Preparation method of difluoroethylamine

Abstract

The invention discloses a preparation method of difluoroethylamine, and relates to the technical field of chemical synthesis. The method comprises the following steps: S1, preparing a catalyst: preparing the catalyst by taking one of aluminum oxide, activated carbon and silicon dioxide as a carrier, taking one of ammonium iodide, sodium iodide and potassium iodide as a main active component and taking nickel nitrate, magnesium nitrate and copper nitrate as auxiliary catalytic components; s2, filling the fixed bed reactor with a catalyst; s3, introducing difluorochloroethane and ammonia water into the fixed bed reactor; and S4, difluorochloroethane and ammonia water react under the action of the catalyst to generate difluoroethylamine and a byproduct, difluoroethylamine is led out from the lower part of the reactor and is cooled and collected by a cold trap, and non-condensable gas is guided to a tail gas treatment system after being absorbed by water. The method has the advantages of mild reaction conditions, simple reaction equipment and easy operation conditions, and can be used for synthesizing difluoroethylamine under continuous conditions. The method has the advantages of low cost, simple post-treatment, less three-waste generation, high product yield and easiness in industrial large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and particularly relates to a method for preparing difluoroethylamine. Background Art

[0002] Difluoroethylamine is an important fluorine-containing fine chemical. It is a key raw material and intermediate for the synthesis of many new fluorine-containing pesticides and fluorine-containing pharmaceutical products. It has a wide range of application values. There are many synthesis methods based on the source of raw materials, mainly:

[0003] 1. Using 1-bromo-2,2-difluoroethane as a raw material, and heating it in a test tube with 2 mol of ammonium acetate at 125°C to 145°C for 3 days, the reactant is completely converted into compounds of difluoroethylamine and tetrafluoroethylamine. The two products are separated by splitting or by converting them into hydrochloride or oxalate. However, the disadvantages of this synthesis method are long reaction time, difficulty in obtaining raw materials, poor selectivity, etc.

[0004] 2. Using ethylamine and fluorooxytrifluoromethane as raw materials, ethylamine and fluorooxytrifluoromethane react in hydrofluoric acid under ultraviolet irradiation to synthesize difluoroethylamine. However, this synthesis method has harsh conditions and requires the use of hydrofluoric acid.

[0005] 3. Using 2,2-difluoroacetamide as a raw material, the product is obtained by treating it with a tetrahydrofuran (THF) solution of diborane. However, this synthesis method uses expensive and harmful raw material diborane, the product post-processing is difficult, and the product yield is low.

[0006] 4. Using amide boron trifluoride ether complex as raw material, 2,2-difluoroethylamine was synthesized with a yield of 60%. However, this method has the problems of expensive and difficult to obtain raw materials and difficult to handle by-products.

[0007] 5. Using difluoroacetonitrile as raw material, N-(2,2-difluoroethyl)amide is first synthesized, and then 2,2-difluoroethylamine is synthesized by acidifying N-(2,2-difluoroethyl)amide. However, this method has many reaction steps, expensive raw materials, various acids and catalysts are required in the process, and there are many three wastes, and the production cost is high.

[0008] 6. 1,1-difluoro-2-nitroethane is used as raw material to synthesize 2,2-difluoroethylamine through catalytic hydrogenation. However, this method also has the problems of expensive and difficult to obtain raw materials, the need to use H2 as a reducing agent, and the use of precious metal catalysts.

[0009] 7. A method for synthesizing difluoroethylamine by using difluoroethanol and liquid ammonia as raw materials in a hydrogen atmosphere under the action of a catalyst. However, this method requires the use of liquid ammonia and H2, the safety of the reaction is poor, and the raw material difluoroethanol is expensive.

[0010] 8. A method for synthesizing difluoroethylamine by catalytic reaction in an autoclave with 2,2-difluoro-1-chloroethane as raw material under the action of liquid ammonia or ammonia gas. However, this method involves high-pressure reaction, has high requirements for equipment, and is an intermittent reaction, which is not conducive to industrial production.

[0011] 9. A method for synthesizing difluoroethylamine by using 2,2-difluoro-1-chloroethane as a raw material and reacting it with ammonia water in a coil under high temperature and high pressure.

[0012] However, this method uses a single-tube reactor, and the pressure and temperature are also relatively high, which places high demands on equipment, is not easy to industrialize and mass-produce, and has problems such as low selectivity.

[0013] Therefore, we provide a method for preparing difluoroethylamine to solve the above problems. Summary of the invention

[0014] The invention aims to provide a method for preparing difluoroethylamine. The method uses difluorochloroethane and ammonia water as raw materials, adopts a supported catalyst, and synthesizes difluoroethylamine under continuous conditions in a fixed bed reactor, thereby solving the problems of expensive raw materials, harsh reaction conditions, expensive catalysts, large amount of three wastes generated, high production cost, low continuous reaction degree, and difficulty in industrial production in the existing synthesis of difluoroethylamine.

[0015] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0016] The present invention is a method for preparing difluoroethylamine, comprising the following steps:

[0017] S1. Catalyst preparation: A catalyst is prepared using one of alumina, activated carbon and silicon dioxide as a carrier, one of ammonium iodide, sodium iodide and potassium iodide as a main active component, and nickel nitrate, magnesium nitrate and copper nitrate as co-catalyst components;

[0018] S2, filling the catalyst into the fixed bed reactor;

[0019] S3, introducing difluorochloroethane and aqueous ammonia into a fixed bed reactor, wherein the volume feed ratio of difluorochloroethane to aqueous ammonia is 1:2-3;

[0020] S4, difluorochloroethane and ammonia water react under the action of the catalyst to generate difluoroethylamine and by-products. The difluoroethylamine is discharged from the lower part of the reactor, cooled and collected by a cold trap, and the non-condensable gas is absorbed by water and then directed to the tail gas treatment system.

[0021] The present invention is further configured such that the mass percentage of the ammonium iodide is 8.0%, the mass percentage of the sodium iodide is 12.0%, and the mass percentage of the potassium iodide is 10.0%.

[0022] The present invention is further configured such that the mass percentages of the nickel nitrate and the copper nitrate are both 1.5%, and the mass percentage of the magnesium nitrate is 1.0%.

[0023] The present invention is further configured such that, in step S3, the liquid phase volume space velocity of difluorochloroethane and aqueous ammonia is 0.5-3.0h-1.

[0024] The present invention is further configured such that the temperature for the reaction of difluorochloroethane and aqueous ammonia is 110-200° C., and the pressure for the reaction is 1-1.8 MPa.

[0025] The present invention has the following beneficial effects:

[0026] 1. The present invention uses a fixed bed reactor, avoids the use of flammable and explosive gases such as liquid ammonia, ammonia gas, hydrogen, etc., has mild reaction conditions, simple reaction equipment, easy operating conditions, and can synthesize difluoroethylamine under continuous conditions.

[0027] 2. The present invention adopts low-cost supported catalysts, avoids the use of precious metal active components, the catalyst and reactants can be automatically separated, the post-treatment is simple, the amount of three wastes generated is small, and the product yield is high.

[0028] 3. The raw material 2,2-difluoro-1-chloroethane used in the present invention is a waste byproduct from the fluorine chemical industry, which complies with the national policy on waste resource utilization, and is widely available, cheap, and easy to scale up for industrial production.

[0029] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0031] Figure 1 The present invention is a schematic flow diagram of a method for preparing difluoroethylamine. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] Alumina is used as a carrier, 8.0% by mass of ammonium iodide is used as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate are used as co-catalyst components to form a catalyst, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 62.3%, and the yield is 50.5%.

[0035] Example 2

[0036] Alumina is used as a carrier, sodium iodide with a mass percentage of 12.0% is used as a main active component, magnesium nitrate with a mass percentage of 1.0% and nickel nitrate and copper nitrate with a mass percentage of 1.5% are used as co-catalyst components to form a catalyst, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 60.4%, and the yield is 51.3%.

[0037] Example 3

[0038] Alumina is used as a carrier, 10.0% by mass of potassium iodide is used as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate are used as co-catalyst components to form a catalyst, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 58.3% and the yield is 49.6%.

[0039] Example 4

[0040] The catalyst is composed of activated carbon as a carrier, 8.0% by mass of ammonium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 68.6%, and the yield is 54.9%.

[0041] Example 5

[0042] The catalyst is composed of activated carbon as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 69.1%, and the yield is 56.3%.

[0043] Example 6

[0044] The catalyst is composed of activated carbon as a carrier, 10.0% by mass of potassium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 64.3%, and the yield is 52.1%.

[0045] Example 7

[0046] The catalyst is composed of silicon dioxide as a carrier, 8.0% by mass of ammonium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 48.7% and the yield is 36.5%.

[0047] Example 8

[0048] The catalyst is composed of silicon dioxide as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 51.4%, and the yield is 38.6%.

[0049] Example 9

[0050] The catalyst is composed of silicon dioxide as a carrier, 10.0% by mass of potassium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 120°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 50.9% and the yield is 40.0%.

[0051] Example 10

[0052] The catalyst is composed of activated carbon as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 140°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 71.5%, and the yield is 59.7%.

[0053] Embodiment 11

[0054] The catalyst is composed of activated carbon as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 160°C, and the reaction pressure is 1.0MPa. The conversion rate of difluoroethylamine is 74.8%, and the yield is 60.6%.

[0055] Example 12

[0056] The catalyst is composed of activated carbon as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 140°C, and the reaction pressure is 1.5MPa. The conversion rate of difluoroethylamine is 83.5%, and the yield is 71.8%.

[0057] Embodiment 13

[0058] The catalyst is composed of activated carbon as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:3, the liquid phase volume space velocity is 2.0h-1, the reaction temperature is 140°C, and the reaction pressure is 2.0MPa. The conversion rate of difluoroethylamine is 87.4%, and the yield is 71.7%.

[0059] Embodiment 14

[0060] The catalyst is composed of activated carbon as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:2.75, the liquid phase volume space velocity is 2.5h-1, the reaction temperature is 140°C, and the reaction pressure is 1.5MPa. The conversion rate of difluoroethylamine is 89.3%, and the yield is 77.7%.

[0061] Embodiment 15

[0062] The catalyst is composed of activated carbon as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:2.6, the liquid phase volume space velocity is 3.0h-1, the reaction temperature is 140°C, and the reaction pressure is 1.5MPa. The conversion rate of difluoroethylamine is 87.0%, and the yield is 72.2%.

[0063] Example 16

[0064] The catalyst is composed of activated carbon as a carrier, 12.0% by mass of sodium iodide as a main active component, 1.0% by mass of magnesium nitrate and 1.5% by mass of nickel nitrate and copper nitrate as co-catalyst components, the volume feed ratio of difluorochloroethane and ammonia water is 1:2.5, the liquid phase volume space velocity is 2.8h-1, the reaction temperature is 145°C, and the reaction pressure is 1.8MPa. The conversion rate of difluoroethylamine is 98.3% and the yield is 87.5%.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0066] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A method for preparing difluoroethylamine, characterized in that: The steps include: S1. Catalyst preparation: A catalyst is prepared using one of alumina, activated carbon and silicon dioxide as a carrier, one of ammonium iodide, sodium iodide and potassium iodide as a main active component, and nickel nitrate, magnesium nitrate and copper nitrate as co-catalyst components; S2, filling the catalyst into the fixed bed reactor; S3, introducing difluorochloroethane and aqueous ammonia into a fixed bed reactor, wherein the volume feed ratio of difluorochloroethane to aqueous ammonia is 1:2-3; S4, difluorochloroethane and ammonia water react under the action of the catalyst to generate difluoroethylamine and by-products. The difluoroethylamine is discharged from the lower part of the reactor, cooled and collected by a cold trap, and the non-condensable gas is absorbed by water and then directed to the tail gas treatment system.

2. The method for preparing difluoroethylamine according to claim 1, characterized in that: The mass percentage of the ammonium iodide is 8.0%, the mass percentage of the sodium iodide is 12.0%, and the mass percentage of the potassium iodide is 10.0%.

3. The method for preparing difluoroethylamine according to claim 1, characterized in that: The mass percentages of the nickel nitrate and the copper nitrate are both 1.5%, and the mass percentage of the magnesium nitrate is 1.0%.

4. The method for preparing difluoroethylamine according to claim 1, characterized in that: In step S3, the liquid phase volume space velocity of difluorochloroethane and ammonia water is 0.5-3.0h -1 .

5. The method for preparing difluoroethylamine according to claim 1, characterized in that: The temperature for the reaction of difluorochloroethane and aqueous ammonia is 110-200° C., and the pressure for the reaction is 1-1.8 MPa.

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