Distillation process comprising at least two distillation steps to obtain purified halogenated carboxylic acid halide, and use of the purified halogenated carboxylic acid halide

Abstract

The present invention concerns a process for the obtention of a halogenated carboxylic halide having a reduced content of impurities, a fraction of the halogenated carboxylic halide having a reduced content of impurities, and its use in the manufacture of agriculturally and pharmaceutically active compounds.

Claims

1. A process for the obtention of a compound of the formula (I) R1-C(O)X having a reduced content of impurities, wherein R1 is a fluorinated and/or chlorinated Cl -C3 alkyl and X is a halogen, wherein the process comprises a) subjecting a crude fraction comprising compound of formula (I) R1-C(O)X and impurities to at least two distillation steps, wherein the at least two distillation steps are performed at different pressures and b) recovering at least a fraction of the compound of the formula (I) having a reduced content of impurities.

2. The process according to claim 1, wherein a) comprises at least three distillation steps, which consist of a high pressure distillation step, a medium pressure distillation step and a low pressure distillation step.

3. The process according to claim 2, wherein the medium pressure distillation step is carried out at a pressure of at least 1 bar lower than the high pressure distillation step, and the low pressure distillation step is carried out at a pressure of at least 0.2 bar lower than the medium pressure distillation step.

4. The process according to claim 1, wherein R1 is selected from the group consisting fluorinated and/or chlorinated methyl and fluorinated and/or chlorinated ethyl.

5. The process according to claim 1, wherein R1 is selected from the group consisting of CF.sub.3, CClF.sub.2, CCl.sub.2F, CHF.sub.2, CHClF, CH.sub.2Cl and CCl.sub.2H.

6. The process according to claim 1, wherein X is selected from the group consisting of Cl, F and Br.

7. The process according to claim 1, wherein the compound of formula (I) is selected from the group consisting of trifluoroacetyl chloride, difluoroacetyl chloride and difluorochloroacetyl chloride.

8. The process according to claim 2, wherein the pressure difference between the high pressure distillation step and the medium pressure distillation step is from 1 to 10 bar, and wherein the pressure difference between the medium pressure distillation step and the low pressure distillation step is from 1 to 8 bar.

9. The process according to claim 2, wherein the pressure in the high pressure distillation step is from 12 to 18 bar, the pressure in the medium pressure distillation step is from 6 to 12 bar, and the pressure in the low pressure distillation step is from 1 to 9 bar.

10. The process according to claim 2, wherein the high pressure distillation step is performed first, the medium pressure distillation step is performed second and the low pressure distillation step is performed third.

11. The process according to claim 2, wherein the fraction of the compound of formula (I) having a reduced content of impurities is recovered from the low pressure distillation step as top product.

12. The process according to claim 2, wherein the fraction of the compound of formula (I) having a reduced content of impurities is recovered from the low pressure distillation step as bottom product.

13. The process according to claim 1, wherein the crude fraction of the compound of formula (I) has been obtained by an oxidation process starting from a compound of formula (II) R1-CHX′.sub.2, wherein each X′ is the same or different, wherein X′ is a halogen selected from the group consisting of Cl, F and Br and wherein R1 is a fluorinated and/or chlorinated Cl-C3 alkyl.

14. The process according to claim 1, wherein the crude fraction comprising the compound of formula (I) R1-C(O)X and impurities contains HX, and wherein a fraction of HX having a reduced content of impurities is recovered, wherein X is a halogen.

15. A fraction of a compound of formula (I) R1-C(O)X having a reduced content of impurities, obtainable by the process according to claim 1.

16. A process for the manufacture of agriculturally or pharmaceutically active compounds, comprising the process according to claim 1.

17. (canceled)

18. The process according to claim 6, wherein X is Cl.

19. The process according to claim 13, wherein each X′ is Cl.

20. A fraction of a compound of formula (I) R1-C(O)X having a reduced content of impurities, obtainable by the process according to claim 13.

21. The fraction according to claim 20, wherein the compound of formula (I) is selected from the group consisting of trifluoroacetyl chloride, difluoroacetyl chloride and difluorochloroacetyl chloride.

Description

EXAMPLES

Manufacture of TFAC

[0043] TFAC is manufactured according to the process described in EP0638539A and the crude product is used as crude fraction containing TFAC and impurities to be subjected to the three-step distillation process.

Example 1

[0044] The fraction containing TFAC and impurities was pressurized at 15 bar and submitted to a first distillation column (DN 50, ceramic fillers with 1 cm diameter, height 6 meters, material : Inox 1.4571 steel). The sump was kept at 63° C.; at the top of the first distillation column, a fraction containing mainly HCl was recovered by trapping at −20° C. The sump contained mainly TFAC, 123, Cl.sub.2 and COCl.sub.2. The sump was then submitted to a second distillation (column DN 50, ceramic fillers with 1 cm diameter, height 6 meters, material : Inox 1.4571 steel) at 9,5 bar. The sump was kept at 63° C., at the top of the column, a fraction containing mainly Cl.sub.2 and a minor fraction of COCl.sub.2, at 53° C. was recovered. The sump of this second distillation was then submitted to a third distillation (column DN 50, ceramic fillers with 1 cm diameter, height 6 meters, material : Inox 1.4571 steel) at 3 bar, where at the top (at 18° C., sump 84° C.) the fraction containing TFAC and a reduced amount of impurities was recovered.

Example 2

[0045] The fraction containing TFAC and impurities was pressurized at 15 bar and submitted to a first distillation column (DN 50, ceramic fillers with 1 cm diameter, height 6 meters, material: Inox 1.4571 steel). The sump was kept at 63° C. ; at the top of the first distillation column, a fraction containing mainly HCl was recovered by trapping at −20° C. The sump contained mainly TFAC, 123, Cl.sub.2 and COCl.sub.2. The sump was then submitted to a second distillation (column DN 50, ceramic fillers with 1 cm diameter, height 6 meters, material: Inox 1.4571 steel) at 7 bar. The sump was kept at 104° C., at the top of the column, a fraction containing mainly TFAC and Cl.sub.2 at 40° C. is recovered. The sump of this second distillation was then submitted to a third distillation (column DN 50, ceramic fillers with 1 cm diameter, height 6 meters, material: Inox 1.4571 steel) at 6 bar, where at the top (at 20° C.) a fraction containing mainly TFAC and Cl.sub.2 was distilled of. The bottom (sump) of this third distillation was recovered as the fraction containing TFAC and a reduced amount of impurities.

TABLE-US-00001 TABLE I Contents in weight %/ppm Example 2 Example 1 Recovered Recovered TFAC TFAC product product fraction fraction (bottom Crude Fraction (top product) product) TFAC 69.17% >99% 99.5% HCl 18.53%  <1% <10 ppm COCl.sub.2  0.1% 0.1 <10 ppm COF.sub.2  0.1% 0.1 <10 ppm 123  0.33%  0%   40 ppm Cl.sub.2   10% <10 ppm <10 ppm F.sup.− 4000 ppm 500 ppm <10 ppm