Methanedisulfonic acid dipotassium salt is synthesised using 1,1-dibromomethane as a raw material by chemical reaction. The specific synthesis steps are as follows:
Raw Materials: CH
2Br
2: 140 g/0.8 mol K
2SO
3 (45% in water) 600 g/1.7 mol [(C
4H
9)4N]Br: 6 g KI: 0.8 g; A mixture of 600 g K
2SO
3-solution (45% in water), 6 g of [(C
4H
9)
4N]Br and 0.8 g KI in 400 ml of water, was heated to 70° C. Within a period of 16 hours, 140 g of CH
2Br
2 were transferred under the surface of the reaction mixture. During the addition of CH
2Br
2, the pressure in the reactor was determined with 1007-1008 mbar. Afterwards the reaction mixture was heated up to 90° C. After a total reaction time of 24 h, K
2[CH
2(SO
3)
2] started to precipitate. After 72 hours at 90° C., complete conversion of CH
2Br
2 to [CH
2(SO
3)
2]
2- has been achieved. The reaction mixture was cooled down to 20° C. The precipitated K
2[CH
2(SO
3)
2] was isolated by suction filtration and washed three times with 100 ml of water. The product was dried 6 hours at 80° C. under atmospheric pressure. Yield: 175 g (86.7%) Composition: Assay: 99.7% (Titration) Br
-: 111 ppm (Ion-chromatography) SO
32-:<50 ppm (Ion-chromatography) SO
42-: 54 ppm (Ion-chromatography); Purification by Recrystallization 175 g of K
2[CH
2(SO
3)
2] were suspended in 600 ml of water. The suspension was heated to about 100° C. At a pressure of about 40 mbar, 362 ml of water were evaporated out of the mixture. The remaining suspension was cooled down to 20° C. The precipitated K
2[CH
2(SO
3)
2] was isolated by suction filtration and dried 6 h at 80° C. under atmospheric pressure. Yield: 165.4 g (94.5%) Overall yield: 81.9% Composition: Assay: 99.8% (Titration) Br-: <10 ppm (potentiometric titration) SO
32-: <50 ppm (Ion-chromatography) SO
42-: <50 ppm (Ion-chromatography).
