CN101948367A - Preparation method taking 1,1,1-trifluoroethane as raw material - Google Patents

Abstract

The invention relates to a preparation method taking 1,1,1-trifluoroethane as a raw material. The method comprises the following steps of: performing photo-chlorination or thermal chlorination on the 1,1,1-trifluoroethane to obtain mixed gas which contains 1,1,1-trifluoro-2-chloroethane, 1,1,1-trifluoro-2,2-dichloroethane and 1,1,1-trifluoro-2,2,2-trifluoroethane besides the 1,1,1-trifluoroethane serving as the raw material, wherein the molar ratio of chlorine gas to the 1,1,1-trifluoroethane is 0.01 to 3.3, the reaction temperature is controlled to be between 100 and 520 DEG C and a reaction pressure is controlled to be between 0 and 0.8 Pa; and performing water washing, alkali washing, fractional distillation and condensation on the mixed gas so as to obtain the 1,1,1-trifluoro-2-chloroethane, the 1,1,1-trifluoro-2,2-dichloroethane and the 1,1,1-trifluoro-2,2,2-trifluoroethane. The method has the advantages of high reaction transformation ratio/selectivity and yield, simple and convenient method and easy industrialized production because R133a, R123 and R113a are synthesized by performing photo-chlorination or thermal chlorination on the 1,1,1-trifluoroethane serving as the raw material.

Description

A kind of preparation method taking 1.1.1-trifluoroethane as raw material

technical field

The invention belongs to the technical field of organic fluorine chemical industry, in particular to a preparation method using 1.1.1-trifluoroethane as a raw material.

Background technique

1.1.1-Trifluoro-2-chloroethane is commercially abbreviated as HCFC133a or R133a, which is an important intermediate for pesticides, medicines and Freon substitutes. Regarding the preparation method of HCFC133a, many documents have been recorded. It is mainly divided into two categories. The first category uses trichlorethylene and anhydrous hydrofluoric acid as raw materials to synthesize HCFC133a by liquid phase fluorination reaction; the second category uses trichlorethylene and anhydrous hydrofluoric acid as raw materials for gas-solid phase reaction. Synthesis of HCFC133a by catalytic fluorination. Chinese patents: CN1127460C, CN1058013A. US patent: US3003003, which is recorded

1.1.1-Trifluoro-2.2-Difluoroethane is commercially abbreviated as HCFC123 or R123. R123 has a wide range of applications, mainly used in refrigeration, fire protection, and foaming industries. It can also be used as a raw material to produce pentafluoroethane Alkane (R125) and so on. The main production method is to use R133a as raw material to prepare R123 through photochlorination and thermal chlorination. Chinese patent: CM1273426C. CN1270156A has records on this.

1.1.1-Trifluoro-2.2.2-Trichloroethane, usually called CFC-113a or R113a, is an important organic intermediate. The main production methods are: (1) CFC-113 catalytic isomerization to prepare CFC -113a. (2) Preparation of R133a by liquid-phase catalytic photochlorination of HCFC-133a as a raw material, as described in patents EP404297 EP407990 EP346612 US4060469.

The above-mentioned patented methods have the following deficiencies: 1. Raw materials are not easy to obtain; 2. The product is relatively simple; 3. There are many impurities in the preparation process. ④The equipment was severely corroded during the preparation process.

Contents of the invention

The present invention aims to solve the above-mentioned shortcomings of the prior art, and provides a preparation method using 1.1.1-trifluoroethane as a raw material, mainly preparing 1.1.1-trifluoro-2- Chloroethane, 1.1.1-trifluoro-2.2-dichloroethane, 1.1.1-trifluoro-2.2.2-trichloroethane method, purify the mixed gas containing R133a, R123, R113a after chlorination, To prepare R133a, R123, R113a products respectively.

The technical solution adopted by the present invention to solve its technical problems: this preparation method using 1.1.1-trifluoroethane as raw material, the steps are as follows: 1.1.1-trifluoroethane is obtained by photochlorination or thermal chlorination to remove raw materials 1.1.1-Trifluoroethane contains 1.1.1-trifluoro-2-chloroethane, 1.1.1-trifluoro-2.2-dichloroethane, 1.1.1-trifluoro-2.2.2-trichloro The mixed gas of ethane, the molar ratio of chlorine and 1.1.1-trifluoroethane is 0.01-3.3, the reaction temperature is controlled at 100-520°C, and the reaction pressure is 0-0.8 MPa; the mixed gas is washed with water and alkali, and fractionated and condensed to obtain 1.1 .1-trifluoro-2-monochloroethane, 1.1.1-trifluoro-2.2-dichloroethane, 1.1.1-trifluoro-2.2.2-trichloroethane.

As a preference, the 1.1.1-trifluoro-2-chloroethane and 1.1.1-trifluoro-2.2-dichloroethane are respectively returned to the reaction in the process, increasing the 1.1.1-trifluoro-2.2-dichloroethane Product ratio of chloroethane, 1.1.1-trifluoro-2.2.2-trichloroethane.

Preferably, the reaction temperature is 150-510° C., the reaction pressure is 0.01-0.8 MPa, and the molar ratio of chlorine gas to 1.1.1-trifluoroethane is 0.03-2.5.

The beneficial effect of the present invention is: take 1.1.1-trifluoroethane HFC-143a (R143a, molecular formula C2H3F3) as raw material photochlorination, thermal chlorination synthesis R133a, R123, R113a, reaction conversion ratio\selectivity and yield The yield is high, the method is simple and convenient, and it is easy to industrialized production.

Description of drawings

Fig. 1 is a process flow diagram of the present invention;

Reference signs: first chlorination reactor 1, second chlorination reactor 2, first water washing tower 3, second water washing tower 4, alkali washing tower 5, gas storage tank 6, compressor 7, first rectification Tower 8, second rectification tower 9, product tank 10.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

This preparation of 1.1.1-trifluoro-2-chloroethane, 1.1.1-trifluoro-2.2-dichloroethane, 1.1.1-trifluoro-2.2.2- The method of trichloroethane, the steps are as follows: 1.1.1-trifluoroethane is obtained through light chlorination or thermal chlorination except raw material 1.1.1-trifluoroethane containing 1.1.1-trifluoro-2-chloroethane The mixed gas of alkane, 1.1.1-trifluoro-2.2-dichloroethane, 1.1.1-trifluoro-2.2.2-trichloroethane, the mixed gas is washed with water and alkali, fractionated and condensed to obtain 1.1.1-trichloroethane Fluoro-2-chloroethane, 1.1.1-trifluoro-2.2-dichloroethane, 1.1.1-trifluoro-2.2.2-trichloroethane. The reaction temperature is 150-510° C., the reaction pressure is 0.01-0.8 MPa, and the molar ratio of chlorine to 1.1.1-trifluoroethane is 0.03-2.5. The 1.1.1-trifluoro-2-chloroethane and 1.1.1-trifluoro-2.2-dichloroethane can be returned to the reaction in the process respectively, increasing the 1.1.1-trifluoro-2.2-dichloroethane Alkanes, 1.1.1-trifluoro-2.2.2-trichloroethane product ratio. The invention can be used in refrigerant and pharmaceutical production industries.

CH3CF3+Cl2→CH2ClCF3+HCl

CH3CF3+2Cl2→CHCl2CF3+2HCl

CH3CF3+3Cl2→Cl3CF3+3HCl

According to different feeding ratios of chlorine gas and 1.1.1-trifluoroethane (R143a), different product ratios are obtained.

The process of the present invention is briefly shown in Figure 1, the first chlorination reactor 1, the second chlorination reactor 2, the first water washing tower 3, the second water washing tower 4, the alkali washing tower 5, and the gas storage tank. 6. A compressor 7, a first rectification tower 8, a second rectification tower 9, and a product tank 10.

The raw materials HFC-143a and chlorine gas come from the storage cylinders respectively, and are fed according to the regulations, and enter the light chlorination and thermal chlorination reactors for reaction. The crude product is obtained by cooling the condenser, and then enters the rectification column for rectification. According to the different boiling points of the three products (R133a.R123.R113a), the products R133a, R123 and R113a are obtained respectively.

The chlorination reactor of the present invention adopts graphite tube, glass or metal tube etc. can also be used. The main factor that affects the reaction result of the present invention comprises feed ratio, reaction temperature, reaction residence time, according to the present invention chlorine and HFC-143a feed molar ratio should preferably be controlled at 0.03～2.5, if be lower than 0.03: 1, chlorine supply Insufficient amount will reduce the reaction conversion rate and increase the by-products, and if the feed molar ratio of chlorine is higher than 2.5:1, the utilization rate of chlorine will decrease and will bring additional burden to post-treatment. The suitable reaction temperature of the present invention is 150-510°C. Whether heating or cooling is required during the reaction depends on the diameter of the reaction tube and heat transfer and heat dissipation. The reaction involved in this reaction is an exothermic reaction. With the addition of light source or external heating, the temperature of the equipment can be adjusted according to the reaction situation.

The residence time of the reaction materials in the reaction tower is another important factor affecting the reaction results. If the reaction residence time is insufficient, the chlorination reaction is insufficient, and the reaction conversion rate and yield will decrease. If the reaction residence time is too long, it will also affect the production capacity. The appropriate reaction residence time should be controlled at 40-60 seconds, and the control of reaction residence time can be realized by adjusting the feed rate of raw materials.

According to the method of the present invention, R133a, R123 and R113a are prepared by chlorination of HCFC-143a. The method is simple and convenient. The raw material can be a crude product with a content of less than 98%, and the reaction conversion rate, selectivity and yield can reach more than 95%. The product of the present invention is analyzed by gas chromatography, the chromatographic stationary phase adopts organic carrier 407, the column length is 2 meters, the column temperature is 120° C., and the carrier gas adopts hydrogen.

Embodiment 1: with long 1800mm, the glass tube of diameter 50mm is made the first chlorination reactor 1, the second chlorination reactor 2, and the reactor periphery is equipped with wavelength 3000-3500A, long 840mm white light emission tube 8 and power 3000KW infrared heating device. After the reaction starts, first turn on the power supply, and then pass the raw materials HCFC-143a and chlorine gas into the reactor respectively. Stop after 5.5 hours, the reaction product passes through the first water washing tower 3, the second water washing tower 4, and the alkali washing tower 5, and cools to obtain 950 grams of crude product. Sampling analysis shows that the content of HCFC-133a is 25.7%, and the content of HCFC-123 is 29.6%. , R113a content was 42.8%.

Embodiment 2: use the same reaction device of Example 1, except that the raw material HCFC-143a is changed into the crude product of content 93.64%, and the intake velocity is changed into HCFC-143a0.92mol/h\chlorine 2.13mol/h, other are all the same by Example 1 The operating conditions were improved, and the reaction was stopped after 5.5 hours. 890 grams of the product were collected and analyzed by sampling. The content of HCFC-133a was 4.7%, the content of HCFC-123 was 37.5%, and the content of R113a was 54.3%.

In addition to the above-mentioned embodiments, the present invention can also have other implementations. All technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention.

Claims (5)

1. a kind of preparation method taking 1.1-trifluoroethane as raw material is characterized in that: the steps are as follows: (1), 1.1.1-trifluoroethane is obtained by photochlorination or thermal chlorination except raw material 1.1.1-trifluoroethane containing 1.1.1-trifluoro-2-chloroethane, 1.1.1- The mixed gas of trifluoro-2.2-dichloroethane and 1.1.1-trifluoro-2.2.2-trichloroethane, the molar ratio of chlorine gas and 1.1.1-trifluoroethane is 0.01-3.3, and the reaction temperature is controlled at 100 -520°C, reaction pressure 0-0.8 MPa; (2) The mixed gas is washed with water and alkali, fractionated and condensed to obtain 1.1.1-trifluoro-2-chloroethane, 1.1.1-trifluoro-2.2-dichloroethane, 1.1.1-trifluoro-2.2 .2-Trichloroethane. 2. the preparation method taking 1.1.1-trifluoroethane as raw material according to claim 1 is characterized in that: described 1.1.1-trifluoro-2-chloroethane, 1.1.1-trifluoro -2.2-dichloroethane is returned to the reaction in the process respectively, increasing the product ratio of 1.1.1-trifluoro-2.2-dichloroethane and 1.1.1-trifluoro-2.2.2-trichloroethane. 3. The preparation method using 1.1.1-trifluoroethane as a raw material according to claim 1, characterized in that: the reaction temperature is 150-510°C. 4. The preparation method using 1.1.1-trifluoroethane as a raw material according to claim 1, characterized in that: the reaction pressure is 0.01-0.8 MPa. 5. The preparation method using 1.1.1-trifluoroethane as a raw material according to claim 1, characterized in that: the molar ratio of chlorine gas to 1.1.1-trifluoroethane is 0.03-2.5.

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