Provided is a compound represented by formula (1): wherein X is an acid to form a salt with a guanidine site; and R1 and R2 are each independently any selected from the group consisting of a hydrogen atom, a C1-18 alkyl group, a cycloalkyl group, an aryl group, an alkylaryl group, and an alkenyl group, each of the groups optionally having one or more substituents each containing a sulfur atom, a nitrogen atom, or an oxygen atom.