JP7252771B2 - Method for producing 1-chloro-2,2-difluoroethylene - Google Patents

Description

The present invention relates to a method for producing 1-chloro-2,2-difluoroethylene using 1,2-dichloro-1,1-difluoroethane as a starting material. 1-Chloro-2,2-difluoroethylene is a useful compound as an intermediate in the production of electronic materials and medicines and agricultural chemicals.

Conventionally, as a method for producing 1-chloro-2,2-difluoroethylene using 1,2-dichloro-1,1-difluoroethane as a raw material, a stoichiometric amount or more of sodium hydroxide is used in a liquid phase. A method of reacting 1,2-dichloro-1,1-difluoroethane (see, for example, Patent Documents 1 and 2), using a reaction tube made of nickel, 1,2-dichloro-1,1- at 500 to 600 ° C. A method of circulating difluoroethane as a gas (see, eg, Patent Document 3) and a method of thermally decomposing at 800 to 1,000° C. are known (see, eg, Patent Document 4).

The conventional method described in Patent Document 1 or 2 has a problem that a large amount of waste liquid is generated due to the reaction with sodium hydroxide in the liquid phase. On the other hand, the methods described in Patent Literatures 3 and 4 have the problem that reactions at high temperatures of 600° C. or higher are required.

On the other hand, Patent Document 5 proposes a method of reacting 1,2-dichloro-1,1-difluoroethane in a gas phase under relatively low temperature conditions of 250 to 550° C. using a solid catalyst. In this method, the life of the catalyst (decrease in reaction conversion rate) when the reaction is carried out for a long time has not been studied, and the reaction is stable even if it is produced under relatively low temperature conditions and for a long time. There has been a desire for an industrially practicable method.

DE 28 46 812 A1. U.S. Pat. No. 2,709,181. U.S. Pat. No. 2,628,989. British Patent Application No. 774125. Japanese Patent Laid-Open No. 2018-127403.

In view of these prior arts, the object of the present invention is to provide a method for producing 1-chloro-2,2-difluoroethylene from 1,2-dichloro-1,1-difluoroethane as a raw material under relatively low temperature conditions. is possible, and the decrease in the reaction conversion rate is extremely small even when the production is carried out for a long time, and the method is more industrially practicable.

Accordingly, the present inventors have extensively studied a method for producing 1-chloro-2,2-difluoroethylene by reacting 1,2-dichloro-1,1-difluoroethane in the presence of a solid catalyst in a gas phase. 1-chloro-2,2-difluoro is obtained at a relatively low temperature by using two or more solid catalysts as a first catalyst and a second catalyst and reacting them in the presence of oxygen. To find a more industrially feasible method for producing 1-chloro-2,2-difluoroethylene, which is capable of producing ethylene and which causes extremely little decrease in reaction conversion rate even when production is carried out for a long time, The present invention has been completed. That is, the present invention relates to the following gists.

(1) 1-chloro-2,2-difluoroethylene in which 1,2-dichloro-1,1-difluoroethane is reacted in a gas phase in the presence of a solid catalyst containing a first catalyst and a second catalyst and oxygen manufacturing method

(2) the first catalyst is an alkali metal or alkaline earth metal oxide, chloride or fluoride; the second catalyst is a transition metal oxide, chloride or fluoride; and the second catalyst supported on a carrier in the presence of a solid catalyst.

(3) the first catalyst is an alkali metal or alkaline earth metal chloride, the second catalyst is a transition metal oxide, and the first catalyst and the second catalyst are supported on a carrier; The method for producing 1-chloro-2,2-difluoroethylene according to (1) above, wherein the reaction is performed in the presence of a solid catalyst.

(4) The method for producing 1-chloro-2,2-difluoroethylene according to any one of (1) to (3) above, wherein the reaction temperature is 250 to 550°C.

The process of the present invention provides an industrial process for producing 1-chloro-2,2-difluoroethylene, in which even when the reaction is continued for a long time under relatively low temperature conditions, the reaction conversion rate and selectivity decrease are extremely small. can.

The present invention will be described in detail below.

The raw material 1,2-dichloro-1,1-difluoroethane used in the present invention is easily prepared by the reaction of 1,1,2-trichloroethylene and hydrogen fluoride.

Specific examples of the alkali metal oxide as the first catalyst contained in the solid catalyst applicable to the present invention include lithium oxide, sodium oxide, potassium oxide, rubidium oxide, and cesium oxide.

Specific examples of the alkali metal chloride as the first catalyst contained in the solid catalyst applicable to the present invention include lithium chloride, sodium chloride, potassium chloride, rubidium chloride, and cesium chloride.

Specific examples of the alkali metal fluoride as the first catalyst contained in the solid catalyst applicable to the present invention include lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, and cesium fluoride. mentioned.

Specific examples of the alkaline earth metal oxide as the first catalyst contained in the solid catalyst applicable to the present invention include beryllium oxide, magnesium oxide, calcium oxide, strontium oxide and barium oxide.

Specific examples of the alkaline earth metal chloride as the first catalyst contained in the solid catalyst applicable to the present invention include beryllium chloride, magnesium chloride, calcium chloride, strontium chloride and barium chloride.

Alkaline earth metal fluorides as the first catalyst contained in the solid catalyst applicable to the present invention are specifically, for example, beryllium fluoride, magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride etc.

Specific examples of the transition metal oxide as the second catalyst contained in the solid catalyst applicable to the present invention include titanium (IV) oxide, vanadium (V) oxide, chromium (III) oxide, manganese oxide ( III), iron(II) oxide, iron(III) oxide, cobalt(II) oxide, cobalt(III) oxide, nickel(II) oxide, copper(II) oxide, zinc(II) oxide, zirconium(IV) oxide , niobium (V) oxide, molybdenum (VI) oxide, ruthenium (III) oxide, and the like.

Specific examples of the transition metal chloride as the second catalyst contained in the solid catalyst applicable to the present invention include titanium (IV) chloride, vanadium (V) chloride, chromium (III) chloride, manganese chloride ( III), iron(II) chloride, iron(III) chloride, cobalt(II) chloride, cobalt(III) chloride, nickel(II) chloride, copper(II) chloride, zinc(II) chloride, zirconium(IV) chloride , niobium chloride (V), molybdenum chloride (VI), ruthenium chloride (III), and the like.

Specific examples of the transition metal fluoride as the second catalyst contained in the solid catalyst applicable to the present invention include titanium (IV) fluoride, vanadium (V) fluoride, chromium (III) fluoride, Manganese (III) fluoride, iron (II) fluoride, iron (III) fluoride, cobalt (II) fluoride, cobalt (III) fluoride, nickel (II) fluoride, copper (II) fluoride, fluoride zinc (II) fluoride, zirconium (IV) fluoride, niobium (V) fluoride, molybdenum (VI) fluoride, ruthenium (III) fluoride and the like.

Examples of carriers applicable to the present invention include silica gel, alumina, magnesia, calcium carbonate, zirconium oxide and titanium oxide.

The alkali metal oxides, alkaline earth metal oxides, transition metal oxides, alkali metal chlorides, alkaline earth metal chlorides, transition metal chlorides, alkali metal fluorides and alkaline earth metal fluorides are added to these supports. A compound or transition metal fluoride is supported by physical mixing or chemical treatment.

As a supporting method, a method known to those skilled in the art in the technical field to which the present invention belongs can be used, but the present invention is not limited.

The amount of the catalyst supported on the carrier is preferably 0.1 to 50 weight ratios, more preferably 0.5 to 30 weight ratios, and even more preferably 1.0 to 20 weight ratios. If the amount of catalyst supported is less than 0.1 weight ratio, sufficient reaction conversion and selectivity may not be obtained. Conversely, even if the loading exceeds 50% by weight, it is difficult to obtain a sufficient increase in reaction conversion rate and selectivity in accordance with the added amount, and there is a possibility that side reactions may easily occur.

The solid catalyst used in the present invention, depending on the size of the reactor, is usually used as a powder or a compact of 1 mm to 30 mm. It may be used by carrying it on a carrier, or it may be formed by carrying a catalyst on a powder carrier and then using it.

The reaction method of the present invention usually uses a reaction tube made of quartz, Pyrex (registered trademark) glass, iron, or nickel, fills the reaction tube with a solid catalyst, heats to a predetermined temperature, and then adds a predetermined amount of oxygen. 1,2-Dichloro-1,1-difluoroethane diluted with nitrogen, helium, argon, or air containing nitrogen is supplied in a gaseous state to carry out the reaction.

The concentration of diluted 1,2-dichloro-1,1-difluoroethane applicable to the present invention ranges from 5.0% by volume to 50.0% by volume.

The oxygen concentration in the diluted 1,2-dichloro-1,1-difluoroethane applicable to the present invention is preferably 0.1% by volume to 20.0% by volume, more preferably 1.0% by volume to 20.0% by volume. 18.0% by volume is more preferred. If the oxygen concentration in the raw material gas is less than 0.1% by volume, it may not be possible to obtain a sufficient effect of suppressing a decrease in catalytic activity and selectivity during the continuation of the reaction.

The reaction temperature in the present invention is preferably 250°C to 550°C, more preferably 300°C to 500°C, and even more preferably 320°C to 450°C, although it depends on the type of solid catalyst. If the reaction temperature is lower than 250°C, a sufficient reaction conversion rate may not be obtained.

The reaction time (contact time with the catalyst) of the present invention can be shortened if the reaction temperature is high and lengthened if the reaction temperature is low in order to control the conversion rate and selectivity of the raw material. However, it is preferably 0.05 to 20 seconds, more preferably 0.1 to 10 seconds, even more preferably 0.3 to 5 seconds. If the reaction time is shorter than 0.05 seconds, sufficient reaction conversion and selectivity may not be obtained. A reaction may occur easily.

The post-treatment after the reaction of the present invention is not particularly limited, but in general, the product is cooled and liquefied, and then purified by distillation under normal or pressurized conditions to obtain purified 1-chloro- 2,2-difluoroethylene is obtained.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited only to these examples.

Example 1 Production of 1-chloro-2,2-difluoroethylene using 1.3% by weight cesium chloride/1.0% by weight ruthenium oxide-supported silica gel under the condition of 17.3% by volume of oxygen in the starting material

A quartz reaction tube with an inner diameter of 6.0 mm was filled with 1.3 wt% cesium chloride/1.0 wt% ruthenium oxide-supported silica gel (filling length: 8.0 mm), and nitrogen was passed through at 30 mL/min at 200°C. After drying for 1 hour, the temperature of the catalyst layer was set to 350° C., and a gas diluted with air to a concentration of 13.7% by volume of 1,2-dichloro-1,1-difluoroethane and a concentration of 17.3% by volume of oxygen was introduced into the reaction tube. The reaction was carried out by feeding at a rate of 13.9 mL/min.

As a result of gas chromatography analysis of the gas flowing out of the reaction tube immediately after the reaction, the conversion of 1,2-dichloro-1,1-difluoroethane was 10.0%, and the desired product, 1-chloro-2,2 - The selectivity for difluoroethylene was 100%.

After 60 minutes of continuing the reaction, the gas flowing out of the reaction tube was analyzed by gas chromatography. The selectivity for -2,2-difluoroethylene was 100%.

Comparative Example 1 Production of 1-chloro-2,2-difluoroethylene using 1.3% by weight cesium chloride/1.0% by weight ruthenium oxide-supported silica gel under conditions of 0.0% by volume oxygen in the raw material

A reaction was carried out in the same manner as in Example 1, except that nitrogen was used as the diluent gas instead of air, and the oxygen concentration in the raw material was adjusted to 0.0% by volume.

As a result of gas chromatography analysis of the gas flowing out of the reaction tube immediately after the reaction, the conversion of 1,2-dichloro-1,1-difluoroethane was 10.0%, and the desired product, 1-chloro-2,2 - The selectivity for difluoroethylene was 100%.

After 60 minutes of continuing the reaction, the gas flowing out of the reaction tube was analyzed by gas chromatography. - chloro-2,2-difluoroethylene selectivity is difficult to measure).

Comparative Example 2 Production of 1-chloro-2,2-difluoroethylene using 1.0% by weight cesium chloride-supported silica gel under conditions of 17.3% by volume oxygen in the raw material

A reaction was carried out in the same manner as in Example 1, except that silica gel supporting 1.0% by weight of cesium chloride was used as the solid catalyst.

As a result of gas chromatography analysis of the gas flowing out of the reaction tube immediately after the reaction, the conversion rate of 1,2-dichloro-1,1-difluoroethane was 2.0%, and the desired product, 1-chloro-2,2 - The selectivity for difluoroethylene was 40%.

After 60 minutes of continuing the reaction, the gas flowing out of the reaction tube was analyzed by gas chromatography. The selectivity for -2,2-difluoroethylene was 56%.

Examples 2 and 3 Using various solid catalysts, production of 1-chloro-2,2-difluoroethylene under conditions of oxygen concentration of 17.3% by volume in raw material diluent gas

A reaction was carried out in the same manner as in Example 1, except that the solid catalyst filled in the reactor was replaced with the solid catalyst shown in Table 1 and the oxygen concentration of the raw material gas was changed to the conditions shown in Table 1. Table 1 shows the results.

From Examples 1, 2, 3 and Comparative Examples 1, 2 shown in Tables 1-1 and 1-2, a solid catalyst in which the first catalyst and the second catalyst are supported on a single substance is used, and a predetermined concentration The conversion rate and selectivity are excellent when the reaction is carried out at an oxygen concentration of , and the conversion rate and selectivity are maintained even after 60 minutes of continuous reaction.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to industrially produce 1-chloro-2,2-difluoroethylene with extremely little decrease in reaction conversion rate and selectivity even when the reaction is continued for a long time under relatively low temperature conditions. rice field. 1-Chloro-2,2-difluoroethylene obtained by the method of the present invention can be used as a raw material for synthesizing various medicines, agricultural chemicals, and electronic materials.

Claims (2)

1,2-dichloro-1,1-difluoroethane is reacted in the gas phase in the presence of oxygen and a solid catalyst comprising cesium chloride as a first catalyst and ruthenium oxide as a second catalyst, 1-chloro- A method for producing 2,2-difluoroethylene. The method according to claim 1, characterized in that the reaction temperature is 250-550°C.