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 production of a fluorinated carboxylic halide having a reduced content of impurities, a fraction of the fluorinated carboxylic halide having a reduced content of impurities, and its use in the manufacture of agriculturally and pharmaceutically active compounds or their intermediates.

Claims

1. A process for the production of a compound of the formula (I) R1-C(O)X having a reduced content of impurities, wherein R1 is CF.sub.2H, CF.sub.3 or CClF2 and X is a halogen, which 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 temperatures 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 R1 is CClF2 and X is chlorine.

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

4. The process according to claim 3, wherein the medium temperature distillation step is carried out at a head temperature of at least 5° C. lower than the high temperature distillation step, and the low temperature distillation step is carried out at a head temperature of at least 5° C. lower than the medium temperature distillation step.

5. The process according to claim 3, wherein the head temperature difference between the high temperature distillation step and the medium temperature distillation step is from 0.5 to 15° C., and wherein the head temperature difference between the medium temperature distillation step and the low temperature distillation step is from 0.5 to 15° C.

6. The process according to claim 3, wherein the low temperature distillation step is performed first, the medium temperature distillation step is performed second and the high temperature distillation step is performed third.

7. The process according to claim 3, wherein the fraction of the compound of formula (I) having a reduced content of impurities is recovered from the high temperature distillation step as bottom product.

8. The process according to claim 1, wherein the process for the production of a compound of the formula (I) R1-C(O)X having a reduced content of impurities is carried out at a pressure of from 0.7 to 1.3 bar.

9. The process according to claim 1, further comprising a process wherein the crude fraction of the compound of formula (I) is obtained by an oxidation process starting from a compound of formula (II) R1-CHX′.sub.2, wherein X′ is the same or different, wherein X′ is a halogen selected from the group consisting of Cl, F and Br, and wherein R1 has the same definition as above.

10. The process according to claim 3, wherein a fraction comprising the compound of formula (I) and at least one impurity is recovered from the high temperature distillation step as top product, and wherein the fraction comprising the compound of formula (I) and at least one impurity is fed into a step of the process for the manufacture of the crude fraction of the compound of formula (I) which is fed to the process for the production of a compound of the formula (I) R1-C(O)X having a reduced content of impurities.

11. The process according to claim 1, wherein the process for the production of a compound of the formula (I) R1-C(O)X having a reduced content of impurities is carried out in a distillation apparatus made or partially made or coated with or partially coated with glass or enamel.

12. The process according to claim 1, wherein the process for the production of a compound of the formula (I) R1-C(O)X having a reduced content of impurities is carried out as a continuous process.

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

14. A process for the manufacture of agriculturally or pharmaceutically active compounds or intermediates of agriculturally or pharmaceutically active compounds, comprising the process according claim 1, and optionally one or more further process steps to convert the intermediates of agriculturally or pharmaceutically active compounds into agriculturally or pharmaceutically active compounds.

15. (canceled)

16. The process according to claim 9, wherein X′ is Cl.

17. The process according to claim 9, wherein a fraction comprising the compound of formula (I) and at least one impurity is recovered from the high temperature distillation step as top product, and wherein the fraction comprising the compound of formula (I) and at least one impurity is fed into a step of the process for the manufacture of the crude fraction of the compound of formula (I) which is fed to the process for the production of a compound of the formula (I) R1-C(O)X having a reduced content of impurities.

Description

EXAMPLE 1

Manufacture of CDFAC

[0033] A Duran 50 photoreactor (volume 6 liter) was heated to 85° C., and irradiated with a 1 kw Hg high pressure lamp. O.sub.2 was fed to a premixer at a rate of 113 g/h, and Cl.sub.2 was fed to the premixer at a rate of 64 g/h. 1-chloro-1,1-difluoro-2,2-dichloroethane (R 122) was heated is a vaporizer to 74° C., and the evaporated R 122 was injected to the premixer. The premixer contents were then injected to the photoreactor. The molar ratio of O.sub.2 to R 122 was 0.44, the molar ration of Cl.sub.2 to R 122 was 0.11. The crude fraction containing CDFAC and byproducts (mainly COF.sub.2, HCl, Cl.sub.2, 122, COCl.sub.2 and R 122a) was continuously drawn off the photoreactor and used further in the distillation process.

[0034] 94.3% of the R 122 was reacted in the process. The selectivity was 97,06% CDFAC, 1.28% COF.sub.2, 1.59% COCl.sub.2 and 0.08% R 112a. The reaction was monitored and analyzed by GC (gas chromatography) and GC-MS (gas chromatography-mass spectrometry).

[0035] The photooxidation is operated continuously.

EXAMPLE 2

Distillation of CDFAC

[0036] The crude fraction containing CDFAC and impurities obtained by example 1 is fed to a first glass distillation column at 1 bar, which is operated at a head temperature of −20° C. A fraction containing mainly COF.sub.2, HCl and Cl.sub.2 is withdrawn at the top of the column and fed to a scrubber. The bottom fraction of the first distillation column is fed to a second glass distillation column at 1 bar, which is operated at a head temperature of −10° C. The bottom product of the second distillation column is a fraction containing mainly R 122 and R 112a and is fed to recycling processes. The top product of the second distillation column is fed to a third glass distillation column at 1 bar, which is operated at a head temperature of 0° C. A fraction containing mainly COCl.sub.2 and CDFAC is withdrawn at the top of the column and fed the pre-mixer or the photoreactor of example 1, where the COCl.sub.2 is further oxidized to CO.sub.2, and the CDFAC is accumulated in downstream distillation steps. The bottom fraction of the third, high temperature (0° C.) distillation step is a CDFAC fraction of 99% purity by GC. The distillation is operated continuously.