Process for the preparation of fluorinated compounds

Patent metadata

Field	Value
Publication number	US-9758451-B2
Application number	US-201514978789-A
Country	US
Kind code	B2
Filing date	Dec 22, 2015
Priority date	Sep 11, 2008
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A subject-matter of the invention is a process for the preparation of 2,3,3,3-tetrafluoro-1-propene which comprises the following stages: (i) hydrogenation of hexafluoropropylene to give 1,1,1,2,3,3-hexafluoropropane; (ii) dehydrofluorination of the 1,1,1,2,3,3-hexafluoropropane obtained in the preceding stage to give 1,2,3,3,3-pentafluoro-1-propene; (iii) hydrogenation of the 1,2,3,3,3-pentafluoro-1-propene obtained in the preceding stage to give 1,1,1,2,3-pentafluoropropane; and (iv) dehydrofluorination of the 1,1,1,2,3-pentafluoropropane obtained in the preceding stage to give 2,3,3,3-tetrafluoro-1-propene. Stages (ii) and (iv) are carried out using a water and potassium hydroxide mixture with the potassium hydroxide representing between 58 and 86% by weight of the mixture and at a temperature of between 110 and 180° C.

First claim

The invention claimed is:

1. A process for the preparation of 2,3,3,3-tetrafluoro-1-propene, comprising:
(i) hydrogenating hexafluoropropylene and 1,2,3,3,3-pentafluoro-1-propene in a single reactor to give 1,1,1,2,3,3-hexafluoropropane and 1,1,1,2,3-pentafluoropropane, respectively;
(ii) separating said 1,1,1,2,3,3-hexafluoropropane and 1,1,1,2,3-pentafluoropropane;
(iii) dehydrofluorinating said 1,1,1,2,3,3-hexafluoropropane and said 1,1,1,2,3-pentafluoropropane in separate reactors, to produce product streams comprising potassium fluoride and 1,2,3,3,3-pentafluoro-1-propene and 2,3,3,3-tetrafluoro-1-propene, respectively, using a water and potassium hydroxide mixture with the potassium hydroxide being between 58 and 86% by weight of the mixture; and
(iv) removing at a least a portion of the potassium fluoride produced in the dehydrofluorination step by a process including a filtration step.

2. The process of claim 1 , wherein dehydrofluorinating takes place at a temperature of between 110 and 180° C.

3. The process of claim 1 , further comprising recycling at least a portion of the 1,2,3,3,3-pentafluoro-1-propene produced in the dehydrofluorinating step back to the hydrogenating step.

4. The process according to claim 1 , wherein the potassium hydroxide is between 60 and 75% by weight of the water-potassium hydroxide mixture in the dehydrofluorinating step.

5. The process according to claim 1 , wherein dehydrofluorinating takes place at a temperature of between 152 and 165° C.

6. The process of claim 1 , wherein at least one product stream resulting from the dehydrofluorinating step is subjected to a purification.

7. The process of claim 1 , wherein the process is carried out continuously.

Assignees

• Arkema France

Inventors

• Pigamo Anne
• Devic Michel
• Wendlinger Laurent

Classifications

• Y02P20/582

  Recycling of unreacted starting or intermediate materials · CPC title

• C07C17/354

  by hydrogenation · CPC title

• C07C17/25 Primary

  by splitting-off hydrogen halides from halogenated hydrocarbons · CPC title

• C07C21/18

  containing fluorine · CPC title

• C07C19/08

  containing fluorine · CPC title