Process for the preparation of asymmetric imidazolium salts

摘要

The present invention relates to a process for preparing an asymmetric imidazolium salt of formula 1A, wherein R1 is an aromatic group and R2 is selected from a secondary cycloaliphatic alkyl group and a heteroalkyl group. , R3 and R4 are independently of each other selected from the group consisting of hydrogen, halide and alkyl groups, and A- is an anion. This process comprises a first step of forming a reaction mixture by contacting 1 equivalent of an aniline and 1 equivalent of a compound having an amino group in the presence of at least 4.5 equivalents of Bronsted acid; Forming a solution containing dicarbonyl, 1 equivalent of formaldehyde, and at least 4.5 equivalents of Bronsted acid of formula 4, and adding the reaction mixture formed in the first step; Including. Stirring at a predetermined temperature for a predetermined time, the intermediate asymmetric imidazolium salt 1A is isolated.