Reacción #76812

Ecuación de reacción

NaHCO3

sulfuric acid

terephthalic acid

1,3,5-trioxane

→

5-carboxyphthalide

Rendimiento 89.0%

Disolventes

water

acetic acid

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.ADDITIONare added at 20-23° C.
2. 2
   Otroat about 15° C
3. 3
   workup.ADDITIONAt the end of the addition
4. 4
   Otrois obtained
5. 5
   Temperaturathe mixture is cooled to 20-22° C.
6. 6
   Otrothe temperature of 23-25° C
7. 7
   TemperaturaThe mass is cooled to −5-0° C.
8. 8
   workup.ADDITIONare added
9. 9
   Otrorises to 43-45° C
10. 10
    workup.ADDITIONAt the end of the addition
11. 11
    workup.STIRRINGunder stirring at 23-25° C.
12. 12
    Filtraciónit is filtered
13. 13
    Lavadothe solid is washed with deionized water abundantly
14. 14
    Otroat room temperature
15. 15
    OtroTo the suspension thus obtained
16. 16
    FiltraciónThe mixture is filtered on Celite®
17. 17
    Lavadowashing with deionized water
18. 18
    workup.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. 19
    workup.WAITThe suspension is kept 1 hour
20. 20
    workup.STIRRINGunder stirring at 22-25° C.
21. 21
    Filtraciónit is filtered
22. 22
    Lavadowashed with deionized water abundantly
23. 23
    OtroThe product is dried in vacuo at about 50° C.

Procedimiento

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%.

Fuente