JP2003261477A - Method for producing (z)-1,2,3,3,4,4-hexafluorocyclobutane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing Z-1,2,3,3,4,4-hexafluorocyclobutane which is a useful compound affording a substitute compound for CFC or HCFC used as a refrigerant, a foaming agent or a detergent in high yield. <P>SOLUTION: This method for producing the (Z)-1,2,3,3,4,4- hexafluorocyclobutane comprises carrying out a hydrogenating reaction (hydrogen reduction) of 1,2-dichlorohexafluorocyclobutane as a raw material in the presence of a rhodium catalyst using especially ≥2 equivalents of hydrogen especially at 150-300°C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is a useful compound (Z) -1,2,3, which can be a substitute compound for CFC and HCFC used as a refrigerant, a foaming agent, and a cleaning agent.
The present invention relates to a method for producing 3,4,4-hexafluorocyclobutane.

[0002]

2. Description of the Related Art As a reaction for obtaining hexafluorocyclobutene from 1,2-dichlorohexafluorocyclobutane, a method of reacting with zinc in alcohol [G. Fulle
r and J. C. Tatlow, J. Chem. Soc., 3198 (1961)] and the like are known.

However, this reaction requires a large amount of solvent, and the treatment of zinc chloride produced by the reaction requires a large amount of cost, so it cannot be said to be an effective process for industrial use.

Further, (Z) -1,2,3,3,4,4-
As a method for producing hexafluorocyclobutane, 1,
A method of reducing 2-dichlorohexafluorocyclobutane with lithium aluminum hydride (LiAlH ₄ ) is known (the above document).

However, according to this known method, the yield of the desired (Z) -1,2,3,3,4,4-hexafluorocyclobutane is as low as 30%, which is a geometric isomer of the desired product. (E) -1,2,3,3,4,4-hexafluorocyclobutane is produced as a by-product in a large amount and is not industrially suitable. Here, (Z) means a Z-form, which corresponds to a cis-form, and (E) means E.
It means the body and corresponds to the trans body.

[0006]

The object of the present invention is to obtain 1,2-dichlorohexafluorocyclobutane in order to obtain (Z) -1,2,3,3,4,4-hexafluorocyclobutane in good yield. By the hydrogen reduction reaction of (Z)-
It is to provide a method for producing 1,2,3,3,4,4-hexafluorocyclobutane in high yield.

[0007]

Means for Solving the Problems The present inventor has (Z)-
As a result of diligent studies on the method for producing 1,2,3,3,4,4-hexafluorocyclobutane, if 1,2-dichlorohexafluorocyclobutane was used as a raw material and hydrogen reduction was carried out in the presence of a rhodium catalyst, high yield was obtained. The inventors have found that the target product can be obtained at a high rate and a high selectivity, and have completed the present invention. This method of the present invention did not produce the geometric isomer (E) -1,2,3,3,4,4-hexafluorocyclobutane of the desired product.

That is, the gist of the present invention is that 1,2-dichlorohexafluorocyclobutane is used as a raw material, and hydrogen is used in an amount of 2 equivalents or more relative to the raw material, particularly in the presence of a rhodium catalyst at 150 to 300 ° C. By carrying out the hydrogenation reaction at a temperature, (Z) -1,2,
It is a method for producing 3,3,4,4-hexafluorocyclobutane.

Palladium, platinum, rhodium, Raney nickel and the like are known as catalysts for hydrogenolysis of halogen compounds, but palladium catalysts (Comparative Example 1 described later)
When 1,2-dichlorohexafluorocyclobutane is hydrogen-reduced using a platinum catalyst (Comparative Example 2 described later), not only the conversion rate of the raw material is low, but also the desired (Z)-
(E) -1,2,3,3,4,4- which is a geometric isomer of 1,2,3,3,4,4-hexafluorocyclobutane
Hexafluorocyclobutane is also formed and the selectivity is low.

On the other hand, when the rhodium catalyst is used according to the present invention, the conversion rate of the raw material is very high, and the geometrical isomer (E) -1,2,3,3,4, is used. Almost no or no 4-hexafluorocyclobutane is produced, and the desired product (Z) -1,2,3,3
It was revealed that 3,4,4-hexafluorocyclobutane can be obtained with high selectivity.

As a catalyst carrier, it is generally known that
A carrier composed of at least one selected from activated carbon, alumina, silica, zirconia and the like can be used, but activated carbon is most preferable and high selectivity of the target substance can be obtained.

The system of the gas phase reaction may be a fixed bed type gas phase reaction, a fluidized bed type gas phase reaction, or the like.

Although the particle size of the carrier has almost no effect on the reaction, it is preferably 0.1 to 10 mm.

A wide range of supported concentrations of 0.05 to 10% can be used, but normally 0.5 to 5% supported product is recommended.

The reaction temperature is usually 150 to 300 ° C, preferably 175 to 250 ° C. At a reaction temperature lower than 150 ° C, the selectivity is high, but the conversion rate tends to decrease, and at a reaction temperature higher than 300 ° C, a large amount of by-products are likely to be formed.

In the above-mentioned hydrogen reduction reaction of 1,2-dichlorohexafluorocyclobutane, the ratio of hydrogen to the raw material varies greatly as long as hydrogen is in a stoichiometric amount or more with respect to 1,2-dichlorohexafluorocyclobutane. Can be done. However, the hydrogenation is usually carried out using 2 to 10 times, especially 2 to 4 times the stoichiometric amount of hydrogen. A much greater than stoichiometric amount, based on the total moles of starting material, eg 1
0 mol or more hydrogen may be used. Excess hydrogen can be recovered and reused.

The reaction pressure is not particularly limited, and it can be carried out under pressure, under reduced pressure, or under normal pressure. However, since the apparatus becomes complicated under reduced pressure, it is preferable to carry out the reaction under pressure or under normal pressure.

The contact time is usually 0.1 to 300 seconds, especially 1 to 30 seconds.

1,2-Dichlorohexafluorocyclobutane, which is a raw material for this hydrogen reduction reaction, is 1,2,2-trifluoro-1-chloroethylene (chlorotrifluoroethylene) under pressure, especially 2 kg / cm ² or more. Pressure of
It can be synthesized by performing a gas phase dimerization reaction in a temperature range of 200 to 400 ° C.

Gas phase 2 of this chlorotrifluoroethylene
When the quantification reaction is carried out under normal pressure, the conversion becomes low at 500 ° C. or lower, and the selectivity decreases due to the formation of a linear compound having 4 carbon atoms at 500 ° C. or higher, which is suitable as an industrial production method. Disappear. However, if this reaction is carried out under pressure, 1,2-dichlorohexafluorocyclobutane can be synthesized with good conversion and selectivity even at 400 ° C. or lower.

The higher the pressure of this dimerization reaction,
The desired 1,2-dichlorohexafluorocyclobutane can be obtained with high conversion and high selectivity at low temperature. When the reaction pressure is further increased, a reactor having a high pressure resistance is required. Therefore, it is usually preferable to carry out the reaction at ² to ²⁰ kg / cm ² .

In this gas phase dimerization reaction, if the flow rate of chlorotrifluoroethylene as a raw material is reduced, the conversion rate improves, but the conversion rate can also be improved by using an appropriate filler. As the filler, glass beads,
Nickel beads, spherical silica, activated carbon and the like can be used.

[0023]

According to the method of the present invention, 1,2-dichlorohexafluorocyclobutane is used as a raw material and hydrogenation reaction (hydrogen reduction) is carried out in the presence of a rhodium catalyst to give a high yield. (Z) -1,2,3,3,4,4, which is a useful compound that can be a substitute compound for CFC or HCFC used as a refrigerant, a foaming agent, or a cleaning agent.
Hexafluorocyclobutane can be produced.

[0024]

The present invention will be described in more detail with reference to the following examples.

Example 1 Rhodium catalyst 1 supported on activated carbon at a concentration of 0.5% in a SUS316 reaction tube having an inner diameter of 7 mm and a length of 150 mm.
225 g in an electric furnace while charging nitrogen and flowing nitrogen gas
After heating to 0 ° C. and reaching a predetermined temperature, 1,2-dichlorohexafluorocyclobutane was introduced at a rate of 1.1 ml / min and hydrogen was introduced at a rate of 10.0 ml / min. Reaction temperature is 225
The temperature was kept at ℃. The produced gas was washed with water and then analyzed by gas chromatography. The results are shown in Table 1 below.

Example 2 The same reactor as in Example 1 was charged with 1 g of rhodium catalyst supported on activated carbon at a concentration of 3%, heated to 225 ° C. in an electric furnace while flowing nitrogen gas, and heated to a predetermined temperature. Then, 1,2-dichlorohexafluorocyclobutane was introduced at a rate of 1.4 ml / min and hydrogen was introduced at a rate of 10.0 ml / min. The reaction temperature was maintained at 225 ° C. The produced gas was washed with water and then analyzed by gas chromatography. The results are shown in Table 1 below.

Example 3 The same reactor as in Example 1 was charged with 1 g of rhodium catalyst supported on activated carbon at a concentration of 3%, heated to 250 ° C. in an electric furnace while flowing nitrogen gas, and heated to a predetermined temperature. Then, 1,2-dichlorohexafluorocyclobutane was introduced at a rate of 1.5 ml / min and hydrogen was introduced at a rate of 10.0 ml / min. The reaction temperature was kept at 250 ° C. The produced gas was washed with water and then analyzed by gas chromatography. The results are shown in Table 1 below.

Example 4 The same reactor as in Example 1 was charged with 1 g of rhodium catalyst supported on activated carbon at a concentration of 3%, heated to 150 ° C. in an electric furnace while flowing nitrogen gas, and heated to a predetermined temperature. Then, 1,2-dichlorohexafluorocyclobutane was introduced at a rate of 1.5 ml / min and hydrogen was introduced at a rate of 10.0 ml / min. The reaction temperature was maintained at 150 ° C. The produced gas was washed with water and then analyzed by gas chromatography. The results are shown in Table 1 below.

Comparative Example 1 The same reactor as in Example 1 was charged with 1 g of a palladium catalyst supported on activated carbon at a concentration of 0.5%, heated to 200 ° C. in an electric furnace while flowing a nitrogen gas, and then heated to a predetermined temperature. After the temperature was reached, 1,2-dichlorohexafluorocyclobutane was introduced at a rate of 1.7 ml / min and hydrogen was introduced at a rate of 10.0 ml / min. The reaction temperature was kept at 200 ° C. The produced gas was washed with water and then analyzed by gas chromatography. The results are shown in Table 1 below.

Comparative Example 2 The same reactor as in Example 1 was charged with 1 g of a platinum catalyst supported on activated carbon at a concentration of 0.5% and heated to 150 ° C. in an electric furnace while flowing a nitrogen gas to a predetermined temperature. After the temperature was reached, 1,2-dichlorohexafluorocyclobutane was introduced at a rate of 1.4 ml / min and hydrogen was introduced at a rate of 10.0 ml / min. The reaction temperature was maintained at 150 ° C. The produced gas was washed with water and then analyzed by gas chromatography. The results are shown in Table 1 below.

[0031]

[Table 1]

From this result, in the method according to the present invention,
It can be seen that the desired (Z) -1,2,3,3,4,4-hexafluorocyclobutane can be obtained with a high selectivity and can be obtained with a high reaction rate depending on the reaction temperature.

Example 5 In a reaction tube made of SUS316 having an inner diameter of 2 cm and a length of 40 cm,
20 ml of glass beads having a diameter of about 1 mm were filled, and the internal pressure of the reaction tube was adjusted to 2 kg / c by a reverse pressure adjusting valve while flowing nitrogen gas.
The temperature was adjusted to m ² , heated to 300 ° C. in an electric furnace, and after reaching a predetermined temperature, chlorotrifluoroethylene was introduced at a rate of 18 ml / min. The reaction temperature was kept at 300 ° C. The produced gas was analyzed by gas chromatography. The results are shown in Table 2 below.

Example 6 In the same apparatus as in Example 5, glass beads 2 having a diameter of about 1 mm were used.
0 ml was filled, the internal pressure of the reaction tube was adjusted to 2 kg / cm ² with a back pressure adjusting valve while flowing nitrogen gas, and 400 ° C. in an electric furnace.
After reaching a predetermined temperature, chlorotrifluoroethylene was introduced at a rate of 18 ml / min. The reaction temperature was kept at 400 ° C. The produced gas was analyzed by gas chromatography. The results are shown in Table 2 below.

Example 7 The same apparatus as in Example 5 was charged with 20 ml of nickel beads having a diameter of about 2 mm, the internal pressure of the reaction tube was adjusted to 4 kg / cm ² by a back pressure adjusting valve while flowing nitrogen gas, and the electric furnace was used. 350
After heating to ℃ and reaching a predetermined temperature, chlorotrifluoroethylene was introduced at a rate of 75 ml / min. The reaction temperature was kept at 350 ° C. The produced gas was analyzed by gas chromatography. The results are shown in Table 2 below.

Example 8 The same apparatus as in Example 5 was charged with 20 ml of spherical silica gel (CARIiACT) having a diameter of about 3 mm, the internal pressure of the reaction tube was adjusted to 4 kg / cm ² by a back pressure adjusting valve while flowing nitrogen gas, and electricity was supplied. After heating to 350 ° C. in a furnace and reaching a predetermined temperature, chlorotrifluoroethylene was introduced at a rate of 75 ml / min. The reaction temperature was kept at 350 ° C. The produced gas was analyzed by gas chromatography. The results are shown in Table 2 below.

[0037]

[Table 2]

From these results, it is possible to obtain 1,2-dichlorohexafluorocyclobutane used as a raw material in Examples 1 to 4 with high selectivity by subjecting chlorotrifluoroethylene to a gas phase dimerization reaction under pressure. I understand.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akinori Yamamoto             Daikin Co., Ltd. 1 Nishiichitsuya, Settsu City, Osaka Prefecture             Yodogawa Manufacturing Co., Ltd. F-term (reference) 4H006 AA02 AC13 AC28 BA24 BA55                       BC10 BC11 BC13 BC30 BC31                       BE20                 4H039 CA40 CD20 CE40

Claims (8)

[Claims] 1. A process for producing (Z) -1,2,3,3,4,4-hexafluorocyclobutane, which comprises hydrogenating 1,2-dichlorohexafluorocyclobutane in the presence of a rhodium catalyst by a gas phase method. . 2. The method according to claim 1, wherein a catalyst in which rhodium is supported on at least one carrier selected from activated carbon, alumina, silica and zirconia is used. 3. The supported concentration of the rhodium catalyst on the carrier is set to 0.
The manufacturing method according to claim 2, wherein the amount is set to 05 to 10%. 4. Hydrogen is used in an amount of 2 to 10 equivalents based on 1,2-dichlorohexafluorocyclobutane.
3. The manufacturing method described in any one of 3. 5. The production method according to any one of claims 1 to 4, wherein the reaction is performed in a temperature range of 150 to 300 ° C. 6. A dimerization reaction of 1,2,2-trifluoro-1-chloroethylene by a gas phase method
Synthesize 2-dichlorohexafluorocyclobutane,
The manufacturing method according to claim 1. 7. The production method according to claim 6, wherein the dimerization reaction is performed in a pressure range of ² to 20 kg / cm ² . 8. The production method according to claim 6, wherein the dimerization reaction is carried out in a temperature range of 200 to 400 ° C.