Sciencemadness Discussion Board - Urea from Urea Oxalate?

Urea from Urea Oxalate?

Velzee - 22-1-2016 at 06:10

I planned to extract the urea found within a fertilizer I had lying around for a few years(MSDS: http://www.homedepot.com/catalog/pdfImages/ad/ad5195a6-ad3b-... ); since alcohol extraction would yield poor results, I chose to use Oxalic acid(as I have two pounds of this stuff) to precipitate out the urea in the form of urea oxalate. The next step of this procedure would be to add it to a sodium bicarbonate solution, leaving the urea in solution and precipitating some some sodium oxalate. My problem is, that sodium oxalate would still remain dissolved, and I currently only prepared ~15 grams or so of urea, so I want the best quality I can get using this method.

My question is, is there another way to isolate urea from this compound, or must I go with the NaHCO3 method?

Btw, here's a photo of some of the urea oxalate I synthesized:

Praxichys - 22-1-2016 at 07:04

You could try adding calcium carbonate to precipitate calcium oxalate, leaving a urea solution.

Velzee - 22-1-2016 at 07:26

Quote: Originally posted by Praxichys

You could try adding calcium carbonate to precipitate calcium oxalate, leaving a urea solution.

Hmm.. The only reasonable source of calcium carbonate I have is around 30 grams of coral I collected from the beach. Do you suggest any other method?

hissingnoise - 22-1-2016 at 12:14

Quote:

The only reasonable source of calcium carbonate I have is around 30 grams of coral I collected from the beach. Do you suggest any other method?

Just use slaked lime . . . ?

Hawkguy - 22-1-2016 at 18:47

Maybe something with Urea Nitrate? I read about that in a different thread somewhere...

macckone - 22-1-2016 at 21:21

Calcium chloride + urea oxalate -> calcium oxalate (precipitate) + urea hydrochloride
eliminating the hydrochloric acid will require a hydroxide that produces a chloride
with a much different solubilty from urea.

inkling3 - 22-1-2016 at 21:25

Quote: Originally posted by macckone

Calcium chloride + urea oxalate -> calcium oxalate (precipitate) + urea hydrochloride
eliminating the hydrochloric acid will require a hydroxide that produces a chloride
with a much different solubilty from urea.

Would calcium hydroxide not accomplish the same thing, and result in the pure Urea in water, and not the HCl salt?

Velzee - 27-1-2016 at 11:36

Sadly, I was only able to make ~4 grams of CaCO3. I've no other reasonable amounts of calcium. Another method is needed—any ideas?

@Hawkguy , could you perhaps link that thread to me? I did a quick search and I didn't really find anything of interest involving urea nitrate.

diggafromdover - 27-1-2016 at 13:42

CaCO3 is chalk, play sand from Home Despot, or lawn lime left in the air too long. If you start at Calais and swim north, you just may encounter some.

The Volatile Chemist - 28-1-2016 at 08:51

Here's a good a place as any to say that urea can be found in pet-safe driveway salt. Just figured this out. It's in grains, and is usually uncontaminated.

mayko - 30-1-2016 at 08:37

Magnesium oxalate is also fairly insoluble in water (1 part in 1500, says Merck.)

I just ran across this report, which says oxalate is decomposed by hydrogen peroxide to CO2. Urea also reacts to form urea peroxide, but you might be able to get this byproduct to regenerate urea through spontaneous or catalyzed decomposition of the peroxide adduct to water and oxygen.
http://web.ornl.gov/info/reports/1981/3445605762877.pdf

deltaH - 30-1-2016 at 10:44

I was reading the same report mayko lol

mayko - 31-1-2016 at 12:26

Quote: Originally posted by deltaH

I was reading the same report mayko lol

Heh, checking out the wiki?
http://www.sciencemadness.org/smwiki/index.php/Oxalic_acid

macckone - 1-2-2016 at 11:31

Quote: Originally posted by inkling3

Quote: Originally posted by macckone

Would calcium hydroxide not accomplish the same thing, and result in the pure Urea in water, and not the HCl salt?

calcium hydroxide is not soluble enough to do this easily.
it would work but it is slow and tedious.

Velzee - 1-2-2016 at 14:08

I attempted the H2O2 method, which did not seem to have any effect on the urea oxalate. I then attempted (with the same solution) the Na2CO3 method, which, overnight, yeilded some crystals (which I assume to be sodium oxalate). I do not know if I should boil down the solution or let it evaporate.

I am trying to convert the rest of the fertilizer to urea oxalate, and then attempt the MgCO3 method, but after what @macckone stated, I do not believe that this would work.

[Edited on 2/1/2016 by Velzee]