A production method of a sulfonium salt compound represented by the following general formula (1):
wherein Ar represents an aromatic compound residue, X represents a halogen atom, which is a substituent on the aromatic compound residue, n represents an integer of from 1 to 7, a plurality of each of Ar, X and n may be the same or different, and Z represents a counteranion other than a halide ion,
the method comprising:
reacting an aryl halide compound with a compound represented by the following general formula (2) in the presence of a Lewis acid
wherein Y1 and Y2 each independently represent a halogen atom, an alkoxy group or an aryloxy group;
terminating the reaction by water in an after-treatment step of the reaction;
isolating a water layer from the reaction mixture that has been separated into two layers;
extraction-treating the water layer by an organic solvent to remove a by-product;
adding a compound represented by the following general formula (3) to the extraction-treated water layer to precipitate the sulfonium salt compound represented by the general formula (1)
M-Z General Formula (3)
wherein Z is as defined above, and M represents a proton or an alkali metal cation; and
isolating the precipitated sulfonium salt compound by solid-liquid separation.