反应详情

A suspension of 341.5 g (l.75 mol) of 2-mercapto-5-pyrid-2-yl-1,3,4-thiadiazole in 4000 ml of dioxane is added to a solution of 230.5 g of 85% potassium hydroxide in 800 ml of water. Then 10 g of potassium iodide and 6 g of tributylammonium bromide are added to the reaction mixture and 750 g (~8.6 mol) of gaseous difluoromethane are introduced over 41/2 hours at 22°-37° C. After evaporating off the dioxane, the reaction mixture is diluted with ethyl acetate, the aqueous phase is separated and the organic solution is washed cold with 1N sodium hydroxide and water, dried over sodium sulfate and clarified with activated carbon. They ethyl acetate is removed under vacuum and the residue is crystallised from ethyl acetate/hexane, affording 321.9 g (75.1%) of the title compound with a melting point of 90°-92° C.

1. additionare introduced over 41/2 hours at 22°-37° C
2. customAfter evaporating off the dioxane
3. additionthe reaction mixture is diluted with ethyl acetate
4. customthe aqueous phase is separated
5. washthe organic solution is washed cold with 1N sodium hydroxide and water
6. dry with materialdried over sodium sulfate
7. customThey ethyl acetate is removed under vacuum
8. customthe residue is crystallised from ethyl acetate/hexane