A green procedure for the protection of carbonyls catalyzed by novel task-specific room-temperature ionic liquid

A cheap and recyclable task-specific ionic liquid N,N,N-trimethyl-N-propanesulfonic acid ammonium hydrogen sulfate [TMPSA]HSO4 was synthesized as dual solvent–catalyst for the protection of carbonyls via formation of acetals or ketals. The satisfactory results were obtained for the protection of carbonyls as cycloacetals or ketals with diols under the mild conditions. The products could be separated from the catalyst simply by decantation and the catalyst could be recycled and reused for several times without noticeably decreasing the catalytic activity after removal of the water.