CN115417744A

CN115417744A - Method for preparing 1-chloro-1,1-difluoroethane

Info

Publication number: CN115417744A
Application number: CN202211040372.8A
Authority: CN
Inventors: 吕剑; 韩升; 曾纪珺; 赵波; 杨志强; 张伟; 唐晓博; 李凤仙; 谷玉杰; 郝志军; 亢建平
Original assignee: Xian Modern Chemistry Research Institute
Current assignee: Xian Modern Chemistry Research Institute
Priority date: 2022-08-29
Filing date: 2022-08-29
Publication date: 2022-12-02
Anticipated expiration: 2042-08-29
Also published as: CN115417744B

Abstract

The invention discloses a preparation method of 1-chloro-1,1-difluoroethane. The disclosed method comprises: under the action of a composite catalyst and at the reaction temperature of 60-120 ℃,1,1-dichloroethylene and HF are subjected to liquid phase fluorination to prepare 1-chloro-1,1-difluoroethane; the composite catalyst is composed of a main catalytic agent and a catalytic auxiliary agent, wherein the main catalytic agent is a metal halide, and the catalytic auxiliary agent is organic amine. The invention has the advantage of high selectivity.

Description

Method for preparing 1-chloro-1,1-difluoroethane

Technical Field

The invention relates to a method for preparing 1-chloro-1,1-difluoroethane, in particular to a method for preparing 1-chloro-1,1-difluoroethane by taking 1,1-dichloroethylene as a raw material through liquid phase fluorination.

Background

1-chloro-1,1-difluoroethane (HCFC-142 b) is used as a high-temperature refrigerant and is mainly applied to refrigeration air conditioners (high-temperature air conditioners), heat pumps, mixed refrigerants and the like in high-temperature environments. HCFC-142b is being gradually banned as a transitional substitute for CFCs, but it is being widely spotlighted as an organic intermediate for the preparation of polyvinylidene fluoride (PVDF) resins, i.e., HCFC-142b is pyrolyzed to prepare vinylidene fluoride (VDF) monomers, which in turn prepare polyvinylidene fluoride (PVDF) resins. With the continuous expansion of the application field of the fluorine-containing polymer, HCFC-142b as a VDF production raw material has wide market development prospect.

2021, wang Qingsong and SnCl ₄ Uses the catalyst to synthesize HCFC-142b by one-step liquid phase fluorination VDC. The reaction is carried out in a liquid phase reaction kettle, the reaction kettle is connected with a fluorination tower and a tower top condenser, and a product generated by the reaction flows back through the fluorination tower and the condenser and is discharged to a post-treatment system; the feed ratio is 1.5-1.8, the reaction temperature is 70-95 ℃, the reaction pressure is 1.1-1.3 MPa, the cold top temperature is 10-25 ℃, the VDC conversion rate is more than 99.9 percent, and the proportion of main reactants HFC-143a and HCFC-142b is 7:3-5:5. The reaction product of the method can not be regulated and controlled, and the selectivity of HCFC-142b is low.

Disclosure of Invention

The invention aims to overcome the defects in the background art and provide a preparation method of 3-chloro-1,1,1,3-tetrafluoropropane with high product selectivity.

In order to realize the purpose of the invention, the invention adopts the technical scheme that: introducing a catalytic assistant to construct a composite catalytic system, and having the dual functions of adjusting the acidity of the catalytic system and preventing 1,1-dichloroethylene from self polymerization, so that 1,1-dichloroethylene and hydrogen fluoride are subjected to liquid phase fluorination to prepare 1-chloro-1,1-difluoroethane with high selectivity.

Therefore, the preparation method of the 1-chloro-1,1-difluoroethane provided by the invention comprises the following steps: under the action of a composite catalyst and at the reaction temperature of 60-120 ℃,1,1-dichloroethylene and HF are subjected to liquid phase fluorination to prepare 1-chloro-1,1-difluoroethane; the composite catalyst is composed of a main catalytic agent and a catalytic auxiliary agent, wherein the main catalytic agent is a metal halide, and the catalytic auxiliary agent is organic amine.

Optionally, the metal halide is SnCl ₄ 、SnF ₄ 、TiCl ₄ Or TiF ₄ . Preferably TiF ₄ Or TiCl ₄ 。

Optionally, the organic amine is one or a mixture of more than two of triethylamine, n-butylamine, imidazole, isopropylamine and ethylenediamine. Preferably, one or a mixture of two of imidazole and n-butylamine.

Optionally, the molar ratio of the catalytic auxiliary agent to the catalytic main agent is 0-1: 1; the molar ratio of HF to 1,1-dichloroethylene is 2-50: 5363 and the feeding molar weight of the 1,1,1-dichloroethylene is 10 to 100 percent of the molar weight of the main catalyst.

Optionally, the molar ratio of the catalytic assistant to the catalytic main agent is 0.4-0.6.

Optionally, the molar ratio of HF to 1,1-dichloroethylene is 5-10, and the feeding molar weight of 1, 1-dichloroethylene is 30-50% of the molar weight of the main catalyst.

Optionally, the reaction time is 0.5 h-10 h. Further optionally, the reaction temperature is 70-90 ℃, and the reaction time is 2-5 h.

Compared with the prior art, the invention has the following beneficial effects: the catalyst activity is adjustable, and the conversion rate of the raw material VDC is basically and completely converted; the product selectivity is high, and the selectivity of HCFC-142b is more than 97 percent; the catalyst can continuously run for 200h, and the activity is stable.

Drawings

FIG. 1 is a GC-MS spectrum of 1-chloro-1,1-difluoroethane prepared in example 1.

Detailed Description

Unless otherwise defined, scientific and technical terms used herein are to be understood as commonly understood by one of ordinary skill in the relevant art. It is also understood that the temperatures, concentrations referred to herein are approximate values and are used for illustrative purposes. Although methods and materials similar or equivalent to those described herein can be used in the practice of the present disclosure, suitable methods and materials are described in part below. Publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety, to the extent that conflicts arise, herein. In addition, the materials, methods, solution concentrations, and examples are illustrative only and not intended to be limiting. In a specific scheme, a person skilled in the art can optimize the material ratio, concentration and operation parameter values involved in the method in a conventional experimental period according to the disclosure of the invention to achieve the purpose of the invention.

In the present invention, the operating pressure of the reaction is mainly controlled by the saturated vapor pressure of the reactants at the reaction temperature, and is generally not strictly controlled, and may be carried out at a pressure lower than, equal to, or higher than atmospheric pressure, preferably higher than atmospheric pressure. In addition, the reaction of the invention can be operated intermittently or continuously, and the reaction itself has no obvious requirements on the reaction form.

On one hand, the catalytic assistant selected by the invention constructs a composite catalytic system with the catalytic main agent, the acidity of the catalytic system is adjusted to be equivalent to the reaction requirement, the performance of the composite catalyst is ensured to reach the optimal state, and the better conversion rate and selectivity are obtained; on the other hand, the unique property of the catalytic assistant and the synergistic effect of the reaction system play a role in preventing or delaying the self-polymerization of 1,1-dichloroethylene, and effectively prolong the service life of the catalyst.

The present invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. In the following examples, GC-MS detection was used for the conversion and selectivity detection of the reactants.

Example 1:

the liquid phase fluorination reaction is carried out to prepare HCFC-142b in a 100mL stainless steel autoclave with stirring; sequentially adding TiF into the reaction kettle ₄ (12.4g, 0.1mol) and imidazole (1.36g, 0.02mol), starting stirring, adding HF (20g, 1mol) and VDC (5.8g, 0.06mol) at one time, and reacting for 5 hours at the reaction temperature of 90 ℃; after the reaction is finished, sampling, washing with water to remove acid, then carrying out gas chromatography analysis, and obtainingThe results showed 99.9% conversion of VDC and 97.9% selectivity for HCFC-142b.

The GC-MS detection result of the product 1-chloro-1,1-difluoroethane is shown in FIG. 1, and the mass spectrum result and the peak value attribution are as follows: there are molecular ion peak at m/z100 and CF at m/z85 ₂ Cl ion peak, m/z65 is CF ₂ ClCH ₃ Ion Peak after dechlorination, m/z45 is CF ₂ ClCH ₃ Ion peaks after dechlorination and F. This data demonstrates that the product produced is 1-chloro-1,1-difluoroethane.

Examples 2 to 5:

examples 2 to 5 liquid phase fluorination reactions HCFC-142b was prepared in the same manner as in example 1, except that the kind of the composite catalyst, the reaction temperature and the reaction time were changed and the reaction results are shown in table 1.

TABLE 1

Example 6:

to a stirred 100mL stainless steel autoclave was added 22.5g TiCl ₄ Then adding 50g of HF for fluorination treatment, starting stirring, discharging generated HCl through a gas phase port, and controlling the pressure within 0.20 MPa; heating to 100 ℃, keeping the temperature for 2h, and finishing the treatment process.

Imidazole (1.36g, 0.02mol), n-butylamine (1.8g, 0.02mol) and VDC (5.8g, 0.06mol) were sequentially charged into a reaction vessel at a reaction temperature of 70 ℃ for 5 hours, and then cooled. The sample was subjected to gas chromatography after acid removal by water washing, and the results showed that the conversion of VDC was 99.5% and the selectivity of HCFC-142b was 97.0%.

Examples 7 to 9:

examples 7 to 9 preparation of HCFC-142b by liquid phase fluorination reaction the same as in example 6 except that the type of the composite catalyst was changed and the reaction results are shown in Table 2.

TABLE 2

Examples 10 to 13:

examples 10-13 preparation of HCFC-142b by liquid phase fluorination the same as in example 1 except that imidazole and TiF were varied ₄ The reaction results are shown in Table 3, along with the ratios of (A) to (B), the reaction temperature and the reaction time.

TABLE 3

Example 14:

continuous liquid phase fluorination was carried out in a 2L stainless steel autoclave equipped with stirring, equipped with a distillation column and reflux condenser above the autoclave, heated at the bottom using an oil pan.

123.4g of TiF are sequentially added into the reaction kettle ₄ 13.6g of imidazole, 18g of n-butylamine and 400g of HF, heating to 80 ℃, and keeping the temperature for 3 hours; VDC and HF were then fed continuously into the reactor by means of a metering pump, the feed rate of VDC was 58g/h, the feed rate of HF was 26g/h, the reaction temperature was 75-85 ℃ and the reaction results are shown in Table 4. As is clear from Table 4, the VDC conversion rate was maintained at 99.5% or more and the HCFC-142b selectivity was 97.0% in 200 hours of continuous operation.

TABLE 4 evaluation of catalyst Life

Comparative examples 1 to 3:

comparative examples 1 to 3 liquid phase fluorination reactions for the preparation of HCFC-142b were the same as in example 6, except that the type of catalyst was changed, and the results are shown in Table 5.

TABLE 5

It can be seen from this that HCFC-142b selectivity is lower with the catalysts of comparative examples 1 to 3.

The above description is only a part of the embodiments of the present invention, and is not intended to limit the present invention in any way, and all simple modifications, equivalent changes and modifications made to the above embodiments according to the technical spirit of the present invention are within the technical scope of the present invention.

Claims

1. A method for preparing 1-chloro-1,1-difluoroethane, characterized in that the method comprises: under the action of a composite catalyst and at the reaction temperature of 60-120 ℃,1,1-dichloroethylene and HF are subjected to liquid phase fluorination to prepare 1-chloro-1,1-difluoroethane; the composite catalyst is composed of a main catalytic agent and a catalytic auxiliary agent, wherein the main catalytic agent is a metal halide, and the catalytic auxiliary agent is organic amine.

2. The method of claim 1-chloro-1,1-difluoroethane as in claim 1 wherein the metal halide is SnCl ₄ 、SnF ₄ 、TiCl ₄ Or TiF ₄ 。

3. The method for preparing 1-chloro-1,1-difluoroethane as claimed in claim 2, wherein said catalyst host is TiF ₄ Or TiCl ₄ 。

4. The method of claim 1-chloro-1,1-difluoroethane as in claim 1, wherein the organic amine is one or a mixture of more than two of triethylamine, n-butylamine, imidazole, isopropylamine and ethylenediamine.

5. The method of claim 1-chloro-1,1-difluoroethane as in claim 1 wherein said organic amine is one or a mixture of imidazole and n-butylamine.

6. The method for preparing 1-chloro-1,1-difluoroethane as claimed in claim 1, wherein the molar ratio of the catalytic assistant to the catalytic host is 0-1: 1; the molar ratio of HF to 1,1-dichloroethylene is 2-50: 5363 and the feeding molar weight of the 1,1,1-dichloroethylene is 10 to 100 percent of the molar weight of the main catalyst.

7. The method for preparing 1-chloro-1,1-difluoroethane as claimed in claim 6, wherein the molar ratio of the catalytic promoter to the catalytic host is 0.4-0.6.

8. The method for preparing 1-chloro-1,1-difluoroethane as claimed in claim 6, wherein the molar ratio of HF to 1,1-dichloroethylene is 5-10, 1-dichloroethylene is 30-50% of the molar amount of the catalyst main agent.

9. The process for the preparation of 1-chloro-1,1-difluoroethane as in claim 1, wherein the reaction time is 0.5 to 10 hours.

10. The process for preparing 1-chloro-1,1-difluoroethane as claimed in claim 1, wherein the reaction temperature is 70 ℃ to 90 ℃ and the reaction time is 2h to 5h.