反应详情

185 g (1 mole) of 2,5-difluoro-4,6-dichloropyrimidine were hydrogenated in 1,800 ml of ethyl acetate, with the addition of 110 g of triethylamine and 15 g of palladium-on-charcoal (5% strength by weight), at 30° C. under a hydrogen pressure of 3.5 bar in a stainless steel stirred autoclave for 95 minutes. The solid contents of the reaction mixture were then filtered off, the residue was washed with ethyl acetate and the filtrate was combined with the wash liquid and distilled under normal pressure over a 30 cm packed column. When the solvent had distilled off, 106 g of 2,5-difluoro-4-chloropyrimidine with a boiling point of 145° to 146° C. were obtained. The yield was accordingly 70.5% of theory. After analysis by gas chromatography, the isolated reaction product had a purity of 94.7%.

1. filtrationThe solid contents of the reaction mixture were then filtered off
2. washthe residue was washed with ethyl acetate
3. distillationdistilled under normal pressure over a 30 cm
4. distillationWhen the solvent had distilled off