4-Dimethylaminopyridine
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| 4-Dimethylaminopyridine | |
|---|---|
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| IUPAC name | 4-Dimethylaminopyridine |
| Other names | DMAP, 4-(Dimethylamino)-pyridine, N,N-Dimethyl-4-aminopyridin |
| Identifiers | |
| CAS number | [] |
| SMILES | CN(C)C1=CC=NC=C1 |
| Properties | |
| Molecular formula | C7H10N2 |
| Molar mass | 122.17 g/mol |
| Melting point |
110-113 °C |
| Boiling point |
162 °C at 50 mmHg |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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- DMAP redirects here. For the cyanide antidote see 4-Dimethylaminophenol
4-Dimethylaminopyridine (DMAP) is a nucleophilic catalyst which catalyzes a variety of reactions. For example esterifications with anhydrides, Baylis-Hillman reaction, silylation, tritylation, Steglich-Rearrangement, Staudinger synthesis of ß-lactams and many more.[1][2]
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[edit] Esterification catalyst
In the case of esterification with acetic anhydride the currently accepted mechanism involves three steps. First, DMAP and acetic anhydride form in an equilibrium reaction a labile ion pair between the acetate and the acetylpyridium ion. In the second step the alcohol attacks the acetyl group to form the ester. In this step the acetate counterion pulls away the proton from the alcohol while the alcohol forms a covalent bond with the acetyl group. The bond from the acetyl group to the catalyst gets cleaved to generate the catalyst and the ester. The acetic acid formed will then protonate the DMAP. In the last step of the catalytic cycle the auxiliary base (usually triethylamine) deprotonates the protonated DMAP, reforming the catalyst.[3]
[edit] References
- ^ Catalysis by 4-dialkylaminopyridines Donald J Berry, Charles V Digiovanna, Stephanie S Metrick and Ramiah Murugan Arkivoc O-401R 2001 Online review
- ^ 4-Dialkylaminopyridines as Highly Active Acylation Catalysts Höfle, G., Steglich, W., Vorbrüggen, H. Angew. Chem. Int. Ed. Engl. 1978 , 17 , 569-583.
- ^ The DMAP-Catalyzed Acetylation of Alcohols - A Mechanistic Study (DMAP = 4-(dimethylamino)-pyridine) S. Xu, I. Held, B. Kempf, H. Mayr, W. Steglich, H. Zipse, Chem. Eur. J. 2005, 11, 4751 - 4757
[edit] Further reading
B. Neises, W. Steiglich, Organic Syntheses, Coll. Vol. 7, p.93 (1990); or Vol. 63, p.183 (1985).
