1. The preparation method of chloroacetyl chloride is characterized by mainly comprising the following steps:

(1) adding a proper amount of acetyl chloride material into the kettle type reactor to a proper liquid level;

(2) firstly, preheating acetyl chloride material to a proper temperature;

(3) in the presence of electromagnetic radiation, introducing a small amount of chlorine from the bottom of the kettle-type reactor until the reaction liquid is obviously green, and then stopping the reaction, and observing the phenomenon in the reactor;

(4) continuously introducing chlorine with a certain flow rate for reaction after the reaction is started, and starting stirring to fully mix acetyl chloride materials and the chlorine at the bottom of the kettle type reactor;

(5) after acetyl chloride reaches a certain conversion rate, continuously pumping the mixed solution in the tank reactor into a first rectifying tower through a pump, circulating the acetyl chloride obtained at the top of the first rectifying tower to the tank reactor for recycling, and obtaining a crude product containing chloroacetyl chloride at the bottom of the first rectifying tower;

(6) and (3) pumping the chloroacetyl chloride-containing crude product obtained from the tower kettle of the first rectifying tower into a second rectifying tower for vacuum rectification, obtaining a chloroacetyl chloride pure product at the tower top of the second rectifying tower, and recovering the tower kettle residual liquid of the second rectifying tower.

2. The method for producing chloroacetyl chloride according to claim 1, characterized in that: the acetyl chloride material in the step (1) contains 0-30% of solvent, and the solvent is one or a mixture of N, N' -bis (4-amino-2, 2,6, 6-tetramethyl piperidyl) -1, 3-benzenedicarboxamide, phenothiazine, p-hydroxy anisole, resorcinol monobenzoate and benzophenone.

3. The method for producing chloroacetyl chloride according to claim 1, characterized in that: the preheating temperature of acetyl chloride in the step (2) is 0-50 ℃; the wavelength of the electromagnetic radiation in the step (3) is 350-550 nm, and the electromagnetic wave generating device is placed in the middle of the kettle type reactor.

4. The method for producing chloroacetyl chloride according to claim 1, characterized in that: the mol ratio of the chlorine to the acetyl chloride entering the kettle type reactor is 0.1-1.0: 1.

5. The method for producing chloroacetyl chloride according to claim 1, characterized in that: in the step (3), the chlorine concentration in the reaction mixture is more than 0.1 wt% of chlorine based on the whole weight of the reaction mixture; step (3) during the reaction step, the reaction mixture is stirred to obtain a turbulent flow, which can be quantified as a reynolds number greater than 3000.

6. The method for producing chloroacetyl chloride according to claim 1, characterized in that: and (3) maintaining the reaction mixture in the kettle type reactor in the step (4) at the temperature of 10-50 ℃ and the pressure of 0.8-10 atmospheric pressure.

7. The method for producing chloroacetyl chloride according to claim 1, characterized in that: the kettle type reactor is a reactor with jacket heating, and the heat can be completely removed by the overhead condenser; the conversion rate of acetyl chloride in the kettle type reactor is controlled to be 10-50%, and the selectivity of the chloroacetyl chloride is controlled to be 95-99.9%.

8. The method for producing chloroacetyl chloride according to claim 1, characterized in that: in the step (5), the temperature of the rectifying tower kettle of the first rectifying tower is 40-100 ℃, and the rectifying pressure is 0.05-0.2 MPa.

9. The method for producing chloroacetyl chloride according to claim 1, characterized in that: chlorine and acetyl chloride fractions obtained from the top of the first rectifying tower are recycled to the kettle type reactor for reuse; and washing and recovering trace free chlorine in the tail gas of the first rectifying tower by using an acetyl chloride raw material.

10. The method for producing chloroacetyl chloride according to claim 1, characterized in that: the temperature of a rectifying tower kettle of the second rectifying tower is 100-150 ℃, and the rectifying pressure is 0.05-0.1 MPa; and 5-40% of the high-boiling residual liquid in the tower kettle of the second rectifying tower is discharged to a system for post-treatment, and the residual liquid of 60-95% is recycled to the kettle type reactor for reuse.

Background

Chloroacetyl chloride, with a density of 1.42g/cm3 and a boiling point of 106 ℃ (normal pressure), is mainly used as a raw material for medicines and pesticides, is particularly used for the production of herbicides such as butachlor, alachlor and the like, is used for preparing amino acids and other organic compounds, and is an important intermediate for medicines and pesticides.

At present, there are various methods for preparing chloroacetyl chloride, which can be generally synthesized by the following methods, and can be classified into acetic acid direct chlorination method, chloroacetic acid chlorination method, ketene chlorination method, acetyl chloride chlorination method, and the like. The acetic acid chlorination method is characterized by using acetic acid and chlorine as raw materials to produce chloracetyl chloride, and has the defects of short synthetic route, less equipment investment, simple operation, rich raw materials, unstable reaction, high sulfur content in the product, low product purity, low efficiency and the like. Chloroacetic acid chlorination processes can employ a variety of chlorinating agents including sulfur dichloride, phosphorus trichloride, phosgene and chlorine. They have the advantages of easily available raw materials, mature technology, short production period, high product purity, little pollution, high production cost, toxic phosgene, high labor protection and equipment requirements, more three wastes and serious equipment corrosion. The ketene chlorination method mainly uses acetic acid as raw material, uses triethyl phosphate as catalyst, and makes the acetic acid undergo the processes of pyrolysis and dehydration to obtain chloroacetyl chloride. The acetyl chloride chlorination method uses acetic anhydride as raw material, uses phosgene as chlorinating agent to prepare acetyl chloride, and uses chlorine gas to make chlorination to prepare chloroacetyl chloride. The method has the advantages of environmental friendliness, simple reaction process and the like.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the preparation method of the chloracetyl chloride, which has the advantages of simple process, environmental protection, safety and environmental protection and is easy for industrial preparation of the chloracetyl chloride. In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:

a method for preparing chloroacetyl chloride by mixing acetyl chloride and chlorine under the condition of electromagnetic radiation mainly comprises the following steps: (1) adding a proper amount of acetyl chloride material into the kettle type reactor to a proper liquid level;

(2) firstly, preheating acetyl chloride material to a proper temperature;

(3) in the presence of electromagnetic radiation, introducing a small amount of chlorine from the bottom of the kettle-type reactor until the reaction liquid is obviously green, and then stopping the reaction, and observing the phenomenon in the reactor;

(4) continuously introducing chlorine with a certain flow rate for reaction after the reaction is started, and starting stirring to fully mix acetyl chloride materials and the chlorine at the bottom of the kettle type reactor;

(5) after acetyl chloride reaches a certain conversion rate, continuously pumping the mixed solution in the tank reactor into a first rectifying tower through a pump, circulating the acetyl chloride obtained at the top of the first rectifying tower to the tank reactor for recycling, and obtaining a crude product containing chloroacetyl chloride at the bottom of the first rectifying tower;

(6) and (3) pumping the chloroacetyl chloride-containing crude product obtained from the tower kettle of the first rectifying tower into a second rectifying tower for vacuum rectification, obtaining a chloroacetyl chloride pure product at the tower top of the second rectifying tower, and recovering the tower kettle residual liquid of the second rectifying tower.

Further, the acetyl chloride material in the step (1) contains 0-30% of a solvent, wherein the solvent is one or a mixture of several of N, N' -bis (4-amino-2, 2,6, 6-tetramethylpiperidyl) -1, 3-benzenedicarboxamide, phenothiazine, p-hydroxyanisole, resorcinol monobenzoate and benzophenone.

Further, the preheating temperature of acetyl chloride in the step (2) is 0-50 ℃; the wavelength of the electromagnetic radiation in the step (3) is 350-550 nm, and the electromagnetic wave generating device is placed in the middle of the kettle type reactor.

Furthermore, the molar ratio of the chlorine gas and the acetyl chloride entering the kettle type reactor is 0.1-1.0: 1.

Further, in the step (3), the chlorine concentration in the reaction mixture is more than 0.1 wt% of chlorine based on the whole weight of the reaction mixture; step (3) during the reaction step, the reaction mixture is stirred to obtain a turbulent flow, which can be quantified as a reynolds number greater than 3000.

Further, the reaction mixture in the tank reactor in the step (4) is maintained at a temperature of 10-50 ℃ and a pressure of 0.8-10 atmospheres.

Wherein the kettle type reactor is a reactor with jacket heating, and the heat can be completely removed by the overhead condenser; the conversion rate of acetyl chloride in the kettle type reactor is controlled to be 10-50%, and the selectivity of the chloroacetyl chloride is controlled to be 95-99.9%.

Further, in the step (5), the temperature of the distillation tower kettle of the first distillation tower is 40-100 ℃, and the distillation pressure is 0.05-0.2 MPa.

Wherein, chlorine and acetyl chloride fractions obtained from the top of the first rectifying tower are recycled to the kettle type reactor for reuse; and washing and recovering trace free chlorine in the tail gas of the first rectifying tower by using an acetyl chloride raw material.

Wherein the temperature of the rectifying tower kettle of the second rectifying tower is 100-150 ℃, and the rectifying pressure is 0.05-0.1 MPa; and 5-40% of the high-boiling residual liquid in the tower kettle of the second rectifying tower is discharged to a system for post-treatment, and the residual liquid of 60-95% is recycled to the kettle type reactor for reuse.

Under the action of electromagnetic radiation, acetyl chloride is contacted with chlorine under a certain pressure state, so that the solubility of the chlorine in a reaction system is increased, and the chloroacetyl chloride is accelerated to be generated in the reactor. In addition, the second rectifying tower kettle contains high-boiling residual liquid, and 60-95% of the residual liquid is mechanically used, so that hazardous waste discharge is reduced, and the selectivity of chloroacetyl chloride can be improved.

Compared with the prior art, the invention has the following beneficial effects:

1) by controlling the acetyl chloride conversion rate to be 10-50%, the product can be diluted to a certain degree, the further chlorination of the product chloroacetyl chloride is reduced, and the selectivity of the product can be further improved;

2) chlorine and acetyl chloride obtained from the top of the first rectifying tower and 60-95% of high-boiling residual liquid in the kettle of the second rectifying tower can be recycled, the discharge of three wastes can be reduced, and the selectivity of chloroacetyl chloride products can be improved, wherein the process system can improve the reaction selectivity of chloroacetyl chloride by about 0-10%;

3) kettle-type stirred tank reactor can be with chlorine and acetyl chloride intensive mixing, and the dispersibility of greatly increased chlorine in acetyl chloride can increase the solubility of chlorine in acetyl chloride under certain pressure state, has improved reaction efficiency.

Drawings

FIG. 1 is a schematic diagram of a process for preparing chloroacetyl chloride according to the present invention.

Wherein the reference numerals are: the device comprises a reactor 1, a condenser 2, an absorption tower 3, a centrifugal pump 4, a first rectifying tower 5 and a second rectifying tower 6.

Detailed Description

The above-mentioned contents of the present invention are further described in detail by way of examples below, but it should not be understood that the scope of the above-mentioned subject matter of the present invention is limited to the following examples, and any technique realized based on the above-mentioned contents of the present invention falls within the scope of the present invention.

The experimental procedures used in the examples below are conventional procedures unless otherwise specified, and the reagents, methods and equipment used therein are conventional in the art unless otherwise specified.

Example 1

Reactor with a reactor shell1 the inner diameter is selected to beThe preparation process flow of chloroacetyl chloride in a kettle type reactor with the height of 1m is as follows:

1) adding acetyl chloride into a kettle-type reactor 1 to a liquid level of 70 percent, wherein the content of a solvent N, N' -bis (4-amino-2, 2,6, 6-tetramethylpiperidyl) -1, 3-benzenedicarboxamide is 5 percent, preheating an acetyl chloride material to 45 ℃, placing an electromagnetic wave generating device in the middle of the kettle-type reactor, introducing 0.2 weight percent of chlorine gas into the reactor from the bottom of the reactor under the condition of electromagnetic radiation with the wavelength of 360nm, and observing the reaction phenomenon.

2) Continuously introducing chlorine with the molar ratio of the chlorine to acetyl chloride of 0.98:1 for reaction after the reaction is started, controlling the temperature of the reactor at 45 ℃, controlling the pressure of the reactor at 0.1MPa, treating tail gas by an absorption tower 3, removing trace organic matters by tail gas treatment, preparing hydrochloric acid, analyzing the composition of reaction mixed liquid by using online detection equipment in the reaction process, and controlling the conversion rate of acetyl chloride to be 30% and the selectivity of chloroacetyl chloride to be 99.5%;

3) continuously extracting the upper material of the reactor from the reaction liquid obtained in the step 2) by using a centrifugal pump 3, pumping the upper material into a first rectifying tower 4, controlling the temperature of a tower kettle of the first rectifying tower 4 to be 70.5 ℃, keeping the vacuum of the first rectifying tower 4 at normal pressure, recycling the chlorine and acetyl chloride fractions obtained at the tower top in the rectifying process, and pumping the crude chloroacetyl chloride material obtained at the tower kettle into a second rectifying tower 5 for vacuum rectification;

4) controlling the temperature of the tower bottom of the second rectifying tower 5 to be 82.6 ℃, the vacuum of the tower top to be 0.08MPa, rectifying the crude chloracetyl chloride material in the second rectifying tower 5 in vacuum to obtain a chloracetyl chloride pure product with the purity of 99.7 percent at the tower top, and circulating 60 percent of high-boiling residual liquid in the tower bottom to the reactor for continuous reaction.

Example 2

This example differs from example 1 in that in step 2) the reactor pressure was controlled to 0.15MPa, the acetyl chloride conversion was controlled to 30% and the chloroacetyl chloride selectivity was controlled to 99.2%; and 4) circulating 80 percent of high-boiling raffinate in the second rectifying tower kettle to the reactor for continuous reaction.

Example 3

This example differs from example 1 in that the reaction was not subjected to electromagnetic radiation and samples were analyzed in step 2) and found to be essentially non-converted to acetyl chloride.

Example 4

The difference between the embodiment and the embodiment 2 is that in the step 1), the preheating temperature of the acetyl chloride material is 40 ℃, the content of the solvent is 10 percent, wherein the mass ratio of the N, N' -bis (4-amino-2, 2,6, 6-tetramethylpiperidyl) -1, 3-phthalic diamide to the p-hydroxyanisole is 1:1, and the electromagnetic wavelength is 350 nm; in the step 2), the conversion rate of acetyl chloride is controlled to be 25 percent, and the selectivity of the chloroacetyl chloride is controlled to be 99.6 percent; in the step 3), the temperature of the tower bottom of the first rectifying tower 4 is 68.3 ℃, and the rectifying pressure is normal pressure; in the step 4), the temperature of the tower bottom of the second rectifying tower 5 is 77.2 ℃, the rectifying pressure is 0.07MPa, and finally, chloroacetyl chloride with the purity of 99.8 percent is obtained at the tower top of the second rectifying tower 5, and 60 percent of high-boiling residual liquid in the tower bottom is circulated to the reactor for continuous reaction.

Example 5

The difference between the embodiment and the embodiment 1 is that in the step 2), the mole ratio of chlorine to acetyl chloride is continuously fed in 0.3:1.0, the temperature of the reactor is controlled at 20 ℃, and the pressure of the reactor is controlled at 0.3 MPa; the conversion rate of acetyl chloride is controlled to be 20 percent, and the selectivity of the chloroacetyl chloride is controlled to be 99.8 percent; in the step 3), the tower kettle temperature of the first rectifying tower 4 is 68.4 ℃, and the operating pressure of the first rectifying tower 4 is normal pressure; in the step 4), the temperature of the tower bottom of the second rectifying tower 5 is 74.1 ℃, the rectifying pressure is 0.07MPa, and finally, chloroacetyl chloride with the purity of 99.7 percent is obtained at the tower top of the second rectifying tower 5.

Example 6

This example differs from example 5 in that in step 2) the reactor temperature was controlled at 45 ℃ and the reactor pressure was controlled at 0.5 MPa; the conversion rate of acetyl chloride is controlled to be 20 percent, and the selectivity of the chloroacetyl chloride is controlled to be 99.6 percent; in the step 4), the residual liquid containing 70 percent of high-boiling residual liquid in the second rectifying tower kettle is circulated to the reactor for continuous reaction.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.