反应详情

温度

100 °C

70 gm. of nicotinic acid-N-oxide was suspended in 300 ml of POCl3. Then 50 gm. of triethyl amine was added drop by drop at room temperature, whereby the nicotinic acid-N-oxide dissolved at about 50° C. (the temperature rise occured due to an exothermic reaction). Then the solution was heated in a water bath at 100° C. for another 4 hours. The main quantity of excess phosphorus oxychloride was distilled off under vacuum. The residue was allowed to flow into water at a temperature below 40° C. After addition of diluted caustic soda solution, the 2-chloronicotnic acid precipitated at a pH value of 2.0 to 2.5. The product had a melting point of 173° to 175° C. (Kofler). The product (2-chloronicotinic acid) yield amounted to 65 to 70 percent of theory.

1. customoccured due to an exothermic reaction)
2. distillationThe main quantity of excess phosphorus oxychloride was distilled off under vacuum
3. customto flow into water at a temperature below 40° C
4. additionAfter addition of diluted caustic soda solution
5. customthe 2-chloronicotnic acid precipitated at a pH value of 2.0 to 2.5