Reacción #76809

Ecuación de reacción

sodium hydroxide

1,3,5-trioxane

sodium hydroxide

hydrochloric acid

HCl

sulfuric acid

terephthalic acid

→

5-carboxyphthalide

Rendimiento 75.8%

Disolventes

—

ice

water

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.ADDITIONare added
2. 2
   Otrothe temperature of 25° C
3. 3
   OtroTo the thick suspension thus obtained
4. 4
   workup.STIRRINGunder stirring
5. 5
   Otrothe temperature of 35° C.
6. 6
   workup.STIRRINGstirring
7. 7
   workup.WAITis continued for 20-30 minutes
8. 8
   Temperaturawithout cooling
9. 9
   Otrorises to 45-50° C
10. 10
    Otroalready at 90° C.
11. 11
    Otrobecomes clear whilst at 120° C.
12. 12
    Otroto 135-140° C
13. 13
    workup.WAITThe mixture is kept 6 hour
14. 14
    workup.STIRRINGunder stirring at this temperature
15. 15
    Temperaturait is cooled to 20° C.
16. 16
    Otrothe temperature of 25° C
17. 17
    OtroTo the mixture thus obtained
18. 18
    Otroat 35-40° C.
19. 19
    Temperaturacooling
20. 20
    Otroat the temperature of 35-40° C.
21. 21
    OtroThe solid is removed by filtration on Dicalite® in a buchner
22. 22
    Lavadowashed with water
23. 23
    OtroTo the filtered solution thus obtained
24. 24
    Otrothe suspension thus obtained
25. 25
    Temperaturais heated to 35° C
26. 26
    FiltraciónThe solid is filtered
27. 27
    Lavadowashed 3 times with 500 ml of deionized water at 40° C.
28. 28
    TemperaturaThe suspension is heated
29. 29
    workup.STIRRINGunder stirring at 50-55° C.
30. 30
    workup.WAITkept 1 hour under these conditions
31. 31
    LavadoThe solid is washed with deionized water
32. 32
    Otrodried in vacuo at 50° C. to constant weight

Procedimiento

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 and without exceeding the temperature of 25° C. To the thick suspension thus obtained, 120 g (1.33 m) of 1,3,5-trioxane are added under stirring without exceeding the temperature of 35° C., then stirring is continued for 20-30 minutes without cooling, whereby the temperature of the mixture rises to 45-50° C. The mixture is heated to 120° C. and it is noted that, already at 90° C., the mass becomes clear whilst at 120° C. a light exothermia is observed which brings the temperature to 135-140° C. The mixture is kept 6 hour under stirring at this temperature, then it is cooled to 20° C. and poured in 3000 g of coushed ice without exceeding the temperature of 25° C. To the mixture thus obtained, a 15% w/w solution of sodium hydroxide is added to a pH≡6 (about 6500-7000 ml thereof are needed), by keeping the temperature at 35-40° C. by water-cooling, then a 5% w/w solution of sodium hydroxide is added thereto at the temperature of 35-40° C. up to pH≡8 (about 300 ml are needed). The solid is removed by filtration on Dicalite® in a buchner and washed with water. To the filtered solution thus obtained, 35% hydrochloric acid is added up to pH≡1 (requiring about 1600-1800 ml of 35% HCl) 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. and suspended in 1000 ml of deionized water. The suspension is heated under stirring at 50-55° C. and kept 1 hour under these conditions, then it is hot filtered. The solid is washed with deionized water and dried in vacuo at 50° C. to constant weight. Thus, 180 g of light-brown coloured 5-carboxyphthalide with a purity (HPLC) >95% are obtained.

Fuente