Process for the preparation of phenolic compounds, for separating phenol from cleavage product mixtures, and an apparatus

1. A process for the preparation of phenolic compounds comprising:

i) oxidizing an alkylaryl compound to produce a cleavage reaction mixture comprising alkylaryl hydroperoxide and the unreacted alkylaryl compound;

ii) subjecting the product from step i) to a cleavage reaction resulting in a cleavage product mixture comprising at least the phenolic compound, a ketone, the corresponding hydroxy ketone and the unreacted alkyl aryl compound;

iii) working-up of the cleavage product mixtures from step ii) by distillation, which comprises separating the cleavage product mixture into at least three fractions in a single distillation step by:

feeding the cleavage product mixture to a distillation column,

removing a first fraction comprising the ketone at the top of the distillation column,

removing a second fraction comprising the phenolic compound at the bottom of the distillation column, and

removing a third fraction comprising unreacted the alkylaryl compound and the hydroxy ketone as side stream, whereby the side stream take-off is situated above the feed of the cleavage product mixture to the distillation column, and

iv) removing heat from the distillation column, wherein the heat takeoff is situated above the side stream take-off of the third fraction.

2. The process of claim 1 , wherein the heat removed from the distillation column is used for heating a second distillation column for obtaining purified ketone from the first fraction.

3. The process as claimed in claim 1 , wherein the cleavage reaction mixture is part of the cleavage product mixture obtained from acid-catalyzed cleavage of alkylaryl hydroperoxide.

4. The process as claimed in claim 1 , wherein the alkylaryl compound is cumene, the phenolic compound is phenol, the ketone is acetone, and the hydroxy ketone is hydroxy acetone.

5. The process as claimed in claim 1 , wherein the cleavage product mixture further comprises water.

6. The process of claim 1 , wherein the step of removing heat from the distillation column provides a temperature at the column top of less than 65° C. at standard pressure.

7. The process of claim 6 , wherein said temperature at the column top is between about 55° C. to about 60° C. at standard pressure.

8. The process of claim 1 , wherein the cleavage product mixture prior feeding into the distillation column is preheated to a temperature of above 70° C. at standard pressure.

9. The process of claim 8 , wherein the cleavage product mixture prior feeding into the distillation column is preheated to a temperature of above 100° C. at standard pressure.

10. The process of claim 8 , wherein the cleavage product mixture prior feeding into the distillation column is preheated to a temperature of between 110° C. and 180° C. at standard pressure.

11. The process of claim 8 , wherein the cleavage product mixture prior feeding into the distillation column is preheated to a temperature of about 140° C. to about 146° C. at standard pressure.

12. A process for separating phenol into at least three fractions in a single distillation step from a cleavage product mixture, said mixture comprising at least acetone, cumene, water and phenol, said process comprising:

feeding the cleavage product mixture to a distillation column through a feed, wherein the cleavage product mixture prior feeding into the distillation column is preheated to a temperature of above 100° C. at standard pressure;

removing a first fraction comprising acetone at the top of the distillation column;

removing a second fraction comprising substituted or unsubstituted phenol at the bottom of the distillation column; and

removing a third fraction comprising hydroxy acetone and cumene as side stream through a side-stream take-off, wherein the side stream take-off is situated above the feed of the cleavage product mixture to the distillation column.

13. The process of claim 12 , wherein the cleavage product mixture prior feeding into the distillation column is preheated to a temperature of between 110° C. and 180° C. at standard pressure.

14. The process of claim 12 , wherein the cleavage product mixture prior feeding into the distillation column is preheated to a temperature of about 140° C. to 146° C. at standard pressure.

15. The process of claim 8 , wherein heat energy for the preheating step is obtained from cooling of the cleavage product mixture after thermal after-treatment of the cleavage product mixture from acid-catalyzed cleavage of cumene hydroperoxide prior to neutralization of the cleavage product mixture.

16. The process as claimed in claims 1 or 12 , wherein the first fraction comprises at least 75% of a ketone present in the cleavage product mixture before the distillation step.

17. The process as claimed in claims 1 or 12 , wherein at least one phenol-containing fraction is obtained containing less than 300 ppm of hydroxy acetone.

18. The process of claim 17 , wherein at least one phenol-containing fraction is obtained containing less than 30 ppm of hydroxy acetone.

19. The process of claim 1 , further comprising

obtaining a further fraction, said further fraction comprising at least hydroxy acetone, cumene and water, and

separating said fraction into an organic phase and an aqueous phase.

20. The process of claim 19 , wherein the organic phase and/or the aqueous phase are returned to the distillation column at least partially.

21. The process as claimed in claims 1 or 12 , wherein the cleavage product mixture comprises α-methylstyrene.

22. The process as claimed in claims 1 or 12 , wherein the cleavage product mixture has a phenol concentration of from 20 to 90% by weight.

23. The process as claimed in claims 1 or 12 , wherein the cleavage product mixture has a hydroxy acetone concentration of from 300 ppm to 5% by weight.