Patent ID: 7501522

Claim:
A process for preparing purified 1,3-substituted imidazolium salts of the formula (I) where the radicals R 1 , R 2 , R 3 and R 4 are each, independently of one another, a carbon-comprising organic, saturated or unsaturated, acyclic or cyclic, aliphatic, aromatic or araliphatic radical which has from 1 to 30 carbon atoms and may comprise one or more heteroatoms and/or be substituted by one or more functional groups or halogens, where adjacent radicals R 1 and R 2 , R 2 and R 3 or R 3 and R 4 may also be joined to one another and the radicals R 2 and R 3 may each also be, independently of one another, hydrogen, halogen or a functional group; and A a− is the partly or fully deprotonated anion of an inorganic or organic protic acid H a A (III), where a is a positive integer and indicates the charge on the anion, which comprises reacting a 1,3-substituted imidazolium salt of the formula (II), where the radicals R 1 , R 2 , R 3 and R 4 are as defined above and the anion Y y− is the partly or fully deprotonated anion of an inorganic or organic protic acid H y Y (IV), where y is a positive integer and indicates the charge on the anion, with a strong base at from 20 to 250° C. while distilling off the 1,3-substituted imidazol-2-ylidene formed, wherein the 1,3-substituted imidazol-2-ylidene which has been distilled off is brought into contact in the gaseous state with the protic acid H a A (III) and/or the 1,3-substituted imidazol-2-ylidene which has been distilled off is passed in the gaseous or condensed state into a receiver comprising the protic acid H a A (III).