Method for Producing Fluoroalkanesulfonic Anhydride

摘要

Disclosed is a method for producing a fluoroalkanesulfonic anhydride, which is characterized by that a reaction is conducted while kneading a fluoroalkanesulfonic acid and diphosphorus pentoxide at a temperature that is 40° C. or higher and is lower than 100° C. by using a kneader-type reactor having a maximum power of 1.0 kW or greater per an actual capacity of 100 L and equipped with at least two-shaft blades, that the fluoroalkanesulfonic anhydride to be generated is discharged, and that, while the residue in the reactor after the discharge is kneaded at a temperature that is 100° C. or higher and is lower than 140° C., the unreacted fluoroalkylsulfonic acid is discharged, recovered and reused as the raw material. It is possible by this method to obtain a fluoroalkanesulfonic anhydride with a high yield.

主权项

1. A method for producing a fluoroalkanesulfonic anhydride represented by the following general formula (2) by introducing a fluoroalkanesulfonic acid represented by the following formula (1) and diphosphorus pentoxide into a kneader-type reactor having a maximum power of 1.0 kW or greater per an actual capacity of 100 L and equipped with at least two-shaft blades and by kneading them in the reactor by a power of 0.5 kW or greater per an actual capacity of 100 L, the method comprising:
a first step of introducing the fluoroalkanesulfonic acid and diphosphorus pentoxide into the reactor such that a molar ratio of a total amount of the fluoroalkanesulfonic acid introduced to a total amount of the diphosphorus pentoxide introduced becomes 2.0 or greater; a second step in which the fluoroalkanesulfonic acid is reacted with the diphosphorus pentoxide, while kneading the fluoroalkanesulfonic acid and the diphosphorus pentoxide, which have been introduced in the first step, at a temperature in the reactor that is 40° C. or higher and is lower than 100° C., to produce the fluoroalkanesulfonic anhydride as a main product and metaphosphoric acid as a by-product, and in which the fluoroalkanesulfonic anhydride as the main product is discharged from the reactor; and a third step of discharging the unreacted fluoroalkanesulfonic acid from the reactor, while further kneading a residue in the reactor, which is obtained by the second step, at a temperature in the reactor that is 100° C. or higher and is lower than 140° C., wherein the method is characterized by that the unreacted fluoroalkanesulfonic acid, which is discharged by the third step, is used as a total or part of the fluoroalkanesulfonic acid introduced in the first step
RfSO3H  (1)(RfSO2)2O  (2) wherein Rf represents a C1-4 straight-chain or C3-4 branched chain, saturated or unsaturated, fluoroalkyl group.