2-chlorophenylhydrazine hydrochloride and preparation process thereof

Abstract

The invention relates to the technical field of preparation of organic compounds, in particular to 2-chlorophenylhydrazine hydrochloride and a preparation process thereof. The 2-chlorophenylhydrazine hydrochloride is prepared from 500-600 parts of ethyl alcohol, 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. According to the preparation method, 2, 4-dichloroaniline hydrochloride is firstly prepared by adopting 2, 4-dichloronitrobenzene as an initial raw material, and due to the relatively stable structure, the chemical property of an intermediate product can be better kept unchanged in the storage, transportation and subsequent reaction waiting links in the whole preparation process; due to the stability, unnecessary chemical reaction or degradation caused by external environment factors can be effectively avoided, so that the subsequent 2-chloroaniline hydrochloride extraction step can be carried out on the basis of a stable starting material, and the stability basis of final product extraction is improved.

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 the fields of medicine, pesticides, dyes, etc.

[0003] In the prior art, such as Chinese Patent Publication No. CN104109103A, a preparation method of 2-chlorophenylhydrazine hydrochloride is disclosed, including 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 strong acidity to ensure that the reaction is carried out smoothly and completely. 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., which not only has good reduction performance, high yield, shortens the reaction time, and impurities such as zinc hydroxide generated after the reaction are easy to remove, so that the product has few impurities and high purity. In the salification step, acetone is used for leaching, which not only improves the purity of the product, but also ensures the appearance of the product. The preparation method has stable and reliable process, is easy to operate, has high product purity (high performance liquid chromatography measures its content ≥99%), and has a yield ≥39%, which fully meets the market demand for 2-chlorophenylhydrazine hydrochloride.

[0004] At present, the traditional preparation process of 2-chloroaniline hydrochloride uses 2-chloronitrobenzene as raw material. In the process of reducing 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, so that the reaction reagent is easily disturbed by solvent molecules and impurities when approaching the reaction center (nitro group), resulting in reduced reaction selectivity, thus making the extraction stability of 2-chloroaniline hydrochloride poor and the purity difficult to control. Summary of the invention

[0005] The purpose of the present invention is to provide a 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, characterized in that it is 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 into a reaction kettle, slowly heat up to 70-80° C., reach reflux state, continue the reaction for 5-8 hours, and monitor the reaction progress by thin layer chromatography until the dissolution rate of 2,4-dichloronitrobenzene reaches 90%, thereby obtaining a crude liquid 2,4-dichloroaniline dissolved in ethanol;

[0010] Step 2, adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating up, 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, weighing hydrochloric acid solution and solid 2,4-dichloroaniline crude product as needed, mixing and dissolving to obtain a mixed solution, adding the mixed solution into a reactor, starting the reactor, continuously treating at a temperature of 0-5°C and a rotation speed of 20-50 r / min, dripping a sodium nitrite solution accounting for 40-50% of the mass of the mixed solution for diazotization reaction, and reacting for 30-60 min to obtain a 2,4-dichloroaniline diazonium salt liquid;

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

[0013] Step 5, 2,4-dichloroaniline hydrochloride is passed through an 80-100 mesh sieve to obtain 2,4-dichloroaniline hydrochloride solid, washed with ice water accounting for 15% of the mass of 2,4-dichloroaniline hydrochloride solid, filtered, and then placed in a vacuum drying oven, at a drying temperature of 40-50° C. and a vacuum degree of 0.08-0.1 MPa, and continued to dry 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 into a stirring kettle, and continuously treated for 30-40 minutes at a stirring speed of 200-300 r / min, and filtered with a sand core funnel at 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, 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 at 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 a 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 comprises 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 in a high-pressure reactor, 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 rate of 2,4-dichloroaniline hydrochloride exceeds 90%, to obtain a reaction solution;

[0023] S2, adding the reaction solution to a pressure filter, filtering and separating 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. Add the filtrate into a distillation kettle, continue distillation at a vacuum degree of 0.08-0.1 MPa and a water bath temperature of 40-50° C., add ether accounting for 12-20% by mass of the residue to the distillation residue for recrystallization, and then cool the recrystallization solution 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 an initial raw material. The two chlorine atoms in the 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 unchanged during storage, transportation and subsequent reaction waiting in the entire preparation process. This stability can effectively avoid unnecessary chemical reactions or degradation due to external environmental factors, thereby ensuring that the subsequent extraction of 2-chloroaniline hydrochloride can be carried out based on stable starting materials, 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 in the conversion process from 2,4-dichloroaniline hydrochloride to 2-chloroaniline hydrochloride, and only the chlorine atom at the 4-position can be removed while the chlorine atom at the 2-position is retained, thereby obtaining high-purity 2-chloroaniline hydrochloride. This high degree of 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 finally obtained 2-chloroaniline hydrochloride meets the high quality requirements, and provides purity guarantee for it in the subsequent fields of medicine, dyes, etc. 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 described embodiments 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 work are within the scope of protection of the present invention.

[0029] Example 1

[0030] A 2-chlorophenylhydrazine hydrochloride, characterized in that it is 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 into a reaction kettle, slowly heat up to 70° C., reach reflux state, continue the reaction for 5 hours, and monitor the reaction progress by thin layer chromatography until the dissolution rate of 2,4-dichloronitrobenzene reaches 90%, to obtain a crude liquid 2,4-dichloroaniline dissolved in ethanol;

[0033] Step 2, adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating up, 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, weighing the hydrochloric acid solution and the solid 2,4-dichloroaniline crude product as needed, mixing and dissolving to obtain a mixed solution, adding the mixed solution into the reactor, starting the reactor, continuously treating at a temperature of 0° C. and a speed of 20 r / min, dripping a sodium nitrite solution accounting for 40% of the mixed solution by mass to carry out a diazotization reaction, and the reaction time is 30 min to obtain a 2,4-dichloroaniline diazonium salt liquid;

[0035] Step 4: Add the stannous chloride solution into 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, 2,4-dichloroaniline hydrochloride is passed through an 80-mesh sieve to obtain 2,4-dichloroaniline hydrochloride solid, washed with ice water (15% by weight of 2,4-dichloroaniline hydrochloride solid), filtered, and then placed 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 for 30 minutes at a stirring speed of 200 r / min. The mixture was filtered with a sand core funnel under normal pressure to remove impurities and obtain a filtrate.

[0039] The filtrate was added to the rotary evaporator, and the rotary evaporator was started. The water bath temperature was 50°C and the vacuum degree was 0.06MPa, 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 0.08MPa vacuum degree.

[0042] High-purity crystals and anhydrous ethanol in a mass ratio of 1:5 were added into 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 comprises the following steps:

[0045] S1: Weigh the reactant as needed, add a palladium catalyst supported on activated carbon with a palladium content of 5%, place it in a high-pressure reactor, 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 rate of 2,4-dichloroaniline hydrochloride exceeds 90%, to obtain a reaction solution;

[0046] S2, adding the reaction solution to a pressure filter, filtering and separating through a microporous ceramic membrane with a pore size of 0.1 μm at 0.2 MPa to obtain a filtrate containing 2-chloroaniline hydrochloride;

[0047] S3. Add the filtrate into a distillation kettle, continue distillation at a vacuum degree of 0.08 MPa and a water bath temperature of 40°C, add ether accounting for 12% by mass of the residue to the distillation residue for recrystallization, and then cool the recrystallization solution to 0°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.

[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, characterized in that it is 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 into a reaction kettle, slowly heat up to 75° C., reach reflux state, continue the reaction for 6 hours, and monitor the reaction progress by thin layer chromatography until the dissolution rate of 2,4-dichloronitrobenzene reaches 90%, to obtain a crude liquid 2,4-dichloroaniline dissolved in ethanol;

[0053] Step 2, adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating up, 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 to obtain a mixed solution, add it into the reactor, start the reactor, and continue to process at a temperature of 3° C. and a speed of 35 r / min, and dropwise add a sodium nitrite solution accounting for 45% of the mass of the mixed solution to carry out a diazotization reaction, and the reaction time is 45 min to obtain a 2,4-dichloroaniline diazonium salt liquid;

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

[0056] Step 5, 2,4-dichloroaniline hydrochloride was passed through a 90-mesh sieve to obtain 2,4-dichloroaniline hydrochloride solid, which was washed with ice water (15% by weight of 2,4-dichloroaniline hydrochloride solid), filtered, and then placed 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 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, and the rotary evaporator was started. The water bath temperature was 55°C and 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 0.09MPa vacuum degree.

[0062] High-purity crystals and anhydrous ethanol in a mass ratio of 1:5 were added into 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 comprises the following steps:

[0065] S1: Weigh the reactant as needed, add a palladium catalyst supported on activated carbon with a palladium content of 5%, place it in a high-pressure reactor, 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 rate of 2,4-dichloroaniline hydrochloride exceeds 90%, to obtain a reaction solution;

[0066] S2, adding the reaction solution to a pressure filter, filtering and separating through a microporous ceramic membrane with a pore size of 0.15 μm at 0.25 MPa to obtain a filtrate containing 2-chloroaniline hydrochloride;

[0067] S3. Add the filtrate into a distillation kettle, continue distillation at a vacuum degree of 0.09 MPa and a water bath temperature of 45°C, add ether accounting for 17% by mass of the residue to the distillation residue for recrystallization, and then cool the recrystallization solution to 03°C in a water bath to precipitate 2-chloroaniline hydrochloride crystals, and then filter, collect and dry 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, characterized in that it is 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 into a reaction kettle, slowly heat up to 80° C., reach reflux state, continue the reaction for 8 hours, and monitor the reaction progress by thin layer chromatography until the dissolution rate of 2,4-dichloronitrobenzene reaches 90%, to obtain a crude liquid 2,4-dichloroaniline dissolved in ethanol;

[0073] Step 2, adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating up, 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, weighing the hydrochloric acid solution and the solid 2,4-dichloroaniline crude product as needed, mixing and dissolving to obtain a mixed solution, adding the mixed solution into the reactor, starting the reactor, and continuously treating at a temperature of 5° C. and a speed of 50 r / min, dripping a sodium nitrite solution accounting for 50% by mass of the mixed solution for diazotization reaction, and the reaction time is 60 min to obtain a 2,4-dichloroaniline diazonium salt liquid;

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

[0076] Step 5, 2,4-dichloroaniline hydrochloride is passed through an 80-100 mesh sieve to obtain 2,4-dichloroaniline hydrochloride solid, washed with ice water (15% by weight of 2,4-dichloroaniline hydrochloride solid), filtered, and then placed 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 treated for 40 minutes at a stirring speed of 300 r / min. The mixture was filtered with a sand core funnel under normal pressure to remove impurities and obtain a filtrate.

[0079] The filtrate was added to the rotary evaporator, and the rotary evaporator was started. The water bath temperature was 60°C and 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 into a three-necked flask, and 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 comprises the following steps:

[0085] S1: Weigh the reactant as needed, add a palladium catalyst supported on activated carbon with a palladium content of 5%, place it in a high-pressure reactor, 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 rate of 2,4-dichloroaniline hydrochloride exceeds 90%, to obtain a reaction solution;

[0086] S2, adding the reaction solution to a pressure filter, filtering and separating through a microporous ceramic membrane with a pore size of 0.2 μm at 0.3 MPa to obtain a filtrate containing 2-chloroaniline hydrochloride;

[0087] S3. Add the filtrate into a distillation kettle, continue distillation at a vacuum degree of 0.1 MPa and a water bath temperature of 50°C, add ether accounting for 20% by mass of the residue to the distillation residue for recrystallization, and then cool the recrystallization solution to 5°C in a water bath to precipitate 2-chloroaniline hydrochloride crystals, and then filter, collect and dry to obtain high-purity 2-chloroaniline hydrochloride.

[0088] Comparative Example 1: The difference between this comparative example and Example 1 is that: in this comparative example, 2,4-dichloroaniline hydrochloride was not prepared, and 2-chloronitrobenzene was directly used to prepare 2-chlorophenylhydrazine hydrochloride.

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

[0090] Comparative Example 3: The difference between this comparative example and Example 1 is that in this comparative example, cold ethanol washing was not used in the preparation of 2'-chlorophenylhydrazine hydrochloride.

[0091] Performance test: The relevant performances 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 for purity test. 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 instrument to test the melting point. Place the sample into the capillary, 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(℃) Embodiment 1 99 185 Embodiment 2 98.5 183 Embodiment 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 its preparation process provided by the present invention have a broader market prospect and are more suitable for promotion.

[0097] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0098] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A 2-chlorophenylhydrazine hydrochloride, characterized in that The invention is 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.

2. A 2-chlorophenylhydrazine hydrochloride according to claim 1, characterized in that, The treatment process of 2,4-dichloronitrobenzene comprises the following steps: Step 1, weighing 2,4-dichloronitrobenzene, ethanol, and reduced iron powder as needed, adding them into a reaction kettle, slowly heating to a reflux state and continuing the reaction to obtain a crude liquid 2,4-dichloroaniline; Step 2, adding the crude 2,4-dichloroaniline to a distillation tower, slowly heating up, filtering to remove iron powder, and then distilling under reduced pressure to remove ethanol to obtain a solid crude 2,4-dichloroaniline; Step 3, weighing hydrochloric acid solution and solid 2,4-dichloroaniline crude product as needed, mixing and dissolving to obtain a mixed solution, adding the mixed solution into a reactor for continuous treatment, and dropping a sodium nitrite solution accounting for 40-50% of the mass of the mixed solution for diazotization reaction, the reaction time is 30-60 minutes, and 2,4-dichloroaniline diazonium salt liquid is obtained; Step 4: Add the stannous chloride solution into a reaction kettle, add 2,4-dichloroaniline diazonium salt liquid dropwise for reduction reaction for 2-3 hours to generate 2,4-dichloroaniline hydrochloride liquid; Step 5: Pass 2,4-dichloroaniline hydrochloride through a 80-100 mesh sieve to obtain 2,4-dichloroaniline hydrochloride solid, wash with ice water (15% by weight of 2,4-dichloroaniline hydrochloride solid), filter out impurities, and then place in a vacuum drying oven and continue drying to obtain 2,4-dichloroaniline hydrochloride for standby use.

3. A 2-chlorophenylhydrazine hydrochloride according to claim 2, characterized in that: The concentration of the hydrochloric acid solution is 2 mol / L, and 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.

4. A 2-chlorophenylhydrazine hydrochloride according to claim 2, characterized in that: Weigh 2,4-dichloroaniline hydrochloride and deionized water in a mass ratio of 1:4, add into a stirring kettle, continue to treat for 30-40 minutes, filter with a sand core funnel under normal pressure to remove impurities, and obtain a filtrate.

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

6. A 2-chlorophenylhydrazine hydrochloride according to claim 5, 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 and dried for 4-5 hours to obtain high-purity crystals.

7. A 2-chlorophenylhydrazine hydrochloride according to claim 6, characterized in that: The parameters of the vacuum drying oven are set as follows: temperature 40-50°C, vacuum degree 0.08-0.1MPa.

8. A 2-chlorophenylhydrazine hydrochloride according to claim 7, characterized in that: High-purity crystals and anhydrous ethanol in a mass ratio of 1:5 are added into 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.

9. A 2-chlorophenylhydrazine hydrochloride according to claim 8, characterized in that: High-purity nitrogen gas 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 a reactant.

10. A 2-chlorophenylhydrazine hydrochloride and a preparation process thereof according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Weigh the reactant 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 gas and pressurize it to 1.5-2.5 MPa, continue the reaction, and obtain a reaction solution; S2, adding the reaction solution to a pressure filter, filtering and separating, and obtaining a filtrate containing 2-chloroaniline hydrochloride; S3. Add the filtrate into a distillation kettle, continue distillation at a vacuum degree of 0.08-0.1 MPa and a water bath temperature of 40-50° C., add ether accounting for 12-20% by mass of the residue to the distillation residue for recrystallization, and then cool the recrystallization solution 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.