Steglich esterification
| Steglich esterification | |
|---|---|
| Named after | Wolfgang Steglich |
| Reaction type | Coupling reaction |
| Identifiers | |
| Organic Chemistry Portal | 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.[1] It is an adaptation of an older method for the formation of amides by means of DCC (dicyclohexylcarbodiimide) and 1-hydroxybenzotriazole (HOBT).[2][3]
Steglich overview
This reaction generally takes place at room temperature. A variety of polar aprotic solvents can be used.[4] 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
[edit | edit source]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
[edit | edit source]- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
Further reading
[edit | edit source]- Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).; Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value)..
- J. Otera: Esterification. 1. Auflage, Wiley-VCH, Weinheim, 2003, Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).