反应详情

温度

95 °C

Chloral hyrdate (17.40 g) is dissolved in water (256 mL) with sodium sulfate (108.75 g). The solution is warmed to 60° C. whereupon hydroxylamine hydrochloride (19.95 g) in water (124 mL) was added. In a separate flask a slurry of 2-iodo 5-aminotoluene (commercially available, Buttpark Ltd, U.K.) in water (139 mL) and CHCl (7.87 mL) was prepared at 80° C. The mixtures were combined and the reaction temperature increased to 95° C. for 20 min. then cooled to room temperature and then at 0° C. for 5 min. The solids were collected by filtration and washed with water (250 mL) and dried under vacuum to afford isonitrosoacetanilide 2.1 as a tan solid. Conc. H2SO4 (75 mL) was warmed to 50° C. and isonitrosoacetanilide 2.1 was added portionwise so that the temperature did not go above 70° C. After the addition the temperature was raised to 80° C. for 10 min. and then the mixture was allowed to cool to ambient temperature and poured onto ice water (10–12× volume). The isatin was filtered and washed with cold water (4×500 mL). The 1:1 isomeric mixture was taken up in 2N NaOH solution (316 mL) and stirred for 2 h then filtered. The filtrate was acidified to approx. pH 6 with acetic acid and refiltered to remove the undesired isatin isomer. The filtrate was acidifed to pH 1 with conc. HCl and filtered and the precipitate (desired isomer 2.7 g) was washed with water and dried by suction. Isatin 2 was converted to the corresponding aldehyde (3.1) as for isatin 1.1 above.

1. additionwas added
2. temperaturethen cooled to room temperature
3. filtrationThe solids were collected by filtration
4. washwashed with water (250 mL)
5. customdried under vacuum