• Source: Steglich esterification

The Steglich esterification is a variation of an esterification with dicyclohexylcarbodiimide as a coupling reagent and 4-dimethylaminopyridine as a catalyst. The reaction was first described by Wolfgang Steglich in 1978. It is an adaptation of an older method for the formation of amides by means of DCC (dicyclohexylcarbodiimide) and 1-hydroxybenzotriazole (HOBT).

This reaction generally takes place at room temperature. A variety of polar aprotic solvents can be used. Because the reaction is mild, esters can be obtained that are inaccessible through other methods for instance esters of the sensitive 2,4-dihydroxybenzoic acid. A characteristic is the formal uptake of water generated in the reaction by DCC, forming the urea compound dicyclohexylurea (DCU).




Reaction mechanism


The reaction mechanism is described as follows:

With amines, the reaction proceeds without problems to the corresponding amides because amines are more nucleophilic. If the esterification is slow, a side-reaction occurs, diminishing the final yield or complicating purification of the product. This side-reaction is a 1,3-rearrangement of the O-acyl intermediate to an N-acylurea which is unable to further react with the alcohol. DMAP suppresses this side reaction, acting as an acyl transfer-reagent in the following manner:




References






Further reading


B. Neises and W. Steglich. "Esterification of Carboxylic Acids with Dicyclohexylcarbodiimide/4-Dimethylaminopyridine: tert-Butyl ethyl fumarate". Organic Syntheses; Collected Volumes, vol. 7, p. 93.
J. Otera: Esterification. 1. Auflage, Wiley-VCH, Weinheim, 2003, ISBN 3-527-30490-8




External links


Mechanism for the Steglich esterification

Kata Kunci Pencarian:

• Steglich esterification
• Fischer–Speier esterification
• Ester
• Shiina esterification
• List of organic reactions
• 4-Dimethylaminopyridine
• Wolfgang Steglich
• N,N'-Dicyclohexylcarbodiimide
• Propyl gallate
• 2-Methyl-6-nitrobenzoic anhydride