The Kolbe nitrile synthesis is a method for the preparation of alkyl
nitrile
In organic chemistry, a nitrile is any organic compound that has a functional group. The name of the compound is composed of a base, which includes the carbon of the , suffixed with "nitrile", so for example is called " propionitrile" (or pr ...
s by reaction of the corresponding
alkyl halide
The haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents of hydrogen atom. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalka ...
with a metal
cyanide
In chemistry, cyanide () is an inorganic chemical compound that contains a functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.
Ionic cyanides contain the cyanide anion . This a ...
. A side product for this reaction is the formation of an
isonitrile because the cyanide ion is an
ambident nucleophile. The reaction is named after
Hermann Kolbe
Adolph Wilhelm Hermann Kolbe (27 September 1818 – 25 November 1884) was a German chemist and academic, and a major contributor to the birth of modern organic chemistry. He was a professor at Marburg and Leipzig. Kolbe was the first to apply t ...
.
:
\underset + \underset -> \underset + \underset
The ratio of product
isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...
s depends on the
solvent
A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...
and the
reaction mechanism
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical reaction occurs.
A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage ...
, and can be predicted by
Kornblum's rule. With the Using alkali cyanides such as
sodium cyanide
Sodium cyanide is a compound with the formula Na C N and the structure . It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also expl ...
and polar solvents, the reaction occurs by an
SN2 mechanism via the more-nucleophilic carbon atom of the cyanide ion.
This type of reaction together with
dimethyl sulfoxide
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula . This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and is ...
as a solvent is a convenient method for the synthesis of nitriles.
The use of DMSO was a major advancement in the development of this reaction, as it works for more
sterically hindered electrophilies (secondary and neopentyl halides) without rearrangement side-reactions.
See also
*
Rosenmund–von Braun reaction, a similar reaction for the synthesis of aromatic nitriles
*, a similar reaction with enones
References
{{DEFAULTSORT:Kolbe Nitrile Synthesis
Substitution reactions
Name reactions