Organocatalytic Imidazolium Ionic Liquids H/D Exchange Catalysts.
Simple 1,2,3-trialkylimidazolium cation associated with basic anions, such as hydrogen carbonate, prolinate, and imidazolate, is an active catalyst for the H/D exchange reaction of various substrates using CDCl3as D source, without the addition of any extra bases or metal. High deuterium incorporation (up to 49%) in acidic C-H bonds of ketone and alkyne substrates (pKafrom 18.7 to 28.8) was found at room temperature. The reaction proceeds through the fast and reversible deuteration of the 2-methyl H of the imidazolium cation followed by D transfer to the substrate. The IL acts as a neutral base catalyst in which the contact ion pair is maintained in the course of the reaction. The basic active site is due to the presence of a remote basic site in the anion namely, OH of bicarbonate, NH of prolinate, and activated water in the imidazolate anion. Detailed kinetic experiments demonstrate that the reaction is first order on the substrate and pseudozero order relative to the ionic liquid, due to the fast reversible reaction involving the deuteration of the ionic liquid by the solvent.
Institute of Chemistry - UFRGS Av. Bento Gonçalves , 9500 Porto Alegre, RS, Agronomia 91501-970, Brazil.
Marcileia
M
Zanatta
Institute of Chemistry - UFRGS Av. Bento Gonçalves , 9500 Porto Alegre, RS, Agronomia 91501-970, Brazil.
Francisco P
0000-0003-1530-9505
FP
Dos Santos
Institute of Chemistry - UFRGS Av. Bento Gonçalves , 9500 Porto Alegre, RS, Agronomia 91501-970, Brazil.
Cristina
C
Biehl
Institute of Chemistry - UFRGS Av. Bento Gonçalves , 9500 Porto Alegre, RS, Agronomia 91501-970, Brazil.
Graciane
G
Marin
Institute of Chemistry - UFRGS Av. Bento Gonçalves , 9500 Porto Alegre, RS, Agronomia 91501-970, Brazil.
Gunter
G
Ebeling
Institute of Chemistry - UFRGS Av. Bento Gonçalves , 9500 Porto Alegre, RS, Agronomia 91501-970, Brazil.
Paulo A
PA
Netz
Institute of Chemistry - UFRGS Av. Bento Gonçalves , 9500 Porto Alegre, RS, Agronomia 91501-970, Brazil.|School of Chemistry, University of Nottingham University Park , Nottingham NG72RD, United Kingdom.
Jairton
0000-0003-3237-0770
J
Dupont