2, 3, 3, 3-tetrafluoropropene and preparation method thereof

Abstract

The invention discloses 2, 3, 3, 3-tetrafluoropropene and a preparation method thereof.The preparation method comprises the steps that hexafluoropropylene reacts with a metal hydride complex in the nitrogen atmosphere, and a product mixture containing 2, 3, 3, 3-tetrafluoropropene is obtained; wherein the molar ratio of the hexafluoropropylene to the metal hydride complex is (1: 3)-(3: 1); according to the preparation method, hexafluoropropylene is taken as a raw material and is directly subjected to a hydrogen-fluorine element selective exchange reaction with a metal hydride complex, the preparation of 2, 3, 3, 3-tetrafluoropropene is efficiently realized by a one-step method, and the preparation method is simple and easy to implement and is beneficial to industrial application; the adopted metal hydride complex has an efficient selective hydrogen-fluorine exchange characteristic, and has the characteristic of high selectivity when being used for preparing 2, 3, 3, 3-tetrafluoropropene through hydrofluorination of hexafluoropropylene.

Description

Technical Field

[0001] The invention belongs to the technical field of synthesis of organic compounds, and particularly relates to 2,3,3,3-tetrafluoropropylene and a preparation method thereof. Background Art

[0002] The fourth-generation refrigerant HFO-1234yf has attracted much attention. This product has the characteristics of zero ozone potential (0DP), slight flammability and low global warming potential (GWP). It is a new generation of ODS substitutes after hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) - hydrofluoroolefins (HFO). In recent years, with the EU's recognition of HFO-1234yf, HFO-1234yf is most likely to replace HFC-134a and become a new generation of automotive refrigerants.

[0003] The main industrialized routes currently include: 1) a two-step hydrogenation and two-step dehydrofluorination route using hexafluoropropylene as raw material; 2) a fluorine-chlorine exchange route using chloropropane or chloropropylene as raw material. Among them, the hexafluoropropylene process route first allows hydrogen to react with hexafluoropropylene (HFP) to generate hexafluoropropane by catalytic addition reaction, followed by elimination reaction to generate pentafluoropropylene (HFO-1225ye); the generated pentafluoropropylene (HFO-1225ye) also undergoes a catalytic addition reaction with hydrogen to generate pentafluoropropane, followed by elimination reaction to finally generate the product 2,3,3,3-tetrafluoropropylene (HFO-1234yf). The main chloropropanes / chloropropylenes are: 1) using tetrachloropropylene as raw material for fluorination to prepare 2-chloro-3,3,3-trifluoropropylene (HCFO-1233xf), and then fluorinating to obtain 2-chloro-2,3,3,3-tetrafluoropropane (HCFC-244bb), and finally dehydrochlorinating to obtain tetrafluoropropylene (HFO-1234yf); 2) using 1,1,1,2,3-pentachloropropane as raw material for reaction with hydrogen fluoride to obtain HCFO-1233xf, and then reacting with hydrogen fluoride to prepare HFO-1234yf.

[0004] In summary, the process of the above-mentioned route is relatively complicated, and multi-step reactions easily lead to problems such as low conversion rate, low selectivity, and poor stability. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and to provide a one-step and efficient method for preparing 2,3,3,3-tetrafluoropropene and the prepared 2,3,3,3-tetrafluoropropene.

[0006] The present invention provides a method for preparing 2,3,3,3-tetrafluoropropene, wherein hexafluoropropene is used as a raw material, and a hydrogen-fluorine element selective exchange reaction is directly carried out with a metal hydride complex, so that the preparation of 2,3,3,3-tetrafluoropropene is efficiently realized in one step. The specific process is: under a nitrogen atmosphere, hexafluoropropene and the metal hydride complex are reacted to obtain a product mixture containing 2,3,3,3-tetrafluoropropene; wherein the molar ratio of hexafluoropropene to the metal hydride complex is 1:3 to 3:1;

[0007] The chemical reaction process is as follows:

[0008]

[0009] Metal hydride complexes are prepared by the complexation of metal hydrides and ligands, which can participate in special hydrogen atom transfer processes.

[0010] Furthermore, the method further comprises passing the obtained product mixture containing 2,3,3,3-tetrafluoropropene into a distillation tower to obtain 2,3,3,3-tetrafluoropropene after separation.

[0011] Furthermore, the metal hydride complex is prepared by complexing a metal hydride with a ligand.

[0012] Furthermore, the metal in the metal hydride is selected from at least one of alkali metals, alkaline earth metals, and transition metals;

[0013] The alkali metal is selected from at least one of lithium, sodium and potassium;

[0014] The alkaline earth metal is selected from at least one of magnesium and calcium;

[0015] The transition metal is selected from at least one of manganese, iron, cobalt and nickel.

[0016] Furthermore, the ligand is selected from at least one of trimethylamine, N,N-dimethylethylamine, N,N-diethylmethylamine and N-methylpyrrolidone.

[0017] Furthermore, the metal content in the metal hydride complex is 5 to 40 wt%.

[0018] Furthermore, the reaction temperature of the hexafluoropropylene and the metal hydride complex is 50-120°C.

[0019] Furthermore, the reaction time of the hexafluoropropylene and the metal hydride complex is 5 to 10 hours.

[0020] Furthermore, the content of 2,3,3,3-tetrafluoropropene in the product mixture containing 2,3,3,3-tetrafluoropropene is 90-91 wt %; and the yield of 2,3,3,3-tetrafluoropropene is higher than 95%.

[0021] Also provided is 2,3,3,3-tetrafluoropropylene, wherein the 2,3,3,3-tetrafluoropropylene is prepared by the above-mentioned preparation method.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The preparation method of the present invention uses hexafluoropropylene as a raw material and directly carries out a hydrogen-fluorine element selective exchange reaction with a metal hydride complex, thereby realizing the preparation of 2,3,3,3-tetrafluoropropylene in a one-step and efficient manner. The preparation method is simple and easy to implement, and is conducive to industrial application;

[0024] 2) The metal hydride complex used in the present invention has a highly efficient and selective hydrogen-fluorine exchange characteristic and is highly selective for preparing 2,3,3,3-tetrafluoropropylene by hydrogenation of hexafluoropropylene. DETAILED DESCRIPTION

[0025] Example 1

[0026] 1) under a nitrogen atmosphere, reacting hexafluoropropylene and nickel hydride N-methylpyrrolidone complex in a molar ratio of 2:1 at 80° C. for 6 hours to obtain a product mixture containing 2,3,3,3-tetrafluoropropylene; the nickel content in the nickel hydride N-methylpyrrolidone complex is 10 wt%;

[0027] 2) The product mixture obtained in step 1) is introduced into a distillation tower to obtain 2,3,3,3-tetrafluoropropene after separation.

[0028] According to detection, the content of 2,3,3,3-tetrafluoropropene in the product mixture obtained in step 1) is 95wt%, and the yield of 2,3,3,3-tetrafluoropropene in step 2) is 99%.

[0029] Example 2

[0030] 1) under a nitrogen atmosphere, reacting hexafluoropropylene and magnesium hydride N,N-dimethylethylamine complex in a molar ratio of 1:2 at 110° C. for 6 hours to obtain a product mixture containing 2,3,3,3-tetrafluoropropylene; wherein the magnesium hydride N,N-dimethylethylamine complex has a magnesium content of 15 wt%;

[0031] 2) The product mixture obtained in step 1) is introduced into a distillation tower to obtain 2,3,3,3-tetrafluoropropene after separation.

[0032] According to detection, the content of 2,3,3,3-tetrafluoropropene in the product mixture obtained in step 1) is 92 wt %, and the yield of 2,3,3,3-tetrafluoropropene in step 2) is 96%.

[0033] Example 3

[0034] 1) under a nitrogen atmosphere, reacting hexafluoropropylene and sodium trimethylamine cyanide complex in a molar ratio of 1:1 at 60° C. for 10 h to obtain a product mixture containing 2,3,3,3-tetrafluoropropylene;

[0035] 2) passing the product mixture obtained in step 1) into a distillation tower to obtain 2,3,3,3-tetrafluoropropene after separation; wherein the sodium content in the sodium cyanide trimethylamine complex is 30wt%;

[0036] According to detection, the content of 2,3,3,3-tetrafluoropropene in the product mixture obtained in step 1) is 97 wt %, and the yield of 2,3,3,3-tetrafluoropropene in step 2) is 98%.

Claims

1. A method for preparing 2,3,3,3-tetrafluoropropene, characterized in that: The specific process is: under a nitrogen atmosphere, hexafluoropropylene reacts with a metal hydride complex to obtain a product mixture containing 2,3,3,3-tetrafluoropropylene; wherein the molar ratio of hexafluoropropylene to the metal hydride complex is 1:3 to 3:1; The chemical reaction process is as follows:

2. The method for preparing 2,3,3,3-tetrafluoropropene according to claim 1, characterized in that: The method also includes passing the prepared product mixture containing 2,3,3,3-tetrafluoropropene into a distillation tower to obtain 2,3,3,3-tetrafluoropropene after separation.

3. The method for preparing 2,3,3,3-tetrafluoropropene according to claim 1, characterized in that: The metal hydride complex is prepared by complexing a metal hydride with a ligand.

4. The method for preparing 2,3,3,3-tetrafluoropropene according to claim 3, characterized in that: The metal in the metal hydride is selected from at least one of alkali metals, alkaline earth metals and transition metals; The alkali metal is selected from at least one of lithium, sodium and potassium; The alkaline earth metal is selected from at least one of magnesium and calcium; The transition metal is selected from at least one of manganese, iron, cobalt and nickel.

5. The method for preparing 2,3,3,3-tetrafluoropropene according to claim 3, characterized in that: The ligand is selected from at least one of trimethylamine, N,N-dimethylethylamine, N,N-diethylmethylamine and N-methylpyrrolidone.

6. The method for preparing 2,3,3,3-tetrafluoropropene according to claim 3, characterized in that: The content of metal in the metal hydride complex is 5-40 wt%.

7. The method for preparing 2,3,3,3-tetrafluoropropene according to claim 1, characterized in that: The reaction temperature of the hexafluoropropylene and the metal hydride complex is 50-120°C.

8. The method for preparing 2,3,3,3-tetrafluoropropene according to claim 1, characterized in that: The reaction time of the hexafluoropropylene and the metal hydride complex is 5 to 10 hours.

9. The method for preparing 2,3,3,3-tetrafluoropropene according to claim 1, characterized in that: The content of 2,3,3,3-tetrafluoropropene in the product mixture containing 2,3,3,3-tetrafluoropropene is 90-91 wt%.

10. A 2,3,3,3-tetrafluoropropylene, characterized in that: The 2,3,3,3-tetrafluoropropylene is prepared by the preparation method according to claim 1.

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