Structural analyses of N-acetylated 4-(dimethylamino)pyridine (DMAP) salts

Autor:	Christian Würtele, Heike Hausmann, Peter R. Schreiner, Michael Serafin, Jörg Glatthaar, Volker Lutz
Rok vydání:	2009
Předmět:	chemistry.chemical_classification Organic Chemistry Matrix isolation Salt (chemistry) General Chemistry Nuclear magnetic resonance spectroscopy Crystal structure Medicinal chemistry Catalysis chemistry.chemical_compound chemistry Nucleophile Organocatalysis Pyridine Organic chemistry Counterion
Zdroj:	Chemistry (Weinheim an der Bergstrasse, Germany). 15(34)
ISSN:	1521-3765
Popis:	We have studied the formation of several N-acetyl-4-(dimethylamino)pyridine (DMAP) salts (with Cl(-), CH(3)COO(-), and CF(3)COO(-) counterions), which are considered to be the catalytically active species in DMAP-catalyzed acetylation reactions of alcohols. Combined crystal structure analyses, variable temperature matrix IR and NMR spectroscopy as well as computational techniques at the UAHF-PCM-B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level were utilized to examine the structures and dynamics of salt formation. We found clear evidence for the formation of tight ion pairs that are stabilized by dynamic hydrogen-bonding interactions. In nonpolar solvents, the nucleophilicity of acetate in its N-acetyl-DMAP salt only allows a steady-state concentration smaller 1% at room temperature. Thus, we propose additional hydrogen-bonding interactions with alcohols to be the key stabilization factor in subsequent acetylations.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c95be54122ba7ef609314539804a6885 https://pubmed.ncbi.nlm.nih.gov/19637264 Zobrazit plný text záznamu Plný text