Process for the production of light-colored lower alkane-sulfonic acids, more particularly methanesulfonic acid

Abstract

The description is of a process for the production of light-colored lower alkane sulfonic acids, especially methane sulphonic acid, by reacting the corresponding alkyl halide with alkaline halides and obtaining the free alkane sulphonic acid. In the process of the invention, the reaction is performed as a liquid/liquid reaction at temperature not exceeding 120 degrees C., and at such high pressures that even the lower alkyl halide is in the liquid phase at the reaction temperature, the aqueous reaction mixture is reduced by water content of some 50% wt. at the most, the alkaline sulphonic acid is liberated from its alkaline salt by the addition of HCl, the solid salt phase still remaining in the reaction mixture is separated out and the free alkaline sulphonic acid is obtained from the liquid phase. To obtain an alkane sulphonic acid which is virtually free of chloride ions, the primary reaction product concentrated into the aqueous salt sludge by the partial removal of water is preferably converted with a multi-molar excess of HCl is extracted from the isolated liquid phase and virtually chloride-free alkane sulphonic acid is obtained together with the residual water as the basic phase of distillation.

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