The zwitterion 1-butylimidazolium-3-(n-butanesulfonate)

The mol­ecule of the title compound, C11H20N2O3S, contains a positively charged imidazolium head group and a negatively charged sulfonate tethered together by a four-carbon chain. There is weak intermolecular hydrogen bonding within the structure between the sulfonate O atoms and the H atoms of the imidazolium ring. The sulfonate group causes a twisting of the butyl chain and a decrease in the dihedral angle between the second and third carbon chain compared to the unsubstituted butyl group.