反应详情

温度

200 °C

Analogously to Example 11, 0.286 g. 5,6-diamino-3,3-dimethylindolin-2-one and 0.18 g. pivalic acid are heated with 3 g. polyphosphoric acid in a pre-heated bath for 30 minutes at 200° C. A further 0.18 g. pivalic acid are then added thereto and further heated for 30 minutes at 200° C. This procedure is repeated three times so that, in all, 0.9 g. pivalic acid are used with a total reaction time of 2.5 hours. After cooling, the mixture is dissolved in about 9 ml. water and adjusted to about pH 7 to 8 with concentrated aqueous ammonia solution. The precipitate obtained is filtered off with suction and washed with water to give 0.28 g. of the title compound; m.p. >300° C. For further purification, it is dissolved in a little hot ethanol, the turbid solution is treated with charcoal, the hot clear filtrate is evaporated in a vacuum and the evaporation residue is triturated with diethyl ether. One mole of the title compound thus obtained contains 1 mole of water; m.p. >300° C.

1. customare used with a total reaction time of 2.5 hours
2. temperatureAfter cooling
3. dissolutionthe mixture is dissolved in about 9 ml
4. customThe precipitate obtained
5. filtrationis filtered off with suction
6. washwashed with water
7. customto give 0.28 g