反应详情

To 1-(2,4,6-trichloro-phenyl)-propan-2-one O-methyl-oxime prepared as described in example P3 (54.2 g; assay 98.4%; 0.20 mol) in acetic acid (115 g; 1.92 mol) was added sulphuric acid (22.5 g; assay 96%; 0.22 mol) at such a rate that the mixture could be kept at 20-23° C. Platinum on charcoal (5.9 g; Evonik F101 N/W 5%, water wet; assay 2.32% Pt) was added. The resulting mixture was transferred to an autoclave, which then was sealed and pressurized with hydrogen (0.8 MPa). The agitator of the autoclave was started and hydrogen pressure is maintained at 0.8 MPa. When no more hydrogen is consumed (usually after 5 hours), hydrogenation was interrupted by stopping agitation. Pressure was released and the atmosphere in the autoclave changed to nitrogen. The hydrogenation mixture was filtered in order to remove the heterogenous catalyst. To the filtrate was added water (220 g) and a pH-probe was mounted. Aqueous sodium hydroxide (304 g; assay 30%; 2.28 mol) was fed until pH is above 9. The resulting mixture was extracted with tert-butyl methyl ether (300 ml). Phases were allowed to separate. The (lower) aqueous phase was separated and discarded. The organic phase was washed with water (2×250 g) and evaporated to dryness. Crude O-Methyl-N-[1-methyl-2-(2,4,6-trichloro-phenyl)-ethyl]-hydroxylamine (53.0 g; assay 93.7%; yield 92.4%) was obtained as clear oil.

1. customcould be kept at 20-23° C
2. customthen was sealed
3. customWhen no more hydrogen is consumed (usually after 5 hours), hydrogenation
4. filtrationThe hydrogenation mixture was filtered in order
5. customto remove the heterogenous catalyst
6. additionTo the filtrate was added water (220 g)
7. extractionThe resulting mixture was extracted with tert-butyl methyl ether (300 ml)
8. customto separate
9. customThe (lower) aqueous phase was separated
10. washThe organic phase was washed with water (2×250 g)
11. customevaporated to dryness