CN106883103B - Preparation method of 2, 4-dichlorophenol - Google Patents
Preparation method of 2, 4-dichlorophenol Download PDFInfo
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- CN106883103B CN106883103B CN201710277943.2A CN201710277943A CN106883103B CN 106883103 B CN106883103 B CN 106883103B CN 201710277943 A CN201710277943 A CN 201710277943A CN 106883103 B CN106883103 B CN 106883103B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/62—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by introduction of halogen; by substitution of halogen atoms by other halogen atoms
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C39/00—Compounds having at least one hydroxy or O-metal group bound to a carbon atom of a six-membered aromatic ring
- C07C39/24—Halogenated derivatives
- C07C39/26—Halogenated derivatives monocyclic monohydroxylic containing halogen bound to ring carbon atoms
- C07C39/27—Halogenated derivatives monocyclic monohydroxylic containing halogen bound to ring carbon atoms all halogen atoms being bound to ring carbon atoms
- C07C39/30—Halogenated derivatives monocyclic monohydroxylic containing halogen bound to ring carbon atoms all halogen atoms being bound to ring carbon atoms the halogen being two chlorine atoms
Abstract
The invention relates to a preparation method of 2, 4-dichlorophenol, which comprises the following steps: taking phenol and chlorine as raw materials, and obtaining the 2, 4-dichlorophenol through chlorination reaction under the catalytic action of phosphorus pentachloride. According to the invention, phosphorus pentachloride is used as a catalyst, the heat generated by chlorination reaction is utilized, the temperature of the whole chlorination process is controlled within a proper range by controlling the chlorine gas introduction speed and the circulation speed of common circulating water, so that the energy is saved, and the 2, 4-dichlorophenol with the content of more than 98% is prepared, the content of chlorinated impurities, namely 2, 6-dichlorophenol, is lower than 0.90 wt%, the content of 2,4, 6-trichlorophenol is lower than 1.30 wt%, and the total content of impurities, such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like, is lower than 0.25 wt%; the 2, 4-dichlorophenol with the content can be directly used as a raw material for preparing 2,4-D technical with the content of more than 96 wt% without distillation or rectification and purification, thereby reducing the energy consumption.
Description
Technical Field
The invention relates to the technical field of organic synthesis, in particular to a method for preparing chlorinated phenol by catalytic chlorination of phenol, and especially relates to a method for preparing 2, 4-dichlorophenol by catalytic chlorination of phenol.
Background
2, 4-dichlorophenol is an important intermediate in the pharmaceutical industry, the pesticide industry and the adjuvant industry, the annual demand is more than 8 ten thousand tons, and the insecticidal thiobischlorophenol, the pesticide herbicide 2,4-D and a series of derivatives used as pesticides thereof, the herbicide oxadiazon, the pesticide fenaminophos, the aclofether, the mildew preventive TCS and a series of substances, wherein the application of the insecticidal herbicide 2,4-D and the series of derivatives used as pesticides thereof is the largest. The production method of 2, 4-dichlorophenol mainly comprises a p-chlorophenol catalytic chlorination method, an o-chlorophenol catalytic chlorination method, a phenol direct chlorination method and the like.
Zhang Mei Fa and Li Zi Bao reported that p-chlorophenol as raw material was catalyzed by a self-made ZMF-1 catalyst to chlorinate p-chlorophenol to successfully prepare 2, 4-dichlorophenol with a content of over 99% (see "research on synthesis process of high-content 2, 4-dichlorophenol", Zhang Mei Fa, Li Zi Bao, Anhui chemical industry, 1996 02, pages 33-34), the method greatly reduces the generation of polychlorinated by-product 2,4, 6-trichlorophenol by selecting a proper chlorine introducing pipe and controlling the aspects of chlorine introducing speed, time, chlorine introducing amount, stirring efficiency and the like, but the p-chlorophenol raw material with the content of 99 percent is obtained by rectifying the chlorinated phenol, therefore, the method for preparing 2, 4-dichlorophenol by using p-chlorophenol with the content of 99% as a raw material has high cost and insufficient economical efficiency for industrialization.
The catalytic chlorination method for preparing 2, 4-dichlorophenol by o-chlorophenol is reported by Sunchang et al (see 'selective chlorination method for synthesizing 2, 4-dichlorophenol', Sunchang et al, Henan chemical engineering, 1990, 11 th period, 19-21 pages), the method takes 96.5% of by-product o-chlorophenol obtained in the industrial production process of p-chlorophenol as raw material, anhydrous aluminum trichloride and diphenyl sulfide as catalysts, sulfuryl chloride as chlorinating agent, and chlorination is carried out at about 15 ℃, so that the content of 2, 4-dichlorophenol in the product is more than 95 wt%, and the rest is about 4 wt% of 2, 6-dichlorophenol; since the boiling point of 2, 6-dichlorophenol (220 ℃ C. at atmospheric pressure) is only 10 ℃ higher than that of 2, 4-dichlorophenol (210 ℃ C. at atmospheric pressure), it is very difficult to obtain 2, 4-dichlorophenol having a content of 99% or more by purifying 95% or more of 2, 4-dichlorophenol by distillation or rectification.
The phenol direct chlorination method is a traditional production process and has the characteristics of low cost, simple process and the like, but the direct chlorination reaction time of phenol and chlorine is longer, the content of 2, 4-dichlorophenol in the obtained chlorination crude product is generally less than 90%, and impurities comprise o-chlorophenol, p-chlorophenol, 2, 6-dichlorophenol, 2,4, 5-trichlorophenol, 2,4, 6-trichlorophenol and the like, particularly the content of 2, 6-dichlorophenol reaches about 8%, and the 2, 4-dichlorophenol is very close to the physical property of 2, 4-dichlorophenol and is difficult to separate. CN102659530A discloses that phenol is used as a raw material, the reaction temperature is controlled to be 40-80 ℃, 2, 4-dichlorophenol is prepared by continuous chlorination in a multistage chlorination tower, and the yield reaches 94.19-96.03 wt%; CN104529757B discloses that a microchannel reactor is adopted to carry out continuous chlorination reaction of phenol, the reaction temperature is controlled at 50 ℃ or 100 ℃, the synthesis yield can reach 98.8 percent at most, and the condition is controlled to ensure that the content of 2, 4-dichlorophenol which is a required product is more than 90 percent by weight. The microchannel reactor is a novel chemical equipment developed and applied in recent years, so that chemical reaction is carried out in a microchannel with the characteristic dimension of micron order, the mass transfer and heat transfer performance of chemical fluid in the microchannel is greatly improved compared with a conventional system due to the miniaturization of the dimension, and a better reaction result is obtained, the advantages of the microchannel reactor are applied to CN104529757B, and the better result that the content of the required 2, 4-dichlorophenol is more than 90 wt% and the yield is up to 98.8% is a great progress, but due to the characteristic of the microchannel structure, the maximum annual output of the microchannel reactor applied to industrial production is 2000 tons, so that the microchannel reactor is not suitable for 2, 4-dichlorophenol products with the annual demand of more than 8 ten thousand tons; furthermore, the specification standard of the world Food and Agriculture Organization (FAO) for the pesticide 2,4-D technical is that the content is not less than 96%, and the 2,4-D technical prepared from 2, 4-dichlorophenol generally undergoes the following three steps of reaction: 1)2, 4-dichlorophenol reacts with sodium hydroxide to prepare 2, 4-dichlorophenol sodium salt, 2)2, 4-dichlorophenol sodium salt is condensed with sodium chloroacetate to prepare 2, 4-dichlorophenoxyacetic acid sodium salt; 3)2, 4-dichlorophenoxyacetic acid sodium salt reacts with hydrochloric acid to obtain 2,4-D (see [0010] and [0011] of CN104529757B specification in detail), the yield of the three steps of reactions is difficult to reach 100 wt%, new impurities are generated or introduced into 2,4-D raw medicines, so that the content of the 2,4-D raw medicines is not less than 96%, and the content of the used 2, 4-dichlorophenol is necessarily higher than 96 wt%; otherwise, the content of the obtained 2,4-D technical product cannot reach the FAO standard, and for realizing sale, the crude 2,4-D technical product with the content lower than 96 wt% needs to be purified by traditional purification methods such as recrystallization and the like to enable the content to reach 96 wt% or more, which increases equipment investment, production cost, three wastes generation and the like. Therefore, the content of the 2, 4-dichlorophenol prepared by the method disclosed in CN102659530A according to the standard of FAO for the pesticide 2,4-D technical material can not necessarily meet the requirement of preparing the 2,4-D technical material; according to the method for preparing 2, 4-dichlorophenol disclosed in CN104529757B, it is not enough to control the content of 2, 4-dichlorophenol to be greater than 90%, the chlorination selectivity is not high enough, the content of 2, 4-dichlorophenol obtained by the reaction may not be too high, and the 2, 4-dichlorophenol can be used for preparing 2,4-D crude drug only after being purified by distillation or rectification, or directly used for preparing 2,4-D crude drug, and then the pesticide 2,4-D crude drug meeting the FAO standard can be obtained after being purified by recrystallization, and the economy of these production processes is also improved.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a preparation method and application of 2, 4-dichlorophenol. Phosphorus pentachloride is used as a catalyst, the heat generated by chlorination reaction is utilized, the temperature of the whole chlorination process is controlled within a proper range by controlling the chlorine gas introduction speed and the circulation speed of common circulating water, energy is saved, 2, 4-dichlorophenol with the content of more than 98 percent is prepared, the impurity content is low, and the 2, 4-dichlorophenol can be directly used as a raw material for preparing 2,4-D technical with the content of 96 percent by weight or more.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a process for the preparation of 2, 4-dichlorophenol, the process comprising:
taking phenol and chlorine as raw materials, and obtaining the 2, 4-dichlorophenol through chlorination reaction under the catalytic action of phosphorus pentachloride.
The invention adopts phosphorus pentachloride as the catalyst, and the high selectivity of chlorination reaction can be realized through the action of the catalyst, and the prepared 2, 4-dichlorophenol has high yield and content and low content of chlorinated impurities.
Preferably, the phosphorus pentachloride is used in an amount of 0.005-0.10% of the molar fraction of the raw phenol, such as 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.10%, preferably 0.01-0.07%, and more preferably 0.03-0.05%.
Preferably, the amount of the chlorine gas is 2.00 to 2.12 equivalents based on the mole number of the raw phenol, for example, 2.00 equivalents, 2.01 equivalents, 2.02 equivalents, 2.03 equivalents, 2.04 equivalents, 2.05 equivalents, 2.06 equivalents, 2.07 equivalents, 2.08 equivalents, 2.09 equivalents, 2.10 equivalents, 2.11 equivalents or 2.12 equivalents, preferably 2.01 to 2.09 equivalents, and more preferably 2.05 equivalents.
Preferably, the reaction temperature is 42-55 ℃, such as 42 ℃, 43 ℃, 44 ℃, 45 ℃, 46 ℃, 47 ℃, 48 ℃, 49 ℃, 50 ℃, 51 ℃, 52 ℃, 53 ℃, 54 ℃ or 55 ℃, preferably 42-47 ℃, further preferably 42-45 ℃.
Preferably, the reaction time is 16-22 h, such as 16h, 16.5h, 17h, 17.5h, 18h, 18.5h, 19h, 19.5h, 20h, 21h or 22h, preferably 16.5-22 h, and further preferably 17-19.5 h.
In the invention, the chlorination reaction process does not need additional heating, but utilizes the heat generated by the chlorination reaction, and controls the temperature of the whole chlorination process within a certain range by controlling the introduction speed of chlorine and the circulation speed of common circulating water, thereby saving energy consumption.
The chlorine gas introduction speed is preferably controlled to be 390 to 410m3In the range of/h, e.g. 391m3/h、393m3/h、394m3/h、395m3/h、396m3/h、399m3/h、400m3/h、401m3H or 403m3H; the circulating speed of the circulating water is preferably controlled to be 0.50-0.70 m3H, e.g. 0.52m3/h、0.54m3/h、0.55m3/h、0.56m3/h、0.58m3/h、0.60m3/h、0.62m3H or 0.65m3H is used as the reference value. It should be understood by those skilled in the art that the introduction rate of chlorine and the circulation rate of the circulating water are realized by using techniques and apparatuses known in the art, and are not particularly limited.
Preferably, the preparation method of the 2, 4-dichlorophenol is carried out under the following conditions:
the dosage of the catalyst phosphorus pentachloride accounts for 0.01-0.07% of the molar fraction of the raw material phenol;
the total introduction amount of the chlorine is 2.01-2.09 equivalents of the mole number of the raw material phenol;
the reaction temperature is 42-47 ℃;
the reaction time of introducing chlorine is 16.5-22 h.
Under the reaction conditions, 2, 4-dichlorophenol with the content of more than 98 wt% can be obtained, the content of main chlorinated impurities, namely 2, 6-dichlorophenol, is lower than 0.90 wt%, the content of 2,4, 6-trichlorophenol is lower than 1.30 wt%, and the total content of impurities, such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like, is lower than 0.25 wt%; the 2, 4-dichlorophenol prepared under the reaction condition can be directly used for preparing 2,4-D raw drug (the content is 96 wt%) meeting FAO standard.
Further preferably, the preparation method of the 2, 4-dichlorophenol is carried out under the following conditions:
the dosage of the catalyst phosphorus pentachloride accounts for 0.03-0.05% of the molar fraction of the raw material phenol;
the total introduction amount of the chlorine is 2.05 equivalent of the mole number of the raw material phenol;
the reaction temperature is 42-47 ℃;
the reaction time of introducing chlorine is 17-19.5 h.
Under the reaction conditions, 2, 4-dichlorophenol with the content of more than 99 wt% can be obtained, the content of main chlorinated impurities, namely 2, 6-dichlorophenol, is lower than 0.40 wt%, the content of 2,4, 6-trichlorophenol is lower than 0.40 wt%, and the total content of impurities, such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like, is lower than 0.25 wt%; the 2, 4-dichlorophenol prepared under the reaction condition can be directly used for preparing a 2,4-D raw drug with the content of 98 wt% (higher than FAO standard), the raw drug has few impurities in the specification, and the adverse effect on the environment and crops is low.
Still more preferably, the preparation process of 2, 4-dichlorophenol is carried out under the following conditions:
the dosage of the catalyst phosphorus pentachloride accounts for 0.05 percent of the mole fraction of the raw material phenol;
the total introduction amount of the chlorine is 2.05 equivalent of the mole number of the raw material phenol;
the reaction temperature is 42-47 ℃;
the reaction time is 17h by introducing chlorine.
Under the reaction conditions, 2, 4-dichlorophenol with the content as high as 99.410 wt% can be obtained, the content of main chlorinated impurities, namely 2, 6-dichlorophenol, is lower than 0.35 wt%, the content of 2,4, 6-trichlorophenol is lower than 0.32 wt%, and the total content of impurities, such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like, is lower than 0.25 wt%; the 2, 4-dichlorophenol prepared under the reaction condition can also be directly used for preparing a 2,4-D technical product with the content of 98 wt% (higher than FAO standard), the technical product has fewer impurities in the standard, and the adverse effect on the environment and crops is lower.
The preparation method of the 2, 4-dichlorophenol provided by the invention specifically comprises the following steps:
adding phosphorus pentachloride serving as a catalyst into a molten phenol solution, introducing chlorine, and controlling the temperature of the whole chlorination process within the range of 42-55 ℃ to react by utilizing the heat generated by chlorination reaction through controlling the introduction speed of the chlorine and the circulation speed of common circulating water to obtain the 2, 4-dichlorophenol.
In a second aspect, the invention also provides the 2, 4-dichlorophenol prepared by the method in the first aspect.
The content of the 2, 4-dichlorophenol prepared by the invention can reach more than 98 percent, and the content of main chlorinated impurities, namely 2, 6-dichlorophenol is lower than 0.90 percent by weight, the content of 2,4, 6-trichlorophenol is lower than 1.30 percent by weight, and the total content of impurities, such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is lower than 0.25 percent by weight, so that the 2, 4-dichlorophenol can be directly used as a raw material for preparing 2,4-D technical pesticide which meets the FAO standard (the content is 96 percent by weight) without distillation or rectification purification, and the energy consumption for preparing high-content 2, 4-dichlorophenol is greatly reduced.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) according to the invention, phosphorus pentachloride is used as a catalyst, the heat generated by chlorination reaction is utilized, the temperature of the whole chlorination process is controlled within a proper range by controlling the chlorine gas introduction speed and the circulation speed of common circulating water, energy is saved, 2, 4-dichlorophenol with the content of more than 98% is obtained by preparation, the impurity content of the 2, 4-dichlorophenol is low, the content of the 2, 6-dichlorophenol is lower than 0.90 wt%, the content of the 2,4, 6-trichlorophenol is lower than 1.30 wt%, the total content of impurities such as o-chlorophenol, p-chlorophenol and 2,4, 5-trichlorophenol is lower than 0.25 wt%, and the phosphorus pentachloride can be directly used as a raw material for preparing 2,4-D bulk drugs with the content of 96 wt% or more;
(2) the invention utilizes the heat generated by chlorination reaction, controls the temperature of the whole chlorination process within a certain range by controlling the introduction speed of chlorine and the circulation speed of common circulating water, thereby saving energy consumption and realizing high yield of 2, 4-dichlorophenol.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
Heating phenol (with the content of 99.9 wt%) in a preheating kettle to 42 ℃, conveying 14000 kg (148.8kmol) to 2 kiloliters to a reaction kettle through a pipeline for heat preservation, adding 3.1 kg (14.8mol, 0.01 mol% equivalent) of phosphorus pentachloride with the content of 99 wt%, stirring uniformly, continuously introducing chlorine gas with the content of 99.8 wt% preheated to room temperature into two thirds of the liquid level of the mixed solution of the phenol and the phosphorus pentachloride through a metering pump under stirring, not providing an external heat source for heat preservation or heating in the reaction process, utilizing the heat released by chlorination reaction, controlling the introduction speed of the chlorine gas and the circulation speed of common circulating water to enable the chlorination reaction to react at 50-55 ℃, and leading tail gas out to a first-stage tail gas absorption kettle through a conduit at the top of the reaction kettle to prepare 30% hydrochloric acid as a byproduct for self-use or sale; and the gas overflowing from the primary absorption kettle enters a secondary absorption kettle filled with 20% sodium hydroxide solution for absorption. When chlorine gas is introduced for 22 hours, the chlorine gas is introduced to 6709.4m3(298.9 kmol equivalent of 2.01mol equivalent of chlorine), the temperature of the reaction solution is 44.5 ℃, samples are taken for HPLC analysis, the phenol area is normalized to be 0.011 percent, the 2, 4-dichlorophenol area is normalized to be 98.505 percent, and the chlorine introduction is stopped after the chlorination is finished; introducing nitrogen (content 99.5%) for 1 hr to remove dissolved hydrogen chloride and small amount of chlorine in the reaction mixture, introducing nitrogen gas 210m3(ii) a Putting the product into a measuring storage tank, weighing 2447 kg, sampling, and carrying out HPLC external standard quantitative analysis, wherein the content of 2, 4-dichlorophenol is 98.015 wt%, the content of phenol is 0.093 wt%, the content of 2,4, 6-trichlorophenol is 0.889 wt%, and the content of 2, 6-dichlorophenol is 0.817 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.186 wt%, and the total content is not respectively quantitatively determined; thus, the yield of the 2, 4-dichlorophenol reaches 99.2 wt%; trace phosphorus pentachloride or its derivative (partial or complete hydrolyzed phosphorus oxychloride, phosphoric acid, etc.) contained in the obtained 2, 4-dichlorophenol is converted into sodium chloride and sodium phosphate when 2, 4-dichlorophenol is prepared into 2, 4-dichlorophenol sodium saltThe compound does not participate in the coupling reaction of sodium chloroacetate and does not have negative effect on the coupling reaction, and the high-content 2, 4-dichlorophenol obtained in the embodiment can be directly used for preparing 96 wt% of 2,4-D technical product.
Example 2
Heating phenol (with the content of 99.9 wt%) in a preheating kettle to 43 ℃, conveying 14000 kilograms (148.8kmol) to 2 kiloliters to a reaction kettle through a pipeline for heat preservation, adding 9.3 kilograms (44.6mol, 0.03 mol% equivalent) of phosphorus pentachloride with the content of 99 wt%, stirring uniformly, continuously introducing chlorine gas with the content of 99.8 wt% preheated to room temperature into two thirds of the liquid level of the mixed solution of the phenol and the phosphorus pentachloride through a metering pump under stirring, not providing an external heat source for heat preservation or heating in the reaction process, utilizing the heat released by chlorination reaction, controlling the introduction speed of the chlorine gas and the circulation speed of common circulating water to enable the chlorination reaction to be carried out at 42-45 ℃, and leading tail gas out to a first-stage tail gas absorption kettle through a conduit at the top of the reaction kettle to prepare 30% hydrochloric acid to be used as a byproduct for self-use or sale; and the gas overflowing from the primary absorption kettle enters a secondary absorption kettle filled with 20% sodium hydroxide solution for absorption. When chlorine gas is introduced for 19.5 hours, the chlorine gas is introduced to 6846.3m3(equivalent to 305.0kmol chlorine gas, 2.05mol equivalent weight), the temperature of the reaction solution is 45 ℃, a sample is taken for HPLC analysis, the phenol area normalization content is 0.009%, the 2, 4-dichlorophenol area normalization content is 99.513%, and the chlorine gas introduction is stopped after the chlorination is finished; introducing nitrogen (content 99.5%) for 1 hr to remove dissolved hydrogen chloride and small amount of chlorine in the reaction mixture, introducing nitrogen gas 210m3(ii) a Putting the product into a measuring storage tank, weighing 24251 kg, sampling and carrying out HPLC external standard quantitative analysis, wherein the content of 2, 4-dichlorophenol is 99.114 wt%, the content of phenol is 0.007 wt%, the content of 2,4, 6-trichlorophenol is 0.317 wt%, and the content of 2, 6-dichlorophenol is 0.340 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.222 wt%, and the total content is not respectively quantitatively determined; therefore, the yield of the 2, 4-dichlorophenol reaches 99.1 wt%, and the 2, 4-dichlorophenol with high content obtained in the embodiment can be directly used for preparing 2,4-D technical with 98 wt%.
Example 3
Phenol (content 99.9 wt.%) was heated to 44 ℃ in a preheated kettle and passed throughConveying 14000 kilograms (148.8kmol, 0.05mol percent equivalent) to 2 kiloliters to a reaction kettle by virtue of pipeline heat preservation, adding 15.5 kilograms (74.4mol) of phosphorus pentachloride with the content of 99wt percent, uniformly stirring, continuously introducing chlorine with the content of 99.8wt percent preheated to room temperature into two thirds of the liquid level of the mixed solution of phenol and phosphorus pentachloride by virtue of a metering pump under stirring, not providing external heat source for heat preservation or heating in the reaction process, utilizing the heat released by chlorination reaction, controlling the introduction speed of the chlorine and the circulation speed of common circulating water to enable the chlorination reaction to react at 42-47 ℃, and leading tail gas out to a first-stage tail gas absorption kettle through a guide pipe at the top of the reaction kettle to prepare 30 percent hydrochloric acid as a byproduct for self use or sale; and the gas overflowing from the primary absorption kettle enters a secondary absorption kettle filled with 20% sodium hydroxide solution for absorption. When chlorine gas is introduced for 17 hours, the chlorine gas is introduced to 6846.3m3(equivalent to 305.0kmol of chlorine and 2.05mol equivalent), the temperature of the reaction solution is 46 ℃, samples are taken for HPLC analysis, the area normalization content of phenol is 0.007%, the area normalization content of 2, 4-dichlorophenol is 99.691%, and the chlorine introduction is stopped after the chlorination is finished; introducing nitrogen (content 99.5%) for 1 hr to remove dissolved hydrogen chloride and small amount of chlorine in the reaction mixture, introducing nitrogen gas 210m3(ii) a The product is put into a measuring storage tank and weighed to 24251 kg, and samples are taken for HPLC external standard quantitative analysis, wherein the content of 2, 4-dichlorophenol is 99.410 wt%, the content of phenol is 0.005 wt%, the content of 2,4, 6-trichlorophenol is 0.152 wt%, and the content of 2, 6-dichlorophenol is 0.193 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.240 wt%, and the total content is not respectively quantitatively determined; therefore, the yield of the 2, 4-dichlorophenol reaches 99.4 wt%, and the 2, 4-dichlorophenol with high content obtained in the embodiment can be directly used for preparing 2,4-D technical with 98 wt%.
Example 4
Heating phenol (with the content of 99.9 wt%) in a preheating kettle to 42 ℃, conveying 14000 kilograms (148.8kmol) to 2 kiloliters to a reaction kettle through a pipeline for heat preservation, adding 21.7 kilograms (103.6mol, 0.07 mol% equivalent weight) of phosphorus pentachloride with the content of 99 wt%, uniformly stirring, continuously introducing chlorine gas with the content of 99.8 wt% preheated to room temperature into two thirds of the liquid level of the mixed solution of the phenol and the phosphorus pentachloride through a metering pump under stirring, and providing no chlorine gas in the reaction processAn external heat source is used for heat preservation or heating, the chlorination reaction is carried out at 42-47 ℃ by utilizing the heat emitted by the chlorination reaction and controlling the introduction speed of chlorine and the circulation speed of common circulating water, and tail gas is led out to a first-stage tail gas absorption kettle through a guide pipe at the top of the reaction kettle to prepare 30% hydrochloric acid to be used as a byproduct for self-use or sale; and the gas overflowing from the primary absorption kettle enters a secondary absorption kettle filled with 20% sodium hydroxide solution for absorption. When chlorine gas is introduced for 16.5 hours, the chlorine gas is introduced to 6846.3m3(equivalent to 305.0kmol of chlorine and 2.05mol equivalent), the temperature of the reaction solution is 46 ℃, samples are taken for HPLC analysis, the area normalized content of phenol is 0.000 percent, the area normalized content of 2, 4-dichlorophenol is 98.545 percent, and the chlorine introduction is stopped after the chlorination is finished; introducing nitrogen (content 99.5%) for 1 hr to remove dissolved hydrogen chloride and small amount of chlorine in the reaction mixture, introducing nitrogen gas 210m3(ii) a The product is put into a measuring storage tank and weighed to be 24641 kg, and a sample is taken for HPLC external standard quantitative analysis, wherein the content of 2, 4-dichlorophenol is 98.036 wt%, the content of phenol is 0.000 wt%, the content of 2,4, 6-trichlorophenol is 1.134 wt%, and the content of 2, 6-dichlorophenol is 0.643 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.187 wt%, and the total content is not respectively quantitatively determined; therefore, the yield of the 2, 4-dichlorophenol reaches 99.6 wt%, and the high-content 2, 4-dichlorophenol obtained in the embodiment can be directly used for preparing 96 wt% of 2,4-D technical material.
Example 5
Heating phenol (with the content of 99.9 wt%) in a preheating kettle to 42 ℃, conveying 14000 kg (148.8kmol) to 2 kiloliters to a reaction kettle through a pipeline for heat preservation, adding 15.5 kg (74.4mol, 0.05 mol% equivalent) of phosphorus pentachloride with the content of 99 wt%, stirring uniformly, continuously introducing chlorine gas with the content of 99.8 wt% preheated to room temperature into two thirds of the liquid level of the mixed solution of the phenol and the phosphorus pentachloride through a metering pump under stirring, not providing an external heat source for heat preservation or heating in the reaction process, utilizing the heat released by chlorination reaction, controlling the introduction speed of the chlorine gas and the circulation speed of common circulating water to enable the chlorination reaction to be carried out at 42-47 ℃, and leading tail gas out to a first-stage tail gas absorption kettle through a conduit at the top of the reaction kettle to prepare 30% hydrochloric acid to be used as a byproduct for self-use or sale; the overflow gas of the first-stage absorption kettle enters into the deviceAnd absorbing by a secondary absorption kettle of 20 percent sodium hydroxide solution. When chlorine gas is introduced for 17.8 hours, the chlorine gas is introduced to 6979.8m3(equivalent to 310.9kmol of chlorine and 2.09mol equivalent), the temperature of the reaction solution is 46 ℃, samples are taken for HPLC analysis, the area normalization content of phenol is 0.000 percent, the area normalization content of 2, 4-dichlorophenol is 98.219 percent, and the chlorine introduction is stopped after the chlorination is finished; introducing nitrogen (content 99.5%) for 1 hr to remove dissolved hydrogen chloride and small amount of chlorine in the reaction mixture, introducing nitrogen gas 210m3(ii) a Putting the product into a measuring storage tank, weighing 24219 kg, sampling and carrying out HPLC external standard quantitative analysis, wherein the content of 2, 4-dichlorophenol is 98.042 wt%, the content of phenol is 0.000 wt%, the content of 2,4, 6-trichlorophenol is 1.236 wt%, and the content of 2, 6-dichlorophenol is 0.550 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.172 wt%, and the total content is not respectively quantitatively determined; therefore, the yield of the 2, 4-dichlorophenol reaches 97.9 wt%, and the high-content 2, 4-dichlorophenol obtained in the embodiment can be directly used for preparing 96 wt% of 2,4-D technical material.
Example 6
Heating phenol (with the content of 99.9 wt%) in a preheating kettle to 42 ℃, conveying 14000 kg (148.8kmol) to 2 kiloliters to a reaction kettle through a pipeline for heat preservation, adding 12.4 kg (59.5mol, 0.04 mol% equivalent) of phosphorus pentachloride with the content of 99 wt%, stirring uniformly, continuously introducing chlorine gas with the content of 99.8 wt% preheated to room temperature into two thirds of the liquid level of the mixed solution of the phenol and the phosphorus pentachloride through a metering pump under stirring, not providing an external heat source for heat preservation or heating in the reaction process, utilizing the heat released by chlorination reaction, controlling the introduction speed of the chlorine gas and the circulation speed of common circulating water to enable the chlorination reaction to be carried out at 42-45 ℃, and leading tail gas out to a first-stage tail gas absorption kettle through a conduit at the top of the reaction kettle to prepare 30% hydrochloric acid to be used as a byproduct for self-use or sale; and the gas overflowing from the primary absorption kettle enters a secondary absorption kettle filled with 20% sodium hydroxide solution for absorption. When chlorine gas is introduced for 19.5 hours, the chlorine gas is introduced to 6846.3m3(equivalent to 305.0kmol of chlorine and 2.05mol equivalent), the temperature of the reaction solution is 45 ℃, samples are taken for HPLC analysis, the area normalized content of phenol is 0.008 percent, the area normalized content of 2, 4-dichlorophenol is 99.605 percent, and the chlorine introduction is stopped after the chlorination is finished; by passing nitrogenThe gas (content: 99.5%) was used for 1h to remove the dissolved hydrogen chloride and a small amount of chlorine from the reaction mixture, and a total of 210m nitrogen was introduced3(ii) a The product is put into a measuring storage tank and weighed to 24229 kg, and sampling is carried out for HPLC external standard quantitative analysis, wherein the content of 2, 4-dichlorophenol is 99.302 wt%, the content of phenol is 0.006 wt%, the content of 2,4, 6-trichlorophenol is 0.235 wt%, and the content of 2, 6-dichlorophenol is 0.278 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.185 wt%, and the total content is not respectively quantitatively determined; therefore, the yield of the 2, 4-dichlorophenol reaches 99.2 wt%, and the 2, 4-dichlorophenol with high content obtained in the embodiment can be directly used for preparing 2,4-D technical with 98 wt%.
Comparative example 1
Same as example 1 except that phosphorus pentachloride was replaced with aluminum trichloride (14.8mol, 0.01 mol% equivalent) compared to example 1.
Through determination and calculation, the content of the prepared 2, 4-dichlorophenol is 92.564 wt%, the content of phenol is 0.000 wt%, the content of 2,4, 6-trichlorophenol is 3.494 wt%, and the content of 2, 6-dichlorophenol is 1.763 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 2.032 wt%.
COMPARATIVE EXAMPLE 2 (REFERENCE CN103435453A)
The procedure is as in example 1 except that the phosphorus pentachloride is replaced with iron powder (14.8mol, 0.01 mol% equivalent) and dibenzo [ b, f ] [1,4] thiazepin-11-one-phosphorus oxychloride (829g) as compared to example 1.
Through measurement and calculation, the content of the prepared 2, 4-dichlorophenol is 96.495 wt%, the content of phenol is 0.014 wt%, the content of 2,4, 6-trichlorophenol is 0.282 wt%, and the content of 2, 6-dichlorophenol is 3.053 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.123 wt%.
Comparative example 3
The preparation of 2, 4-dichlorophenol was carried out by the method disclosed in example 3 of CN 102659530A.
Through determination and calculation, the content of the prepared 2, 4-dichlorophenol is 94.512 wt%, the content of the impurity 2,4, 6-trichlorophenol is 0.889 wt%, and the content of the 2, 6-dichlorophenol is 3.654 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.872 wt%.
Comparative example 4
The preparation of 2, 4-dichlorophenol was carried out by the method disclosed in example four of CN 104529757B.
Through determination and calculation, the content of the prepared 2, 4-dichlorophenol is 95.121 wt%, the content of the impurity 2,4, 6-trichlorophenol is 1.673 wt%, and the content of the 2, 6-dichlorophenol is 2.415 wt%; the total content of impurities such as o-chlorophenol, p-chlorophenol, 2,4, 5-trichlorophenol and the like is 0.740 wt%.
Comparing the above examples 1-6 with the comparative examples 1-2, it can be seen that when phosphorus pentachloride is used as a catalyst in examples 1-6, the 2, 4-dichlorophenol prepared by using the catalyst has higher content and lower content of chlorinated impurities than other catalysts used in comparative examples 1-2, which indicates that the phosphorus pentachloride is more beneficial to harvest 2, 4-dichlorophenol with high content and low content of impurities by using the catalyst; comparing the examples 1 to 6 with the comparative examples 3 to 4, it can be seen that the 2, 4-dichlorophenol prepared in the examples 1 to 6 also has higher content and lower content of chlorinated impurities compared with the comparative examples 3 to 4, which indicates that the 2, 4-dichlorophenol prepared in the examples 1 to 6 can be obtained with higher content by improving the process method, has low content of impurities, and can be directly used as a raw material for preparing 2,4-D raw pesticide with content of 96 wt% or more, so that the process is saved, the energy consumption is reduced, and the method has important application value.
The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (12)
1. A preparation method of 2, 4-dichlorophenol, which is characterized by comprising the following steps:
taking phenol and chlorine as raw materials, and obtaining 2, 4-dichlorophenol through chlorination reaction under the catalytic action of phosphorus pentachloride; the reaction temperature is 42-55 ℃;
the content of chlorinated impurities 2, 6-dichlorophenol contained in the 2, 4-dichlorophenol prepared by the method is lower than 0.90 wt%, the content of 2,4, 6-trichlorophenol is lower than 1.30 wt%, and the total content of impurities of o-chlorophenol, p-chlorophenol and 2,4, 5-trichlorophenol is lower than 0.25 wt%;
the phosphorus pentachloride is used as a catalyst for chlorination reaction, and the dosage of the phosphorus pentachloride accounts for 0.005-0.10% of the mole fraction of the raw material phenol.
2. The method of claim 1, wherein the phosphorus pentachloride is used in an amount of 0.01 to 0.07% of the molar fraction of the starting phenol.
3. The method of claim 2, wherein the phosphorus pentachloride is used in an amount of 0.03 to 0.05 mole percent of the starting phenol.
4. The method of claim 1 or 2, wherein the chlorine gas is used in an amount of 2.00 to 2.12 equivalents based on moles of the starting phenol.
5. The method of claim 4, wherein the chlorine gas is used in an amount of 2.01 to 2.09 equivalents based on moles of the starting phenol.
6. The method of claim 5 wherein the chlorine gas is used in an amount of 2.05 equivalents based on moles of starting phenol.
7. The process according to claim 1, wherein the reaction temperature is 42 to 47 ℃.
8. The process according to claim 7, wherein the reaction temperature is 42 to 45 ℃.
9. The method of claim 1, wherein the reaction time is 16 to 22 hours.
10. The method of claim 9, wherein the reaction time is 16.5 to 22 hours.
11. The method of claim 10, wherein the reaction time is 17 to 19.5 hours.
12. The method of claim 1, wherein the method comprises:
adding phosphorus pentachloride serving as a catalyst into a molten phenol solution, introducing chlorine, controlling the temperature of the whole chlorination process within the range of 42-55 ℃ for reaction by controlling the introduction speed of the chlorine and the circulation speed of common circulating water by utilizing the heat generated by chlorination reaction to obtain the 2, 4-dichlorophenol; the dosage of the phosphorus pentachloride accounts for 0.005-0.10% of the molar fraction of the raw material phenol;
the content of chlorinated impurities 2, 6-dichlorophenol contained in the 2, 4-dichlorophenol prepared by the method is lower than 0.90 wt%, the content of 2,4, 6-trichlorophenol is lower than 1.30 wt%, and the total content of impurities of o-chlorophenol, p-chlorophenol and 2,4, 5-trichlorophenol is lower than 0.25 wt%.
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| CN101085722A (en) * | 2007-01-10 | 2007-12-12 | 胡汉忠 | Industrial preparation method for p-chloroalkylphenols |
| CN102659530A (en) * | 2012-04-27 | 2012-09-12 | 沙隆达集团公司 | Continuous preparation method of herbicide intermediate of 2, 4-dichlorophenol |
| CN106349025A (en) * | 2016-07-28 | 2017-01-25 | 连云港致诚化工有限公司 | Preparation process of 2,4-dichlorophenol |
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| CN101085722A (en) * | 2007-01-10 | 2007-12-12 | 胡汉忠 | Industrial preparation method for p-chloroalkylphenols |
| CN102659530A (en) * | 2012-04-27 | 2012-09-12 | 沙隆达集团公司 | Continuous preparation method of herbicide intermediate of 2, 4-dichlorophenol |
| CN106349025A (en) * | 2016-07-28 | 2017-01-25 | 连云港致诚化工有限公司 | Preparation process of 2,4-dichlorophenol |
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