反应详情

温度

60 °C

A solution of potassium hydroxide (90% titre; 30.3 g; 0.48 mols) in water (225 mL) and ethanol (65 mL) is added with ethyl 2-(4-methylphenyl)-6-methylimidazo[1,2-a]-pyridine-3-glyoxalate (141.5 g; 0.44 mols). The suspension is refluxed to obtain a yellow-orange solution, which is concentrated to reach a temperature of 98-100° C. and added with hydrazine (51.7% titre, 27.5 g; 0.44 mols). The solution is refluxed for 14 hours, then cooled to about 60° C., added with potassium hydroxide (90% titre, 54.9 g; 0.88 mols), then distilled under atmospheric pressure to reach the inner temperature of 122÷124° C., keeping the resulting suspension under reflux until nitrogen evolution ceases. The mixture is cooled to about 100° C., diluted with water (500 mL), cooled at room temperature and filtered through Celite. The resulting clear solution is dropped in about one hour into an acetic acid solution (91 g; 1.52 mols) in methanol (500 mL). The resulting suspension is cooled to 0÷5° C., filtered and the solid is washed with water, then dried at 60° C. under vacuum to obtain 2-(4-methylphenyl)-6-methylimidazo[1,2-a]-pyridine-3-acetic acid (118.4 g, 98.5% titre, K.F. 1.4%, yield 96.5%).

1. temperatureThe suspension is refluxed
2. customto obtain a yellow-orange solution, which
3. concentrationis concentrated
4. customa temperature of 98-100° C.
5. temperatureThe solution is refluxed for 14 hours
6. distillationdistilled under atmospheric pressure
7. customthe inner temperature of 122÷124° C.
8. temperatureunder reflux until nitrogen evolution ceases
9. temperatureThe mixture is cooled to about 100° C.
10. additiondiluted with water (500 mL)
11. temperaturecooled at room temperature
12. filtrationfiltered through Celite
13. temperatureThe resulting suspension is cooled to 0÷5° C.
14. filtrationfiltered
15. washthe solid is washed with water
16. customdried at 60° C. under vacuum