JP7532576B2 - Uses of 1,1,2-trichloro-2-fluoroethene (TCFE) - Google Patents

Description

The present invention relates to a new method for producing 1,1,2-trichloro-2-fluoroethene (hereinafter referred to as TCFE or "trichloromonofluoroethene") and a new use thereof.

TCFE is a known substance (CAS No. 359-29-5), but no clear use has been found to date. Because the usefulness of TCFE has not been discovered, an efficient method for synthesizing TCFE has not been developed.

The object of the present invention is to provide a new method for efficiently producing TCFE. Another object of the present invention is to provide a new use for TCFE.

The present invention provides the following:
[1]
A method for producing 1,1,2-trichloro-2-fluoroethene (TCFE), comprising the steps of:
(a) fluorinating pentachloroethane at a temperature of 0-80° C. to produce monofluoropentachloroethane, and (b) reacting the monofluoropentachloroethane obtained in (a) with zinc to produce TCFE.
[2]
The method according to [1], wherein the fluorination in (a) is carried out using a mixture of _F2 gas and an inert gas with an _F2 gas concentration of 1 to 100% by volume.
[3]
The method according to [1] or [2], wherein the fluorination in (a) is carried out in a solvent.
[4]
The method according to any one of [1] to [3], wherein the reaction (b) is carried out at a temperature of −50 to 120° C.
[5]
The method according to any one of [1] to [4], wherein the reaction (b) is carried out in a solvent.
[6]
The method according to any one of [1] to [5], wherein the pentachloroethane used in (a) is obtained by chlorinating trichloroethene (TCE).
[7]
Use of a composition comprising 1,1,2-trichloro-2-fluoroethene (TCFE) as a solvent or cleaning agent.
[8]
Use of a composition comprising the TCFE according to [7] as a cleaning agent for cleaning flux or processing oil.
[9]
A method for removing contaminants from a substrate comprising contacting the substrate with a composition comprising TCFE.
[10]
The method according to claim 9, wherein the contaminant is a flux or a processing oil.

According to the present invention, a new method for efficiently producing TCFE from pentachloroethane via monofluoropentachloroethane is provided. According to the present invention, the process of fluorinating pentachloroethane to obtain monofluoropentachloroethane can be carried out with a conversion rate of almost 100% and a selectivity rate of 95% or more, and the process of obtaining TCFE from monofluoropentachloroethane can also be carried out with a conversion rate and selectivity rate of over 99%. Therefore, by combining a conventionally known method of obtaining pentachloroethane in high yield by chlorinating trichloroethene (TCE), the target TCFE can be obtained in a yield of 90% or more from easily available TCE. Since each process has a conversion rate of 99% or more and a selectivity of 95% or more, it is not necessary to isolate and purify the product before using it in the next process, and the work efficiency is extremely good. According to the present invention, a new use of TCFE, particularly as a solvent or cleaning agent, is also provided.

[Action]
Conventionally, the process of fluorinating pentachloroethane to obtain monofluoropentachloroethane has been considered to have poor reaction efficiency and should be carried out at a high reaction temperature of about 90°C. However, the present inventors unexpectedly found that by carrying out the above process at a low temperature of about 20°C, side reactions do not occur, the yield (conversion rate and selectivity) is improved, and monofluoropentachloroethane can be obtained in high yield. In the present invention, the reaction conditions were examined and the process of obtaining TCFE from monofluoropentachloroethane was also successfully carried out in high yield. Thus, according to the present invention, TCFE can be obtained in a yield of 90% or more from easily available TCE via pentachloroethane and monofluoropentachloroethane.

In accordance with the present invention, it has been unexpectedly discovered that TCFE is useful as a solvent, cleaning agent, and the like. It has also been discovered that TCFE is suitable for use as a cleaning agent, since its boiling point is 71°C and it can be easily dried.

[Production method of TCFE]
The present invention relates to a method for producing 1,1,2-trichloro-2-fluoroethene (TCFE), comprising the steps of:
This method comprises the steps of (a) fluorinating pentachloroethane at a temperature of 0 to 80° C. to produce monofluoropentachloroethane, and (b) reacting the monofluoropentachloroethane obtained in (a) with zinc to produce TCFE. The present invention is characterized in that the fluorination reaction in step (a) is carried out at a temperature of 0 to 80° C., particularly 10 to 30° C., and the dechlorination reaction in step (b) is carried out using zinc. By adopting such reaction conditions, the yields of steps (a) and (b) can both be carried out with a conversion rate of 99% or more and a selectivity of 95% or more, and therefore the reaction liquid can be used as a raw material for the next step without purification or isolation of the product between each step.

The fluorination in step (a) can be carried out using a mixture of _F2 gas with a _F2 gas concentration of 1 to 100% by volume, particularly 20 to 50% by volume, and an inert gas, such as nitrogen ( _N2 ) gas, He, Ne, Ar, or Xe.

Steps (a) and (b) can be carried out as a liquid phase reaction using a solvent that does not react with the fluorinating agent or zinc, such as an organic solvent such as carbon tetrachloride, perfluorocarbon (PFC), hydrofluorocarbon (HFC), hydrochlorofluorocarbon (HCFC), chlorofluorocarbon (CFC), perfluoroether (PFE), hydrofluoroether (HFE), methanol, ethanol, 2-methoxyethanol, diglyme, tetrahydrofuran, N,N-dimethylformamide, dimethylsulfoxide, or acetonitrile. The melting point of the product (monofluoropentachloroethane) of step (a) is 101°C, so if no organic solvent is used, the product will be present as a solid in the reaction vessel at the reaction temperature of step (a). In addition, when step (b) is carried out at a temperature below 101°C, it is desirable to use an organic solvent and use the raw material of step (b) in the form of a solution. In particular, 2-methoxyethanol has a boiling point of 124°C, so it does not easily evaporate at room temperature, but it can be separated from the product by either reduced pressure distillation or normal pressure distillation.

The reaction in step (b) is desirably carried out at a temperature of -50 to 120°C, particularly -50 to 100°C, and particularly -20 to 80°C. From the standpoint of reaction efficiency and handling, it is also desirable that the zinc used in step (b) be in granular or powder form. If the solvents used in steps (a) and (b) are different, solvent replacement will be performed. This solvent replacement can be carried out, for example, by removing the solvent used in step (a) from the reaction vessel by distillation and adding the solvent used in step (b) to the reaction vessel.

The pentachloroethane used in step (a) can be obtained, for example, by chlorinating trichloroethene (TCE). The chlorination reaction of TCE is well known in the art, and can provide the raw material for step (a) in high yield.

[Uses of TCFE]
According to the present invention, a new use of TCFE as a solvent and cleaning agent has been found. TCFE can be mixed in any ratio with organic solvents such as ketones such as acetone and acetophenone, nitriles such as acetonitrile and propionitrile, ethers such as diisopropyl ether, t-butyl methyl ether, tetrahydrofuran, diglyme and 1,4-dioxane, sulfoxides such as dimethyl sulfoxide and sulfolane, amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone, hydrocarbons such as hexane, heptane, cyclohexane, benzene and toluene, and alcohols such as methanol, ethanol and isopropyl alcohol. Therefore, it was found that TCFE can be used in a wide range of applications as a mixed solvent. In addition, it was found that TCFE is particularly excellent in solubility of oil and can be suitably used as a cleaning agent. Since the boiling point of TCFE is 71°C, it dries easily and is suitable for use as a cleaning agent.

The present invention will be described with reference to the following examples, but the scope of the present invention is not limited to these examples.

（上記反応式において、「ｒｔ」は室温を意味し、「M」は反応基質のモル濃度（ｍｏｌ
／Ｌ）を意味し、「ｈ」は時間を意味し、Ｆ_２ガスの濃度は体積％である。） TCFE was produced from TCE according to the following reaction process.

(In the above reaction formula, "rt" means room temperature, and "M" means the molar concentration of the reactant (mol
/L), "h" means time, and the concentration of _F2 gas is in volume percent.

[Example 1] First _step (TCE → _C2Cl5H )
500g (3.8mol) of TCE was weighed into a 500mL glass three-neck flask. After replacing the inside of the system with nitrogen, the reaction solution was cooled in an ice bath. Then, _Cl2 was introduced at 180mL/min while stirring. After introducing 1.0 equivalent (270g, 3.8mol) of _Cl2 , nitrogen was introduced to expel _Cl2 remaining in the system. As a result, 723g (yield 99%) of the target pentachloroethane was obtained as a colorless transparent liquid with a GC purity of 97.9%.

[Example 2] _Second step ( _C2Cl5H → _{C2Cl5F )}
A 5L PFA (perfluoroalkoxyalkane resin) reactor equipped with a condenser was charged with 700g (3.5mol) of pentachloroethane and _3L of CCl4. The reactor was replaced with nitrogen, and the temperature of the reaction solution was adjusted to 20°C using a water bath. The nitrogen flow was then stopped, and 20% by volume _F2 / _N2 was introduced at 110mL/min (volume percent concentration in the mixed gas with _N2 ) for 91 hours (1.55 equivalents). After the introduction of _F2 was completed, the temperature was raised to room temperature under nitrogen flow. The reaction solution obtained was washed with 10mL of 5% by weight sodium bicarbonate water, and then analyzed by GC, and the conversion rate was 99% and the selectivity was 97%.

The present inventors have found that in the second step of the reaction process of _C2Cl5H → _{C2Cl5F ,} the selectivity of the product is increased in a specific temperature range by changing the reaction conditions and carrying out the reaction on a small scale multiple times, as shown in Table 1 below (at temperatures above 80°C, _{perchloroethene} (PCE) is mainly produced as a by-product, and at temperatures below 0°C, the reaction hardly proceeds). Note that since _C2Cl5F is a solid _, the introduction of _F2 gas is stopped at 0.5 equivalents without a solvent and at or below the melting point (101°C).

(Footnote) * Both conversion and selectivity were determined from the area percentage of GC analysis.

外観：白色固体
^１９ＦＮＭＲ（ＣＤＣｌ_３）：－６２．９（ｓ，１Ｆ）
^１３ＣＮＭＲ（ＣＤＣｌ_３）：１０１．０（ｄ，Ｊ＝３４Ｈｚ），１２２．０（ｄ，Ｊ＝３０９） The data for the product of step 2, C ₂ Cl ₅ F, is shown below.

Appearance: White solid
¹⁹ FNMR (CDCl ₃ ): -62.9 (s, 1F)
¹³ CNMR ( _CDCl3 ): 101.0 (d, J = 34 Hz), 122.0 (d, J = 309)

[Example 3] _Third step ( _C2Cl5F →TCFE)
291g (1.1 equivalents) of Zn powder and 200mL of 2-methoxyethanol were charged into a 2L glass three-neck flask equipped with a Dimroth condenser and a dropping funnel as a reactor, and the reactor was immersed in an ice bath. Then, 809g of C ₂ Cl ₅ F dissolved in 740mL of 2-methoxyethanol was charged into the dropping funnel. Then, the C ₂ Cl ₅ F solution was dropped over 5 hours, the temperature was raised to room temperature, and the mixture was stirred for another 12 hours. As a result, the conversion rate was 99% and the selectivity was 99% (determined by ¹⁹ F NMR), so the reaction was judged to be complete. The dropping funnel and Dimroth condenser were removed from the reactor, and a simple distillation apparatus was assembled. The temperature of the oil bath was gradually raised from 80°C to 120°C under normal pressure, and this was continued until no distillate was produced. As a result, 431g of TCFE crude product was obtained as a colorless, transparent liquid. The crude TCFE product was then purified by rectification. The fraction at the top of the column at 71° C. was collected, yielding 361.3 g of TCFE with a GC purity of 99% or more.

外観：無色透明液体
^１９Ｆ ＮＭＲ（ＣＤＣｌ_３）：－７８．６（ｓ，１Ｆ）
^１３Ｃ ＮＭＲ（ＣＤＣｌ_３）：１０７．５（ｄ，Ｊ＝４４Ｈｚ），１４３．２（ｄ，Ｊ＝３０２Ｈｚ）
沸点：７１℃
密度：１．５２７１（２５℃） Data for TCFE, the product of step 3, is shown below.

Appearance: Colorless transparent liquid
^19F NMR (CDCl ₃ ): -78.6 (s, 1F)
^13C NMR ( _CDCl3 ): 107.5 (d, J = 44 Hz), 143.2 (d, J = 302 Hz)
Boiling point: 71°C
Density: 1.5271 (25℃)

[Cleaning power evaluation test]
The solubility (cleaning ability) of each evaluation target in TCFE is shown in Table 2. The values in the table indicate the number of grams of each evaluation target dissolved in 100 g of solvent. "Compatible" means that 100 g of the evaluation target was dissolved in 100 g of solvent.

*1: Reference material: Development of Cleaning Technology, CMC Publishing *2: Zeorora (registered trademark) HTA, AE-3000, and AK-225 are all product names of cleaning agents.
*3: 1233Z is the abbreviation for cis-1-chloro-3,3,3-trifluoropropene.

As can be seen from Table 2 above, TCFE was mixed in any ratio with the punching oil, cutting oil, and natural oil (vegetable oil) tested, and abietic acid, the main component of the flux, showed 40 to 150 times the solubility of existing fluorine-based cleaners. In other words, it was found to have cleaning power.

Claims (2)

Use of a composition comprising 1,1,2-trichloro-2-fluoroethene (TCFE) as a solvent for dissolving flax or a processing oil comprising at least one selected from the group consisting of castor oil and olive oil . 2. The use of a composition comprising TCFE according to claim 1, wherein said flux comprises abietic acid.