Química Orgánica 2 · Hidrólisis y esterificación
Acid hydrolysis of urea to ammonium and CO2
Condiciones: H3O⁺, H2O, Δ
Dibuja este problema tú mismo
Arrastra desde los electrones que se mueven hasta donde van, o toca uno y luego el otro. Cada flecha se revisa; Pista te ayuda cuando te atascas. No necesitas cuenta.
El mecanismo, paso a paso
Siguiente reproduce las flechas curvas de cada paso y las explica. Los pasos escritos están abajo.
Leer los 11 pasos escritos
Protonate the urea oxygen
Hydronium protonates the carbonyl oxygen of urea. Two nitrogen lone pairs stabilise the cation, which is why urea is so unreactive and needs heat.
Las flechas curvas
- The carbonyl oxygen lone pair takes the proton.
- The O–H bond pair stays on the water oxygen.
Water adds
Water attacks the activated carbon, giving a tetrahedral oxonium ion.
Las flechas curvas
- A water lone pair forms the new C–O bond.
- The C=O π electrons move onto the protonated oxygen.
Water removes the extra proton
A water molecule takes the proton from the oxonium oxygen.
Las flechas curvas
- A lone pair on the base takes the proton.
- The O–H bond pair stays on the atom that loses the proton.
Protonate a nitrogen
Hydronium protonates one nitrogen; in the tetrahedral intermediate it is an ordinary basic amine nitrogen.
Las flechas curvas
- The nitrogen lone pair takes the proton.
- The O–H bond pair stays on the atom that loses the proton.
Ammonia leaves
An OH lone pair re-forms the C=O and neutral ammonia departs, giving protonated carbamic acid.
Las flechas curvas
- An oxygen lone pair forms the C=O π bond.
- The C–N bond breaks onto nitrogen.
Ammonia is protonated
Ammonia takes the proton from the protonated carbamic acid, giving ammonium.
Las flechas curvas
- The ammonia lone pair takes the proton.
- The O–H bond pair stays on the atom that loses the proton.
What happens to carbamic acid?
Carbamic acid is not a stable compound.
Protonate the carbamic acid nitrogen
Fresh hydronium protonates the nitrogen of carbamic acid, turning it into a neutral ammonia leaving group.
Las flechas curvas
- The nitrogen lone pair takes the proton.
- The O–H bond pair stays on the atom that loses the proton.
Decarboxylation
Water removes the O–H proton; those electrons form a second C=O as the C–N bond breaks, releasing CO2 and ammonia.
Las flechas curvas
- A water lone pair takes the O–H proton.
- The O–H bond pair forms the new C=O π bond.
- The C–N bond breaks onto nitrogen.
The second ammonia is protonated
Ammonia takes a proton from hydronium; in acid both nitrogens end as ammonium.
Las flechas curvas
- The ammonia lone pair takes the proton.
- The O–H bond pair stays on the atom that loses the proton.
Ammonium and CO2
Two ammonium ions and carbon dioxide form from one urea and one water (two hydronium ions consumed).
Qué vas a practicar
Draw acid hydrolysis of urea: O-protonation, water addition, proton relay to nitrogen, loss of ammonia, then N-protonation and decarboxylation of carbamic acid.
Acabas de dibujar cada flecha de este problema.
Cada uno de los 5349 problemas de Orgánica 1 y 2 funciona así: comentarios en cada flecha, pistas cuando te atascas y un modo examen sin pistas. Gratis con una cuenta, sin tarjeta.
¿Atascado con tu propia tarea?
Tómale una foto: el primer escaneo es gratis, sin registrarte
¿Escaneas cada semana? Scan Standard: por unos problemas