JPH0977701A - Production of dichlorohexafluorobutene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain dichlorohexafluorobutene which is useful as an intermediate for specific chlorofluorocarbon substitute, medicines and agrochemicals in high yield under mild conditions by fluorination of hexachloro-1,3-butadiene with antimony halide followed by regeneration of the antimony halide with a specific chemical. SOLUTION: (A) An antimony halide, for example, a mixture of a pentavalent antimony compound of an average formula SbFx Cly (x>0; x+y=5) with a trivalent antimony compound of SbFa Clb (a>0; a+b=3), is used to effect the liquid phase fluorination of (B) hexachloro-1,3-butadiene followed by regeneration of the component A with (C) anhydrous hydrogen fluoride and (D) chlorine to give 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to hexachloro-
1,3-Butadiene is fluorinated in the liquid phase to give 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2.
-A method for producing butenes. 2,3-dichloro-
1,1,1,4,4,4-hexafluoro-2-butene is not only useful as an intermediate raw material for HFCs used as a foaming agent, a cleaning agent or a refrigerant as a substitute for specific freon, etc. It is also useful as an intermediate such as.

[0002]

2. Description of the Prior Art 2,3-Dichloro-1,1,1,4,4,4 by fluorinating hexachloro-1,3-butadiene
As a method for obtaining hexafluoro-2-butene, a reaction between anhydrous hydrogen fluoride and chlorine in a gas phase in the presence of a catalyst is known (USP3965201, DE1278).
429, DE 393652 specification, etc.). However, these gas phase reactions require a reaction temperature of at least 300 ° C or higher. A method of reacting anhydrous hydrogen fluoride and chlorine in a liquid phase using antimony as a catalyst is also known, but the reaction time is long and the yield is low (USP243635).
No. 7). In addition, SbF ₃ as a fluorinating agent, S
A method of using an excess amount of bF ₃ Cl ₂ as an oxidant is also known (J. Am. Chem. Soc. [69] p.
1820 (1947)), it is difficult to carry out industrially because a large amount of expensive antimony is used.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to fluorinate hexachloro-1,3-butadiene in a liquid phase under mild conditions in good yield to give 2,3-dichloro-1,1,1,
It is to provide a method for producing 4,4,4-hexafluoro-2-butene.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have fluorinated hexachloro-1,3-butadiene in a liquid phase to give 2,
As a result of earnest research on a method for producing 3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene, hexachloro-1 was obtained by using antimony halide as a fluorinating agent and an oxidizing agent. It was found that antimony halide as a fluorinating agent and an oxidizing agent can be easily regenerated with anhydrous hydrogen fluoride and chlorine after completion of fluorination of 3,3-butadiene, and the present invention has been completed.

That is, the present invention relates to hexachloro-1,3-
Fluorination of butadiene in the liquid phase gives 2,3-dichloro-
In producing 1,1,1,4,4,4-hexafluoro-2-butene, antimony halide is used as a fluorinating agent and an oxidizing agent, and anhydrous after the fluorination of hexachloro-1,3-butadiene is completed. 2,3-dichloro-1, characterized by regenerating antimony halide as a fluorinating agent and an oxidizing agent with hydrogen fluoride and chlorine,
The present invention relates to a method for producing 1,1,4,4,4-hexafluoro-2-butene.

In accordance with the present invention, the reaction and regeneration are repeated to produce a substantially catalytic amount of antimony 2,3-dichloro-.
1,1,1,4,4,4-hexafluoro-2-butene can be produced in high yield. Hexachloro-1,
3-butadiene to 2,3-dichloro-1,1,1,
In order to obtain 4,4,4-hexafluoro-2-butene, pentavalent antimony halide is required as an oxidant as well as a fluorinating agent.

The form of antimony may be pentavalent antimony halide containing fluorine, but preferably SbF _x Cl _y (x> 0, x +) as an average composition.
It is a pentavalent antimony represented by y = 5). In the method of the present invention, the amount of pentavalent antimony used can be greatly changed, and may be in the range of 0.1 to 20 times the molar ratio to hexachloro-1,3-butadiene. To increase the conversion of raw materials, hexachloro-
The stoichiometric amount or more is preferable with respect to 1,3-butadiene, and the molar ratio may be 1 to 10 times, preferably 2 to 5 times.

Trivalent antimony halide is also effective as the fluorinating agent. Further, it can be used in the reaction as a mixture of pentavalent antimony halide and trivalent antimony halide containing fluorine, and preferably has an average composition of SbF _x Cl _y (x> 0, x + y = 5). With pentavalent antimony and SbF _a Cl _b (a> 0,
It can be used in the reaction as a mixture with trivalent antimony represented by a + b = 3). Since the reaction proceeds even with pentavalent antimony, the amount of trivalent used may be in the range of 0 to 10 times, preferably 0 to 2 times the molar ratio of hexachloro-1,3-butadiene.

The antimony halide used as a fluorinating agent for hexachloro-1,3-butadiene only needs to be partially fluorinated, but in order to increase the conversion rate of the raw material, a stoichiometric amount of fluorine atom or more is required. It is preferable to include. The stoichiometric amount in this case is an amount of fluorine atoms corresponding to 6 times the mole of hexachloro-1,3-butadiene.

If the reaction temperature for fluorinating hexachloro-1,3-butadiene is too low, the production rate will be slow, and if it is too high, by-products will increase and the pressure will increase, so that the reaction temperature will range from room temperature to 300 ° C. It is sufficient that the temperature is in the range of 50 to 200 ° C. The reaction pressure can be adjusted by pulling the product out of the system so that the reaction pressure does not become too high, but the reaction pressure may be left to the progress and is not particularly limited.

After the fluorination of hexachloro-1,3-butadiene, when regenerating antimony halide as a fluorinating agent and an oxidizing agent with anhydrous hydrogen fluoride and chlorine, antimony and antimony are added to suppress side reactions. It is preferable to separate the product and the unreacted raw material, and the separation method is preferably to extract the product and the unreacted raw material by distillation.

Regeneration of antimony halide is carried out by a step of fluorination with anhydrous hydrogen fluoride and from trivalent to 5 with chlorine.
It consists of the process of oxidation to valence. The fluorination and the chlorine oxidation may be performed simultaneously or separately, but hydrogen chloride is by-produced in the fluorination reaction, and it is necessary to remove it, so it is preferable to perform it sequentially. Either of the order of fluorination and chlorine oxidation may be performed first, but since trivalent antimony fluoride is a solid having a high melting point, it is preferable to perform chlorine oxidation first because it is easy to handle.

The amount of chlorine used for regeneration may be in the range of 0.1 to 20 times the molar ratio of trivalent antimony in the system, and the amount of pentavalent antimony after chlorine oxidation is In addition, the amount may be sufficient to produce 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene from hexachloro-1,3-butadiene.
The reaction temperature for chlorine oxidation may be in the range of 0 ° C to 300 ° C, preferably 30 ° C to 150 ° C.

When fluorinating antimony, the amount of anhydrous hydrogen fluoride to be used in the reaction can be varied greatly. However, similar to chlorine oxidation, the amount of fluorine on trivalent and pentavalent antimony after fluorination is as follows. From hexachloro-1,3-butadiene to 2,3-dichloro-1,1,1,4,4,4-
The amount may be sufficient to produce hexafluoro-2-butene. Reaction temperature is from 0 ℃ to 300 ℃
In the range of, preferably from 50 ℃ to 150 ℃
Range. The reaction pressure is from normal pressure to 5 MPa, preferably from 0.2 MPa to 2 MPa, and it is preferable to withdraw the hydrogen chloride produced as a by-product from the system.

When the amount of trivalent antimony halide is large during the reproduction of antimony halide, the solidification is likely to occur. In particular, since antimony trifluoride has a high melting point of 292 ° C., it becomes difficult to handle it when the proportion of antimony halide is large. According to the knowledge of the present inventors, in order to maintain the fluidity of antimony halide, it is necessary to add 5 to trivalent antimony.
It is preferable that the ratio of valency antimony is 2 or more in molar ratio. Within the range, it can be handled as a fluid substance under a temperature condition of at least 100 ° C.

After regenerating the antimony halide and before fluorinating the hexachloro-1,3-butadiene,
It is desirable to sufficiently remove anhydrous hydrogen fluoride, hydrogen chloride and chlorine in the system. When these are present, a by-product is produced and the selectivity of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene is lowered. Especially in the presence of anhydrous hydrogen fluoride, 2-chloro-1,1,1,4,4,4-, in which one of the chlorines in the molecule is replaced by hydrogen
Hexafluoro-2-butene is easily generated. 2,3-dichloro-1,1,1,4,4,4 with a selectivity of 90% or more
In order to obtain hexafluoro-2-butene, hexachloro-1,3 which reacts with the amount of residual anhydrous hydrogen fluoride
-It is desirable to make it 10 mol% or less of butadiene.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following examples.

[0018]

Example 1 72.2 g (0.40 g) of antimony trifluoride
Mol) and 24.9 g of chlorine (0.35 mol) in 200 ml
Was charged into the Hastelloy C reactor. The reactor is equipped with a stirrer, condenser, thermometer and pressure gauge, and the outlet of the condenser is equipped with a valve for adjusting the pressure. A 500 W mantle heater was attached to this reactor to start heating. Inner temperature is 135 ° C
The antimony was chlorinated by keeping the temperature at 70 ° C. and the temperature was lowered to 70 ° C. or lower after the pressure drop stopped. Hexachloro-1,3
-Butadiene 26.1 g (0.10 mol) was fed into the reactor and reacted at 100 ° C for 30 minutes and at 155 ° C for 2 hours. The reaction pressure was 0.1 MPa to 0.75 MPa in gauge pressure as a result of being left as it was. Temperature 15
The pressure was released while the temperature was kept at 5 ° C, and the product was extracted through a condenser.

As a result of analysis by gas chromatography,
2,3-Dichloro-1,1,1,4,4,4-hexafluoro-2-butene was obtained with a yield of 95%. Next, the reactor was cooled, 14 g (0.7 mol) of anhydrous hydrogen fluoride was fed, and the temperature was raised to 100 ° C. Reaction pressure 1MP
It was kept at a and reacted until the hydrogen chloride gas disappeared.
The inside of the reactor was in a fluid state and was in a state capable of stirring.
After releasing the pressure and purging with nitrogen at 80 ° C. to drive off unreacted anhydrous hydrogen fluoride, 7.8 g (0.11 mol) of chlorine was fed. After chlorination under the above-mentioned conditions, it was cooled to 70 ° C. or lower and hexachloro-1,3-butadiene 26.1
g (0.10 mol) was fed into the reactor. 100
After reacting at 30 ° C. for 30 minutes and at 155 ° C. for 2 hours, the product was extracted through a condenser.

As a result of analysis by gas chromatography,
2,3-Dichloro-1,1,1,4,4,4-hexafluoro-2-butene was obtained with a yield of 94%.

[0021]

Example 2 The same procedure as in Example 1 was carried out except that the antimony regeneration method was first chlorinated with chlorine and then hydrated with anhydrous hydrogen fluoride. The reaction after regeneration gave 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene in a yield of 94%.

[0022]

Example 3 72.2 g (0.40 g) of antimony trifluoride
Mol) and chlorine 17.8 g (0.25 mol) in 200 ml
Was charged into the Hastelloy C reactor. The reactor is equipped with a stirrer, condenser, thermometer and pressure gauge, and the outlet of the condenser is equipped with a valve for adjusting the pressure. A 500 W mantle heater was attached to this reactor to start heating. Inner temperature is 135 ° C
The antimony was chlorinated by keeping the temperature at 70 ° C. and the temperature was lowered to 70 ° C. or lower after the pressure drop stopped. Hexachloro-1,3
-Butadiene (39.2 g, 0.15 mol) was fed into the reactor and reacted at 100 ° C for 30 minutes and at 155 ° C for 2 hours. The reaction pressure was 0.1 MPa to 0.75 MPa in gauge pressure as a result of being left as it was. Temperature 15
The pressure was released while the temperature was kept at 5 ° C, and the product was extracted through a condenser.

As a result of analysis by gas chromatography,
2,3-Dichloro-1,1,1,4,4,4-hexafluoro-2-butene was obtained with a yield of 95%. Next, the reactor was cooled, 22 g (1.1 mol) of anhydrous hydrogen fluoride was fed, and the temperature was raised to 100 ° C. Reaction pressure 1MP
It was kept at a and reacted until the hydrogen chloride gas disappeared.
At this point, the stirrer hardly rotated, and the inside of the reactor was in a state where it could not be stirred. After releasing the pressure and purging with nitrogen at 80 ° C to drive off unreacted anhydrous hydrogen fluoride, chlorine 1
2.1 g (0.17 mol) was fed. After chlorinating under the above conditions, cool it to below 70 ° C and add hexachloro-
39.2 g (0.15 mol) of 1,3-butadiene was fed into the reactor. 30 minutes at 100 ℃, 2 at 155 ℃
After reacting for a time, the product was extracted through a condenser.

As a result of analysis by gas chromatography,
2,3-Dichloro-1,1,1,4,4,4-hexafluoro-2-butene was obtained with a yield of 92%.

[0025]

[Comparative Example 1] The same procedure as in Example 1 was carried out except that the temperature at which anhydrous hydrogen fluoride was removed during regeneration of antimony was set to 50 ° C. Calculated from the amounts of hydrogen fluoride and hydrogen chloride extracted, 0.8 g (0.04 mol) of anhydrous hydrogen fluoride remained inside the reactor. 2,3-dichloro-in the reaction after regeneration
1,1,1,4,4,4-hexafluoro-2-butene was obtained with a yield of 72%, and 2-chloro-1, as a by-product,
1,1,4,4,4-hexafluoro-2-butene was obtained with a yield of 21%.

[0026]

INDUSTRIAL APPLICABILITY According to the production method of the present invention, it is useful not only as an intermediate raw material for HFCs used as a foaming agent, a cleaning agent or a refrigerant as a substitute for specific CFCs, but also as an intermediate for medical and agricultural chemicals. , 2,3-dichloro-1,
1,1,4,4,4-hexafluoro-2-butene,
It can be produced in good yield in a liquid phase under mild conditions.

Claims (4)

[Claims] 1. Hexachloro-1,3-butadiene is fluorinated in the liquid phase to give 2,3-dichloro-1,1,1,
When producing 4,4,4-hexafluoro-2-butene, antimony halide is used as a fluorinating agent and an oxidizing agent, and after completion of fluorination of hexachloro-1,3-butadiene, anhydrous hydrogen fluoride and chlorine are added. 2,3-dichloro-1,1,1,4, characterized in that antimony halide as a fluorinating agent and an oxidizing agent is regenerated with
A method for producing 4,4-hexafluoro-2-butene. 2. Antimony halide used as a fluorinating agent and an oxidizing agent has an average composition of SbF _x Cl.
The method according to claim 1, which is pentavalent antimony represented by _y (x> 0, x + y = 5). 3. An antimony halide used as a fluorinating agent and an oxidizing agent has an average composition of SbF _x Cl.
pentavalent antimony represented by _y (x> 0, x + y = 5) and 3 represented by SbF _a Cl _b (a> 0, a + b = 3)
Process according to claim 1, characterized in that it is a mixture with valency antimony. 4. The method according to claim 1, wherein the ratio of pentavalent to trivalent antimony is 2 or more in terms of moles in the stage after the completion of the fluorination of hexachloro-1,3-butadiene. .