Debus-Radziszewski imidazole synthesis
Encyclopedia
The Debus-Radziszewski imidazole synthesis is an organic reaction
describing the synthesis of an imidazole
from a diketone
, an aldehyde
and ammonia
. It is an example of a multicomponent reaction.
In step one the diketone and ammonia form an diimine
:
In the second step the diimine condenses
with the aldehyde:
This reaction is named after Heinrich Debus
and Bronisław Leonard Radziszewski
A modification of this general method, where one equivalent of ammonia is replaced by an amine, affords N-substituted imidazoles in good yields.
Organic reaction
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis,...
describing the synthesis of an imidazole
Imidazole
Imidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is a diazole and is classified as an alkaloid. Imidazole refers to the parent compound, whereas imidazoles are a class of heterocycles with similar ring structure, but varying substituents...
from a diketone
Diketone
A diketone is a molecule containing two ketone groups. The simpliest diketone is diacetyl, also known as 2,3-butanedione. Diacetyl, acetylacetone, and hexane-2,5-dione are examples of 1,2-, 1,3-, and 1,4-diketones, respectively...
, an aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
and ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
. It is an example of a multicomponent reaction.
In step one the diketone and ammonia form an diimine
Imine
An imine is a functional group or chemical compound containing a carbon–nitrogen double bond, with the nitrogen attached to a hydrogen atom or an organic group. If this group is not a hydrogen atom, then the compound is known as a Schiff base...
:
Condensation reaction
A condensation reaction is a chemical reaction in which two molecules or moieties combine to form one single molecule, together with the loss of a small molecule. When this small molecule is water, it is known as a dehydration reaction; other possible small molecules lost are hydrogen chloride,...
with the aldehyde:
Heinrich Debus (chemist)
Heinrich Debus was a German chemist.-Education and career:In 1938, he attended a trade school in Kassel, where he was taught by Robert Wilhelm Bunsen. He studied chemistry from 1845 to 1848 in Marburg, and served as Bunsen's assistant from 1847. In 1848, he earned his doctorate by investigating a...
and Bronisław Leonard Radziszewski
A modification of this general method, where one equivalent of ammonia is replaced by an amine, affords N-substituted imidazoles in good yields.