Process for purifying 2,5-dichlorophenol

Patent metadata

Field	Value
Publication number	US-9701604-B2
Application number	US-201415101080-A
Country	US
Kind code	B2
Filing date	Dec 1, 2014
Priority date	Dec 4, 2013
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A process for purifying 2,5-dichlorophenol, the process comprising the steps of distillation and subsequent crystallization.

First claim

The invention claimed is:

1. A process for purifying 2,5-dichlorophenol, the process comprising the steps of:
(i) subjecting a mixture (M) comprising 2,5-dichlorophenol, 2,4-dichlorophenol and optionally 3,4-dichlorophenol to distillation to obtain a distillate (D), and
(ii) subjecting the distillate (D) to a melt crystallization step to obtain a crystalline fraction (C) and a mother liquor (L).

2. The process of claim 1 , further comprising the step of:
(iii) combining a composition obtained from the mother liquor (L) in step (ii) with a feed (F), comprising 2,5-dichlorophenol, 2,4-dichlorophenol and optionally 3,4-dichlorophenol, to obtain mixture (M) to be subjected to distillation in step (i).

3. The process of claim 2 , wherein the feed (F) is obtained from hydrolyzing 1,2,4-trichlorophenol in the presence of an alkali metal hydroxide or alkali metal alkoxide.

4. The process of claim 2 , wherein the mixture (M) and/or the feed (F) comprises 40 to 95 wt.-% of 2,5-dichlorophenol; 5 to 60 wt.-% of 2,4-dichlorophenol; and optionally 0 to 30 wt.-% of 3,4-dichlorophenol.

5. The process of claim 1 , wherein the distillate (D) obtained in step (i) comprises 50 to 95 wt.-% of 2,5-dichlorophenol.

6. The process of claim 1 , wherein the crystalline fraction (C) obtained in step (ii) comprises 80 to 99.9 wt.-% of 2,5-dichlorophenol.

7. The process of claim 1 , wherein the distillation step (i) is carried out in a distillation column at a pressure of 5 kPa to 25 kPa, and a bottom temperature of 60° C. to 230° C.

8. The process of claim 1 , wherein the melt crystallization step (ii) is carried out using layer melt crystallization or suspension melt crystallization.

9. The process of claim 8 , wherein the step of suspension melt crystallization further comprises a step of separating the obtained crystals from the melt.

10. The process of claim 2 , wherein 2,5-dichlorophenol is present in the mixture (M) and/or the feed (F) in an amount of 50 to 85 wt.-%.

11. The process of claim 10 , wherein 2,5-dichlorophenol is present in the mixture (M) and/or the feed (F) in an amount of 40 to 80 wt-%.

12. The process of claim 11 , wherein 2,4-dichlorophenol is present in the mixture (M) and/or the feed (F) in an amount of 10 to 40 wt-%.

13. The process of claim 12 , wherein 2,4-dichlorophenol is present in the mixture (M) and/or the feed (F) in an amount of 10 to 20 wt.-%.

Assignees

• Basf Se

Inventors

• Klauber Eric George
• Rack Michael
• Zierke Thomas
• Wloch Sebastian
• Holub Nicole
• Dudenhoeffer Stefan
• Schmelebeck Gerald
• Ji Junmin
• CORTES David

Classifications

• C07C39/30

  the halogen being two chlorine atoms · CPC title

• C07C37/84

  by crystallisation · CPC title

• C07C37/74 Primary

  by distillation · CPC title