US 9,063,416 B2  135  136  It is preferable that at least one of Rs" and R $^{611 }$represents an  aryl group which may have a substituent, and it is more  preferable that both of Rs" and R  611  represent an aryl group  which may have a substituent.  Specific examples of the cation moiety (I+(Rs")(R  6 "))  in  the formula (b-2) include diphenyliodonium and bis( 4-tert› butylphenyl)iodonium.  In formulas (b-1) and (b-2), R 4 "  represents an alkyl group,  a halogenated alkyl group, an aryl group or an alkenyl group  which may have a substituent.  The alkyl group for R 4 "  may be any oflinear, branched or  cyclic.  The linear or branched alkyl group for R 4 "  preferably has 1  to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and  most preferably 1 to 4 carbon atoms.  The cyclic alkyl group for R 4 "  preferably has 4 to 15 carbon  atoms, more preferably 4 to 10, and most preferably 6 to 10.  When R 4 "  represents an alkyl group, examples of  "R$^{4}$"SO$_{3 }$_,, includes alkylsulfonates such as methane- sulfonate, n-propanesulfonate, n-butanesulfonate, n-octane› sulfonate, 1-adamantanesulfonate, 2-norbomanesulfonate,  d-camphor-10-sulfonate.  The halogenated alkyl group for R 4 "  is a group in which  part of all of the hydrogen atoms in the alkyl group have been  substituted with a halogen atom. As the alkyl group, an alkyl  group of 1 to 5 carbon atoms is preferred. Among these, a  linear or branched alkyl group is preferred, and more prefer› ably a methyl group, an ethyl group, a propyl group, an  isopropyl group, an n-butyl group, a tert-butyl group, a tert- pentyl group or an isopentyl group. Examples of the halogen  atom which substitutes the hydrogen atoms include a fluorine  atom, a chlorine atom, an iodine atom and a bromine atom.  With respect to the halogenated alkyl group, 50 to 100% of  the hydrogen atoms in the alkyl group (alkyl group before  halogenation) are preferably substituted with the halogen  atoms, and all of the hydrogen atoms are more preferably  substituted with the halogen atoms.  As the halogenated alkyl group, a fluorinated alkyl group is  desirable. The fluorinated alkyl group preferably has 1 to 10  carbon atoms, more preferably 1 to 8 carbon atoms, and most  preferably 1 to 4 carbon atoms.  Further, the fluorination ratio of the fluorinated alkyl group  is preferably from 10 to 100%, more preferably from 50 to  100%, and it is most preferable that all hydrogen atoms are  substituted with fluorine atoms because the acid strength  mcreases.  Specific examples of the fluorinated alkyl group include a  trifluoromethyl group, a heptafluoro-n-propyl group and a  nonafluoro-n-butyl group.  As examples of the aryl group for R 4 ",  the same aryl groups  as those described above for R 1 " to R 3 ", Rs" and R 6 " can be  used. Among these, the substituent is preferably an aryl group  of 6 to 20 carbon atoms.  As examples of the alkenyl group for R 4 ",  the same aryl  groups as those described above for R 1 " to R 3 ", Rs" and R 6 "  can be used. Among these, an alkenyl group of2 to 10 carbon  atoms is preferable.  The alkyl group, halogenated alkyl group, aryl group or  alkenyl group for R 4 "  may have a substituent.  The expression "may have a substituent" means that part of  or all of the hydrogen atoms within the aforementioned linear,  branched or cyclic alkyl group, halogenated alkyl group, aryl  group or alkenyl group may be substituted with substituents  (atoms other than hydrogen atoms, or groups).  R 4 "  may have one substituent, or two or more substituents.  Examples of the substituent include a halogen atom, a  hetero atom, an alkyl group, and a group represented by the  As the aryl group, alkyl group or alkenyl group which may  have a substituent for Rs" and R 6 "  in the formula (b-2), the 65  same aryl group, alkyl group or alkenyl group which may  have a substituent as those described above for R 1 " to R 3 ".  In formula ( ca-1 ),  Rd  represents a substituent. Examples of  substituents include the same groups as those described above  for substituents which the phenyl group or naphthyl group for  R 9  may have. Specific examples thereof include an alkyl  group, an alkoxy group, a halogen atom, a halogenated alkyl  group, a hydroxy group, an oxo group (=0), a cyano group,  an aryl group, an alkoxyalkyloxy group, an alkoxycarbony› lalkyloxy group, ----C(=O)-O-R 6 ’, ---O-C(=O)-R 7 ’,  -O-R 8 ’, ---O-R 9 ’, a halogenated alkylsulfonyoxy group  and---O-Q$^{1}$-[O-R$^{11}$"-S+(R$^{21}$")(R $^{31}$")lx•  Each ofR 7 ", R 8 "  and R 9 "  independently represents a hydrogen atom or a  hydrocarbon group.  -continued  (ca-14-4)  (ca-14-5)  (ca-15-1)  (ca-15-2) 