Sciencemadness Discussion Board

Urea hydrolisis

plante1999 - 30-8-2012 at 14:52

Urea can be considered as ammonium cyanate from Friedrich Wöhler work. It is know that cyanic acid hydrolise to CO2 and ammonia. Some enzyme are able to operate complete hydrolisis of urea to CO2 and ammonia in sligthly basic medium, for a chemist complete hydrolysis can be made using strong base like NaOH.

If urea is hydrolised with H2SO4, fallowing the logic that I would explain, it could possibly make CO2 and ammonium (bi)sulphate.

The logic:

NH4OCN + H2SO4 -) HOCN + NH4HSO4
HOCN + H2O -) NH3 + CO2
NH3 + H2SO4 -) NH4HSO4

My question:
Is this sound plausible, does it worth experimentation?

Thanks!

[Edited on 30-8-2012 by plante1999]

woelen - 30-8-2012 at 22:01

Cyanates indeed react quickly in the way as you suggest, but the step from urea to cyanate is a slow one. A normal solution of urea in water only hydrolyses very slowly and I do not think that this is a suitable way of making ammonium sulfate at all.

In the soil, urea is hydrolysed slowly as well, possibly with the help of some biological catalysts. In the soil this is advantageous, because it allows slow release of nitrogen in a form, suitable for plants.

You might try to heat urea and then add acid. Another option could be addition of urea to strong acid and heat that solution. I'm not sure though, just give it a try. Other people with more knowledge of organic chemistry may jump in and give more conclusive answers on the feasibility of making ammonium sulfate by heating a urea/H2SO4 mix.

Rogeryermaw - 31-8-2012 at 01:03

we all know that wiki is not the best source for chemistry related information but it shows that both ammonium sulfate and ammonium bisulfate are products of reaction of ammonia treated with sulfuric acid. i wonder if ammonia being in aqueous solution is the difference.

http://en.wikipedia.org/wiki/Ammonium_sulfate#Preparation
and
http://en.wikipedia.org/wiki/Ammonium_bisulfate

it also goes on to say you can decompose ammonium sulfate to ammonium bisulfate through heating.
Quote:
Ammonium sulfate decomposes upon heating above 250 °C, first forming ammonium bisulfate. Heating at higher temperatures results in decomposition into ammonia, nitrogen, sulfur dioxide, and water.