A kind of 2-chlorophenylhydrazine hydrochloride and preparation process thereof

Abstract

The present invention relates to the technical field of preparation of organic compounds, and in particular to 2-chlorophenylhydrazine hydrochloride and a preparation process thereof: 500-600 parts of ethanol, 500-600 parts of stannous chloride solution, 300-350 parts of hydrochloric acid solution, 100-120 parts of 2,4-dichloronitrobenzene, and 10-12 parts of reduced iron powder. In the present invention, 2,4-dichloronitrobenzene is used as an initial raw material to first prepare 2,4-dichloroaniline hydrochloride. Due to its relatively more stable structure, the intermediate product can better maintain its chemical properties unchanged during storage, transportation, and subsequent reaction waiting steps throughout the entire preparation process. This stability can effectively prevent the intermediate product from undergoing unnecessary chemical reactions or degradation due to external environmental factors, thereby ensuring that the subsequent step of extracting 2-chloroaniline hydrochloride can be performed based on the stable starting material, thereby improving the stability basis for extraction of the final product.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of organic compounds, in particular to 2-chlorophenylhydrazine hydrochloride and a preparation process thereof. Background Art

[0002] 2-Chlorophenylhydrazine hydrochloride is an important organic synthesis intermediate and is widely used in medicine, pesticides, dyes and other fields.

[0003] In the prior art, as in Chinese Patent Publication No. CN104109103A, a preparation method of 2-chlorophenylhydrazine hydrochloride is disclosed, comprising the steps of diazotization, reduction, purification, and salification. In the step of diazotization reduction, concentrated hydrochloric acid is used to keep the reaction solution in a strongly acidic state to ensure that the reaction is smoothly and completely carried out. In the reduction step, zinc powder-concentrated hydrochloric acid is used as a reducing agent to replace sodium thiosulfate, sodium bisulfite, stannous chloride-hydrochloric acid, etc., not only has good reducing properties, but also has a high yield and shortens the reaction time. Impurities such as zinc hydroxide generated after the reaction are convenient to remove, making product impurities less and having a high purity. In the salification step, acetone rinse is used to improve the purity of the product and ensure the outward appearance of the product. This preparation method is stable and reliable, easy to operate, and has a high product purity (high performance liquid chromatography measures its content ≥99%), and a yield ≥39%, which fully meets the needs of the market for 2-chlorophenylhydrazine hydrochloride.

[0004] At present, the traditional preparation process of 2-chloroaniline hydrochloride uses 2-chloronitrobenzene as raw material. During the reduction of nitro group (-NO2) to amino group (-NH2), since there is only one chlorine atom on the benzene ring, its electronic effect and steric hindrance effect are relatively weak. As the reaction reagent approaches the reaction center (nitro group), it is easily interfered by solvent molecules and impurities, resulting in reduced reaction selectivity. As a result, the extraction stability of 2-chloroaniline hydrochloride is poor and the purity is difficult to control. Summary of the Invention

[0005] The present invention aims to provide 2-chlorophenylhydrazine hydrochloride and a preparation process thereof. The 2-chlorophenylhydrazine hydrochloride prepared by the present invention has better stability and controllability.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A 2-chlorophenylhydrazine hydrochloride is characterized by being composed of the following raw materials in parts by weight: 500-600 parts of ethanol, 500-600 parts of stannous chloride solution, 300-350 parts of hydrochloric acid solution, 100-120 parts of 2,4-dichloronitrobenzene, and 10-12 parts of reduced iron powder.

[0008] Preferably, the treatment process of 2,4-dichloronitrobenzene comprises the following steps:

[0009] Step 1: Weigh 2,4-dichloronitrobenzene, ethanol, and reduced iron powder as needed, add them to a reactor, slowly heat to 70-80°C, reach reflux, and continue the reaction for 5-8 hours. Detect the reaction progress by thin layer chromatography until the solubility of 2,4-dichloronitrobenzene reaches 90%, thereby obtaining a liquid crude 2,4-dichloroaniline dissolved in ethanol;

[0010] Step 2: adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating, filtering to remove iron powder, and then distilling under reduced pressure to remove ethanol to obtain a solid crude 2,4-dichloroaniline;

[0011] Step 3: Weigh the hydrochloric acid solution and the solid 2,4-dichloroaniline crude product as needed, mix and dissolve them to obtain a mixed solution, add it to the reactor, start the reactor, and continuously process it at a temperature of 0-5°C and a speed of 20-50 r / min. Add a sodium nitrite solution accounting for 40-50% by mass of the mixed solution dropwise to carry out a diazotization reaction. The reaction time is 30-60 min to obtain a 2,4-dichloroaniline diazonium salt liquid;

[0012] Step 4: Add the stannous chloride solution to the reactor, start the reactor, and dropwise add 2,4-dichloroaniline diazonium salt liquid at a temperature of 5-10°C and a stirring speed of 500-600 r / min for a reduction reaction of 2-3 hours to generate 2,4-dichloroaniline hydrochloride liquid;

[0013] Step 5: Pass 2,4-dichloroaniline hydrochloride through an 80-100 mesh sieve to obtain a 2,4-dichloroaniline hydrochloride solid, wash it with ice water (15% by weight of the 2,4-dichloroaniline hydrochloride solid), filter out impurities, and then place it in a vacuum drying oven at a drying temperature of 40-50° C. and a vacuum degree of 0.08-0.1 MPa for 6-8 hours to obtain 2,4-dichloroaniline hydrochloride for standby use.

[0014] Preferably, the concentration of the hydrochloric acid solution is 2 mol / L, the stannous chloride solution is prepared by dissolving stannous chloride in the hydrochloric acid solution, and the mass ratio of stannous chloride to the hydrochloric acid solution is 1:25.

[0015] Preferably, 2,4-dichloroaniline hydrochloride and deionized water are weighed in a mass ratio of 1:4, added to a stirring kettle, and continuously treated for 30-40 minutes at a stirring speed of 200-300 r / min. The mixture is filtered with a sand core funnel under normal pressure to remove impurities to obtain a filtrate.

[0016] Preferably, the filtrate is added to a rotary evaporator, the rotary evaporator is started, the water bath temperature is 50-60°C, and the vacuum degree is 0.06-0.1MPa, and the volume of the original solution is concentrated. 1 / 4, cooled to room temperature to obtain crystals.

[0017] Preferably, the crystals are extracted through a Buchner funnel, washed with 10-12% cold ethanol by weight of the crystals, and then transferred to a vacuum drying oven and dried for 4-5 hours to obtain high-purity crystals.

[0018] Preferably, the parameters of the vacuum drying oven are set to a temperature of 40-50° C. and a vacuum degree of 0.08-0.1 MPa.

[0019] Preferably, high-purity crystals and anhydrous ethanol in a mass ratio of 1:5 are added to a three-necked flask, and mixed at a stirring speed of 300-400 r / min and a reflux cooling water temperature of 10-20° C. to obtain a mixture.

[0020] Preferably, high-purity nitrogen is introduced into the three-necked flask containing the mixture at a flow rate of 20-30 mol / min for 10-15 min to complete deoxygenation and obtain a reactant.

[0021] Furthermore, a 2-chlorophenylhydrazine hydrochloride and a preparation process thereof comprise the following steps:

[0022] S1: Weigh the reactants as needed, add a palladium catalyst supported on activated carbon with a palladium content of 5%, place the mixture in an autoclave, evacuate to 0.08-0.1 MPa, introduce nitrogen and pressurize to 1.5-2.5 MPa, and continue the reaction at a temperature of 40-60°C and a stirring speed of 500-700 r / min until the conversion of 2,4-dichloroaniline hydrochloride exceeds 90%, thereby obtaining a reaction solution;

[0023] S2. Add the reaction solution to a pressure filter, filter and separate through a microporous ceramic membrane with a pore size of 0.1-0.2 μm at 0.2-0.3 MPa to obtain a filtrate containing 2-chloroaniline hydrochloride;

[0024] S3. The filtrate is added to a distillation kettle, and distillation is continued at a vacuum degree of 0.08-0.1 MPa and a water bath temperature of 40-50° C., and 12-20% by weight of ether is added to the distillation residue for recrystallization. The recrystallization solution is then cooled to 0-5° C. in a water bath to precipitate 2-chloroaniline hydrochloride crystals, which are then filtered, collected, and dried to obtain high-purity 2-chloroaniline hydrochloride.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention first prepares 2,4-dichloroaniline hydrochloride by using 2,4-dichloronitrobenzene as the initial raw material. The two chlorine atoms in its molecular structure increase the stability of the molecule to a certain extent. Compared with 2-chloroaniline hydrochloride, this relatively more stable structure enables the intermediate product to better maintain its chemical properties during storage, transportation, and subsequent reaction waiting stages throughout the entire preparation process. This stability can effectively prevent it from undergoing unnecessary chemical reactions or degradation due to external environmental factors, thereby ensuring that the subsequent extraction step of 2-chloroaniline hydrochloride can be carried out based on the stable starting material, thereby improving the stability basis for the extraction of the final product.

[0027] 2. The key to the preparation process of the present invention is that 2,4-dichloroaniline hydrochloride is first prepared and then 2-chloroaniline hydrochloride is extracted. The selective dechlorination reaction can be achieved during the conversion process from 2,4-dichloroaniline hydrochloride to 2-chloroaniline hydrochloride. The chlorine atom at the 4-position can be precisely controlled to be removed while retaining the chlorine atom at the 2-position, thereby obtaining high-purity 2-chloroaniline hydrochloride. This high controllability of the reaction selectivity effectively avoids the impurity problem that may be caused by poor reaction selectivity in the traditional direct preparation process, greatly improves the purity of the extracted product, ensures that the final 2-chloroaniline hydrochloride meets high quality requirements, and provides purity guarantee for its subsequent use in pharmaceuticals, dyes and other fields. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Example 1

[0030] A 2-chlorophenylhydrazine hydrochloride is characterized by being composed of the following raw materials in parts by weight: 500 parts of ethanol, 500 parts of stannous chloride solution, 300 parts of hydrochloric acid solution, 100 parts of 2,4-dichloronitrobenzene, and 10 parts of reduced iron powder.

[0031] The treatment process of 2,4-dichloronitrobenzene includes the following steps:

[0032] Step 1: Weigh 2,4-dichloronitrobenzene, ethanol, and reduced iron powder as needed, add them to a reactor, slowly heat to 70°C, reach reflux, and continue the reaction for 5 hours. Detect the reaction progress by thin layer chromatography until the solubility of 2,4-dichloronitrobenzene reaches 90%, thereby obtaining a liquid crude 2,4-dichloroaniline dissolved in ethanol;

[0033] Step 2: adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating, filtering to remove iron powder, and then distilling under reduced pressure to remove ethanol to obtain a solid crude 2,4-dichloroaniline;

[0034] Step 3: Weigh the hydrochloric acid solution and the solid 2,4-dichloroaniline crude product as needed, mix and dissolve them to obtain a mixed solution, add it to the reactor, start the reactor, and continuously process it at a temperature of 0°C and a speed of 20 r / min. Add a sodium nitrite solution accounting for 40% by mass of the mixed solution dropwise to carry out a diazotization reaction. The reaction time is 30 min to obtain a 2,4-dichloroaniline diazonium salt liquid;

[0035] Step 4: Add the stannous chloride solution to the reactor, start the reactor, and dropwise add 2,4-dichloroaniline diazonium salt liquid at a temperature of 5°C and a stirring speed of 500 r / min for a reduction reaction for 2 hours to generate 2,4-dichloroaniline hydrochloride liquid;

[0036] Step 5: Pass 2,4-dichloroaniline hydrochloride through an 80-mesh sieve to obtain a 2,4-dichloroaniline hydrochloride solid, wash it with ice water (15% by weight of the 2,4-dichloroaniline hydrochloride solid), filter out impurities, and then place it in a vacuum drying oven at a drying temperature of 40° C. and a vacuum degree of 0.08 MPa for 6 hours to obtain 2,4-dichloroaniline hydrochloride for standby use.

[0037] The concentration of the hydrochloric acid solution is 2 mol / L, the stannous chloride solution is prepared by dissolving stannous chloride in the hydrochloric acid solution, and the mass ratio of stannous chloride to the hydrochloric acid solution is 1:25.

[0038] 2,4-Dichloroaniline hydrochloride and deionized water were weighed in a mass ratio of 1:4, added into a stirring kettle, and continuously treated at a stirring speed of 200 r / min for 30 minutes. The mixture was filtered through a sand core funnel under normal pressure to remove impurities and obtain a filtrate.

[0039] The filtrate was added to the rotary evaporator, the rotary evaporator was started, the water bath temperature was 50 ° C, the vacuum degree was 0.06 MPa and the volume of the original solution was concentrated. 1 / 4, cooled to room temperature to obtain crystals.

[0040] The crystals were extracted through a Buchner funnel, washed with 10% cold ethanol by weight of the crystals, and then transferred to a vacuum drying oven and dried for 4 hours to obtain high-purity crystals.

[0041] The parameters of the vacuum drying oven were set to 40°C temperature and 0.08 MPa vacuum degree.

[0042] High-purity crystals and anhydrous ethanol in a mass ratio of 1:5 were added to a three-necked flask, and mixed at a stirring speed of 300 r / min and a reflux cooling water temperature of 100° C. to obtain a mixture.

[0043] High-purity nitrogen was introduced into the three-necked flask containing the mixture at a flow rate of 20 mol / min for 10 min to complete deoxygenation and obtain a reactant.

[0044] Furthermore, a 2-chlorophenylhydrazine hydrochloride and a preparation process thereof comprise the following steps:

[0045] S1: Weigh the reactants as needed, add a palladium catalyst supported on activated carbon with a palladium content of 5%, place the mixture in an autoclave, evacuate to 0.08 MPa, introduce nitrogen and pressurize to 1.5 MPa, and continue the reaction at a temperature of 40°C and a stirring speed of 500 r / min until the conversion of 2,4-dichloroaniline hydrochloride exceeds 90%, thereby obtaining a reaction solution;

[0046] S2. Add the reaction solution to a pressure filter and filter through a 0.1 μm pore size microporous ceramic membrane at 0.2 MPa to obtain a filtrate containing 2-chloroaniline hydrochloride;

[0047] S3. The filtrate was added to a distillation kettle, and distillation was continued at a vacuum degree of 0.08 MPa and a water bath temperature of 40° C., and 12% by weight of ether was added to the distillation residue for recrystallization. The recrystallization solution was then cooled to 0° C. in a water bath to precipitate 2-chloroaniline hydrochloride crystals, which were then filtered, collected, and dried to obtain high-purity 2-chloroaniline hydrochloride.

[0048] Example 2

[0049] The preparation process of 2-chlorophenylhydrazine hydrochloride in this embodiment is basically the same as that in Example 1, except that the specific ratios of the raw materials used in the two are different. The specific ratios of the raw materials used to prepare 2-chlorophenylhydrazine hydrochloride in this embodiment and the preparation process of the functional additives are as follows:

[0050] A 2-chlorophenylhydrazine hydrochloride is characterized by being composed of the following raw materials in parts by weight: 550 parts of ethanol, 550 parts of stannous chloride solution, 320 parts of hydrochloric acid solution, 110 parts of 2,4-dichloronitrobenzene, and 11 parts of reduced iron powder.

[0051] The treatment process of 2,4-dichloronitrobenzene includes the following steps:

[0052] Step 1: Weigh 2,4-dichloronitrobenzene, ethanol, and reduced iron powder as needed, add them to a reactor, slowly heat to 75°C, reach reflux, and continue the reaction for 6 hours. Detect the reaction progress by thin layer chromatography until the solubility of 2,4-dichloronitrobenzene reaches 90%, thereby obtaining a liquid crude 2,4-dichloroaniline dissolved in ethanol;

[0053] Step 2: adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating, filtering to remove iron powder, and then distilling under reduced pressure to remove ethanol to obtain a solid crude 2,4-dichloroaniline;

[0054] Step 3: Weigh the hydrochloric acid solution and the solid 2,4-dichloroaniline crude product as needed, mix and dissolve them to obtain a mixed solution, add it to the reactor, start the reactor, and continuously process it at a temperature of 3°C and a speed of 35 r / min. Add a sodium nitrite solution accounting for 45% of the mass of the mixed solution dropwise to carry out a diazotization reaction. The reaction time is 45 minutes to obtain a 2,4-dichloroaniline diazonium salt liquid;

[0055] Step 4: Add the stannous chloride solution to the reactor, start the reactor, and dropwise add 2,4-dichloroaniline diazonium salt liquid at a temperature of 8°C and a stirring speed of 550 r / min for a reduction reaction of 2.5 hours to generate 2,4-dichloroaniline hydrochloride liquid;

[0056] Step 5: Pass 2,4-dichloroaniline hydrochloride through a 90-mesh sieve to obtain a 2,4-dichloroaniline hydrochloride solid, wash it with ice water (15% by weight of the 2,4-dichloroaniline hydrochloride solid), filter out impurities, and then place it in a vacuum drying oven at a drying temperature of 45° C. and a vacuum degree of 0.09 MPa for 7 hours to obtain 2,4-dichloroaniline hydrochloride for standby use.

[0057] The concentration of the hydrochloric acid solution is 2 mol / L, the stannous chloride solution is prepared by dissolving stannous chloride in the hydrochloric acid solution, and the mass ratio of stannous chloride to the hydrochloric acid solution is 1:25.

[0058] 2,4-Dichloroaniline hydrochloride and deionized water were weighed in a mass ratio of 1:4, added into a stirring kettle, and continuously treated for 35 minutes at a stirring speed of 250 r / min. The impurities were removed by filtering with a sand core funnel under normal pressure to obtain a filtrate.

[0059] The filtrate was added to the rotary evaporator, the rotary evaporator was started, the water bath temperature was 55 ° C, the vacuum degree was 0.08 MPa and the volume of the original solution was concentrated. 1 / 4, cooled to room temperature to obtain crystals.

[0060] The crystals were extracted through a Buchner funnel, washed with 11% cold ethanol by weight of the crystals, and then transferred to a vacuum drying oven and dried for 4.5 hours to obtain high-purity crystals.

[0061] The parameters of the vacuum drying oven were set to 45°C temperature and 0.09 MPa vacuum degree.

[0062] High-purity crystals and anhydrous ethanol in a mass ratio of 1:5 were added to a three-necked flask, and mixed at a stirring speed of 350 r / min and a reflux cooling water temperature of 15° C. to obtain a mixture.

[0063] High-purity nitrogen was introduced into the three-necked flask containing the mixture at a flow rate of 25 mol / min for 13 min to complete deoxygenation and obtain a reactant.

[0064] Furthermore, a 2-chlorophenylhydrazine hydrochloride and a preparation process thereof comprise the following steps:

[0065] S1: Weigh the reactants as needed, add a palladium catalyst supported on activated carbon with a palladium content of 5%, place the mixture in an autoclave, evacuate to 0.09 MPa, introduce nitrogen and pressurize to 2 MPa, and continue the reaction at a temperature of 50° C. and a stirring speed of 600 r / min until the conversion of 2,4-dichloroaniline hydrochloride exceeds 90%, thereby obtaining a reaction solution;

[0066] S2. Add the reaction solution to a pressure filter and filter through a 0.15 μm pore size microporous ceramic membrane at 0.25 MPa to obtain a filtrate containing 2-chloroaniline hydrochloride;

[0067] S3. The filtrate was added to a distillation kettle, and distillation was continued at a vacuum degree of 0.09 MPa and a water bath temperature of 45° C., and 17% by weight of ether was added to the distillation residue for recrystallization. The recrystallization solution was then cooled to 03° C. in a water bath to precipitate 2-chloroaniline hydrochloride crystals, which were then filtered, collected, and dried to obtain high-purity 2-chloroaniline hydrochloride.

[0068] Example 3

[0069] The preparation process of 2-chlorophenylhydrazine hydrochloride in this embodiment is basically the same as that in Example 1, except that the specific ratios of the raw materials used in the two are different. The specific ratios of the raw materials used to prepare 2-chlorophenylhydrazine hydrochloride in this embodiment and the preparation process of the functional additives are as follows:

[0070] A 2-chlorophenylhydrazine hydrochloride is characterized by being composed of the following raw materials in parts by weight: 600 parts of ethanol, 600 parts of stannous chloride solution, 350 parts of hydrochloric acid solution, 120 parts of 2,4-dichloronitrobenzene, and 12 parts of reduced iron powder.

[0071] The treatment process of 2,4-dichloronitrobenzene includes the following steps:

[0072] Step 1: Weigh 2,4-dichloronitrobenzene, ethanol, and reduced iron powder as needed, add them to a reactor, slowly heat to 80°C, reach reflux, and continue the reaction for 8 hours. Detect the reaction progress by thin layer chromatography until the solubility of 2,4-dichloronitrobenzene reaches 90%, thereby obtaining a liquid crude 2,4-dichloroaniline dissolved in ethanol;

[0073] Step 2: adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating, filtering to remove iron powder, and then distilling under reduced pressure to remove ethanol to obtain a solid crude 2,4-dichloroaniline;

[0074] Step 3: Weigh the hydrochloric acid solution and the solid 2,4-dichloroaniline crude product as needed, mix and dissolve them to obtain a mixed solution, add it to the reactor, start the reactor, and continuously process it at a temperature of 5° C. and a speed of 50 r / min. Add a sodium nitrite solution with a mass percentage of 50% of the mixed solution to carry out a diazotization reaction. The reaction time is 60 min to obtain a 2,4-dichloroaniline diazonium salt liquid;

[0075] Step 4: Add the stannous chloride solution to the reactor, start the reactor, and dropwise add 2,4-dichloroaniline diazonium salt liquid at a temperature of 10° C. and a stirring speed of 600 r / min for a reduction reaction for 3 hours to generate 2,4-dichloroaniline hydrochloride liquid;

[0076] Step 5: Pass 2,4-dichloroaniline hydrochloride through an 80-100 mesh sieve to obtain a 2,4-dichloroaniline hydrochloride solid, wash it with ice water (15% by weight of the 2,4-dichloroaniline hydrochloride solid), filter out impurities, and then place it in a vacuum drying oven at a drying temperature of 50° C. and a vacuum degree of 0.1 MPa for 8 hours to obtain 2,4-dichloroaniline hydrochloride for standby use.

[0077] The concentration of the hydrochloric acid solution is 2 mol / L, the stannous chloride solution is prepared by dissolving stannous chloride in the hydrochloric acid solution, and the mass ratio of stannous chloride to the hydrochloric acid solution is 1:25.

[0078] 2,4-Dichloroaniline hydrochloride and deionized water were weighed in a mass ratio of 1:4, added into a stirring kettle, and continuously treated at a stirring speed of 300 r / min for 40 min. The mixture was filtered through a sand core funnel under normal pressure to remove impurities and obtain a filtrate.

[0079] The filtrate was added to the rotary evaporator, the rotary evaporator was started, the water bath temperature was 60 ° C, the vacuum degree was 0.1 MPa and the volume of the original solution was concentrated. 1 / 4, cooled to room temperature to obtain crystals.

[0080] The crystals were extracted through a Buchner funnel, washed with 12% cold ethanol by weight of the crystals, and then transferred to a vacuum drying oven and dried for 5 hours to obtain high-purity crystals.

[0081] The parameters of the vacuum drying oven were set to 50°C temperature and 0.1 MPa vacuum degree.

[0082] High-purity crystals and anhydrous ethanol in a mass ratio of 1:5 were added to a three-necked flask, and the mixture was mixed at a stirring speed of -400 r / min and a reflux cooling water temperature of 20° C. to obtain a mixture.

[0083] High-purity nitrogen was introduced into the three-necked flask containing the mixture at a flow rate of 30 mol / min for 15 min to complete deoxygenation and obtain a reactant.

[0084] Furthermore, a 2-chlorophenylhydrazine hydrochloride and a preparation process thereof comprise the following steps:

[0085] S1: Weigh the reactants as needed, add a palladium catalyst supported on activated carbon with a palladium content of 5%, place the mixture in an autoclave, evacuate to 0.1 MPa, introduce nitrogen and pressurize to 2.5 MPa, and continue the reaction at a temperature of 60°C and a stirring speed of 700 r / min until the conversion of 2,4-dichloroaniline hydrochloride exceeds 90%, thereby obtaining a reaction solution;

[0086] S2. Add the reaction solution to a pressure filter and filter through a 0.2 μm pore size microporous ceramic membrane at 0.3 MPa to obtain a filtrate containing 2-chloroaniline hydrochloride;

[0087] S3. The filtrate was added to a distillation kettle, and distillation was continued at a vacuum degree of 0.1 MPa and a water bath temperature of 50° C., and ether accounting for 20% by mass of the residue was added to the distillation residue for recrystallization. The recrystallization solution was then cooled to 5° C. in a water bath to precipitate 2-chloroaniline hydrochloride crystals, which were then filtered, collected, and dried to obtain high-purity 2-chloroaniline hydrochloride.

[0088] Comparative Example 1: This comparative example differs from Example 1 in that 2,4-dichloroaniline hydrochloride was not prepared in this comparative example, and 2-chlorophenylhydrazine hydrochloride was directly prepared using 2-chloronitrobenzene.

[0089] Comparative Example 2: This comparative example differs from Example 1 in that ice water washing and impurity filtration are not used in the preparation of 2,4-dichloroaniline hydrochloride in this comparative example.

[0090] Comparative Example 3: This comparative example differs from Example 1 in that cold ethanol washing was not used in the preparation of 2'-chlorophenylhydrazine hydrochloride in this comparative example.

[0091] Performance test: The relevant properties of the 2-chlorophenylhydrazine hydrochloride samples provided in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were tested respectively;

[0092] In performance testing,

[0093] Purity test: High performance liquid chromatography (HPLC) was used to test the purity of the sample. The content of 2-chlorophenylhydrazine hydrochloride in the sample was calculated by comparing the retention time and peak area of ​​the standard.

[0094] Melting point test: Use a capillary melting point apparatus to perform the melting point test. Place the sample into the capillary tube, heat until the sample melts, and record the melting point. The test data is recorded in the following table:

[0095] Test items purity(%) Melting point (℃) Example 1 99 185 Example 2 98.5 183 Example 3 98.5 182 Comparative Example 1 89 164 Comparative Example 2 92 175 Comparative Example 3 94 174

[0096] By comparing and analyzing the relevant data in the table, it can be seen that the purity and melting point of the 2-chlorophenylhydrazine hydrochloride prepared in Comparative Examples 1, 2, and 3 are lower than those in Examples 1, 2, and 3; this shows that the 2-chlorophenylhydrazine hydrochloride obtained by this preparation process has better stability and controllability. This shows that the 2-chlorophenylhydrazine hydrochloride and the preparation process provided by the present invention have a broader market prospect and are more suitable for promotion.

[0097] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0098] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A preparation process for 2-chlorophenylhydrazine hydrochloride, characterized in that, The following steps are involved: Step 1: Weigh 2,4-dichloronitrobenzene, ethanol, and reduced iron powder as needed, add them to a reactor, slowly heat to reflux, and continue the reaction to obtain a crude liquid 2,4-dichloroaniline product; Step 2: adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating, filtering to remove iron powder, and then distilling under reduced pressure to remove ethanol to obtain a solid crude 2,4-dichloroaniline; Step 3: Weigh hydrochloric acid solution and solid 2,4-dichloroaniline crude product as needed, mix and dissolve to obtain a mixed solution, add it into a reactor for continuous treatment, and dropwise add sodium nitrite solution accounting for 40-50% by mass of the mixed solution to carry out diazotization reaction for 30-60 minutes to obtain 2,4-dichloroaniline diazonium salt liquid; Step 4: Add the stannous chloride solution to the reactor, add 2,4-dichloroaniline diazonium salt liquid dropwise and react for 2-3 hours to generate 2,4-dichlorophenylhydrazine hydrochloride liquid; Step 5, 2,4-dichlorophenylhydrazine hydrochloride was passed through an 80-100 mesh sieve to obtain 2,4-dichlorophenylhydrazine hydrochloride solid, which was washed with ice water (15% by weight of the 2,4-dichlorophenylhydrazine hydrochloride solid), filtered, and then placed in a vacuum drying oven for continuous drying to obtain 2,4-dichlorophenylhydrazine hydrochloride for standby use; Step 6: Weigh the reactant 2,4-dichlorophenylhydrazine hydrochloride as needed, add a palladium catalyst supported on activated carbon with a palladium content of 5%, place it in a high-pressure reactor, introduce nitrogen and pressurize it to 1.5-2.5 MPa, and continue the reaction to obtain a reaction solution; Step 7: Add the reaction solution to a pressure filter and filter to obtain a filtrate containing 2-chlorophenylhydrazine hydrochloride; Step 8. The filtrate is added to a distillation kettle and distilled continuously at a vacuum degree of 0.08-0.1 MPa and a water bath temperature of 40-50 ° C. 12-20% by weight of ether is added to the distillation residue for recrystallization. The recrystallization solution is then cooled to 0-5 ° C in a water bath to precipitate 2-chlorophenylhydrazine hydrochloride crystals, which are then filtered, collected, and dried to obtain high-purity 2-chlorophenylhydrazine hydrochloride.

2. a preparation technology of 2-chlorophenylhydrazine hydrochloride according to claim 1, is characterized in that: The concentration of the hydrochloric acid solution is 2 mol / L. The stannous chloride solution is prepared by dissolving stannous chloride in the hydrochloric acid solution. The mass ratio of stannous chloride to the hydrochloric acid solution is 1:

25.

3. A preparation technology for 2-chlorophenylhydrazine hydrochloride according to claim 2, characterized in that, The post-treatment process of step five includes: weighing 2,4-dichlorophenylhydrazine hydrochloride and deionized water in a mass ratio of 1:4, adding them into a stirring kettle, continuously treating for 30-40 minutes, filtering with a sand core funnel under normal pressure to remove impurities, and obtaining a filtrate.

4. a preparation technology of 2-chlorophenylhydrazine hydrochloride according to claim 3, is characterized in that: The filtrate was added to a rotary evaporator and concentrated to 1 / 4 of the original solution volume, and then cooled to room temperature to obtain crystals.

5. a preparation technology of 2-chlorophenylhydrazine hydrochloride according to claim 4, is characterized in that: The crystals were extracted through a Buchner funnel, washed with 10-12% cold ethanol by weight of the crystals, and then transferred to a vacuum drying oven for 4-5 hours to obtain high-purity crystals.

6. A process for preparing 2-chlorophenylhydrazine hydrochloride according to claim 5, wherein: The parameters of the vacuum drying oven are set as follows: temperature 40-50°C and vacuum degree 0.08-0.1MPa.

7. A process for preparing 2-chlorophenylhydrazine hydrochloride according to claim 6, wherein: High-purity crystals and anhydrous ethanol in a mass ratio of 1:5 are added to a three-necked flask, and mixed at a stirring speed of 300-400 r / min and a reflux cooling water temperature of 10-20° C. to obtain a mixture.

8. A process for preparing 2-chlorophenylhydrazine hydrochloride according to claim 7, wherein: High-purity nitrogen was introduced into the three-necked flask containing the mixture at a flow rate of 20-30 mol / min for 10-15 min to complete deoxygenation and obtain the reactant 2,4-dichlorophenylhydrazine hydrochloride.