反应详情

温度

12.5 °C

To 800 ml of fuming sulfuric acid, containing about 27% of SO3, 260 g (1.56 m) of terephthalic acid are added, under stirring, in 15 minutes without exceeding the temperature of 25° C. By maintaining the stirring, 60 g (0.665 m) of 1,3,5-trioxane are added portionwise to the thick suspension thus obtained, whereby the temperature rises to about 25° C. The mixture is cooled to 10-15° C. in 30 minutes, then a further 60 g (0.665 m) of 1,3,5-trioxane is added thereinto. The mixture is heated and it is observed that at 90° C. the mass becomes clear. The temperature is brought to 120° C. and the mixture is kept 10-15 minutes under these conditions, whereby the temperature may rise to 135-140° C. If no exothermia is observed, the mixture is nevertheless heated to 130-135° C. and kept 4 hours under these conditions. The cooled mixture is poured, in about 1 hour and without exceeding the temperature of 25-35° C., into 3000 g of crushed ice. To the mixture thus obtained, 8000-8500 ml of a 15% w/w solution of sodium hydroxide are added to a pH=5-6, by letting the temperature to rise to 35-40° C. and by keeping it at these values by a water-cooling. Then, at 35-40° C., 300 ml of 5% w/w solution of sodium hydroxide are added to the mixture to a pH≡8. The solid is removed by filtration on a Dicalite® bed in a buchner and washed with water. To the solution thus obtained, 2000 ml of 35% hydrochloric acid are added to a pH≡1 and the suspension thus obtained is heated to 35° C. The solid is filtered, washed 3 times with 500 ml of deionized water at 40° C. The wet product is treated with 4000 ml of warm deionized water (about 45° C.) and the suspension is heated 30 minutes under stirring at 45° C. Without cooling, the product is filtered, washed with deionized water and dried in vacuo at 50° C. to constant weight. Thus, 215-225 g of light-brown coloured 5-carboxyphthalide with a purity (HPLC)>95% are obtained.

1. additionare added
2. customthe temperature of 25° C
3. additionare added portionwise to the thick suspension
4. customthus obtained
5. customrises to about 25° C
6. temperatureThe mixture is heated
7. customis observed that at 90° C.
8. customis brought to 120° C.
9. waitthe mixture is kept 10-15 minutes under these conditions, whereby
10. custommay rise to 135-140° C
11. temperaturethe mixture is nevertheless heated to 130-135° C.
12. waitkept 4 hours under these conditions
13. additionThe cooled mixture is poured, in about 1 hour
14. customthe temperature of 25-35° C.
15. customTo the mixture thus obtained
16. customto rise to 35-40° C.
17. temperaturecooling
18. customThe solid is removed by filtration on a Dicalite® bed in a buchner
19. washwashed with water
20. customTo the solution thus obtained
21. customthe suspension thus obtained
22. temperatureis heated to 35° C
23. filtrationThe solid is filtered
24. washwashed 3 times with 500 ml of deionized water at 40° C
25. additionThe wet product is treated with 4000 ml of warm deionized water (about 45° C.)
26. temperaturethe suspension is heated 30 minutes
27. stirringunder stirring at 45° C
28. temperatureWithout cooling
29. filtrationthe product is filtered
30. washwashed with deionized water
31. customdried in vacuo at 50° C. to constant weight