反应详情

温度

373 K

22 g of 7-tert-butyl-3-hydroxy-5-methyl-3H-benzofuran-2-one (prepared as described in Ex. 2 of U.S. Pat. No. 5,614,572) are placed in 50 ml of toluene, and 3 drops of DMF and 15 ml of thionyl chloride are added thereto. The solution is then slowly heated to 373 K at such a rate that the evolution of HCl and SO2 remains vigorous yet controllable. It is then stirred at 373 K for a further hour. Approximately 50 ml of liquid are then distilled off in order to remove the excess thionyl chloride. The residue is diluted with 160 ml of toluene and, at room temperature, 14 ml of triethylamine are added dropwise. The thick, red reaction mixture is then heated under reflux for 30 min. After cooling to room temperature, the triethylamine hydrochloride which has precipitated is filtered off, and the residue is concentrated to an oily consistency using a rotary evaporator. The isoxindigo is crystallised out by adding 200 ml of acetonitrile, is filtered off, washed with acetonitrile and dried, yielding 11.6 g (57% of the theoretical yield) of 7,7′-di-tert-butyl-5,5′-dimethyl-[3,3′]bibenzofuranylidene-2,2′-dione of formula (LIa).

1. distillationApproximately 50 ml of liquid are then distilled off in order
2. customto remove the excess thionyl chloride
3. additionThe residue is diluted with 160 ml of toluene and, at room temperature
4. addition14 ml of triethylamine are added dropwise
5. temperatureThe thick, red reaction mixture is then heated
6. temperatureunder reflux for 30 min
7. temperatureAfter cooling to room temperature
8. customthe triethylamine hydrochloride which has precipitated
9. filtrationis filtered off
10. concentrationthe residue is concentrated to an oily consistency
11. customa rotary evaporator
12. customThe isoxindigo is crystallised out
13. additionby adding 200 ml of acetonitrile
14. filtrationis filtered off
15. washwashed with acetonitrile
16. customdried
17. customyielding 11.6 g (57% of the