Salt and process for producing acid generator

A process for producing a salt represented by the formula (B1):

• wherein Q1 and Q2 each independently represent a fluorine atom or a C1-C6 perfluoroalkyl group, L1 represents a divalent C1-C17 saturated hydrocarbon group in which one or more —CH2— can be replaced by —O— or —CO—, L2 represents —O— or —HR3— in which R3 represents a hydrogen atom or a C1-C4 alkyl group, X1 represents a single bond or a C1-C6 alkanediyl group, Y represents a C1-C18 alkyl group which can have one or more substituents or a C3-C18 saturated cyclic hydrocarbon group which can have one or more substituents and one or more —CH2— in the alkyl group and the saturated cyclic hydrocarbon group can be replaced by —O—, —SO2— or —CO—, and Z′+ represents a monovalent organic cation, which comprises reacting a salt represented by the formula (I′):
• wherein Q1, Q2, L1 and Z′+ are the same as defined above, with a compound represented by the formula (IV):
• Y—X1-L2-H (IV)
• wherein L2, X1 and Y are the same as defined above.