Method for producing boron tetrafluoride salt, boron tetrafluoride salt obtained by the method, electrolytic solution for electric double layer capacitor using the same, and a process for producing the same

摘要

(A) Q⁺X^-With a salt compound (Q⁺Represents an onium ion or a metal ion, X^-Is BF₄^-(B) orthoboric acid, metaboric acid, tetraboric acid, boric oxide, and B (OR¹) (OR²) (OR³), A borate ester (R¹Is an alkyl group having 1 to 10 carbon atoms, R²And R³Represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R¹, R²And R³, Which may be the same or different, and (C) at least one boron compound selected from the group consisting of Q⁺BF₄^-, A boron tetrafluoride salt obtained by the method and an electrolytic solution for an electric double layer capacitor using the tetrafluoroborate salt and a process for producing the same. According to the present invention, a high purity tetrafluoroborate salt used for an electrolytic solution for an electric double layer capacitor is used as an expensive and highly toxic BF₃It can be industrially advantageously produced without using a gas. Especially, a tetrafluoroborate salt having good physical properties as a nonaqueous electrolytic solution for an electric double layer capacitor can be manufactured industrially extremely advantageously, so that a nonaqueous electrolytic solution for an electric double layer capacitor having high performance can be economically Can be obtained advantageously.