View source for Debus–Radziszewski imidazole synthesis

{{Reactionbox
| Name = Debus–Radziszewski imidazole synthesis
| Type = Ring forming reaction
| NamedAfter = [[Heinrich Debus (chemist)|Heinrich Debus]] <br/> {{ill|Bronisław Leonard Radziszewski|de}}
}}
The '''Debus–Radziszewski imidazole synthesis''' is a [[multi-component reaction]] used for the synthesis of [[imidazole]]s from a 1,2-[[dicarbonyl]], an [[aldehyde]], and [[ammonia]] or a [[primary amine]]. The method is used commercially to produce several imidazoles.<ref name=Ebel>Ebel, K., Koehler, H., Gamer, A. O., & Jäckh, R. "Imidazole and Derivatives." In Ullmann’s Encyclopedia of Industrial Chemistry; 2002 Wiley-VCH, {{doi|10.1002/14356007.a13_661}}</ref>  The process is an example of a [[multicomponent reaction]].

The reaction can be viewed as occurring in two stages.  In the first stage, the dicarbonyl and two ammonia molecules [[condensation reaction|condense]] with the two [[carbonyl group]]s to give a [[diimine]]:
:[[Image:Radziszewski-Synthese 2.svg|400px|Debus-Radziszewski imidazole synthesis part I]]

In the second stage, this diimine [[condensation reaction|condenses]] with the aldehyde:
:[[Image:Radziszewski-Synthese 1.svg|400px|Debus-Radziszewski imidazole synthesis part I]]

However, the actual reaction mechanism is not certain.<ref>{{cite journal |title= Microwave-Mediated Synthesis of Lophine: Developing a Mechanism To Explain a Product |first1= R. David |last1= Crouch |first2= Jessica L. |last2= Howard |first3= Jennifer L. |last3= Zile |first4= Kathryn H. |last4= Barker |journal= J. Chem. Educ. |year= 2006 |volume= 83 |issue= 11 |pages= 1658–1660 |doi= 10.1021/ed083p1658 }}</ref><ref name=Gelens>{{cite journal |title= Efficient library synthesis of imidazoles using a multicomponent reaction and microwave irradiation |first1= E. |last1= Gelens |first2= F. J. J. |last2= De Kanter |first3= R. F. |last3= Schmitz |first4= L. A. J. M. |last4= Sliedregt |first5= B. J. |last5= Van Steen |first6= Chris G. |last6= Kruse |first7= R. |last7= Leurs |first8= M. B. |last8= Groen |first9= R. V. A. |last9= Orru |journal= Molecular Diversity |volume= 10 |pages= 17–22 |year= 2006 |issue= 1 |doi= 10.1007/s11030-006-8695-3 |pmid= 16404525 }}</ref>

This reaction is named after [[Heinrich Debus (chemist)|Heinrich Debus]]<ref>{{cite journal | title = Ueber die Einwirkung des Ammoniaks auf Glyoxal | journal = [[Justus Liebigs Annalen der Chemie]] | doi = 10.1002/jlac.18581070209 | year = 1858 | last1 = Debus | first1 = Heinrich | volume = 107 | issue = 2 | pages = 199–208| url = https://zenodo.org/record/1427107 }}</ref> and {{ill|Bronisław Leonard Radziszewski|de}}.<ref>{{cite journal | title = Ueber Glyoxalin und seine Homologe | journal =  [[Berichte der deutschen chemischen Gesellschaft]] | doi = 10.1002/cber.188201502245 | year = 1882 | last1 = Radzisewski | first1 = Br. | volume = 15 | issue = 2 | pages = 2706–2708| url = https://zenodo.org/record/1425278 }}</ref><ref name=Damilano/>

A modification of this general method, where one equivalent of ammonia is replaced by an amine, affords ''N''-substituted imidazoles in good yields.<ref name=Gelens/>

:[[Image:Debus-Radziszewski_imidazole_synthesis.svg|500px|Arduengo imidazoles]]

This reaction has been applied to the synthesis of a range of 1,3-dialkylimidazolium [[ionic liquid]]s by using various readily available alkylamines.<ref name=Damilano>{{cite journal |title= One-pot synthesis of symmetric imidazolium ionic liquids ''N'',''N''-disubstituted with long alkyl chains |first1= Giacomo |last1= Damilano |first2= Demian |last2= Kalebić |first3= Koen |last3= Binnemans |first4= Wim |last4= Dehaen
|journal= RSC Adv. |year= 2020 |volume= 10 |issue= 36 |pages= 21071–21081 |doi= 10.1039/D0RA03358H |pmid= 35518762 |pmc= 9054310 }}</ref>

==References==
{{Reflist}}

{{DEFAULTSORT:Debus-Radziszewski imidazole synthesis}}
[[Category:Nitrogen heterocycle forming reactions]]
[[Category:Name reactions]]
[[Category:Multicomponent ring-condensations]]