Process for producing 1,2,3,4-tetrachlorohexafluorobutane

1. A process for producing 1,2,3,4-tetrachlorohexafluorobutane which process comprises:

(1) a step of chlorinating 1,3-butadiene, thereby preparing a mixture containing 1,2,3,4-tetrachlorobutane, and

(2) a step of allowing the 1,2,3,4-tetrachlorobutane prepared in the step (1) to react with a fluorine gas in the presence of a diluting gas in a gas phase, thereby preparing a mixture containing 1,2,3,4-tetrachlorohexafluorobutane.

2. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 1 wherein the step (2) comprises allowing the 1,2,3,4-tetrachlorobutane prepared in the step (1) to react with a fluorine gas in the absence of a catalyst, thereby preparing a mixture containing 1,2,3,4-tetrachlorohexafluorobutane.

3. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 1 wherein the step (1) comprises chlorinating 1,3-butadiene, thereby preparing a mixture containing 1,2,3,4-tetrachlorobutane and 3,4-dichlorobutene-1.

4. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 3 wherein the 1,2,3,4-tetrachlorobutane is a by-product.

5. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 1 which process further comprises:

(3) a step of separating 1,2,3,4-tetrachlorobutane from the mixture containing 1,2,3,4-tetrachlorobutane prepared in the step (1),

wherein the step (2) comprises allowing the 1,2,3,4-tetrachlorobutane prepared in the step (3) to react with a fluorine gas thereby preparing a mixture containing 1,2,3,4-tetrachlorohexafluorobutane.

6. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 1 which process further comprises:

(4) a step of separating 3,4-dichlorobutene-1 from the mixture containing 1,2,3,4-tetrachlorobutane prepared in the step (1) and

(5) a step of chlorinating the 3,4 dichlorobutene-1 prepared in the step (4), thereby preparing 1,2,3,4-tetrachlorobutane,

wherein the step (2) comprises allowing the 1,2,3,4-tetrachlorobutane prepared in the step (5) to react with a fluorine gas, thereby preparing a mixture containing 1,2,3,4-tetrachlorohexafluorobutane.

7. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 1 wherein the diluting gas is at least one gas selected from the group consisting of nitrogen, helium, argon, neon and hydrogen fluoride.

8. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 5 or 6 wherein the step (2) comprises allowing 1,2,3,4-tetrachlorobutane to react with a fluorine gas in a reactor having at least two feed openings by feeding a mixed gas (A) of 1,2,3,4-tetrachlorobutane prepared in the step (3) or (5) and the diluting gas from at least one feed opening and feeding a mixed gas (B) of a fluorine gas and the diluting gas from at least one of the other openings, thereby preparing a mixture containing 1,2,3,4-tetrachlorohexafluorobutane, and the concentration of 1,2,3,4-tetrachlorobutane is from 0.5 to 4% by mole based on the total amount of the mixed gases (A) and (B).

9. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 5 or 6 wherein the step (2) comprises allowing 1,2,3,4-tetrachlorobutane to react with a fluorine gas in a reactor having at least two feed openings by feeding a mixed gas (A) of 1,2,3,4-tetrachlorobutane prepared in the step (3) or (5) and the diluting gas from at least one feed opening and feeding a mixed gas (B) of a fluorine gas and the diluting gas from at least one of the other openings, thereby preparing a mixture containing 1,2,3,4-tetrachlorohexafluorobutane, and the concentration of a fluorine gas is from 0.5 to 10% by mole based on the total amount of the mixed gases (A) and (B).

10. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 5 or 6 wherein the step (2) comprises allowing the 1,2,3,4-tetrachlorobutane prepared in the step (3) or (5) to react with a fluorine gas at a pressure of from 0.05 to 1 MPa, thereby preparing a mixture containing 1,2,3,4-tetrachlorohexafluorobutane.

11. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 5 or 6 wherein the step (2) comprises allowing the 1,2,3,4-tetrachlorobutane prepared in the step (3) or (5) to react with a fluorine gas at a temperature of from 50 to 500° C., thereby preparing a mixture containing 1,2,3,4-tetrachlorohexafluorobutane.

12. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 8 which process further comprises:

(6) a step of liquid-liquid separating the mixture containing 1,2,3,4-tetrachlorohexafluorobutane prepared in the step (2) and allowing a resulting 1,2,3,4-tetrachlorohexafluorobutane-rich phase to contact with an alkali, thereby preparing crude 1,2,3,4-tetrachlorohexafluorobutane, and

(7) a step of dehydrating the crude 1,2,3,4-tetrachlorohexafluorobutane prepared in the step (6), thereby preparing crude 1,2,3,4-tetrachlorohexafluorobutane.

13. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 9 which process further comprises:

(6) a step of liquid-liquid separating the mixture containing 1,2,3,4-tetrachlorohexafluorobutane prepared in the step (2) and allowing a resulting 1,2,3,4-tetrachlorohexafluorobutane-rich phase to contact with an alkali, thereby preparing crude 1,2,3,4-tetrachlorohexafluorobutane, and

(7) a step of dehydrating the crude 1,2,3,4-tetrachlorohexafluorobutane prepared in the step (6), thereby preparing crude 1,2,3,4-tetrachlorohexafluorobutane.

14. The process for producing 1,2,3,4-tetrachlorohexafluorobutane according to claim 12 or 13 which further comprises (8) a step of feeding the crude 1,2,3,4-tetrachlorohexafluorobutane prepared in the step (7), to at least one distillation column, separating an intermediate in the reaction of step (2) and feeding at least a part of the intermediate to the reactor.