In chemistry, ammonolysis (/am·mo·nol·y·sis/) is the process of splitting ammonia into NH2- + H+.
Organic compounds such as alkyl halides, hydroxyls (hydroxyl nitriles and carbohydrates), carbonyl (aldehydes/ketones/esters/alcohols), and sulfur (sulfonyl derivatives) can all undergo ammonolysis in liquid ammonia.
Organic synthesis
Mechanism: Ammonolysis of Esters
This mechanism
is similar to the hydrolysis of esters, the ammonia attacks the electrophilic carbonyl carbon forming a tetrahedral intermediate. The reformation of the C-O double bond ejects the ester. The alkoxide deprotonates the ammonia forming an alcohol and amide as products.
Of haloalkanes
On heating a
haloalkane and concentrated ammonia in a sealed tube with ethanol, a series of amines are formed along with their salts.
The tertiary amine is usually the major product.
- NH3 ->\ce{RX} RNH2 ->\ce{RX} R2NH ->\ce{RX} R3N ->\ce{RX} R4N+
This is known as Hoffmann's ammonolysis.
Of alcohols
Alcohols can also undergo ammonolysis when in the presence of ammonia. An example is the conversion of
phenol to
aniline, catalyzed by
stannic chloride.
- ROH + NH3 A ->\ce{SnCl4} RNH2 + H2O
Of carbonyl compounds
The reaction between a
ketone and ammonia results in an
imine and byproduct water. This reaction is water sensitive and thus
Desiccant such as aluminum chloride or a Dean–Stark apparatus must be employed to remove water. The resulting imine will react and decompose back into the ketone and the ammonia when in the presence of water. This is due to the fact that this reaction is reversible:
- R2CO + NH3 <=> R2CNH + H2O .
Inorganic synthesis
Ammonolysis can be used to synthesize
nitrides (and
) by reacting various metal precursors with ammonia, some options include chemical vapor deposition,
treating metals or metal oxides with ammonia gas,
or liquid supercritical ammonia (also known as "ammonothermal" synthesis, analogous to hydrothermal synthesis).
- M + NH3 -> MN + 3/2 H2
- MO2 + 4/3 NH3 -> MN + 2 H2O + 1/6 N2
The products of these reactions may be complex, with mixtures of oxygen, nitrogen, and hydrogen that can be difficult to characterize.
