[CH3:1][N:2]1[C:6]([C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=2)=[CH:5][C:4]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)=[N:3]1.[CH3:19]O.[S:21](=[O:25])(=[O:24])([OH:23])[OH:22]>ClCCCl>[CH3:19][O:24][S:21]([O-:23])(=[O:22])=[O:25].[CH3:1][N+:2]1[N:3]([CH3:19])[C:4]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)=[CH:5][C:6]=1[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=146.8 g (0.2 mol) of 1-methyl-3,5-diphenylpyrazole together with 40 g (1.25 mol) of methanol are introduced into the reaction vessel. After 19.4 g (0.19 mol) of 96% strength sulfuric acid have been added, the reaction solution is brought to 160° C. by distilling off methanol. 608 g (19 mol) of methanol are metered in below the surface of the reaction mixture in the course of 7.5 hours. After the mixture has been cooled to 70° C., 25 g of 1,2-dichloroethane are added, and the mixture is cooled to room temperature with stirring. The reaction mixture is filtered and washed with 12.5 g of 1,2-dichloroethane. 67.7 g of 1,2-dimethyl-3,5-diphenylpyrazolium methylsulfate with a content of 97.5% (HPLC) of m.p. 157°-159° C. are obtained, which corresponds to a yield of 91.7% of theory.
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