Method for producing 1-chloro-2,2-difluoroethane

• US 10,640,439 B2
• Filed: 09/25/2017
• Issued: 05/05/2020
• Est. Priority Date: 09/27/2016
• Status: Active Grant

• Current Assignee: Arkema France (Arkema)
• Original Assignee: Arkema France (Arkema)
• Inventors: Garrait, Dominique, Herdt, Charlotte, Scherpereel, Camille
• Primary Examiner(s): Bahta, Medhanit W
• Application Number:
  US16/333,600
• Publication Number:
  US 20200002253A1
• Time in Patent Office: Days
• Field of Search: None
• CPC Class Codes: C07C 17/206 the other compound being HX
• CPC Class Codes: C07C 17/38 Separation; Purification; Stabilisation; Use of additives
• CPC Class Codes: C07C 17/383 by distillation
• CPC Class Codes: C07C 19/12 having two carbon atoms

Abstract

The invention relates to a method for producing 1-chloro-2,2-difluoroethane from 1,1,2-trichloroethane, comprising at least one step of separating 1-chloro-2,2-difluoroethane from the organic phase produced during the method; said step comprising a) purification of the organic phase obtained in step (iii) so as to form a first stream comprising 1-chloro-difluoroethane and hydrofluoric acid and a second stream comprising 1,1,2-trichloroethane; b) the elimination of the hydrofluoric acid from said first stream in order to form a third stream comprising 1-chloro-difluoroethane; and c) a purification of said third stream comprising 1-chloro-difluoroethane.

Claims

1. A process for producing 1-chloro-2,2-difluoroethane from 1,1,2-trichloroethane, comprising:

(i) at least one step comprising reacting the 1,1,2-trichloroethane with hydrofluoric acid in the gas phase, in the presence or absence of a fluorination catalyst, so as to give a stream comprising 1-chloro-2,2-difluoroethane, hydrochloric acid, hydrofluoric acid, unreacted 1,1,2-trichloroethane and at least one compound A selected from the group consisting of 1,2-dichloroethylenes (cis and trans), 1-chloro-2-fluoroethylenes (cis and trans), and 1,2-dichloro-2-fluoroethane;

(ii) at least one step comprising separating the compounds resulting from the reaction step, so as to give a first stream comprising hydrochloric acid and a second stream comprising hydrofluoric acid, 1-chloro-2,2-difluoroethane, at least a portion of the at least one compound A and unreacted 1,1,2-trichloroethane;

(iii) at least one step comprising separating the second stream, so as to give an organic phase comprising the 1-chloro-2,2-difluoroethane, at least a portion of the at least one compound A, HF and unreacted 1,1,2-trichloroethane and a nonorganic phase comprising HF; and

(iv) at least one step comprising separating the 1-chloro-2,2-difluoroethane from the organic phase obtained in (iii);

wherein step (iv) comprises;

a) purifying the organic phase obtained in step (iii) so as to form a first stream comprising 1-chloro-2,2-difluoroethane, at least a portion of the at least one compound A and hydrofluoric acid and a second stream comprising 1,1,2-trichloroethane;

b) eliminating the hydrofluoric acid from said first stream so as to form a third stream comprising 1-chloro-2,2-difluoroethane and at least a portion of the at least one compound A; and

c) purifying said third stream comprising 1-chloro-2,2-difluoroethane.

2. The process as claimed in claim 1, wherein step a) of purification of the organic phase obtained in (iii) is a distillation, carried out at a temperature between 30 and 80°

C. and at an absolute pressure of between 1 and 4 bar.

3. The process as claimed in claim 1, wherein the second stream comprising 1,1,2-trichloroethane from step (iv)(a) is recycled to step (i).

4. The process as claimed in claim 1, wherein step b) comprises a step of washing said first stream so as to form an intermediate stream B comprising 1-chloro-2,2-difluoroethane and said at least one of the compounds A selected from the group consisting of cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, cis-1-chloro-2-fluoroethylene, trans-1-chloro-2-fluoroethylene and 1,2-dichloro-2-fluoroethane and an intermediate stream C comprising hydrofluoric acid.

5. The process as claimed in claim 4, wherein said intermediate stream B is dried so as to form said third stream.

6. The process as claimed in claim 5, wherein the drying is carried out at a temperature of from 0 to 30°

C. and an absolute pressure of between 1 and 4 bar.

7. The process as claimed in claim 1, wherein the first stream obtained in step a) and the third stream obtained in step b) also comprise trans-1,2-dichloroethylene.

8. The process as claimed in claim 1, wherein step c) comprises at least one distillation.

9. The process as claimed in claim 4, wherein the first stream obtained in step a), the intermediate stream B and/or the third stream obtained in step b) comprise trans-1,2-dichloroethylene and at least one of the compounds A selected from the group consisting of cis-1,2-dichloroethylene, cis-1-chloro-2-fluoroethylene, trans-1-chloro-2-fluoroethylene and 1,2-dichloro-2-fluoroethane.

10. The process as claimed in claim 1, wherein the at least one compound A comprises trans-1,2-dichloroethylene and step c) forms a fourth stream comprising 1-chloro-2,2-difluoroethane and trans-1,2-dichloroethylene and a fifth stream comprising at least one of the compounds A selected from the group consisting of cis-1,2-dichloroethylene, cis-1-chloro-2-fluoroethylene, trans-1-chloro-2-fluoroethylene and 1,2-dichloro-1-fluoroethane.