GB190614122A - An Improved Method in the Manufacture of Saccharin. - Google Patents

Abstract

14,122. Lynde, W. A. June 20. Saccharin.-In the production of saccharin from toluene without the intermediate production of p-toluene sulphochloride the methyl group is oxidized to the carboxyl group before the sulpho- or sulphamide group is introduced. For example, toluene is oxidized at a low temperature with a mixture of sulphuric and nitric acids, and the o- and p-nitrotoluenes are separated by fractional distillation or other known means. The o-nitrotoluene is then oxidized, preferably with potassium permanganate, to o-nitrobenzoic acid. This is then reduced to o-aminobenzoic acid, which is diazotized and treated with cuprous chloride, to convert it into o-chlorbenzoic acid, which is then treated with sodium sulphite with the formation of sodium o-sulphobenzoic acid. The sodium salt is transformed into the bichloride by means of phosphorus trichloride and chlorine. The bichloride is then treated with ammonium carbonate, and the saccharin precipitated by acid and filtered. In another example, the o-nitrotoluene is reduced to o-toluidine, which, by being diazotized and treated as described above, is converted into o-chlortoluene. This latter is then oxidized to o-chlorbenzoic acid, and the sulpho group is then introduced and further operations carried out as described in the first example.