Study Set Content:
A better method for preparing primary amines from alkyl halides is to use
azide ion
synthesis of amines from an aldehyde/ketone with ammonia in the presence of a reducing agent,
Reductive amination:
synthesis of amines from an aldehyde/ketone with ammonia in the presence of a reducing agent,
NaBH4 (sodium borohydride)
Ammonia, primary amines, and secondary amines can all be used in the reductive amination reaction, yielding
- primary, secondary, and tertiary amines, respectively.
- are prepared by nitration of an aromatic starting material, followed by reduction of the nitro group
Arylamines
an amide is treated with bromine and base (usually NaOH or KOH).
Hofmann rearrangement
Upon heating, an intermediate is formed
isocyanate
In the presence of water, the isocyanate loses carbon dioxide ("decarboxylates") to give an
Amine
acyl azide is heated
Curtius rearrangement
- the isocyanate can be isolated, but is usually transformed further into other species such a carbamate, a urea, or (via decarboxylation, as in the Hofmann) to an amine
Curtius
General reactions of amines are
- alkylation and acylation
- can be alkylated by reaction with alkyl halides
Primary, secondary, and tertiary amines
- can also be acylated by nucleophilic acyl substitution reactions with acid chlorides or acid anhydrides to give amides.
Primary and secondary (but not tertiary) amines
Primary amines react with aldehydes and ketones to give
Imines
amines is methylated by iodomethane (CH3I) to produce quaternary ammonium salt
Hofmann Elimination
- Amino group is strongly activating and ortho/para directing
Electrophilic Aromatic Substitution
Acetylation of aniline gives
acetanilide
Acetylation of aniline gives acetanilide (first step in the following equation), which undergoes nitration at low temperature, yielding the
para-nitro product in high yield
The modifying acetyl group can then be removed by acid-catalyzed hydrolysis (last step), to yield
para-nitroaniline.
Primary arylamines react with HNO2 to yield
- arene diazonium salts.
