Reactions

The dominant reactivity of amines is their nucleophilicity. Most primary amines are good ligands for metal ions to give coordination complexes. Amines are alkylated by alkyl halides. Acyl chlorides and acid anhydrides react with primary and secondary amines to form amides (the "Schotten-Baumann reaction").

Similarly, with sulfonyl chlorides, one obtains sulfonamides. This transformation, known as the Hinsberg reaction, is a chemical test for the presence of amines.

Because amines are basic, they neutralize acids to form the corresponding ammonium salts R₃NH⁺. When formed from carboxylic acids and primary and secondary amines, these salts thermally dehydrate to form the corresponding amides.

Amines react with nitrous acid to give diazonium salts. The alkyl diazonium salts spontaneously decompose by losing N₂ to produce a mixture of alkenes, alkanols or alkyl halides, with alkanols as the major product. This reaction is of little synthetic importance because the diazonium salt formed is too unstable.

Primary aromatic amines, such as aniline ("phenylamine") form more stable diazonium salts, which can be isolated in the crystalline form. These species undergo a variety of synthetically useful transformations. With cuprous cyanide the corresponding nitrile is formed. Arenediazonium ions undergo coupling with electron-rich aromatic compounds such as a phenol to form an azo compound. These species are widely used as dyes.

Imine formation is an important reaction. Primary amines react with ketones and aldehydes to form imines. In the case of formaldehyde (R' = H), these products typically exist as cyclic trimers.

RNH₂ + R'₂C=O → R'₂C=NR + H₂O

Reduction of the imines gives secondary amines:

R'₂C=NR + H₂ → R'₂CH-NHR

Similarly, secondary amines react with ketones and aldehydes to form enamines:

R₂NH + R'(R"CH₂)C=O → R"CH=C(NR₂)R' + H₂O

An amine reaction overview is given below:

Reaction name	Reaction product	Comment
Amine alkylation	amines	degree of substitution increases
Schotten-Baumann reaction	amides	Reagents: acyl chlorides, acid anhydrides
Hinsberg reaction	sulfonamides	Reagents: sulfonyl chlorides
Amine-carbonyl condensation	imines
Organic oxidation	nitroso compounds	Reagent: peroxymonosulfuric acid
Organic oxidation	diazonium salt	Reagent: nitrous acid
Zincke reaction	Zincke aldehyde	reagent pyridinium salts , with primary and secondary amines
Emde degradation	tertiary amine	reduction of quaternary ammonium cations
Hofmann-Martius rearrangement	aryl substituted anilines
Von Braun reaction	Organocyanamide	By cleavage (tertiary amines only) with cyanogen bromide