A method for synthesizing 3-chloropropionyl chloride and a continuous reaction device

Abstract

The present invention relates to 3-chloropropionyl chloride, and in particular to a 3-chloropropionyl chloride synthesis method and a continuous reaction device. After 3-chloropropionic acid and benzyl chloride enter a tubular reactor for reaction, they enter a thin film tubular reactor at the bottom of a reactive distillation tower for reaction aging, and benzoyl chloride is discharged from the bottom. The top 3-chloropropionyl chloride and hydrogen chloride gas are cooled by a primary and a secondary condenser to recover 3-chloropropionyl chloride in a 3-chloropropionyl chloride gas-liquid separator. Hydrogen chloride and acrylic acid react to generate 3-chloropropionyl chloride, and a continuous reaction is carried out. The reaction route of the present invention is simple, free of waste gas, waste water, and solid waste, and the cost is low and safe and controllable. Specifically, the present invention has an atomic utilization rate of 100%, and the cost is reduced from 35,000 yuan / ton to 10,000 yuan / ton; the continuous reaction is adopted to reduce the risk; there is basically no three wastes, and the subsequent treatment problem of by-products such as sulfoxide or phosphorus trichloride is avoided. The invention is a green, environmentally friendly, safe and efficient synthesis model.

Description

Technical Field

[0001] The present invention relates to 3-chloropropionyl chloride, and in particular to a 3-chloropropionyl chloride synthesis method and a continuous reaction device. Technical Background

[0002] The current synthesis process for 3-chloropropionyl chloride primarily involves the reaction of acrylic acid with 30% hydrochloric acid to produce 3-chloropropionic acid, followed by the reaction of 3-chloropropionic acid with thionyl chloride or phosphorus trichloride. These reactions produce numerous waste products, high costs, and significant safety risks. The reaction of thionyl chloride with 3-chloropropionic acid produces a byproduct gaseous mixture of sulfur dioxide and hydrogen chloride, which is difficult to handle due to its high toxicity and the high cost and cumbersome process of treating it with alkali. The reaction of phosphorus trichloride with 3-chloropropionic acid produces byproducts of phosphorous acid and hydrogen chloride, making phosphorus-containing waste difficult to dispose of and resulting in a high concentration of acidic wastewater and exhaust gas.

[0003] Therefore, a preparation method with less three wastes and high utilization rate is needed. Summary of the Invention

[0004] The present invention aims to solve the problems in the prior art of complicated process flow, generation of hazardous wastes such as phosphorous acid or sulfur dioxide as by-products, and environmental pollution, and proposes a clean production process and equipment for 3-chloropropionyl chloride.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention adopts a continuous reaction device and a 3-chloropropionyl chloride synthesis method

[0007] A continuous reaction device, comprising a 3-chloropropionic acid reactor, a 3-chloropropionyl chloride gas-liquid separator, a primary condenser, a secondary condenser, a reactive distillation tower, a tubular reactor, a second circulation pump, and a flow meter;

[0008] The 3-chloropropionic acid reactor is composed of a Venturi reactor, a reaction tank, and a first circulation pump, from top to bottom: a Venturi reactor, a reaction tank, and a first circulation pump;

[0009] The reactive distillation tower is composed of a distillation tower and a thin film shell and tube reactor, from top to bottom: a distillation tower and a thin film shell and tube reactor;

[0010] The upper end of a reaction tank in a 3-chloropropionic acid reactor is connected to the lower end of a venturi reactor via a pipeline, and the lower end of the reaction tank is communicated with an inlet of a first circulation pump via a pipeline; the outlet of the first circulation pump is communicated with the lower end of the tubular reactor via a pipeline; the upper end of the tubular reactor is communicated with a side opening of a distillation tower via a pipeline; the discharge port at the lower end of the reaction distillation tower is connected to a second circulation pump via a pipeline; a primary condenser and a secondary condenser are respectively provided at an upper outlet of the reaction distillation tower, the condensers are connected via pipelines, the secondary condenser is connected to an air inlet of a 3-chloropropionyl chloride gas-liquid separator via a pipeline, and the air outlet of the 3-chloropropionyl chloride gas-liquid separator is connected to the upper end of the venturi reactor via a pipeline.

[0011] The continuous reaction device is characterized in that a 3-chloropropionic acid feeding port is provided above the venturi reactor; an acrylic acid feeding port is provided in the 3-chloropropionic acid reactor; a 3-chloropropionyl chloride feeding port is provided on the right side of the reactive distillation tower; a 3-chloropropionyl chloride discharge port is provided at the lower end of the 3-chloropropionyl chloride gas-liquid separator; a second circulating pump is provided with a benzoyl chloride discharge port; and flow meters are provided between the first circulating pump and the tubular reactor, at the trichlorobenzyl feeding port, and at the 3-chloropropionic acid reactor.

[0012] Benzyl trichloride reacts with acrylic acid to produce benzoyl chloride and 3-chloropropionyl chloride;

[0013] The above reaction is a combination of two steps:

[0014] The details are as follows:

[0015] Overall reaction: Benzyl chloride reacts with acrylic acid to form benzoyl chloride and 3-chloropropionyl chloride (reaction 1). Benzyl chloride reacts with 3-chloropropionic acid to form 3-chloropropionyl chloride, benzoyl chloride reacts with hydrogen chloride (reaction 2), and hydrogen chloride reacts with acrylic acid to form 3-chloropropionic acid (reaction 3), which together constitute reaction (1).

[0016]

[0017] In reaction 2, catalysts are used: Lewis acids such as ferric chloride, zinc chloride, barium chloride, and aluminum chloride;

[0018] In the above continuous reaction device, hydrogen chloride reacts with aqueous acrylic acid through a Venturi reactor to generate 3-chloropropionic acid, and benzoyl chloride is produced at the bottom of the distillation tower. 3-Chloropropionic acid and tribenzyl chloride are fed into a tubular reactor for reaction, and then fed into a distillation tower for aging. Benzoyl chloride is produced at the bottom, and the 3-chloropropionyl chloride gas at the top is cooled through primary and secondary condensers and recovered in a 3-chloropropionyl chloride gas-liquid separator for a cyclic reaction.

[0019] More specifically:

[0020] In a continuous reaction apparatus, 80 kg of 3-chloropropionyl chloride and 53 g of ferric chloride were first added to the 3-chloropropionic acid reactor, with the temperature controlled at 35-40°C for circulation. Then, 100 kg of benzoyl chloride was added to the distillation column, with the temperature controlled at 130-137°C and a vacuum of -0.05 MPa, and continuous feeding began. Benzyl chloride (285 g / min) and 3-chloropropionic acid (153 g / min) were added to the tubular reactor. After 60 minutes of reaction, a vacuum of -0.05 MPa was established for reflux, and acrylic acid (102.1 g / min) was added. The acrylic acid was a mixture of 100 g of acrylic acid, 2 g of water, and 0.1 g of ferric chloride. Simultaneously, benzoyl chloride (205 g / min) and 3-chloropropionyl chloride (174 g / min) were withdrawn from the column bottom and the top of the column top. The reflux ratio was 1:1, and the reaction continued for 5 hours, completing the cycle.

[0021] The present invention adopts a full-tank start-up, i.e., a fixed amount of 3-chloropropionic acid and benzoyl chloride is pre-added into the circulating reaction device. This has the advantage that, as shown in reaction (2), 3-chloropropionic acid and trichlorobenzyl chloride can generate benzoyl chloride, 3-chloropropionyl chloride and hydrogen chloride, without the need to add additional hydrogen chloride. The generated hydrogen chloride reacts with aqueous acrylic acid under the action of a catalyst to form 3-chloropropionic acid, so the pre-added 3-chloropropionic acid is equivalent to an inducer. If 3-chloropropionic acid is not pre-added, but acrylic acid is added into the circulating device according to the prior art, although it can generate benzoyl chloride and 3-chloropropionyl chloride with trichlorobenzyl chloride as shown in reaction 1, no hydrogen chloride is generated, and the reaction cannot be sustained. In addition, because acrylic acid is unstable, it will produce polymers, especially at high temperatures (above 100° C.), and even at low temperatures, a small amount of polymers are easily generated. Therefore, acrylic acid in this reaction requires special attention and cannot be added in large quantities at one time. In addition, it is best to quickly convert it into other stable compounds. Based on this, the cyclic reaction device and method of the present invention have been configured accordingly. Specifically, by controlling the sample addition amount while maintaining low temperature and vacuum conditions, the acrylic acid containing a small amount of water added in the 3-chloropropionic acid reactor rapidly reacts with the aforementioned hydrogen chloride (reaction 3). The resulting 3-chloropropionic acid is introduced into a tubular reactor via a circulating pump to react with trichlorobenzyl chloride. The resulting hydrogen chloride and 3-chloropropionyl chloride, due to their low boiling points, are separated from the high-boiling-point benzoyl chloride in a reactive distillation column and a condenser. Additionally, a small amount of acrylic acid remains in the 3-chloropropionic acid, which reacts with hydrogen chloride in the tubular reactor to form stable 3-chloropropionic acid, ensuring that acrylic acid fully reacts and again preventing acrylic acid polymerization. The separation of 3-chloropropionyl chloride and hydrogen chloride is achieved in the 3-chloropropionic acid gas-liquid separator, while hydrogen chloride, through a venturi reactor, gathers in the 3-chloropropionic acid reactor and reacts with aqueous acrylic acid, achieving a cyclic reaction.

[0022] The present invention has several main points:

[0023] 1. It is necessary to control the temperature and vacuum degree. The vacuum is maintained in this device. The temperature in different reactors is different. For example, the temperature of the 3-chloropropionic acid reactor is controlled at 35-40°C, while the temperature at the lower end of the reactive distillation tower is controlled at 130-140°C.

[0024] 2. In addition to the initial pre-added reactants, other reactants need to be added in small amounts at a fixed flow rate to achieve a continuous cycle reaction. The amount of addition is also a key point of the present invention. In particular, the amount of acrylic acid needs to be strictly controlled.

[0025] Beneficial effects

[0026] The present invention features a simple process, zero waste gas and wastewater, low cost, and controllable safety. Specifically, the invention achieves 100% atomic utilization, reducing costs from 35,000 yuan / ton to 10,000 yuan / ton. The continuous reaction reduces risk, and the production of virtually no waste products (e.g., sulfoxide or phosphorus trichloride) avoids the subsequent disposal challenges of byproducts such as sulfoxide and phosphorus trichloride. This invention exemplifies a green, environmentally friendly, safe, and efficient synthesis method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of a continuous reaction device of the present invention;

[0028] Among them, 1. Venturi reactor; 2. Reaction tank; 3. First circulation pump; 34. 3-chloropropionyl chloride gas-liquid separator; 5. Primary condenser; 6. Secondary condenser; 7. Reaction distillation tower; 8. Tubular reactor; 9. Second circulation pump; 10. Flow meter; 11. Thin film shell and tube reactor; 12. Distillation tower; 13 is 3-chloropropionic acid reactor. DETAILED DESCRIPTION

[0029] Example 1

[0030] A continuous reaction device, comprising a 3-chloropropionic acid reactor 13, a 3-chloropropionyl chloride gas-liquid separator 4, a primary condenser 5, a secondary condenser 6, a reactive distillation tower 7, a tubular reactor 8, a second circulation pump 9, and a flow meter 10; wherein the 3-chloropropionic acid reactor 13 is composed of a Venturi reactor 1, a reaction tank 2, and a first circulation pump 3, which are, from top to bottom, the Venturi reactor 1, the reaction tank 2, and the first circulation pump 3;

[0031] The reactive distillation tower 7 is composed of a distillation tower 12 and a thin film shell and tube reactor 11, which are the distillation tower 12 and the thin film shell and tube reactor 11 from top to bottom;

[0032] The venturi reactor is a vacuum system that provides vacuum for the continuous reaction device.

[0033] The upper end of the reaction tank 2 is connected to the lower end of the venturi reactor 1 through a pipeline, and the upper end of the reaction tank 2 is provided with an acrylic acid feeding port; the lower end of the reaction tank 2 is connected to the first circulation pump 3 through a pipeline; the first circulation pump 3 is connected to the lower end of the tubular reactor 4 and the venturi reactor 1 through pipelines respectively. The purpose of connecting with the venturi reactor 1 is to allow part of the acrylic acid vapor to pass through the venturi reactor 1 again and mix with hydrogen chloride to continue the reaction, so that the reaction is complete, and most of the 3-chloropropionic acid produced is in liquid form due to the low temperature condition (35-40°C) and enters the tubular reactor 4 through the first circulation pump 3; the upper end of the tubular reactor 4 is connected to the reaction distillation tower 7 through a pipeline The left openings are connected; the upper end of the reaction distillation tower 7 is a distillation tower 12, and the lower end is a thin film shell and tube reactor 11; the discharge port at the lower end of the reaction distillation tower 7 is connected to the second circulation pump 9 through a pipeline, and the upper outlet of the reaction distillation tower 7 is respectively provided with a primary condenser 5 and a secondary condenser 6, and a 3-chloropropionyl chloride feed port is provided on the right side of the reaction distillation tower 7. The feed port is for allowing part of the uncondensed 3-chloropropionyl chloride vapor in the 3-chloropropionyl chloride gas-liquid separator 4 to re-enter the distillation tower 7 for re-condensation and recovery; the second circulation pump 9 is provided with a benzoyl chloride discharge port and a flow meter 10, and the benzoyl chloride discharge port can also be used as a feed port. The primary condenser 5 and the secondary condenser 6 are connected by a pipeline, the secondary condenser 6 is connected to the upper end of the 3-chloropropionyl chloride gas-liquid separator 4 by a pipeline, the upper end outlet of the 3-chloropropionyl chloride gas-liquid separator 4 is connected to the upper end 1 of the venturi reactor by a pipeline, the lower end of the 3-chloropropionyl chloride gas-liquid separator is provided with a 3-chloropropionyl chloride discharge port; and a 3-chloropropionic acid feeding port is provided above the venturi reactor 1.

[0034] Flow meters are provided at the first circulation pump 3, the tubular reactor 4, the trichlorobenzyl feeding port, and the benzoyl chloride outlet to control the feeding amount.

[0035] In the continuous reaction device, first add 80 kg of qualified 3-chloropropionyl chloride and 53 g of ferric chloride to the reaction tank 2 and control the temperature at 35-40 ° C for circulation; add 100 kg of benzoyl chloride to the reactive distillation tower 7 and circulate it, control the temperature at 130-137 ° C, and the vacuum at -0.05 MPa; start continuous feeding,

[0036] Benzyl chloride 285 g / min, 3-chloropropionic acid 153 g / min, after 60 min of reaction, vacuum -0.05 MPa reflux, began to feed acrylic acid (a mixture of 100 g of acrylic acid and 2 g of water, 0.1 g of ferric chloride) at 102.1 g / min; it should be noted that ferric chloride is dissolved in the aqueous acrylic acid and enters the tubular reactor 8 with the first circulation pump to act as a catalyst.

[0037] At the same time, 205 g / min of benzoyl chloride was produced from the bottom of the tower, and 174 g / min of 3-chloropropionyl chloride was produced from the top of the tower. The reflux ratio was 1:1, and a cyclic reaction was carried out. After 5 hours of reaction, samples were taken for analysis, showing 98.7% of 3-chloropropionyl chloride and 1% of acryloyl chloride; 95.5% of benzoyl chloride and 4% of trichlorobenzyl chloride; the yield of 3-chloropropionyl chloride was 98.4% (calculated based on acrylic acid), and the yield of benzoyl chloride was 99.0%.

Claims

1. A continuous reaction device comprising a 3-chloropropionic acid reactor, a 3-chloropropionyl chloride gas-liquid separator, a primary condenser, a secondary condenser, a reactive distillation column, a tubular reactor, a second circulation pump, and a flow meter; in: The 3-chloropropionic acid reactor consists of a Venturi reactor, a reaction tank, and a first circulation pump. From top to bottom: the Venturi reactor, the reaction tank, and the first circulation pump; The reactive distillation tower is composed of a distillation tower and a thin film shell and tube reactor, from top to bottom: a distillation tower and a thin film shell and tube reactor; The upper end of the reaction tank in the 3-chloropropionic acid reactor is connected to the lower end of the Venturi reactor through a pipeline, and the lower end of the reaction tank is connected to the inlet of a first circulation pump through a pipeline; the outlet of the first circulation pump is respectively connected to the lower end of the tubular reactor and the Venturi reactor through pipelines; the upper end of the tubular reactor is connected to a side opening of a reactive distillation tower through a pipeline; the discharge port at the lower end of the reactive distillation tower is connected to the second circulation pump through a pipeline; a primary condenser and a secondary condenser are respectively provided at the upper outlet of the reactive distillation tower, the condensers are connected through pipelines, the secondary condenser is connected to the air inlet of a 3-chloropropionyl chloride gas-liquid separator through a pipeline, and the air outlet of the 3-chloropropionyl chloride gas-liquid separator is connected to the upper end of the Venturi reactor through a pipeline; A 3-chloropropionic acid feeding port is provided above the venturi reactor; an acrylic acid feeding port is provided at the upper end of the reaction tank; a 3-chloropropionyl chloride feeding port is provided on the right side of the reactive distillation tower, through which part of the 3-chloropropionyl chloride vapor that has not condensed in the 3-chloropropionyl chloride gas-liquid separator is re-entered into the distillation tower for re-condensation and recovery; a 3-chloropropionyl chloride discharge port is provided at the lower end of the 3-chloropropionyl chloride gas-liquid separator; a benzoyl chloride discharge port is provided at the second circulation pump; flow meters are provided between the first circulation pump and the tubular reactor, at the tribenzyl chloride feeding port, and at the benzoyl chloride outlet, and 3-chloropropionic acid and tribenzyl chloride are fed into the tubular reactor for reaction.

2. A method for synthesizing 3-chloropropionyl chloride, characterized in that: The reaction is carried out in the continuous reaction device according to claim 1, and the specific steps are as follows: Reaction (1) is the reaction of benzyl trichloride and acrylic acid to produce benzoyl chloride and 3-chloropropionyl chloride; Reaction (1) is the overall reaction, which is specifically formed by combining the following two steps: Reaction (2): Benzyl trichloride reacts with 3-chloropropionic acid to produce 3-chloropropionyl chloride, benzoyl chloride and hydrogen chloride; Reaction (3): Hydrogen chloride and acrylic acid react to form 3-chloropropionic acid; in: Hydrogen chloride reacts with aqueous acrylic acid via a Venturi reactor to generate 3-chloropropionic acid, and benzoyl chloride is produced at the bottom of a reactive distillation column. 3-Chloropropionic acid and benzyl chloride react in a tubular reactor and then enter a reactive distillation column for aging. Benzoyl chloride is produced at the bottom, and the 3-chloropropionyl chloride gas at the top is cooled by primary and secondary condensers and recovered in a 3-chloropropionyl chloride gas-liquid separator, thereby performing a continuous reaction. The vacuum degree of the continuous reaction device is -0.03 MPa to -0.07 MPa; the reaction temperature in the reaction tank is 35-40°C; the reaction temperature of the tubular reactor is controlled at 130-140°C, and the temperature of the thin film tube-in-tube reaction part is controlled at 130-140°C; First, add 80 kg of 3-chloropropionic acid and 53 g of ferric chloride to the 3-chloropropionic acid reactor, control the temperature at 35-40 ° C, and circulate; add 100 kg of benzoyl chloride to the reactive distillation tower, circulate, control the temperature at 130-140 ° C, and vacuum at -0.03 MPa to -0.07 MPa; start continuous feeding, add 285 g / min of benzyl chloride and 153 g / min of 3-chloropropionic acid to the tubular reactor, react for 60 minutes, and then reflux under vacuum at -0.05 MPa. Start feeding 102.1 g / min of acrylic acid, wherein Acrylic acid is a mixture of 100 g of acrylic acid, 2 g of water and 0.1 g of ferric chloride; at the same time, 205 g / min of benzoyl chloride is produced from the bottom of the tower, 174 g / min of 3-chloropropionyl chloride is produced from the top of the tower, the reflux ratio is 1:1, the reaction is carried out for 5 hours, and a cyclic reaction is performed.

3. A method for synthesizing 3-chloropropionyl chloride according to claim 2, characterized in that, The catalyst used in reaction (2) is a Lewis acid, wherein the Lewis acid is ferric chloride, zinc chloride, barium chloride or aluminum chloride.

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