Patent ID: 7396960

Claim:
A sulfonium salt represented by formula (1): wherein R 1 represents a linear or branched C2 to C9 divalent hydrocarbon group; each of R 2 to R 5 represents a hydrogen atom or a linear or branched C1 to C3 hydrocarbon group; each of R 6 and R 7 represents a phenyl group or a phenyl group which has a substituent having a C1 to C30 alkyl group, or R 6 and R 7 together with S atom to which they are attached form a heterocyclic ring with a saturated carbon of C3 to C9 alkyl groups; and X − is an anion which is represented by formula (2), or represented by formula (3) which is a bis(perfluoroalkylsulfon)imide ion, or Cl − , Br − , I − , BF 4 − , AsF 6 − , SbF 6 − , or PF 6 − , C k H m F n SO 3 − (2) wherein each of k, m, and n is an integer of ≧0; when m is 0, k is an integer of 1 to 8, n is 2k+1, and formula (2) represents a perfluoroalkylsulfonate ion; when n is 0, k is an integer of 1 to 15, m is an integer of ≧1, and formula (2) represents an alkylsulfonate ion, a benzenesulfonate ion, or an alkylbenzenesulfonate ion; and when each of m and n is an integer of ≧1, k is an integer of 1 to 10, and formula (2) represents a fluorinated benzenesulfonate ion, a fluorinated alkylbenzenesulfonate ion, or a fluorinated alkylsulfonate ion, (C p F 2p+1 SO 2 ) 2 N − (3) wherein p represents an integer of 1 to 8.