Process for preparing bromotrichloromethane

Abstract

The present invention relates to a process for preparing bromotrichloromethane comprising a) providing bromine in chloroform; and b) radiation of the resulting solution with light in the range of 350 to 550 nm, wherein said solution of bromine in chloroform is not radiated with radiation of a wavelength below 350 nm.

Claims

1. A process for preparing bromotrichloromethane comprising a) providing a solution of bromine in chloroform; and b) radiation of the resulting solution with light in the range of 350 to 550 nm, wherein said solution of the bromine in the chloroform is not radiated with radiation of a wavelength below 350 nm.

2. The process of claim 1, wherein the light is a light-emitting diode.

3. The process of claim 1, wherein the wavelength of the radiation is in the range of 380 to 550 nm.

4. The process of claim 1, wherein the light is monochromatic.

5. The process of claim 1, wherein the process is carried out in the absence of oxygen.

6. The process of claim 1, wherein said process is carried out in the absence of alcohols.

7. The process of claim 1, wherein the light does not emit radiation below 350 nm.

8. The process of claim 1, wherein reaction temperature is from −20° C. to 60° C.

9. The process of claim 1, wherein reaction pressure is in the range of 0.1-20 bar.

10. The process of claim 1, wherein content of the bromine in the solution of the bromine in the chloroform in step a) is from 0.1 to 10% by weight.

11. The process of claim 1, wherein the bromine is generated in situ.

12. The process of claim 1, wherein the process is carried out under a nitrogen atmosphere.

13. The process of claim 5, wherein: reaction temperature is from −20° C. to 60° C.; reaction pressure is in the range of 0.1-20 bar; and content of the bromine in the solution of the bromine in the chloroform in step a) is from 0.1 to 10% by weight.

Description

EXAMPLES

(1) The examples are carried out as described below at 20° C. under nitrogen atmosphere. Quantitative analysis of the resulting reaction mixture was carried out by gas-chromatography (Column: RTX-200-MS 30m). The chloroform used was stabilized with amylene and contained less than 0.5 wt % of ethanol.

Example 1

1% Bromine in Chloroform, 470 nm

(2) A solution of 4,8 g (30,0 mmol) bromine in 477 g (4 mol) chloroform is radiated for 2 h by 100 LEDs' (wavelength 470 nm, 20° C.). Analysis of the resulting mixture revealed 4.8 g trichlorobromomethane (24.3 mmol, 81% yield).

Example 2

2% Bromine in Chloroform, 470 nm

(3) A solution of 9.7 g (61 mmol) bromine in 477 g (4 mol) chloroform is radiated for 3 h by 100 LEDs' (wavelength 470 nm, 20° C.). Analysis of the resulting mixture revealed 10.7 g trichlorobromomethane (54 mmol, 89% yield).

Example 4

4% Bromine in Chloroform, 470 nm

(4) A solution of 19.9 g (124.5 mmol) bromine in 477 g (4 mol) chloroform is radiated for 7 h by 100 LEDs' (wavelength 470 nm, 20° C.). Analysis of the resulting mixture revealed 20.4 g trichlorobromomethane (103 mmol, 83% yield).

Example 5

4% Bromine in Chloroform, 405 nm

(5) A solution of 130 g (810 mmol) bromine in 3120 g (26 mol) chloroform is radiated for 3.5 h by 88 LEDs' (wavelength 405 nm, 20° C.). Analysis of the resulting mixture revealed 132.2 g trichlorobromomethane (667 mmol, 82%).

Example 6-24

Continuous Flow Reactor

(6) A solution of bromine in chloroform was pumped through a photo continuous flow reactor at various temperature and flow rates, as shown in the following table. Samples of the resulting reaction mixtures were taken and analyzed by gas chromatography.

(7) TABLE-US-00001 Temperature Br.sub.2 in CHCl.sub.3 Flow rate CBrCl.sub.3 Yield Example [° C.] [%] [g/h] [g/h] [%] 6 15 5.0 269.48 8.08 48.0 7 15 5.0 314.11 0.02 41.1 8 15 5.0 357.95 8.23 37.9 9 15 5.0 379.92 7.98 34.5 10 35 5.0 264.30 15.33 92.8 11 35 5.0 303.03 17.58 92.8 12 35 5.0 338.38 19.63 92.8 13 35 5.0 371.24 20.79 89.6 15 50 5.2 386.04 22.78 94.4 16 50 5.2 545.03 34.34 98.5 17 50 5.2 633.46 39.91 98.5 18 50 5.2 719.93 44.64 97.0 19 50 5.2 803.47 47.40 92.3 20 59 5.0 562.98 34.90 100.6 21 59 5.0 717.81 44.50 100.6 22 59 5.0 870.41 53.97 100.6 23 59 5.0 1038.42 63.34 99.0 24 59 5.0 1192.73 71.56 97.4

Example 25

Bromination with Br.SUB.2 .and HBrO.SUB.3., 405 nm LED

(8) A 2 l reaction vessel, equipped with a 405 nm LED photo closed loop reactor, is charged with 25 g (0.1564 mol) bromine dissolved in 1800 g chloroform. A solution of 11.8 g (0.0782 mol) sodium bromate in 75 g water and 7.67 g (0.04 mol) 50% H.sub.2SO.sub.4 is added. The biphasic system is stirred slowly at 25° C. The lower, organic phase is pumped for 7.25 h through the photo loop reactor and irradiated from 88 LEDs, emitting light at 405 nm. The reaction mixture gets colorless when conversion is completed. After separation of the two phases, the organic phase is analyzed by gas chromatography. 1826.9 g (4.2%, 75.63 g, 0.3814 mol, 97.6%) bromotrichloromethane are obtained.

Example 26

Bromination with Br.SUB.2 .and HBrO.SUB.3., White LEDs

(9) A 2 l reaction vessel, equipped with a LED lamp (720 Lumen), is charged with 10 g (0.0626 mol) bromine dissolved in 882 g chloroform. A solution of 4.72 g (0.0313 mol) sodium bromate in 60 g water and 3.07 g (0.0156 mol) 50% H.sub.2SO.sub.4 is added. The biphasic system is stirred vigorously at 30° C. and irradiated with a LED lamp, emitting white light. The reaction mixture gets colorless when conversion is completed. After separation of the two phases, the organic phase is analyzed by gas chromatography. 905.2 g (3.46%, 31.3 g, 0.158 mol, 100%) bromotrichloromethane are obtained.

Example 27

Bromination with HBr and HBrO.SUB.3., 470 nm LED

(10) A 470 nm LED photo closed loop reactor, is charged with 259 g chloroform, a solution of 13.7 g (0.0906 mol) sodium bromate in 45 g water and 9.26 g (0.0906 mol) 96% H.sub.2SO.sub.4. 29.3 g (0.181 mol) 50% HBr is added within 30 min. The biphasic mixture is irradiated at 40° C. from 100 LEDs, emitting light at 470 nm. The reaction mixture gets colorless when conversion is completed. After separation of the two phases, the organic phase is analyzed by gas chromatography. 274.4 g (18.5 w %, 0.256 mol, 94.2%) bromotrichloromethane are obtained.

Comparative Examples

(11) A solution of bromine in chloroform was irradiated a certain period of time with light from a medium pressure mercury lamp (TQ150Z2) or from monochromatic diodes as indicated below. Afterwards, a sample was taken, washed with aqueous sodium carbonate and measured by GC. The ratio chloroform/bromodichloromethane was calculated from the area % of each individual compound and is displayed in table 1 below:

(12) TABLE-US-00002 TABLE 1 w % Ratio No Br2 t (h) λ (nm) (BrCCl.sub.3/BrCHCl.sub.2) 1* 4 7 470 265 2* 6 4 405 >265 3** 10  5 TQ150Z2 3.8 4** 2 7 TQ150Z2 5.9 *according to the present invention **comparative example

(13) The results in table 1 show that high amounts of by-product bromodichloromethane (bp.: 90° C.) was produced, if medium pressure mercury lamp (TQ150Z2) was used as radiation source.