Urea is known to react with an acid to form salt. The carbonyl oxygen of urea is protonated in the process to form uronium ion. But, I have not seen conclusive reaction of urea with an alkali. So, if urea is dissolved in NaOH, what are the possible reactions? Can hydrogen be abstracted from one or both NH2 group? What reagent can afford this abstraction if any.
(NH2)2CO + HCl --> (NH2)2COH+ Cl-
(NH2)2CO + NaOH --> ?
(NH2)2CO + ? --> HNCONH2 ]-
(NH2)2CO + ? --> HNCONH ]2-