反应详情

温度

131.5 °C

To 892 g of fuming sulfuric acid, containing 25-27% of SO3, 100 g (0.6 m) of terephthalic acid are added at 20-23° C., under stirring, then 46 g (0.5 m) of 1,3,5-trioxane are added portionwise thereto at about 15° C. At the end of the addition, the mixture is heated 2 hours at 130-133° C. whereby a dark, clear solution is obtained. When the reaction is complete, as shown by a HPLC control, the mixture is cooled to 20-22° C. and 210 g of glacial acetic acid are slowly added thereto, without exceeding the temperature of 23-25° C. The mass is cooled to −5-0° C. and 1800 ml of cold deionized water are added thereto. During this operation the temperature rises to 43-45° C. At the end of the addition, the mixture is kept 1 hour under stirring at 23-25° C., then it is filtered, the solid is washed with deionized water abundantly and suspended, still wet, in 1200 ml of deionized water at room temperature. To the suspension thus obtained, about 1550 g of a 7% solution of NaHCO3 are added to a constant pH of 7,6-7,8. The mixture is filtered on Celite®, washing with deionized water. The pH of the filtrate is brought to about 1 by slow addition of about 120 ml of 35% hydrochloric acid at 22-25° C. The suspension is kept 1 hour under stirring at 22-25° C., then it is filtered and washed with deionized water abundantly. The product is dried in vacuo at about 50° C. to give 81 g of 5-carboxyphthalide with a titer (HPLC)>94% and purity (HPLC)>95%.

1. additionare added at 20-23° C.
2. customat about 15° C
3. additionAt the end of the addition
4. customis obtained
5. temperaturethe mixture is cooled to 20-22° C.
6. customthe temperature of 23-25° C
7. temperatureThe mass is cooled to −5-0° C.
8. additionare added
9. customrises to 43-45° C
10. additionAt the end of the addition
11. stirringunder stirring at 23-25° C.
12. filtrationit is filtered
13. washthe solid is washed with deionized water abundantly
14. customat room temperature
15. customTo the suspension thus obtained
16. filtrationThe mixture is filtered on Celite®
17. washwashing with deionized water
18. additionThe pH of the filtrate is brought to about 1 by slow addition of about 120 ml of 35% hydrochloric acid at 22-25° C
19. waitThe suspension is kept 1 hour
20. stirringunder stirring at 22-25° C.
21. filtrationit is filtered
22. washwashed with deionized water abundantly
23. customThe product is dried in vacuo at about 50° C.