反应详情

321 g of 5-chloro-2-aminopyridine are added dropwise to 1.25 l of concentrated sulfuric acid. The reaction mixture is then stirred until the educt has completely dissolved. Then 172.5 g of sodium nitrite, dissolved in 240 ml of water, are added at a temperature of 40°-45° C. and the reaction mixture is stirred for 15 minutes. Subsequently 125 ml of 100% nitric acid are added dropwise at 50° C. over 40 minutes. The reaction mixture is kept for 1 hour at 55° C. and then poured onto 5 kg of ice-water. The product in the form of a yellow precipitate is isolated by filtration, washed copiously with water and subsequently dried at 60° C., giving 351 g of 5-chloro-2-hydroxy-3-nitropyridine (80.5% of theory) with a melting point of 229°-231° C.

1. dissolutionhas completely dissolved
2. additionare added at a temperature of 40°-45° C.
3. stirringthe reaction mixture is stirred for 15 minutes
4. customThe product in the form of a yellow precipitate is isolated by filtration
5. washwashed copiously with water
6. customsubsequently dried at 60° C.