Urea manufacture

[stanfield]

Is there a way to produce not-too-bad quality urea ?

thanx...

[the freshmaker]

I can buy Carbamide from my chem-supply.
Is this Urea or what?

I don't know how to produce Urea but in "Chemistry of Powder & Explosives" there is alot of info on Urea Nitrate, Nitro Urea, etc.

[Lagen]

Urea = NH2C(=O)NH2 = Carbamide = Carbonyldiamide

http://www.tlchm.bris.ac.uk/~paulmay/misc/motm/urea/urea.gif

The cheapest source of urea I know is urea fertilizer, I'm getting it for about $0.50/kg. The purity is about 98%, if needed, it can be recrystallized from alcohol. Urea is produced commercially by several steps, which begin with the direct reaction of ammonia with carbon dioxide in a high pressure, high temperature reactor. This cannot be done at home.

Preparation of Urea from Urine: (and a shortcut route to urea nitrate)
Fresh urine, gently evaporated to the consistency of syrup, is treated with its own volume of 34% nitric acid. The mixture is then shaken and immersed in an ice bath to solidify the crystals of urea nitrate; these are washed with ice cold water, drained, and pressed between sheets of blotting paper or filter paper. The product from this operation is then dissolved in water to which potassium carbonate is added, whereby the nitric acid is taken up, and the urea set at liberty. This new solution is evaporated at a gentle heat, nearly to dryness, the residue is treated with pure alcohol, which only dissolves the urea, the alcohol+urea solution is then filtered and evaporated from which the urea crystallizes.

[This message has been edited by Lagen (edited August 11, 2001).]

[mongo blongo]

You can use Sodium carbonate instead of potassium carbonate right?

[Lagen]

It would work quite well IMHO, but some sodium nitrate will dissolve in the alcohol. (KNO3 is completely insoluble in it.) You can counter it with more careful recrystallization (you will get a lower yield). Similarly, if you can get and wish to sacrifice some barium carbonate, you will get better results than with potash (see below).

There are numerous alternative ways of urea or urea nitrate manufacture from urine. Maybe you will have to do some calculations first (I'm not using these procedures, but I'm sure they will come handy in a few years if our masters decide to ban everything), the following are not recipes, it's a *hint*:
Urea is usually obtained from urine by treating the concentrated filtered liquid with hot saturated solution of oxalic acid and decomposing the sparingly soluble urea oxalate thus obtained with powdered chalk; the filtrate is decolorized with animal charcoal and evaporated until the urea crystallises out on cooling. (Note by Lagen: For animal charcoal, use powder from the black tablets for treating digestive disorders, I don't know the correct English name, but I'm sure its charcoal from animal blood.) Another method consists in extracting the urea with alcohol from syrup obtained by evaporating the urine, precipitating the urea as the sparingly soluble nitrate by the addition on concentrated nitric acid, and decomposing the salt by boiling with barium carbonate and alcohol; the urea is obtained by crystallization from the filtrate. Another process for urea nitrate: 60% nitric acid is added to urine 1:2 in volume, and the resulting mixture is evaporated in a hood or outside and in glass container until it has been reduced to 40% of its original volume. The mixture is chilled and urea nitrate separates in nice crystals.
Note that fresh urine must be used, fermented urine contains loads of other stuff (like binary amines - smell extremely) so if you decide to scale up your urea production, don't start by digging a cavern under public restrooms! http://theforum.virtualave.net/ubb/smilies/biggrin.gif More seriously, avoid the "recipes" that go like "boil down pee to dryness and voila, you got urea!" Urine contains hundreds of substances, several of them in substantial concentrations (uric acid, hippuric acid, other amines, and mineral salts).

[mongo blongo]

Im gona try this (with more careful
recrystallization)I will be using it for treating red HNO3 for RDX so i will have to get as much of that Sodium Carbonate out as possible.
Urea Nitrate is something i haven't yet made though and will be interesting; would this be useful with HNO3?.
It don't really matter about the yield (i got me a lifetime supply of piss) http://theforum.virtualave.net/ubb/smilies/biggrin.gif
How much sodium carbonate should i add? Untill it stops bubbling right?
Could i use Methylated Spirits instead of alcohol?

[Lagen]

If you use urea to scavenge the noxious gases you should bubble a little air through the solution. It works much better. Urea Nitrate is a very easygoing stuff on all aspects. One of my favourites. It doesn't work for removing NOx, if that's what you mean. As to the sodium carbonate, I would suggest a stoichiometric amount (equivalent to the amount of nitric acid), or slightly less. You definitely cannot use methylated spirits (whatever it is, if it has a high percentage of methanol then urea will not dissolve much in it). I think you should make sure there is not much water in the (ethyl)alcohol. It might seem beneficial - to dissolve any Na2CO3 or urea nitrate left over. But the water on the other hand will dissolve a lot of NaNO3 which will coprecipitate during evaporation, so you will have to estimate the amount of impurities (which will be mostly NaNO3) from the first step and recrystallize a second time from warm water. That should yield you a very pure product.

[mongo blongo]

Thanx for the info dude! I think i will use a small excess of HNO3.
Is the alcohol denatured?

[Anthony]

Methylated spirits is ethanol denatured with methanol. IIRC it's 11% methanol.

[tom haggen]

Sodium carbonate is just as insoluble in CH3CH2OH as potassium carbonate.

[Zeitgeist]

Methylated spirit that we have over here, is typically 95% EtOH, and the remainder 5% being MeOH and denaturants

[newdle]

Zeitgeist "Methylated spirit that we have over here, is typically 95% EtOH, and the remainder 5% being MeOH and denaturants"

You are kidding, right?
I think you forget that we are in the land of the aboriginals, infamous for drinking 'methylated spirits'.
Due to being unable to control this factor, the recepie was changed, as the government did not want to be held responsible for death. Think about it. One bottle is plenty to send a person blind, yet i'm positive some people have drunk 100's of bottles in thier lifetime.

Instead, ethanol is azeotroped with methyl isobutyl ketone (hexone), which is not so immediately damaging like methanol is.

[Useless] On an interesting but sad note, in the Northern Territory in some outback pubs, methylated spirits is actually able to be bought 'pre-chilled'.

[FUTI]

well industry use ammonia and carbon-dioxide to make ammonium-carbamate (don't remember is it posible to make this in home lab, but if you find that this require high pressure forget it) which is then heated AFAIR to make urea...as for the other things mentioned here it can work but I don't know does it worth the effort. Happy experimenting:)

[Mumble]

There is a method in vogel to make it(p, 441). There is a slight problem though. It requires Sodium Cyanate. The most practical way to obtain this is heating NaOH and Urea.

2NaCNO + (NH4)2SO4 —> 2NH4CNO + Na2SO4
NH4CNO —> NH3 + HNC=O —> HN=C(OH)NH2 —> CO(NH2)2

It may not be the most practical proceedure to make urea, as urea is basically a precursor.

[FireFly]

I thought this might be of some help...
"Urea forms tetragonal prisms, which develop an odor of ammonia. Urea has a cooling saline taste. It has a melting point of 132.7 Celsius, and it decomposes above 133 Celsius into ammonia, biuret, and cyanuric acid. 1 gram dissolves in 1 milliliter of water. Urea is soluble in alcohol, and glycerol. It is also soluble in acids, forming salts. Urea is insoluble in ether, and chloroform. Water solutions of urea decompose on heating yielding ammonia and carbon dioxide. Urea is widely used in fertilizers, and is a readily available commercial chemical."

[10fingers]

Urea is a common fertilizer, it's available from most agricultural suppliers for around $8.00 for a 50 lb bag. It's called 60-0-0. It's very easy to purify by crystallizing from alcohol.

[Mendeleev]

I believe urea can be made from ammonium nitrate. I think it involves heating an intimate mixture of ammonium nitrate with an alkali carbonate in a crucible to high temperature. I may be mistaken though...