CN115043732A - Preparation method of 2, 4-dinitrochlorobenzene - Google Patents
Preparation method of 2, 4-dinitrochlorobenzene Download PDFInfo
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- CN115043732A CN115043732A CN202110264964.7A CN202110264964A CN115043732A CN 115043732 A CN115043732 A CN 115043732A CN 202110264964 A CN202110264964 A CN 202110264964A CN 115043732 A CN115043732 A CN 115043732A
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Abstract
The invention discloses a preparation method of 2, 4-dinitrochlorobenzene. The preparation method comprises the following steps: step (1), chlorobenzene is subjected to mononitration in the presence of nitric acid and sulfuric acid in a continuous flow reactor A to obtain a mononitrated product; in the step (2), in a continuous flow reactor B, carrying out dinitration reaction on the mononitrated product in the presence of nitric acid and sulfuric acid to obtain 2, 4-dinitrochlorobenzene; the reaction temperature of the primary nitration reaction is 70-110 ℃; in the step (1), the molar ratio of chlorobenzene to nitric acid is 1: 1.0-1: 1.8; in the step (1), the molar ratio of chlorobenzene to sulfuric acid is 1: 2-1: 5. The preparation method disclosed by the invention has the advantages of high yield of the product, high selectivity of the product, high purity of the product, simplicity in operation, high efficiency, short reaction time, safety, controllability, environmental friendliness and reusability of waste acid.
Description
Technical Field
The invention relates to a preparation method of 2, 4-dinitrochlorobenzene.
Background
2, 4-dinitrochlorobenzene is an important fine chemical intermediate and is widely applied to the fields of medicines, pesticides, dyes, explosives, chemical auxiliaries and the like. In the industrial production method of 2, 4-dinitrochlorobenzene, the nitric-sulfuric mixed acid is mostly used as a nitrating agent, and the kettle type operation of simultaneously dripping raw materials is adopted, so that the production efficiency is low, the energy consumption is high, and the safety is poor.
The method for preparing 2, 4-dinitrochlorobenzene by using a continuous flow reactor has more defects, for example, the method for preparing 2, 4-dinitrochlorobenzene by using a continuous flow reactor, which is reported in 2014 (Liqingqiang, Guowali, Wangyang, et al. chlorobenzene tube type continuous nitration preparation 2, 4-dinitrochlorobenzene [ J ]. Fine petrochemical industry, 2014(02):20-24.) is as follows: at the preheating temperature of 50 ℃, the reaction pressure of 0.15Mpa and the heat preservation temperature of 75 ℃, the mixed acid consists of m (sulfuric acid): m (nitric acid): under the conditions of m (water) being 0.7:0.19:0.11, flow rate being 0.062m/s and space time being 3.5min, the selectivity of 2, 4-dinitrochlorobenzene is only 85.93%, and the conversion rate is reduced due to the volatilization of nitric acid after the reaction temperature reaches 100 ℃, so that the reaction temperature can only be maintained at a low level.
Disclosure of Invention
The invention aims to overcome the defects of low yield, complex operation, low efficiency, long reaction time and the like of the existing preparation method of 2, 4-dinitrochlorobenzene, and provides the preparation method of the 2, 4-dinitrochlorobenzene. The preparation method has the advantages of high product yield, high product selectivity, high product purity, simple operation, high efficiency, short reaction time, safety, controllability, environmental protection and reuse of waste acid.
The present invention solves the above technical problems by the following technical solutions.
The invention provides a preparation method of 2, 4-dinitrochlorobenzene, which comprises the following steps:
step (1), chlorobenzene is subjected to mononitration in the presence of nitric acid and sulfuric acid in a continuous flow reactor A to obtain a mononitrated product;
in the step (2), carrying out dinitration reaction on the mononitrated product in the presence of nitric acid and sulfuric acid in a continuous flow reactor B to obtain 2, 4-dinitrochlorobenzene;
the reaction temperature of the primary nitration reaction is 70-110 ℃;
in the step (1), the molar ratio of chlorobenzene to nitric acid is 1: 1.0-1: 1.8;
in the step (1), the molar ratio of the chlorobenzene to the sulfuric acid is 1: 2-1: 5.
In step (1), said continuous flow reactor a may be a continuous flow reactor conventional to the type of reaction in the art, preferably a microchannel reactor or a tubular reactor.
In the step (1), the nitric acid is preferably an aqueous nitric acid solution with a nitric acid mass fraction of 90-98% (e.g. 95%).
In the step (1), the sulfuric acid is preferably an aqueous sulfuric acid solution with a sulfuric acid mass fraction of 90-98% (e.g., 90%).
In the step (1), the molar ratio of chlorobenzene to nitric acid is preferably 1:1.0 to 1:1.5, for example, 1:1.07, 1:1.1, 1:1.13, 1:1.18, 1:1.21, 1:1.23, or 1: 1.36.
In step (1), the molar ratio of chlorobenzene to sulfuric acid is preferably 1:2 to 1:4, for example 1:2.45, 1:2.46, 1:2.47, 1:2.48, 1:2.5, 1:2.51, 1:2.53, 1:2.55, 1:2.56, 1:2.59, 1:2.62, 1:2.68, 1:2.93 or 1: 3.53.
In step (1), the temperature of the mononitration is preferably 90 to 110 ℃, for example 90 ℃, 100 ℃ or 110 ℃.
In step (1), the chlorobenzene can be fed at a flow rate of 4.3mL/min to 7.0mL/min (e.g., 4.42mL/min, 4.45mL/min, 4.66mL/min, 4.77mL/min, 4.88mL/min, 4.93mL/min, or 6.3mL/min), preferably 4.4mL/min to 5.0 mL/min.
In step (1), the feed rates of the nitric acid and sulfuric acid may be 9.0mL/min to 13.0mL/min (e.g., 9.56mL/min, 9.67mL/min, 9.7mL/min, 9.84mL/min, 10.05mL/min, or 12.66mL/min), and preferably 9.5mL/min to 11.0 mL/min.
In step (1), it will be understood by those skilled in the art that in such reactions, there is some correspondence between residence time and reaction temperature; when the reaction temperature is higher and the residence time is correspondingly shorter, the reaction temperature is lower and the residence time is correspondingly longer, and impurities are as few as possible under the condition of ensuring that the reaction is as complete as possible. In the present invention, the residence time of the chlorobenzene, nitric acid and sulfuric acid in the continuous flow reactor for the mononitration reaction is determined by the disappearance or no further reaction of the chlorobenzene, and for example, the residence time may be 55s to 120s (e.g., 58.3s, 58.9s, 60.12s, 60.59s, 60.73s, 61.61 or 63.11s), and more preferably 55s to 65 s.
In step (1), the mononitration is preferably carried out under normal pressure.
In step (1), the mononitrated product may be one or more of 2-nitrochlorobenzene, 4-nitrochlorobenzene and 2, 4-dinitrochlorobenzene, preferably 2-nitrochlorobenzene, 4-nitrochlorobenzene and 2, 4-dinitrochlorobenzene.
After the mononitration reaction is completed, preferably, the obtained reaction solution is subjected to layering to obtain an organic phase, and the organic phase is directly subjected to the dinitration reaction in the step (2).
In step (2), said continuous flow reactor B may be a continuous flow reactor conventional to the type of reaction in the art, preferably a microchannel reactor or a tubular reactor.
In the step (2), the nitric acid is preferably an aqueous nitric acid solution with a nitric acid mass fraction of 90-98% (e.g. 95%).
In the step (2), the sulfuric acid is preferably an aqueous sulfuric acid solution with a sulfuric acid mass fraction of 90-98% (e.g., 98%).
In step (2), the temperature of the dinitration is preferably 70 ℃ to 130 ℃, for example 70 ℃, 80 ℃, 90 ℃, 110 ℃ or 130 ℃.
In the step (2), the molar ratio of the mononitrated product to the nitric acid is preferably 1:1 to 1:1.5 (e.g., 1:1.07, 1:1.08, 1:1.09, 1:1.11, 1:1.12, 1:1.13, 1:1.15, 1:1.24), more preferably 1:1.07 to 1: 1.3.
In step (2), the molar ratio of the mononitrated product to the sulfuric acid is preferably 1:3.0 to 1:5.0, for example 1: 3.5.
In step (2), the feed rate of the mononitrated product and the sulfuric acid may be 20mL/min to 100mL/min (e.g., 25.1mL/min, 49.55mL/min, 61.02mL/min, 62.5mL/min, 62.75mL/min, 73.89mL/min, 79.24mL/min, 84.08mL/min, 84.67mL/min, or 87.01mL/min), preferably 45mL/min to 90 mL/min.
In step (2), the feed rate of nitric acid may be 3mL/min to 20mL/min (e.g., 3.77mL/min, 7.56mL/min, 10.38mL/min, 10.46mL/min, 10.54mL/min, 12.52mL/min, 13.38mL/min, 14.31mL/min, 14.42mL/min, 14.77mL/min, or 14.85mL/min), preferably 3.5mL/min to 15 mL/min.
In certain embodiments of the invention, the mononitration and dinitration reactions may be carried out in a reaction unit. The reaction unit comprises one or more reactor modules or reactor module groups, wherein the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and each reactor module can realize feeding, mixing, heat exchange and reaction. The reactor modules and the reactor module groups are connected in series. Each reactor module or group of modules has one or more feed inlets and one or more feed outlets. One reactor module is a continuous flow reactor.
The reaction unit can be set with a single temperature zone, and different sub-temperature zones can be set for different reactor modules or reactor module groups.
In the step (2), after the dinitration reaction is finished, the obtained feed liquid can be further cooled. The temperature reduction may be to 60 ℃ to 80 ℃, for example 70 ℃.
The temperature reduction can be carried out in a temperature reduction device. The cooling equipment can be conventional cooling equipment in the field. The cooling device is also called as a cooling unit.
In step (2), the mononitrated product and sulfuric acid are subjected to a preheating treatment before the dinitration is carried out. The preheating temperature may be from 50 ℃ to 80 ℃, more preferably from 65 ℃ to 75 ℃.
The preheating may be carried out in a preheating apparatus. The preheating device may be one conventional in the art. The preheating device is also called a preheating unit.
In the invention, the preheating unit, the reaction unit and the cooling unit in the step (2) form an integrated continuous flow reactor device together.
In step (2), it will be understood by those skilled in the art that in such reactions, there is some correspondence between residence time and reaction temperature; when the reaction temperature is higher, and correspondingly the residence time is shorter, the reaction temperature is lower, and correspondingly the residence time is longer, it is sufficient that the impurities are as few as possible while ensuring as complete a reaction as possible. In the present invention, the residence time of the mononitration product, nitric acid and sulfuric acid in the continuous flow reactor B for the dinitration is based on the disappearance or no longer reaction of the mononitration product, and for example, the residence time may be 1s to 50s (e.g., 1.5s, 2.5s, 4.9s, 5s, 10.25s, 10.26s, 11.55s, 13.92s, 13.98s, 14.28s or 16.36s), more preferably 5s to 20 s.
In step (2), the dinitration reaction may be carried out under pressure. The pressure may be 1 to 10bar (e.g. 1bar, 2.5bar, 4bar, 5bar, 6bar, 7bar or 8bar), preferably 5 to 8 bar.
In the step (2), after the temperature reduction is finished, the obtained feed liquid can be further subjected to liquid separation. The conditions and operations for the separation may be those conventional in the art.
In certain embodiments of the present invention, the continuous flow reactor may be any one or more reactors capable of realizing continuous flow reactions, including one or more of microreactors, tubular reactors, cascade mixers, and static mixers. The tubular reactor is a continuous operation reactor with large length-diameter ratio. According to different requirements, the tubular reactor can be a single tube or a plurality of tubes connected in parallel, and can be an empty tube or a filling tube.
In certain embodiments of the present invention, the starting material for the mononitration consists only of said nitric acid, said sulfuric acid and said chlorobenzene.
In certain embodiments of the invention, the starting material for the dinitration consists solely of said nitric acid, said sulfuric acid and said mononitrated product.
The above preferred conditions can be arbitrarily combined to obtain preferred embodiments of the present invention without departing from the common general knowledge in the art.
The reagents and starting materials used in the present invention are commercially available.
The positive progress effects of the invention are as follows:
(1) the method comprises the steps of (1) carrying out sectional continuous nitration, wherein a mononitrate is prepared by continuous nitration, and a dinitrate is prepared continuously without purifying a crude product;
(2) the primary nitrification section and the secondary nitrification section both use a continuous flow process, so that the method is intrinsically safe and has the advantage of process safety;
(3) 98% concentrated sulfuric acid is used in the dinitration section, the sulfuric acid concentration of waste acid after nitration is 90%, the waste acid is extracted by a solvent and then is recycled to the mononitration section, theoretically, no waste acid is generated, and the method has the advantage of environmental protection;
(4) the reaction time of the primary nitration section is shortened to 1min, the conversion rate is more than 99.5 percent, and the content of the 2, 6-dinitrochlorobenzene is less than 1 percent;
(5) the retention time of the dinitration reaction is shortened to 5s, the selectivity of the 2, 4-dinitrochlorobenzene in the reaction liquid is 95 percent, and the yield is 95 percent. The method is remarkably superior to the continuous dinitration reaction result (86%) reported in the literature;
(6) the technical scheme can realize the continuous dinitration of chlorobenzene to prepare the 2, 4-dinitrochlorobenzene compound with higher content, and meets the chemical production requirement of specific chemicals. The waste acid after the dinitration can be completely reused in the primary nitration section, thereby avoiding the generation of the waste acid, realizing the intrinsic safety and solving the problem of environmental protection pain points.
Drawings
FIG. 1 is a diagram of a reaction apparatus of a nitrification section.
FIG. 2 is a diagram of a reaction apparatus of the dinitration stage.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. Experimental procedures without specifying specific conditions in the following examples were selected in accordance with conventional procedures and conditions, or in accordance with commercial instructions.
1. Description of the continuous nitration process:
1.1 the primary nitration stage process:
mixed acid prepared by 90 percent sulfuric acid (waste acid after dinitration) aqueous solution and 95 percent nitric acid aqueous solution is adopted, the temperature of the prepared mixed acid is controlled below 20 ℃, and the mixed acid and chlorobenzene enter a microreactor from a plunger pump under the condition of normal temperature and react in the microreactor. And (4) placing the discharged liquid in a constant temperature separator for standing and layering, and directly carrying out the dinitration stage reaction on the separated oil phase.
1.2 dinitration stage process:
the method comprises the steps of preparing a solution by adopting concentrated sulfuric acid and a product of a primary nitration section, keeping the temperature of the prepared solution at 65-75 ℃, feeding the prepared solution and fuming nitric acid into a microreactor through a plunger pump (the prepared solution is fed at high temperature, and the plunger pump is used for heat preservation), and reacting in the microreactor. And (3) placing the discharged liquid in a heat-preservation separator for standing and layering, washing an oil phase by a hot sodium bicarbonate aqueous solution and a hot water solution, separating a water layer, drying to obtain a dinitrated product, and adsorbing an acid phase to obtain the dinitrated product.
2. Examples of the embodiments
2.1 continuous mononitration section
2.1.1 reaction apparatus diagram
The reaction device of a nitration section is shown in figure 1:
wherein:
m1 is a mixer, and the mixer plays a role in mixing materials;
c1 is a pipeline reactor;
c. the material A is chlorobenzene with the concentration of 99 percent, and the material B is mixed acid of sulfuric acid and nitric acid which is freshly prepared according to the mixture ratio.
2.1.2 continuous mononitration examples
The screening results of the conditions for the mononitration are shown in items 1 to 11 (i.e., Entry1 to 11) of Table 1 and items 1 to 7 (i.e., Entry1 to 7) of Table 2 below:
note:
RT is the residence time in temperature zone T1;
b.P front pressure shows the result of back end back pressure;
c. the mixed acid is prepared by 90 percent of sulfuric acid and 95 percent of nitric acid.
Note:
rt is the residence time through temperature zone T1;
b. the mixed acid is prepared by 90 percent of sulfuric acid and 95 percent of nitric acid.
As shown in the above Table 2, the equivalent of nitric acid is preferably 1.2eq (Entry 1-4); the reaction temperature is increased, the conversion rate is obviously improved, the optimal temperature interval is 100-110 ℃, the raw materials are almost completely converted, and the conversion rate is lower when the temperature is 130 ℃ (Entry 4-7); the optimal conditions are obtained by screening, namely at 110 ℃, the raw material is completely converted when the nitric acid equivalent is 1.2eq, the ortho-isomer is 30 percent, and the reaction result is remarkably lower than the reaction result (35 to 40 percent) of kettle type mononitration reported in literature (the process of preparing the nitrochlorobenzene by the Xuchangsong-chlorobenzene is advanced [ J ] Liaoning chemical industry, 1993,000(001):13 to 15). The impurity with the largest influence on the chlorobenzene dinitration is 2, 6-dinitrochlorobenzene, the content of the 2-nitrochlorobenzene is controlled, the selectivity of the 4-nitrochlorobenzene is improved, the impurity is reduced, and the product yield and the quality of the 2, 4-dinitrochlorobenzene are improved.
2.2 continuous dinitration stage
2.2.1 reaction apparatus diagram
The reaction apparatus diagram of the dinitration stage is shown in FIG. 2 (the process conditions of the mononitration stage are entry5 in Table 2 above):
wherein:
a. the material A is a solution prepared by concentrated sulfuric acid and a mononitration product according to an equivalent ratio, and the material B is fuming nitric acid;
t1 is a reaction temperature zone, and T2 is a cooling temperature zone;
c, C1 and C2 are microchannel reactors.
2.2.2 continuous dinitration example
The screening results of dinitration conditions are shown in items 1-11 (i.e., Entry 1-11) in Table 3 below:
note:
RT refers to the residence time through the temperature zone T1 (except Entry 1);
b.P "-" indicates no back pressure at the back end;
nd means not detected;
t2 "-" indicates that no cooling module is provided.
Claims (10)
1. A preparation method of 2, 4-dinitrochlorobenzene is characterized by comprising the following steps:
step (1), chlorobenzene is subjected to mononitration in the presence of nitric acid and sulfuric acid in a continuous flow reactor A to obtain a mononitrated product;
in the step (2), in a continuous flow reactor B, carrying out dinitration reaction on the mononitrated product in the presence of nitric acid and sulfuric acid to obtain 2, 4-dinitrochlorobenzene;
the reaction temperature of the primary nitration reaction is 70-110 ℃;
in the step (1), the molar ratio of chlorobenzene to nitric acid is 1: 1.0-1: 1.8;
in the step (1), the molar ratio of the chlorobenzene to the sulfuric acid is 1: 2-1: 5.
2. The process for the preparation of 2, 4-dinitrochlorobenzene according to claim 1, wherein:
in the step (1), the continuous flow reactor A is a micro-channel reactor or a tubular reactor;
and/or in the step (1), the nitric acid is a nitric acid aqueous solution with the mass fraction of 90-98%;
and/or in the step (1), the sulfuric acid is a sulfuric acid aqueous solution with a sulfuric acid mass fraction of 90-98%;
and/or in the step (1), the molar ratio of the chlorobenzene to the nitric acid is 1: 1.0-1: 1.5;
and/or in the step (1), the molar ratio of chlorobenzene to sulfuric acid is 1: 2-1: 4;
and/or in the step (1), the temperature of the primary nitration reaction is 90-110 ℃;
and/or the residence time of the chlorobenzene, the nitric acid and the sulfuric acid for the mononitration reaction in the continuous flow reactor is 55-120 s;
and/or, in step (1), the mononitration is carried out at atmospheric pressure;
and/or, in the step (1), the mononitration product is one or more of 2-nitrochlorobenzene, 4-nitrochlorobenzene and 2, 4-dinitrochlorobenzene.
3. The process for the preparation of 2, 4-dinitrochlorobenzene according to claim 2, characterized in that:
in the step (1), the nitric acid is a nitric acid aqueous solution with the mass fraction of 95 percent;
and/or, in the step (1), the sulfuric acid is a sulfuric acid aqueous solution with a sulfuric acid mass fraction of 90%;
and/or, in the step (1), the molar ratio of the chlorobenzene to the nitric acid is 1:1.07, 1:1.1, 1:1.13, 1:1.18, 1:1.21, 1:1.23 or 1: 1.36;
and/or, in step (1), the molar ratio of chlorobenzene to sulfuric acid is 1:2.45, 1:2.46, 1:2.47, 1:2.48, 1:2.5, 1:2.51, 1:2.53, 1:2.55, 1:2.56, 1:2.59, 1:2.62, 1:2.68, 1:2.93 or 1: 3.53;
and/or, in step (1), the temperature of the mononitration reaction is 90 ℃, 100 ℃ or 110 ℃;
and/or the residence time of the chlorobenzene, the nitric acid and the sulfuric acid for the mononitration reaction in the continuous flow reactor is 55-65 s;
and/or, in the step (1), the mononitration products are 2-nitrochlorobenzene, 4-nitrochlorobenzene and 2, 4-dinitrochlorobenzene.
4. The process for the preparation of 2, 4-dinitrochlorobenzene according to claim 3, characterized in that:
the residence time of the chlorobenzene, nitric acid and sulfuric acid in the continuous flow reactor for mononitration is 58.3s, 58.9s, 60.12s, 60.59s, 60.73s, 61.61 or 63.11 s.
5. The process for the production of 2, 4-dinitrochlorobenzene according to claim 1, wherein: and (3) after the primary nitration reaction is finished, layering the obtained reaction liquid to obtain an organic phase, and directly carrying out the dinitration reaction in the step (2) on the organic phase.
6. The process for the preparation of 2, 4-dinitrochlorobenzene according to claim 1, wherein:
in the step (2), the continuous flow reactor B is a micro-channel reactor or a tubular reactor;
and/or in the step (2), the nitric acid is a nitric acid aqueous solution with the mass fraction of 90-98%;
and/or in the step (2), the sulfuric acid is a sulfuric acid aqueous solution with a sulfuric acid mass fraction of 90-98%;
and/or, in the step (2), the temperature of the dinitration reaction is 70-130 ℃;
and/or in the step (2), the molar ratio of the mononitrated product to the nitric acid is 1: 1-1: 1.5;
and/or, in the step (2), the molar ratio of the mononitrated product to the sulfuric acid is 1: 3.0-1: 5.0;
and/or, in the step (2), after the dinitration reaction is finished, further cooling the obtained feed liquid;
and/or, in step (2), before carrying out the dinitration reaction, carrying out a preheating treatment on the mononitrated product and sulfuric acid;
and/or, in the step (2), the residence time of the mononitration product, nitric acid and sulfuric acid in the continuous flow reactor B for dinitration is 1-50 s;
and/or, in the step (2), the dinitration reaction is carried out under a certain pressure, wherein the pressure is 1-10 bar.
7. The process for the preparation of 2, 4-dinitrochlorobenzene according to claim 6, wherein:
in the step (2), the nitric acid is a nitric acid aqueous solution with the mass fraction of 95 percent;
and/or, in the step (2), the sulfuric acid is a 98% sulfuric acid aqueous solution in mass fraction;
and/or, in step (2), the temperature of the dinitration reaction is 70 ℃, 80 ℃, 90 ℃, 110 ℃ or 130 ℃;
and/or, in step (2), the molar ratio of the mononitrated product to the nitric acid is 1:1.07, 1:1.08, 1:1.09, 1:1.11, 1:1.12, 1:1.13, 1:1.15, 1: 1.24;
and/or, in step (2), the molar ratio of said mononitrated product to said sulfuric acid is 1: 3.5;
and/or, in the step (2), after the dinitration reaction is finished, when the obtained feed liquid is further cooled, the temperature is reduced to 60-80 ℃;
and/or, in the step (2), before the dinitration reaction, when the mononitration product and the sulfuric acid are subjected to preheating treatment, the preheating temperature is 50-80 ℃;
and/or, in step (2), said mononitrated product, nitric acid, and sulfuric acid are dinitrated in said continuous flow reactor B at a residence time of 1.5s, 2.5s, 4.9s, 5s, 10.25s, 10.26s, 11.55s, 13.92s, 13.98s, 14.28s, or 16.36 s;
and/or, in step (2), the pressure is 1bar, 2.5bar, 4bar, 5bar, 6bar, 7bar or 8 bar.
8. The process for the production of 2, 4-dinitrochlorobenzene according to claim 7, wherein:
in the step (2), the molar ratio of the mononitrated product to the nitric acid is 1: 1.07-1: 1.3;
and/or, in the step (2), after the dinitration reaction is finished, further cooling the obtained feed liquid to 70 ℃;
and/or, in the step (2), when the mononitrated product and the sulfuric acid are subjected to preheating treatment before the dinitration reaction, the preheating temperature is 65-75 ℃;
and/or, in the step (2), the residence time of the mononitration product, nitric acid and sulfuric acid in the continuous flow reactor B for dinitration is 5-20 s;
and/or in the step (2), the pressure is 5-8 bar.
9. The process for the preparation of 2, 4-dinitrochlorobenzene according to claim 7, wherein: in the step (2), after the temperature reduction is finished, the obtained feed liquid is further subjected to liquid separation.
10. The process for the preparation of 2, 4-dinitrochlorobenzene according to claim 1, wherein: the continuous flow reactor is one or more of a micro reactor, a tubular reactor, a laminated mixer and a static mixer;
and/or, the raw material of the mononitration reaction only consists of the nitric acid, the sulfuric acid and the chlorobenzene;
and/or the starting material for the dinitration consists exclusively of the nitric acid, the sulfuric acid and the mononitration product.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115850081A (en) * | 2022-10-25 | 2023-03-28 | 康宁反应器技术有限公司 | Process for preparing 2, 4-dinitrochlorobenzene |
| CN116891416A (en) * | 2023-06-16 | 2023-10-17 | 泰兴锦云染料有限公司 | Preparation method of 3, 5-diaminobenzoic acid |
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| CN116891416A (en) * | 2023-06-16 | 2023-10-17 | 泰兴锦云染料有限公司 | Preparation method of 3, 5-diaminobenzoic acid |
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