Method for preparing bis(fluorosulfonyl)imide acid and salts thereof
View Patent ↗The invention relates to a method for preparing bis(fluorosulfonyl)imide acid, comprising: the reaction of sulphamic acid or one of the salts thereof with a halogenosulfuric acid and at least one fluorinating agent selected from SOF 2 , F—SO 2 —F and SF 4 , and the subsequent recovery of bis(fluorosulfonyl)imide acid. The invention also relates to a method for producing salts of bis(fluorosulfonyl)imide from the bis(fluorosulfonyl)imide acid thus produced.
1. A process for preparing bis(fluorosulfonyl)imide acid of formula F—SO 2 —NH—SO 2 —F, the process comprising the reaction of sulfamic acid or a salt thereof with at least one halosulfuric acid and at least one fluorinating agent selected from the group consisting of SOF 2 , F—SO 2 —F and SF 4 , then the recovery of the bis(fluorosulfonyl)imide acid.
2. The process for preparing bis(fluorosulfonyl)imide acid as claimed in claim 1 , wherein the halosulfuric acid has the formula X—SO 2 —OH wherein X is a halogen selected from the group consisting of fluorine, chlorine, bromine and iodine.
3. The process for preparing bis(fluorosulfonyl)imide acid as claimed in claim 1 , wherein said reaction is carried out in the presence of an organic solvent.
4. The process for preparing bis(fluorosulfonyl)imide acid as claimed in claim 1 , wherein the halosulfuric acid represents from 1 mol % to 5 molar equivalents expressed relative to the sulfamic acid or salts thereof and the fluorinating agent is F—SO 2 —F.
5. The process for preparing bis(fluorosulfonyl)imide acid as claimed in claim 4 , wherein the halosulfuric acid represents from 5 mol % to 1 molar equivalent expressed relative to the sulfamic acid or salts thereof.
6. The process for preparing bis(fluorosulfonyl)imide acid as claimed in claim 1 , wherein the halosulfuric acid represents from 1 to 5 molar equivalent(s) expressed relative to the sulfamic acid or salts thereof and the fluorinating agent is SOF 2 or SF 4 .
7. The process for preparing bis(fluorosulfonyl)imide acid as claimed in claim 1 , wherein said fluorinating agent represents from 1 to 10 molar equivalent(s) expressed relative to the sulfamic acid or salts thereof.
8. The process for preparing bis(fluorosulfonyl)imide acid as claimed in claim 1 , wherein said reaction is performed at a temperature between 0 and 180° C.
9. The process for preparing bis(fluorosulfonyl)imide acid as claimed in claim 1 , wherein said bis(fluorosulfonyl)imide acid is recovered by distillation, by sublimation or by extraction.
10. A process for preparing at least one bis(fluorosulfonyl)imide salt, the process comprising preparing the bis(fluorosulfonyl)imide acid according to the process as defined in claim 1 , followed by bringing said acid into contact with at least one salification agent.
11. The process for preparing at least one bis(fluorosulfonyl)imide salt as claimed in claim 10 , wherein the salification agent is a metal hydroxide, a metal halide, a metal hydride, a metal trifluoroacetate or a metal trifluoromethanesulfonate.
12. The process for preparing at least one bis(fluorosulfonyl)imide salt as claimed in claim 10 , wherein said salt has the general formula F—SO 2 —N-M-SO 2 —F, where M represents an alkali metal, an alkaline-earth metal, a transition metal or a metal selected from lanthanides.
13. The process for preparing at least one bis(fluorosulfonyl)imide salt as claimed in claim 10 , wherein said salt is lithium bis(fluorosulfonyl)imide.
14. The process for preparing at least one bis(fluorosulfonyl)imide salt as claimed in claim 10 , also comprising a step of purifying said salt.
15. The process for preparing at least one bis(fluorosulfonyl)imide salt as claimed in claim 14 , wherein the purification step consists of a recrystallization.