Synthesis of 1-Butyl-3-

Methylimidazolium Derivatives

Austin Letcher &

Mathew Amundson

Dr. Duane Weisshaar &

Dr. Gary Earl

Overview

• Background• Experimental

• Initial Synthesis Reaction▫ Analysis by HNMR, CNMR, HPLC

• Anion Exchange Reaction▫ Analysis by HNMR, CNMR, HPLC

• Conclusions• Future Work

• Acknowledgements• References

Background

Earl et al. developed green method for quaternizing alkylamines using dimethylcarbonate (DMC)1

Desire to expand scope to include aromatic amines

Target 1-butyl-3-methylimidazolium salts for a collaboration with Dr. Mary Berry’s (USD) citrate encased nanoparticles

1-methylimidazole forms multiple products with DMC2

Experimental

Initial Synthesis Reaction Conditions:

135℃, 20 hours, in a Parr pressure reactor, O2

purge by N2 sparge

Anion Exchange Reaction Conditions:

citric acid (monohydrate) refluxed in reaction mixture from the Parr under N2 for 2 hours

Initial Synthesis

1-butylimidazole

dimethyl carbonate (DMC)1-butyl-3-methylimidazolium methylcarbonate

2-carboxylate zwitterion

Initial Synthesis Analysis: 1HNMR

Initial Synthesis Analysis: 13CNMR

Initial Synthesis Analysis: HPLC

Anion Exchange:

+ CO2 + MeOH

+ H2O

Anion Exchange Analysis: 1HNMR

Anion Exchange Analysis: 13CNMR

Anion Exchange Analysis: HPLC

ConclusionsQuaternization reaction complete in 20 hrs with <1%

reactants

Mixture of desired imidazolium methylcarbonate quatand 2-carboxylate zwitterion

“Tris”-citrate anion exchange completed cleanly in < 2 hours

Citrate product is a honey colored, viscous liquid

The zwitterion, like the methylcarbonate, reacts with acids3

Citrate quat was desired by Dr Berry to have a pH~7

Citric acid (pKa1= 3.09, pKa2= 4.75, pKa3= 6.41)

NMR confirms bis product was isolated

Future Work

Acknowledgements

Augustana College

Brandon Gustafson

Marlys Vant Hul

NPURC

EPSCoR/BRIN

Research Colleagues

References

• 1 Earl, G. W.; Weisshaar, D. E.; Wineinger, D.; Moeckly, S.; Hanson, M.; Uilk, J.; Rekken, B.; Villa, E.; Zierke, J. P. Quaternary Methyl Carbonates: Novel Agents For Fabric Conditioning. Journal of Surfactants and Detergents 2004, 8(4), 325-29.

• 2 Holbrey, J. D.; Reichert, M. W.; Tkatchenko, I.; Bouajila, E.; Walter, O.; Tommasi, I.; Rogers, R. D. 1,3-Dimethylimidazolium-2-carboxylate: the unexpected synthesis of an ionic liquid precursor and carbine-CO2 adduct. Chem. Comm. 2003, 28-29.

• 3 Smiglak, S; Holbrey, J. D.; Griffin, S. T.; Reichert, W. M.; Swatloski, R. P.; Katritzky, A. R.; Yang, H.; Zhang, D.; Kirichenko, K.; Rogers, R. D. Ionic Liquids Via Reaction of the Zwitterionic 1,3-Dimethylimidazolium-2carboxylate With Protic Acids. Overcoming Synthetic Limitations and Establishing New Halide Free Protocols For the Formation of ILs. Green Chem. 2007, 9, 90-98.