; + OC(NH<sub>2</sub>)<sub>2</sub> <s>&nbsp;&nbsp;&nbsp;></s> HOC(R)(R&#039;)NHCONH<sub>2</sub> <s><&nbsp;&nbsp;&nbsp;></s> R(R&#039;)C=NCONH<sub>2</sub> +H<sub>2</sub>O
+ RCOR&#039; <s>&nbsp;&nbsp;&nbsp;></s> HOC(R)(R&#039;)NHCONHC(R)(R&#039;)OH <s><&nbsp;&nbsp;&nbsp;></s> (R)(R&#039;)C=NCONHC(R)(R&#039;)OH +H<sub>2</sub>O <s><&nbsp;&nbsp;&nbsp;></s> (R)(R&#039;)C=NCON=C(R)(R&#039;) +2H<sub>2</sub>O
edit: modified the tags that hadn't worked.

[Edited on 30-10-2003 by KABOOOM(pyrojustforfun)]

Iv4 - 25-10-2003 at 23:01

Thanks for the links.Could it be carried out without the catalyst?

Theoretic - 26-11-2003 at 05:43

"to Theoretic if you got Qsulfate just dissolve it with stoichiometric amount of Ca(NO3)2 filter....
or if you just have KNO3/NaNO3 you can use them but need to add alcohol to precipitate the sufate. u know the rest..."

If you use calcium nitrate, then a thick CaSO4 slug will be produced. A pain in a certain bodypart to filter...
What about (OK, this is completely new) urea + quicklime? I assume it would react as follows:
CO(NH2)2 + 2CaO => CaCO3 + Ca(NH2)2.
Could be then reacted:
Na2CO3 + Ca(NH2)2 =>2NaNH2 + CaCO3.
Who doesn't want easy sodium amide... :cool::cool::cool:
Another crazy idea of mine is to reduce the carbonyl in urea with atomic hydrogen and then treating the resulting compound wiht strong HCl solution and ZnCl2 as a catalyst:
1)CO(NH2)2 + 2H => OHCH(NH2)2 (diaminemethanol).
2)OHCH(NH2)2 + 5HCl => CHCl3 + 2NH4Cl + H2O.
Chloroform from urea!
Reacting urea with alkali and alkali earth carbonates with urea (well known), reducing the resulting cyanate with iron, aluminium or charcoal, then reducing the cyanide with atomic hydrogen to make methylamine (that's in solution, in a melt, using NaOH as a source of hydroxide and aluminium as a reducing agent sodium methylamide, sodium aluminate and sodium oxide are made!).
And finally, dehydrating urea with SO3 to make NH2CN (cyanamide), then reducing cyanamide with atomic hydrogen to make diaminomethane. The latter could be reacted with strong HCl solution to make DCM and NH4Cl...
OK, I'm getting carried away now, but the reactions sound too neat to be wrong... :D:D:D

Acetamide attempt

chloric1 - 8-12-2003 at 18:12

Today I tried to make acetamide from acetic acid and urea and it falied. At 210 Celciuc, I had a reddish solid that smelled of sweaty feet. Acetamide melts around 80 C and the mixture should have remained liquid. I raised the temperature over a period of 45 minutes. Did i heat too fast? Should I maintained at lower heat to drive off carbamic acid? Anyone tried this method?

Nick F - 9-12-2003 at 08:02

There was a patent mentioned, in which urea was reacted with sulphamide to produce guanidine sulphate:

SO2(NH2)2 + 2 CO(NH2)2 --> (C(NH2)3)2SO4

I just had a quick go at trying a similar reaction, using the commonly available sulphamic acid instead of sulphamide:

HSO3NH2 + CO(NH2)2 --> C(NH2)3HSO4

Sulphamic acid (3g) and urea (2g, a slight excess) were mixed, and heated gently over a gas flame. When nearly all had become molten, a brief but significant effervescence occured, lasting maybe 30s. During this time, the colour (which had been bright orange due to an indicator contained in the sulphamic acid, which was obtained as a descaler) changed to a blue/green. A small sample was removed and allowed to cool. It remained blue/green, so the colour change was not temperature dependant (like ZnO is, for example), and when added to some dil. HCl, an orange colour was obtained, showing that the indicator was not decomposed. The colour change therefore indicated some sort of reaction.
After approx. 30mins heating I got bored and allowed it to cool. Approx. 50mL of warm water was added, and the blue, toffee-like mass dissolved slowly (Edit: while it was dissolving, the orange colour returned, but now the solution appears mostly colourless).
BUT, it did not all dissolve. There is a substantial quantity of a buff-coloured, fine precipitate. I'm letting it settle at the moment, before I do more playing around with the solid and solution...

So, something has happened, at least...

[Edited on 9-12-2003 by Nick F]

Theoretic - 11-12-2003 at 08:13

It seems that red gunk just doesn't stay out of the flask of an organic chemist... :D
Sodium acetate heated with ammonium chloride also make acetamide, and I also think this method has less potential to make vile, polymeric red gunk.

KABOOOM(pyrojustforfun) - 13-12-2003 at 21:01

Theoretic: that's no different from heating ammonium acetate. where the urea? it's UREA explorations after all. ya sure the amide/nitride reactions work? they seem impossible.
I read US 3,009,949 Mephisto was talking about. CO(NH<sub>2</sub>;)<sub>2</sub> + NH<sub>4</sub>PO<sub>3</sub> <s>&nbsp;&nbsp;&nbsp;></s> C(NH<sub>2</sub>;)<sub>3</sub>H<sub>2</sub>PO<sub>4</sub>
I'm thinking one can modify the process for NQ by replacing ammonium metaphosphate with a mix of metaphosphoric acid & ammonium nitrate. after melting and keeping for 1 hour let cool. add the remaining solid in conc sulfuric acid then pour on water. wash the crystals with water (biuret, phosphoric acid(s), unreacted urea & ammonium nitrate are removed) then boil in hot water (the traces of nitrourea will disappear). ya can easily make metaphosphoric acid from almost any conc of phosphoric acid or ammonium phosphoate fertilizer by heating it to redness

Theoretic - 15-12-2003 at 04:41

I think it can work, because ammonia can also oxidize metals at high temperatures, so why can't urea do it? The urea molecule can deprotonate, but electron transfer with subsequent neat cleavage of the urea molecule into amide and carbamide anions seems more probable. Either one of them should happen, since hydrogen bonded to nitrogen should behave no differently from as if it was in ammonia. If deprotonation does occur, then electron transfer and again cleavage seems the option. Carbamide/carbimide ions don't seem probable...
The reactions with quicklime and slaked lime are alkalisys, which urea easily undergoes in aqueouis solutions...

Friedrich Wöhler - 11-2-2004 at 11:00


It should be able (I read) to add *CO*-group from urea on carbonyl-building metals such as nickel. It should be possible in solution at low temp. If this info is correctly, there would be a childish simple method building hydrazine.

4 NH2-CO-NH2 + Ni ------> 4 N2H4 + Ni(CO)4

[Edited on 11-2-2004 by Friedrich Wöhler]

guaguanco - 11-2-2004 at 13:11

Originally posted by Friedrich Wöhler
It should be able (I read) to add *CO*-group from urea on carbonyl-building metals such as nickel.

I don't think so. Ni(CO)4 is produced by passing CO gas over powdered Ni, not from solutions of nickel ions. And urea is quite a polar molecule; the carbonyl portion isn't going to easily fly off as a carbon monoxide molecule.

Friedrich Wöhler - 11-2-2004 at 14:47

not from solutions of nickel ions

Where did you read this...?? I have this not written.

But...I had that could write. Because of its correctly!

Ni(CO)4 is produced by passing CO gas over powdered Ni, not from solutions of nickel ions


Generally there are different methods getting carbonyles in addition of that gas - metal-powder - reaction. For example:
~ CO under high pressure on Me-sulfides or Me-chlorides (Hieber-Method) (known carbonyles from minimal 12 metals.)
~ Cr(CO)6 Effect of CO at a etheric solution of CrCl3 under presence of Grignard-compounds
~ [Mn(CO)5]2 CO under pressure at activatet MnI2 in ether, catalysed by Mg
~ Ni(CO)5 already from shaking an alcalic suspension of fresh NiS2 with CO-gas

Get knowledge from chemistry books before contradict so strictly!

A good man erect only his cock - but never his finger... (Bin Laden's ugliest gesture) :P

guaguanco - 11-2-2004 at 15:25

You are correct, I did insufficient homework, you can use nickel ions. :( I still don't think you'll be able to use urea as a carbonyl source. :)

Polverone - 11-2-2004 at 15:52

See <A HREF="">this thread</A>. The use of nickel and urea for producing hydrazine has been patented, but the nickel is supposed to act catalytically, its carbonyl decomposing to again yield metallic nickel and CO.

guaguanco - 11-2-2004 at 17:27

Well, my humiliation is well and truly complete.:cool:
My wife still likes me, anyway...

Friedrich Wöhler - 12-2-2004 at 11:38


My wife still likes me, anyway...

I know why: she didn't read this forum. :D:D:D:D:D

Ok ok, don't make suicide, the life will continue! ;)

Axt - 1-10-2004 at 19:08

What is the correct term for salts of nitrourea? Ive been using "nitrocarbamate" but now im not entirely sure??

Theoretic - 2-10-2004 at 08:56

I'd just say "nitrourate".

Organikum - 24-5-2006 at 18:31

Thats a old one but hey!

Polyethlene is a nice reducing agent. isn´t it`?

Melts better into the brew then charcoal.


Jor - 3-2-2008 at 04:23

What real uses has urea , besides a good way of neutralizing NOx vapors?
I used UTFSE , but only came across organic synthesis and preparation of potassium/sodium cyanate (this one needs temperatures around 250C, wich is no options as I only have a spiritus burner (altho I will get a propane/butane one later on))
I do not have a fumehood.

Edit by Chemoleo: You didn't search well enough. Merged with urea exploration thread.

[Edited on 3-2-2008 by chemoleo]

solo - 3-2-2008 at 04:56

You might start your research here ..........

.....then move on with some of the references given to get a deeper view of the compound.

YT2095 - 3-2-2008 at 09:22

Originally posted by Jor
preparation of potassium/sodium cyanate (this one needs temperatures around 250C, wich is no options as I only have a spiritus burner

your Alcohol burner Should be quite capable of well over 3x this heat (250c). ;)

Velzee - 19-7-2016 at 15:08

Quote: Originally posted by Polverone  

I know it's rather silly of me to just start trying things when I could look them up, but I love the hands on parts of chemistry and I was disconnected from the net at the time.

I have the same situation going right now. I don't know what to do with all of this urea.