反应详情

温度

130 °C

14.8 g of isatin (99 mmol, 98.2% purity) were initially charged into a 250 ml three-neck flask and 150 ml of 2-ethylhexanol were added. 6.0 g of hydrazine hydrate (117 mmol; 98% purity) were added with stirring. The reaction mixture was heated to 90° C. for 15 min to form the isatin hydrazone (yellow suspension). The water of reaction was azeotropically removed at 90° C./100 mbar using 1-hexanol. 2.4 g of DABCO (21 mmol, 98%) were then added and the suspension heated to 130° C. for 2.5 h. After the end of the reaction (GC analysis: hydrazone 0.3 area %), 100 ml of 1-hexanol were distilled off (80° C./50 mbar). The remaining solution was cooled to 5° C., the precipitated solid filtered off and dried in a vacuum drying cupboard at 70° C. Altogether, 8.0 g of dry 2-oxindole product (light brown) were obtained which corresponded to an overall yield of 66.5%. Purity: 99.9 area %.

1. customwas azeotropically removed at 90° C./100 mbar
2. distillationwere distilled off (80° C./50 mbar)
3. temperatureThe remaining solution was cooled to 5° C.
4. filtrationthe precipitated solid filtered off
5. customdried in a vacuum
6. customdrying cupboard at 70° C