In this video it is mentioned that urea and sodium hydroxide will react to produce ammonia. However, I can't seem to find a clear explanation of the reaction and the other products generated.
One explanation I found says that the NaOH causes the urea to hydrolyze, yielding sodium carbamate, which will then further hydrolyze to sodium carbonate.
Another says that the urea tautomerizes to ammonium cyanate, which preforms a substitution with the NaOH to yield ammonium hydroxide and sodium cyanate.
Which of the two reactions occurs? Do they both occur? Neither?
Answer
Urea can be attacked by nucleophiles like any carbonyl. The immediate intermediate is a tetrahedral orthoacid which will break down to liberate ammonia once. The same process can be repeated a second time to liberate the second molecule of ammonia.
Technically, this is a hydrolysis catalysed by hydroxide. Hydroxide may be the reactive species but it is regenerated in the course of the reaction.
For urea to tautomerise to ammonium cyanate, a significant rearrangement and breaking a $\ce{C-N}$ bond would be required. Neither is likely in any way.
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