Aim and Objective:
In the present work, 1, 1’-sulfinyldiethylammonium bis (hydrogen
sulfate) as a novel room temperature dicationic ionic liquid was synthesized and used as a catalyst
for xanthenediones synthesis.
Material and Method:
The dicationic ionic liquid has been synthesized using ethylamine and thionyl
chloride as precursors. Then, by the reaction of [(EtNH2)2SO]Cl2 with H2SO4, [(EtNH2)2SO][HSO4]2
was prepared and after that, it was characterized by FT-IR, 1H NMR, 13C NMR as well as Hammett
acidity function. This dicationic ionic liquid was used as a catalyst for the synthesis of
xanthenediones via condensation of structurally diverse aldehydes and dimedone under solvent-free
conditions. The progress of the reaction was monitored by thin layer chromatography (ethyl
acetate/n-hexane = 3/7).
Results:
An efficient solvent-free method for the synthesis of xanthenediones has been developed in
the presence of [(EtNH2)2SO][HSO4]2 as a powerful catalyst with high to excellent yields, and short
reaction times. Additionally, recycling studies have demonstrated that the dicationic ionic liquid can
be readily recovered and reused at least four times without significant loss of its catalytic activity.
Conclusion:
This new dicationic ionic liquid can act as a highly efficient catalyst for xanthenediones
synthesis under solvent-free conditions.
The Hammett Acidity Function H0 of Trifluoromethanesulfonic Acid-Trifluoroacetic Acid and Related Acid Systems. A Versatile Nonaqueous Acid System.