High-yield trichloroacetyl chloride preparation system and method

Abstract

The invention provides a high-yield trichloroacetyl chloride preparation method, comprising the following steps: introducing chlorine into an acyl chloride mixture to generate trichloroacetyl chloride by deep chlorination reaction; in the later stage of the reaction, detecting the component content of the material in the reactor, if the acid component content is high, adding disulfur dichloride into the reactor, and the generated acyl chloride mixture continues to generate deep chlorination reaction with chlorine to generate trichloroacetyl chloride. In the process of the reaction in the reactor, after the deep chlorination of the acyl chloride mixture and chlorine is completed, chloroacetic acid and dichloroacetic acid may remain. At this time, the material components in the reactor are analyzed and detected, and disulfur dichloride is added from a supplementary tank according to the detection result. The amount of disulfur dichloride added is controlled by a flow valve and a control valve, so that the acid continues to generate monochloroacetyl chloride and dichloroacetyl chloride completely by chlorination reaction, and then continues to be deeply chlorinated to be converted into trichloroacetyl chloride, thereby improving the yield of trichloroacetyl chloride.

Description

Technical Field

[0001] The invention relates to the technical field of trichloroacetyl chloride preparation, and in particular to a system and method for preparing trichloroacetyl chloride with high yield. Background Art

[0002] Trichloroacetyl chloride is an important intermediate for the synthesis of organophosphorus insecticides chlorpyrifos and chlorpyrifos-methyl. Currently, most trichloroacetyl chloride on the market is used for the production of chlorpyrifos. Chlorpyrifos is an organophosphorus pesticide with high efficiency, broad spectrum, low residue and low resistance, and is one of the pesticide varieties with large production and sales volume. With the banning of five highly toxic organophosphorus pesticides such as methyl parathion and fipronil, chlorpyrifos will become one of the main alternatives. As an intermediate of chlorpyrifos, trichloroacetyl chloride has broad market space in the future.

[0003] There are many methods for preparing trichloroacetyl chloride, for example, it can be obtained by reacting acetyl chloride or acetaldehyde with chlorine in the presence of activated carbon. The reaction of oxygen and tetrachloroethylene in the presence of ultraviolet light and a catalyst can also produce trichloroacetyl chloride. Nitric acid and trichloroacetaldehyde react to obtain trichloroacetic acid, and then phosphorus trichloride is added to the trichloroacetic acid for reaction. After the reaction is completed, the product is separated to obtain trichloroacetyl chloride. There is also a method for preparing trichloroacetyl chloride by chlorinating chloroacetic acid waste liquid with chlorine. However, the yield of the existing method for preparing trichloroacetyl chloride by chlorination of chloroacetic acid waste liquid is relatively low. Summary of the invention

[0004] It is necessary to provide a high-yield trichloroacetyl chloride preparation system and method.

[0005] A high-yield trichloroacetyl chloride preparation system comprises a first reactor, a first condenser, a first gas-liquid separator, a second reactor, a second condenser, a second gas-liquid separator and a supplementing tank, wherein an acyl chloride mixture prepared from a chloroacetic acid mother liquor is added into the first reactor, a hole for introducing chlorine gas is arranged in the first reactor, a gas phase outlet of the first reactor is connected to a gas phase inlet of the first condenser, a liquid phase outlet of the first condenser is connected to an inlet of the first gas-liquid separator, a gas phase outlet of the first gas-liquid separator is connected to the supplementing tank, and a liquid phase outlet of the first gas-liquid separator is connected to a liquid phase reflux port of the first reactor; an acyl chloride mixture prepared from a chloroacetic acid mother liquor is added into the second reactor, a hole for introducing chlorine gas is arranged in the first reactor, a gas phase outlet of the first reactor is connected to a gas phase inlet of the first condenser, a liquid phase outlet of the first condenser is connected to an inlet of the first gas-liquid separator, a gas phase outlet of the first gas-liquid separator is connected to the supplementing tank, and a liquid phase outlet of the first gas-liquid separator is connected to a liquid phase reflux port of the first reactor; The second reactor is provided with a hole for introducing chlorine, the gas phase outlet of the second reactor is connected to the gas phase inlet of the second condenser, the liquid phase outlet of the second condenser is connected to the inlet of the second gas-liquid separator, the gas phase outlet of the second gas-liquid separator is connected to the replenishing tank, the liquid phase outlet of the second gas-liquid separator is connected to the liquid phase reflux port of the second reactor, the replenishing tank is provided with a port for discharging tail gas and a feed port for adding disulfur dichloride, the replenishing tank is also connected to the first reactor and the second reactor respectively, and a first flow valve, a first switch valve, a second flow valve, and a second switch valve are arranged between the replenishing tank and the first reactor and the second reactor.

[0006] A method for preparing trichloroacetyl chloride with high yield comprises the following steps:

[0007] Chlorine gas is introduced into the acyl chloride mixture to cause a deep chlorination reaction to generate trichloroacetyl chloride. In this step, the main reactions that occur are shown in Formula 1 to Formula 3:

[0008]

[0009] At the end of the reaction, the content of the substance in the reactor is tested. If the acid content is high, disulfur dichloride is added to the reactor to produce reactions of Formula 4 to Formula 6:

[0010]

[0011] The generated acyl chloride mixture continues to react with chlorine gas to undergo deep chlorination reactions of Formula 1 to Formula 3 to generate trichloroacetyl chloride.

[0012] This scheme has two sets of trichloroacetyl chloride reactors, and the two share a supplementary tank to supplement disulfur dichloride, and the two reactors are controlled by flow valves and switch valves respectively. The reaction is uninterrupted for one reactor, that is, the substance content is detected in the later stage of the reaction, and chlorine is kept in the reactor at this time, and the detection time is short. In order to react all the acid substances, disulfur dichloride is directly added instead of sulfur, because if sulfur is added to the supplementary tank, although sulfur and chlorine react to generate disulfur dichloride, the progress of the reaction of the two and the amount of disulfur dichloride generated cannot be accurately grasped, and the reaction of the two still requires time, so adding disulfur dichloride directly from the supplementary tank is the most preferred scheme. Through the metering of the flow valve, according to the calculation results, the amount of disulfur dichloride is accurately added to the reactor, so that the purity or yield of trichloroacetyl chloride generated by the reaction can reach 99%.

[0013] In this scheme, during the reaction in the reactor, after the deep chlorination of the acyl chloride mixture (monochloroacetyl chloride, dichloroacetyl chloride) and chlorine gas is completed, chloroacetic acid and dichloroacetic acid may remain. At this time, the material components in the reactor are analyzed and tested, and disulfur dichloride is added from the replenishing tank according to the test results. The amount of disulfur dichloride added is controlled by the flow valve and the control valve, so that the acid continues to chlorinate to completely generate monochloroacetyl chloride and dichloroacetyl chloride, and then continues to be deeply chlorinated and converted into trichloroacetyl chloride, thereby improving the yield of trichloroacetyl chloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the connection of a high-yield trichloroacetyl chloride preparation system.

[0015] Figure 2 The figure is a connection schematic diagram of a high-yield trichloroacetyl chloride preparation system of another hinged embodiment.

[0016] In the figure: a first reaction kettle 10, a first flow valve 11, a first switch valve 12, a first condenser 20, a first gas-liquid separator 30, a second reaction kettle 40, a second flow valve 41, a second switch valve 42, a second condenser 50, a second gas-liquid separator 60, a replenishing tank 70, a feed inlet 71 for adding disulfur dichloride, a feed inlet 72 for adding sulfur, a primary acylation kettle 80, and a sulfidation kettle 90. DETAILED DESCRIPTION

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] See also Figure 1 The embodiment of the present invention provides a high-yield trichloroacetyl chloride preparation system, comprising a first reactor 10, a first condenser 20, a first gas-liquid separator 30, a second reactor 40, a second condenser 50, a second gas-liquid separator 60, and a replenishing tank 70. An acyl chloride mixture prepared from a chloroacetic acid mother liquor is added to the first reactor 10. The first reactor 10 is provided with a hole for introducing chlorine gas. The gas phase outlet of the first reactor 10 is connected to the gas phase inlet of the first condenser 20. The liquid phase outlet of the first condenser 20 is connected to the inlet of the first gas-liquid separator 30. The gas phase outlet of the first gas-liquid separator 30 is connected to the replenishing tank 70. The liquid phase outlet of the first gas-liquid separator 30 is connected to the liquid phase reflux port of the first reactor 10. The acyl chloride mixture prepared from a chloroacetic acid mother liquor is added to the second reactor 40. The second reactor 40 is provided with a hole for introducing chlorine gas. The gas phase outlet of the first reactor 10 is connected to the gas phase inlet of the first condenser 20. The liquid phase outlet of the first condenser 20 is connected to the inlet of the first gas-liquid separator 30. The gas phase outlet of the first gas-liquid separator 30 is connected to the replenishing tank 70. The liquid phase outlet of the first gas-liquid separator 30 is connected to the liquid phase reflux port of the first reactor 10. A hole for introducing chlorine is provided, the gas phase outlet of the second reactor 40 is connected to the gas phase inlet of the second condenser 50, the liquid phase outlet of the second condenser 50 is connected to the inlet of the second gas-liquid separator 60, the gas phase outlet of the second gas-liquid separator 60 is connected to the replenishing tank 70 (unreacted chlorine is recovered into the replenishing tank 70), the liquid phase outlet of the second gas-liquid separator 60 is connected to the liquid phase reflux port of the second reactor 40, the replenishing tank 70 is provided with a port for discharging tail gas and a feed port 71 for adding disulfur dichloride, the replenishing tank 70 is also connected to the first reactor 10 and the second reactor 40 respectively, and a first flow valve 11, a first switch valve 12 (a metering valve with flow monitoring and switch control functions can also be used), a second flow valve 41, and a second switch valve 42 are provided between the replenishing tank 70 and the first reactor 10 and the second reactor 40.

[0019] Since monochloroacetyl chloride is also one of the main products produced by the applicant, a large amount of chloroacetic acid mother liquor will be produced in the process of preparing monochloroacetyl chloride. The present scheme is to use the chloroacetic acid mother liquor to prepare trichloroacetyl chloride. The preparation of monochloroacetyl chloride is to first generate disulfur dichloride with chlorine and sulfur, and then react acetic acid, disulfur dichloride and chlorine to obtain the obtained acyl chloride, which enters a distillation tower for separation, and a large amount of chloroacetic acid mother liquor is produced in the process; the chloroacetic acid mother liquor is then distilled to obtain an anhydrous mother liquor, and then the anhydrous chloroacetic acid mother liquor is once chlorinated with disulfur dichloride to generate an acyl chloride mixture (mainly monochloroacetyl chloride, dichloroacetyl chloride and chloroacetic acid that is not completely reacted, and other impurities that remain in the chloroacetic acid mother liquor or are not fully reacted by themselves, such as monochloroacetic acid, dichloroacetic acid, etc.), the acyl chloride mixture is added to the first reactor 10 or the second reactor 40, chlorine is introduced, a catalyst is added, and deep chlorination is performed to obtain trichloroacetyl chloride.

[0020] In order to improve the yield of trichloroacetyl chloride, during the reaction of the first reactor 10 and the second reactor 40, the components of the substances in the reactor are detected. If the detection reaction shows that the acyl chloride has been completely chlorinated, but there are still chloroacetic acid substances (such as chloroacetic acid and dichloroacetic acid) remaining, these substances are mixed in trichloroacetyl, resulting in a low yield of trichloroacetyl chloride. Therefore, at this time, the amount of sulfur chloride to be added is converted according to the detection ratio, and the sulfur chloride is added to the replenishing tank 70, and then added to the reactor through the replenishing tank 70 to acylate chloroacetic acid and dichloroacetic acid, and the chlorine gas is continuously introduced to continue deep chlorination to generate trichloroacetyl chloride, thereby improving the yield.

[0021] This is different from the prior art, in the patent of CN200410021491.4, it is also the process of preparing trichloroacetyl chloride by chloroacetic acid mother liquor, in this invention, part of the process is the same as the present invention, but there is just the problem to be solved by the present application, as after the acylation of chloroacetic acid mother liquor in step b, rectification and separation obtains monochloroacetyl chloride, dichloroacetyl chloride mixture, and trichloroacetyl chloride is produced under the action of catalyst pyridine in step c.But in step b, chloroacetic acid mother liquor is refined, and the concept of this refinement can be explained in two ways, the first, if high purity can not be reached after refinement, then still residual acid impurity substances, so during acyl chloride reaction, due to the presence of no disulfur dichloride, chloroacetic acid can not all react, still can remain, remain in monochloroacetyl chloride, dichloroacetyl chloride mixture in the form of chloroacetic acid or unacylated dichloroacetic acid, so naturally there will be the problem to be solved in the present invention, and do not propose or solve this problem in this invention.The second, if the concept of this refinement is completely high-purity, then no residual acid substances, just do not have technical problem of the present invention. Similarly, the problem also exists in the patent CN201110330108.3. Although in claim 3, the chloroacetic acid waste liquid is distilled at 130-140°C to remove low-boiling substances, and then the acyl chloride mixture is prepared by chlorine and sulfur catalytic reaction, even if the low-boiling substances are removed, the chlorination reaction of chlorine and chloroacetic acid itself cannot react completely. Then, chlorine is introduced into the acyl chloride mixture and pyridine catalyst is added to generate trichloroacetyl chloride. However, since chloroacetic acid uses waste liquid, residual chloroacetic acid and dichloroacetic acid must exist in the generated acyl chloride mixture. Therefore, the problem of the present invention still exists when using the acyl chloride mixture to prepare trichloroacetyl chloride; if the pure acyl chloride mixture is directly used to prepare trichloroacetyl, such as CN2016106822456 and CN201510534467.9, the problem of the present invention does not exist, and the present invention is not applicable.

[0022] Furthermore, the replenishing tank 70 is also provided with a feeding port 72 for feeding sulfur.

[0023] See also Figure 2 Further, the high-yield trichloroacetyl chloride preparation system also includes a primary acylation kettle 80 and a sulfurization kettle 90. The sulfurization kettle 90 is used to introduce chlorine gas and sulfur to generate disulfur dichloride by a sulfurization reaction. The discharge port of the sulfurization kettle 90 is connected to the primary acylation kettle 80. The primary acylation kettle 80 is used to add disulfur dichloride and anhydrous chloroacetic acid mother liquor after distillation to generate a primary chlorination reaction to mainly generate monochloroacetyl chloride and dichloroacetyl chloride. The outlet of the primary acylation kettle 80 is connected to the inlet of the first reactor 10 and the second reactor 40.

[0024] The present invention also provides a method for preparing trichloroacetyl chloride with high yield, comprising the following steps:

[0025] Chlorine gas is introduced into the acyl chloride mixture to cause a deep chlorination reaction to generate trichloroacetyl chloride. In this step, the main reactions that occur are shown in Formula 1 to Formula 3:

[0026]

[0027] At the end of the reaction (e.g., the last 1 / 3-1 / 2 of the preset reaction time), the content of the substance in the reactor is detected. If the acid content is high (e.g., more than 1%), disulfur dichloride is added to the reactor to produce reactions of Formula 4-Formula 6:

[0028]

[0029] The generated acyl chloride mixture continues to react with chlorine gas to undergo deep chlorination reactions of Formula 1 to Formula 3 to generate trichloroacetyl chloride.

[0030] By this method, the acid substances remaining in the late reaction kettle are converted into an acyl chloride mixture, the acid substances are removed, chlorine is continuously passed through the reaction kettle, and then the acyl chloride mixture is deeply chlorinated to generate trichloroacetyl chloride.

[0031] Furthermore, the high-yield trichloroacetyl chloride preparation method is characterized by comprising the following steps:

[0032] In the early stage of the reaction of the reactor (for example, the first 1 / 2-2 / 3 of the preset reaction time), sulfur is added to the supplementary tank 70, and the excess chlorine in the reactor reacts with sulfur in the supplementary tank 70 to generate disulfur dichloride. The chlorine introduced into the reactor is excessive, and this scheme can make full use of the excess chlorine in the reactor, avoid being discharged into the tail gas system, reduce the tail gas treatment pressure, and the chlorine utilization rate is high. At the same time, the supplementary tank 70 is vacant before the reaction, and the chlorine is directly discharged after entering. During this period of time, part of sulfur is added to the supplementary tank 70, and disulfur dichloride can also be generated, which is supplemented to the reactor during the later deep chlorination. Since disulfur dichloride only needs to be added in the later stage, the time of the early reaction can be used for the reaction of excess chlorine with sulfur to generate disulfur dichloride, which is connected before and after, and when disulfur dichloride is injected into the reactor in the later stage, it is a metering method, and the supply of disulfur dichloride in the supplementary tank 70 can reduce the amount of disulfur dichloride added externally.

[0033] Further, the method also includes the step of preparing the acyl chloride mixture:

[0034] Chlorine and sulfur react in the sulfurizing kettle 90 to generate disulfur dichloride; the main reactions occurring in this step are:

[0035]

[0036] The disulfur dichloride is added into the acylation kettle to react with the anhydrous chloroacetic acid mother liquor to mainly generate an acyl chloride mixture of acetyl chloride, monochloroacetyl chloride and dichloroacetyl chloride. The main reactions occurring in this step are Formula 4 to Formula 6.

[0037] The modules or units in the device of the embodiment of the present invention may be combined, divided or deleted according to actual needs.

[0038] What is disclosed above is only the preferred embodiment of this patent document, and of course it cannot be used to limit the scope of rights of the present invention. Moreover, the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. A person of ordinary skill in the art can understand that the implementation of all or part of the processes of the above-mentioned embodiments and the equivalent changes made in accordance with the claims of the present invention still fall within the scope covered by the invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention. Any mark in the claims should not be regarded as limiting the claims involved.

[0039] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing trichloroacetyl chloride with high yield, characterized in that The following steps are involved: Chlorine gas is introduced into the acyl chloride mixture to cause a deep chlorination reaction to generate trichloroacetyl chloride. In this step, the main reactions that occur are shown in Formula 1 to Formula 3: In the later stage of the reaction, the content of the substances in the reactor is detected. If the acid content is high, disulfur dichloride is added to the reactor to produce reactions of formula 4 to formula 6: The generated acyl chloride mixture continues to react with chlorine gas to produce a deep chlorination reaction of Formula 1 to Formula 3 to generate trichloroacetyl chloride; In the early stage of the reaction of the reactor, sulfur is added to the supplementary tank, and the excess chlorine in the reactor reacts with the sulfur in the supplementary tank to form disulfur dichloride; Also included is the step of preparing the acyl chloride mixture: Chlorine and sulfur react in the sulfiding kettle to generate disulfur dichloride; the main reactions in this step are: The disulfur dichloride is added into the acylation kettle to react with the anhydrous chloroacetic acid mother liquor to mainly generate an acyl chloride mixture of acetyl chloride, monochloroacetyl chloride and dichloroacetyl chloride. The main reactions occurring in this step are Formula 4 to Formula 6.

2. The method for preparing trichloroacetyl chloride with high yield as claimed in claim 1, characterized in that: The high-yield trichloroacetyl chloride preparation method is implemented in a high-yield trichloroacetyl chloride preparation device: the high-yield trichloroacetyl chloride preparation device comprises a first reactor, a first condenser, a first gas-liquid separator, a second reactor, a second condenser, a second gas-liquid separator, and a replenishing tank, an acyl chloride mixture prepared from chloroacetic acid mother liquor is added into the first reactor, a hole for introducing chlorine gas is provided in the first reactor, a gas phase outlet of the first reactor is connected to a gas phase inlet of the first condenser, a liquid phase outlet of the first condenser is connected to an inlet of the first gas-liquid separator, a gas phase outlet of the first gas-liquid separator is connected to the replenishing tank, and a liquid phase outlet of the first gas-liquid separator is connected to a liquid phase reflux port of the first reactor. ; The acyl chloride mixture prepared from chloroacetic acid mother liquor is added into the second reactor, the second reactor is provided with a hole for introducing chlorine, the gas phase outlet of the second reactor is connected to the gas phase inlet of the second condenser, the liquid phase outlet of the second condenser is connected to the inlet of the second gas-liquid separator, the gas phase outlet of the second gas-liquid separator is connected to the replenishing tank, the liquid phase outlet of the second gas-liquid separator is connected to the liquid phase reflux port of the second reactor, the replenishing tank is provided with a port for discharging tail gas and a feed port for adding disulfur dichloride, the replenishing tank is also connected to the first reactor and the second reactor respectively, and a first flow valve, a first switch valve, a second flow valve, and a second switch valve are arranged between the replenishing tank and the first reactor and the second reactor.

3. The method for preparing trichloroacetyl chloride with high yield as claimed in claim 2, characterized in that: The replenishing tank is also provided with a feeding port for feeding sulfur.

4. The method for preparing trichloroacetyl chloride with high yield as claimed in claim 3, characterized in that: The high-yield trichloroacetyl chloride preparation device also includes a primary acylation kettle and a sulfidation kettle. The sulfidation kettle is used to introduce chlorine gas and sulfur. The discharge port of the sulfidation kettle is connected to the primary acylation kettle. The primary acylation kettle is used to add disulfur dichloride and anhydrous chloroacetic acid mother liquor after distillation to generate a primary chlorination reaction to mainly generate monochloroacetyl chloride and dichloroacetyl chloride. The outlet of the primary acylation kettle is connected to the inlet of the first reaction kettle and the second reaction kettle.

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