Nitrilium
Encyclopedia
A nitrilium ion is a nitrile
that has been protonated, [RCNH]+, or alkylated, [RCNR′]+.
s.
Nitrilium salts can be prepared by reacting nitriles with trialkyloxonium salts
. The nitrilium ions thus formed can then be reduced to secondary amines with sodium borohydride
in diglyme
. This is a convenient route to secondary amines of the form RCH2—NH—R′.
, the Friedel-Crafts cyclization of amines to isoquinolines, the Schmidt reaction
with ketones, and the Ugi
, Ritter
and Passerini
reactions.
Nitrile
A nitrile is any organic compound that has a -C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, one example being super glue .Inorganic compounds containing the -C≡N group are not called...
that has been protonated, [RCNH]+, or alkylated, [RCNR′]+.
Synthesis
Nitriles are only weakly basic and are poor nucleophiles, but they will attack very reactive electrophiles such as carbocationCarbocation
A carbocation is an ion with a positively-charged carbon atom. The charged carbon atom in a carbocation is a "sextet", i.e. it has only six electrons in its outer valence shell instead of the eight valence electrons that ensures maximum stability . Therefore carbocations are often reactive,...
s.
Nitrilium salts can be prepared by reacting nitriles with trialkyloxonium salts
Oxonium ion
The oxonium ion in chemistry is any oxygen cation with three bonds. The simplest oxonium ion is the hydronium ion H3O+. Another oxonium ion frequently encountered in organic chemistry is obtained by protonation or alkylation of a carbonyl group e.g...
. The nitrilium ions thus formed can then be reduced to secondary amines with sodium borohydride
Sodium borohydride
Sodium borohydride, also known as sodium tetrahydridoborate, is an inorganic compound with the formula NaBH4. This white solid, usually encountered as a powder, is a versatile reducing agent that finds wide application in chemistry, both in the laboratory and on a technical scale. Large amounts are...
in diglyme
Diglyme
Diglyme, or bis ether, is a solvent with a high boiling point. It is an organic compound which is the dimethyl ether of diethylene glycol. It is a clear, colorless liquid with a slight ether-like odor...
. This is a convenient route to secondary amines of the form RCH2—NH—R′.
As intermediates
Nitrilium ions are believed to be intermediates in the hydrolysis of nitriles, the Beckmann rearrangementBeckmann rearrangement
The Beckmann rearrangement, named after the German chemist Ernst Otto Beckmann , is an acid-catalyzed rearrangement of an oxime to an amide...
, the Friedel-Crafts cyclization of amines to isoquinolines, the Schmidt reaction
Schmidt reaction
The Schmidt reaction is an organic reaction involving alkyl migration over the carbon-nitrogen chemical bond in an azide with expulsion of nitrogen...
with ketones, and the Ugi
Ugi reaction
The Ugi reaction is a multi-component reaction in organic chemistry involving a ketone or aldehyde, an amine, an isocyanide and a carboxylic acid to form a bis-amide.The reaction is named after Ivar Karl Ugi, who first published this reaction in 1959....
, Ritter
Ritter reaction
The Ritter reaction is a chemical reaction that transforms a nitrile into a N-alkyl amide using various alkylating reagents, for example, strong acid and isobutylene....
and Passerini
Passerini reaction
The Passerini reaction is a chemical reaction involving an isocyanide, an aldehyde , and a carboxylic acid to form a α-acyloxy amide. This organic reaction was discovered by Mario Passerini in 1921 in Florence, Italy...
reactions.