[F:1][C:2]1[N:6]([CH3:7])[N:5]=[C:4]([CH3:8])[C:3]=1[C:9]([NH:11][C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][C:13]=1[C:18]([OH:24])(C)[CH2:19]C(C)C)=[O:10].C(OC)(OC)OC.S([O-])([O-])(=O)=O.[Na+].[Na+]>C1(C)C=CC=CC=1.S(=O)(=O)(O)O>[C:18]([C:13]1[CH:14]=[CH:15][CH:16]=[CH:17][C:12]=1[NH:11][C:9]([C:3]1[C:4]([CH3:8])=[N:5][N:6]([CH3:7])[C:2]=1[F:1])=[O:10])(=[O:24])[CH3:19]14 g (80% pure, 33.6 mmol) of 5-fluoro-N-[2-(1-hydroxy-1,3-dimethylbutyl)phenyl]-1,3-dimethyl-1H-pyrazole-4-carboxamide and 4.28 g (40.3 mmol) of trimethyl orthoformate are dissolved in 420 ml of toluene, and 5 drops of concentrated sulphuric acid are added. The solution is boiled for 1 h, treated with sodium sulphate and filtered off, and the filtrate is concentrated under reduced pressure. The residue is treated with 300 ml of heptane. This results in the N-(2-acetylphenyl)-5-fluoro-1,3-dimethyl-1H-pyrazole-4-carboxamide still present in the starting material precipitating out. The filtrate is concentrated using a rotary evaporator, giving 10.7 g of a yellow oil. Examination by GC/MS shows the following composition: 24% A, 25% B, 29% C and 7% of a methanol adduct.
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