Central Glass Company, Limited

Tamio Nakamura

Yoshiyuki Kobayashi

Minoru Aramaki

Hiroaki Sakaguchi

Yasushi Kita

Hisaji Nakano

Takashi Suenaga

Masahiro Tainaka

Kenji Fujii

Takashi Yokoyama

Seigo Okamura

Kimitaka Okamoto

Shoji Okabayashi

The present invention relates to a method for producing a fluoroalkylsulfonic acid anhydride represented by a general formula of (C.sub.n F.sub.2n+1 SO.sub.2).sub.2 O where n is an integer ranging from 1 to 8. This method includes a step of (a) reacting diphosphorus pentoxide with a fluoroalkylsulfonic acid represented by a general formula of C.sub.n F.sub.2n+1 SO.sub.3 H where n is an integer ranging from 1 to 8, in a fluorine-containing solvent, thereby to form the fluoroalkylsulfonic acid anhydride in the fluorine-containing solvent. A fluoroalkylsulfonic acid anhydride produced by this method is high in purity and yield.

Method for producing high-purity fluoroalkylsulfonic acid anhydride

A process for producing methanesulfonyl fluoride involves reacting methanesulfonyl chloride, a metal fluoride and water to obtain a reaction product, subjecting the reaction product to distillation in the presence of water in an amount of 0.7 times or more the amount of the methanesulfonyl chloride to obtain a distillate. The distillate has a water layer and a methanesulfonyl fluoride layer. The distillate is subjected to phase separation to separate the methanesulfonyl fluoride layer from the water layer, and the methanesulfonyl fluoride is recovered.

Process for the production of high purity methanesulphonyl fluoride at

A process for refining a crude fluoroalkylsulfonic acid represented by the general formula RfSO.sub.3 H wherein Rf is a fluoroalkyl group having 1 to 4 carbon atoms into a highly refined one substantially free of impurities, said process comprising the steps of: (a) providing said crude fluoroalkylsulfonic acid, (b) mixing said crude fluoroalkylsulfonic acid with water or said water and an active silica to obtain a mixture, (c) stirring said mixture while maintaining said mixture at a higher temperature than room temperature, and (d) subjecting the mixture treated in said step (c) to distillation.

Process for refining crude fluoroalkylsulfonic acid with the use of water

A fluorocarbon carboxylic acid Rf(COOH).sub.m (Rf is C.sub.1 -C.sub.10 perfluoroalkyl group, m is 1 or 2) is prepared by the steps of hydrolyzing Rf(COF).sub.m with water to obtain an acidic solution, neutralizing the acidic solution with aqueous solution of KOH to form Rf(COOK).sub.m, precipitating and separating Rf(COOK).sub.m from the solution and converting Rf(COOK).sub.m into Rf(COOH).sub.m by acid decomposition. The content of free fluorine can extremely be reduced by treating Rf(COOK).sub.m with sulfuric acid and silica. The mother liquor is recycled after removing KF by treatment with a metal hydroxide and replenishing with KOH. In preparing a fluorocarbon sulfonic acid RfSO.sub.3 H (Rf is C.sub.1 -C.sub.3 perfluoroalkyl group) in substantially the same way, RfSO.sub.3 K is formed in aqueous solution of KOH by bringing gaseous RfSO.sub.2 F into contact with the KOH solution under normal pressure, while controlling the feed rate of RfSO.sub.2 F per unit area of gas-liquid contact at a sufficiently low level.

Process of preparing fluorocarbon carboxylic or sulfonic acid from its

In preparing a fluoroalkylsulfonate RfSO.sub.3 M, where Rf is a perfluoroalkyl gruop having not more than 6 carbon atoms and M is an alkali metal, by neutralization reaction between a fluoroalkylsulfonic acid RfSO.sub.3 H and an alkali metal carbonate or hydroxide, the reaction is carried out under acidic conditions such that at the end of the reaction pH of the reaction liquid is lower than 6, and preferably not higher than 3. By so maintaining the reaction liquid acidic, the obtained RfSO.sub.3 M becomes very low in the concentrations of anionic impurities such as free fluorine, free chlorine and carbonate radical and, besides becomes low in moisture absorbency.

Method of preparing alkali metal fluoroalkylsulfonates of high purity

NF.sub.3 is prepared with good yields by reaction between fluorine gas and an ammonium complex of a metal fluoride, such as (NH.sub.4).sub.3 AlF.sub.6, in solid phase. The metal flouride ammonium complex may be one additionally containing an alkali metal, such as (NH.sub.4).sub.2 NaAlF.sub.6. The gas-solid reaction is carried out preferably at temperatures above 80.degree. C. and at relatively low partial pressures of fluorine in the gas phase of the reaction system, so that the reaction is easy to control.

Process of preparing nitrogen trifluoride by gas-solid reaction

A process of precipitating cryolite from a reaction solution given by mixing a sodium aluminate solution with a fluoride solution containing silica dissolved therein as impurity at reaction temperatures above 60.degree. C. To reduce silica content in the precipitated cryolite, the reaction solution is made to contain carbonate ions, 1-20 g/l as CO.sub.2, by introducing either carbon dioxide gas or a soluble carbonate into the fluoride solution Moreover, ignition loss of the cryolite can be decreased by preheating the sodium aluminate solution to 90.degree. C. or above.

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Ube, Japan

Tamio Nakamura