375  US 9,323,150 B2  376  carbon atoms. A connecting group, such as an oxygen atom or  a sulfur atom, may be introduced in the alkylene chain. In  particular, an alkylene group, 30 to 100% of the hydrogen  atoms of which are substituted with fluorine atoms, is pre› ferred.  It  is more preferred for the carbon atom bonded to the 5  Q-moiety to have a fluorine atom. Further, perfluoroalkylene  groups are preferred. A perfluoroethylene group, a perfluoro› propylene group and a perfluorobutylene group are more  preferred.  The monovalent organic group represented by Rx prefer- ably has 4 to 30 carbon atoms. As such, there can be men› tioned, for example, an alkyl group, a cycloalkyl group, an  aryl group, an aralkyl group, an alkenyl group or the like.  Each of these groups may further have a substituent.  A substituent may be introduced in the alkyl group repre- sented by Rx. The alkyl group is preferably a linear or  branched alkyl group having 1 to 20 carbon atoms.  An  oxygen  atom, a sulfur atom or a nitrogen atom may be introduced in  the alkyl chain.  The bivalent organic group represented by Ry is preferably  an alkylene group.  As the ring structure that may be formed by the mutual  bonding of Rx and Ry, there can be mentioned a 5 to 10-mem› bered, especially preferably 6-membered, ring containing a  nitrogen atom.  As the substituted alkyl group, in particular, there can be  mentioned a linear or branched alkyl group substituted with a  cycloalkyl group (for example, an adamantylmethyl group,  an adamantylethyl group, a cyclohexylethyl group, a cam› phor residue, or the like).  A substituent may be introduced in the cycloalkyl group  represented by Rx. The cycloalkyl group preferably has 3 to  20 carbon atoms.  An  oxygen atom may be introduced in the  ring.  A substituent may be introduced in the aryl group repre- sented by Rx. The aryl group preferably has 6 to 14 carbon  atoms.  A substituent may be introduced in the aralkyl group rep› resented by Rx. The aralkyl group preferably has 7 to 20  carbon atoms.  A substituent may be introduced in the alkenyl group rep› resented by Rx. For example, there can be mentioned groups  each resulting from the introduction of a double bond at an  arbitrary position of any of the alkyl groups mentioned above  as being represented by Rx.  The functional group with proton acceptor properties rep› resented by R is as mentioned above. There can be mentioned  groups with, for example, a nitrogen-atom-containinghetero› cyclic aromatic structure, such as an azacrown ether, a pri› mary to tertiary amine, pyridine or imidazole.  With respect to the organic group containing any of these  structures, the organic group preferably has 4 to 30 carbon  atoms. As such, there can be mentioned an alkyl group, a  cycloalkyl group, an aryl group, an aralkyl group, an alkenyl  group or the like.  The functional group with proton acceptor propertie or  alkyl group containing an ammonium group, cycloalkyl  group, aryl group, aralkyl group, and alkenyl group repre› sented by Rare the same as the alkyl group, cycloalkyl group,  aryl group, aralkyl group and alkenyl group set forth above as 60  being represented by Rx.  As substituents that may be introduced in these groups,  there can be mentioned, for example, a halogen atom, a  hydroxyl group, a nitro group, a cyano group, a carboxyl  group, a carbonyl group, a cycloalkyl group (preferably 3 to  10 carbon atoms), an aryl group (preferably 6 to 14 carbon  atoms), an alkoxy group (preferably 1 to 10 carbon atoms), an  acyl group (preferably 2 to 20 carbon atoms), an acyloxy  group (preferably 2 to 10 carbon atoms), an alkoxycarbonyl  group (preferably 2 to 20 carbon atoms), an aminoacyl group  (preferably 2 to 20 carbon atoms) and the like. Further, with  respect to the ring structure of the aryl group, cycloalkyl  group, etc. and the aminoacyl group, an alkyl group (prefer- ably 1 to 20 carbon atoms) can be mentioned as a substituent.  When Bis -N(Rx)Ry-, it is preferred for Rand Rx to be  bonded to each other to thereby form a ring. When a ring  structure is formed, the stability thereof is enhanced, and thus  the storage stability of the composition containing the same is  enhanced. The number of carbon atoms constituting the ring  is preferably in the range of 4 to 20. The ring may be mono› cyclic or polycyclic, and an oxygen atom, a sulfur atom or a  nitrogen atom may be introduced in the ring.  As the monocyclic structure, there can be mentioned a 4- to  8-membered ring containing a nitrogen atom, or the like. As  the polycyclic structure, there can be mentioned structures  each resulting from a combination of two, three or more  monocyclic structures. Substituents may be introduced in the  monocyclic structure and polycyclic structure. As preferred  substituents, there can be mentioned, for example, a halogen  atom, a hydroxyl group, a cyano group, a carboxyl group, a  carbonyl group, a cycloalkyl group (preferably 3 to 10 carbon  atoms), an aryl group (preferably 6 to 14 carbon atoms), an  alkoxy group (preferably 1 to 10 carbon atoms), an acyl group  (preferably 2 to 15 carbon atoms), an acyloxy group (prefer› ably 2 to 15 carbon atoms), an alkoxycarbonyl group (pref› erably 2 to 15 carbon atoms), an aminoacyl group (preferably  2 to 20 carbon atoms) and the like. Further, with respect to the  ring structure of the aryl group, cycloalkyl group, etc., an  alkyl group (preferably 1 to 15 carbon atoms) can be men› tioned as a substituent. Further, with respect to the aminoacyl  group, one or more alkyl groups (each preferably 1 to 15  carbon atoms) can be mentioned as substituents.  Rf of-X$_{1 }$NHX$_{2}$Rfrepresented by Q is preferably an alkyl  group having 1 to 6 carbon atoms in which a fluorine atom is  optionally contained, more preferably a perfluoroalkyl group  having 1 to 6 carbon atoms. Preferably, at least one ofX$_{1 }$and  X$_{2 }$ is -SO$_{2}$-. More preferably, both of X 1  and X$_{2 }$ are  -SO$_{2}$ -.  Among the compounds of general formula (PA-1), the  compounds wherein the Q-moiety is sulfonic acid can be  synthesized by using a common sulfonamidation reaction.  For example, these compounds can be synthesized by a  method in which one sulfonyl halide moiety of a bissulfonyl  halide compound is caused to selectively react with an amine  compound to thereby form a sulfonamido bond and thereafter  the other sulfonyl halide moiety is hydrolyzed, or altema- tively by a method in which a cyclic sulfonic anhydride is  caused to react with an amine compound to thereby effect a  ring opening.  It  is preferred for the compound (PA) to be an ionic com› pound. The functional group with proton acceptor properties  may be contained in whichever moiety, an anion moiety or a  cation moiety. Preferably, the functional group is contained in  an anion moiety.  The compound (PA) is preferably any of the compounds of  general formulae ( 4) to ( 6) below.  In general formulae (4) to (6),A, X, n, B, R, Rf, X$_{1 }$andX$_{2 }$ are as defined above in connection with general formula  (PA-1).  R.,---X$_{2}$-W-X$_{1}$-A-(X)n-B-R[C]+  (4)  R-S0$_{3}$-[C]’  (5)  (6) 