CN114702421B - Preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as raw material - Google Patents
Preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as raw material Download PDFInfo
- Publication number
- CN114702421B CN114702421B CN202210407407.0A CN202210407407A CN114702421B CN 114702421 B CN114702421 B CN 114702421B CN 202210407407 A CN202210407407 A CN 202210407407A CN 114702421 B CN114702421 B CN 114702421B
- Authority
- CN
- China
- Prior art keywords
- temperature
- reaction
- hydrogen sulfide
- pressure
- primary amine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C335/00—Thioureas, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
- C07C335/04—Derivatives of thiourea
- C07C335/06—Derivatives of thiourea having nitrogen atoms of thiourea groups bound to acyclic carbon atoms
- C07C335/08—Derivatives of thiourea having nitrogen atoms of thiourea groups bound to acyclic carbon atoms of a saturated carbon skeleton
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
- C07D233/04—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member
- C07D233/28—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D233/30—Oxygen or sulfur atoms
- C07D233/42—Sulfur atoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
- C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
- C07D239/06—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member
- C07D239/08—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with hetero atoms directly attached in position 2
- C07D239/10—Oxygen or sulfur atoms
Abstract
The invention discloses a preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as a raw material, which comprises the following steps: (1) mixing water and primary amine compound and stirring uniformly; (2) Dropwise adding carbon disulfide to carry out nucleophilic addition reaction condensation to generate ammonium salt of thiocarbamic acid; (3) heating to reflux, and recovering excessive carbon disulfide; (4) nucleophilic addition reaction to produce symmetrical thiourea; (5) And (3) raising the temperature of the system to a higher temperature in a closed or close state to completely convert the intermediate, and cooling and filtering to obtain the product. The invention takes water as a reaction medium to carry out sectional reaction, the pressure and the reaction temperature of a system are regulated by utilizing an exhaust valve through gradient heating and strictly controlling the reaction condition, no catalyst or auxiliary materials are added, the product can realize high yield and high quality, the discharged hydrogen sulfide can prepare sodium sulfide with better quality through alkali liquor absorption, the mother liquor can be recycled, and the whole process flow realizes safety, high efficiency and no three wastes.
Description
Technical Field
The invention relates to the field of fine chemical industry, in particular to a preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as a raw material.
Background
In the field of fine chemical industry, the hydrocarbyl thiourea compound is widely applied and is an important chemical raw material and an intermediate. The alkyl thiourea compound can be used as a nitrogenous fertilizer synergist in agriculture, and can also be used for preventing and controlling citrus mould, inhibiting sprouting of potatoes and the like; the method is mainly used for producing thiazole medicines in the chemical medicine industry. The alkyl thiourea compound is an important sulfide ore collecting agent and analysis reagent, wherein the symmetrical alkyl thiourea such as 1, 3-diethyl thiourea, 1, 3-dibutyl thiourea, tetrahydroimidazole-2-thione, 3,4,5, 6-4H-2-pyrimidine mercaptan and the like is widely applied, and has important application as a special accelerator and environmental-friendly substitute for chloroprene rubber.
The existing preparation methods of the 1, 3-disubstituted symmetrical thiourea with industrialized value all take primary amine and carbon disulfide as main raw materials, and mainly comprise the following preparation methods according to the different added auxiliary materials and catalysts:
one is to add primary amine and carbon disulfide to ethanol solution of potassium hydroxide to prepare 1, 3-disubstituted symmetrical thiourea. The product obtained by the process has high purity and high melting point, but potassium hydroxide, glacial acetic acid and sodium bisulphite are required to be introduced into the reaction to serve as reaction system regulators, so that a large amount of waste salt is generated in the system, and the yield of the product is low; the flammable and explosive ethanol is used as a solvent, and needs to be recovered in a rectification mode, so that the production cost is increased, and the safety in the production process is reduced.
Under the action of zinc-aluminum composite catalyst, primary amine and carbon disulfide are used as raw materials to prepare 1, 3-disubstituted symmetrical thiourea through high-pressure closed reaction. The process has the advantages of high product yield and high raw material utilization rate; the method has the defects that the process is a high-pressure closed reaction, the system pressure is very high due to excessive low-boiling carbon disulfide and generated gas hydrogen sulfide in the system, the equipment requirement is high, an autoclave is needed, and the safety risk is high; recrystallization is required to remove insoluble catalyst, increasing the difficulty of operation.
The preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by using water as a solvent is also reported, but because of insufficient understanding of reaction mechanism and operation process control problems, excessive low-boiling-point raw material carbon disulfide in a system is recovered after the condensation reaction is finished, high-pressure closed reaction is still adopted in the addition reaction section for discharging hydrogen sulfide, so that the safety risk exists in the process with higher pressure and the product quality is poor. Because the generated hydrogen sulfide and primary amine easily generate ammonium salt, the nucleophilicity of the primary amine is reduced, the addition of the primary amine and isothiocyanate is prevented from generating 1, 3-disubstituted symmetrical thiourea, and the ammonium salt can be thoroughly decomposed into the primary amine only at a high temperature exceeding the boiling point of water, so that the common process is a high-pressure closed reaction. The process conditions can decompose most of ammonium salt, but because a large amount of hydrogen sulfide is sealed in the system, a small amount of primary amine still exists in the form of ammonium salt, so that the reaction is incomplete, the product quality is poor, and the requirements of high-end rubber product customers cannot be met.
Disclosure of Invention
Aiming at the technical defects, the invention provides a preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as a raw material. The specific process is as follows: mixing water and primary amine compound in a certain proportion in a kettle and stirring uniformly. At a certain temperature, a certain amount of carbon disulfide is dripped into the kettle to carry out nucleophilic addition reaction condensation to generate ammonium salt of thiocarbamic acid. Heating to reflux, and recovering excessive carbon bisulfide. And (3) raising the temperature to a certain temperature in a closed state, carrying out nucleophilic addition reaction to generate the symmetrical thiourea, discharging most of byproduct hydrogen sulfide, and absorbing the released hydrogen sulfide by alkali liquor. The system is completely sealed, the intermediate is completely converted at a higher temperature, a small amount of generated hydrogen sulfide gas is slowly released in time, the temperature is reduced, and the product is obtained by filtering, and the mother solution is recovered and reused.
The preparation method comprises the following steps:
(1) And (3) a reaction section: mixing primary amine with water, stirring uniformly, controlling the temperature below 45 ℃, dropwise adding carbon disulfide into the solution, and preserving heat after the dropwise adding is finished;
(2) And (3) an elimination reaction section: heating until reflux is carried out to generate elimination reaction and recycling excessive carbon disulfide in the system;
(3) An addition reaction section: the system is increased to a certain temperature in a close state to discharge byproduct hydrogen sulfide and carries out nucleophilic addition reaction to generate the product 1, 3-disubstituted symmetrical thiourea, wherein the pressure of the system is controlled to be not more than 0.2Mpa in the hydrogen sulfide discharge process;
the hydrogen sulfide discharging process cannot be a totally-enclosed system, the pressure of the system is increased by means of generated hydrogen sulfide so as to reach a temperature higher than the boiling point of water, and meanwhile, the hydrogen sulfide gas can be slowly discharged out of the system so as to prevent the pressure from being excessively high.
(4) Complete conversion section: heating the system in a closed state, controlling the pressure of the system to be 0.2Mpa, and completely converting the intermediate; if the system pressure exceeds 0.2Mpa, releasing pressure, then continuously maintaining the temperature in a closed state, and if the pressure is not exceeded, ending the reaction;
(5) And (3) post-reaction treatment: cooling and filtering to obtain the product of the symmetrical thiourea.
The reaction mechanism is as follows:
the primary amine is monoamine or diamine, the monoamine is specifically ethylamine and n-butylamine, and the symmetrical thiourea of the corresponding products is 1, 3-diethyl thiourea and 1, 3-dibutyl thiourea, the diamine is ethylenediamine and 1, 3-propylenediamine, and the corresponding products are tetrahydroimidazole-2-thione and 3,4,5, 6-4H-2-pyrimidine mercaptan;
the mass ratio of the primary amine raw material to water or mother liquor is 1:2-1:5, the mol ratio of the carbon disulfide to the monoamine is 1:1-1:2, and the mol ratio of the carbon disulfide to the diamine is 1:0.5-1:1;
the condensation reaction temperature is 20-45 ℃, and the heat preservation time is 2-5 h;
in the elimination reaction section, when primary amine is monoamine, the temperature of refluxing and recycling excessive carbon disulfide is 45-90 ℃ for 2-5 hours; when the primary amine is diamine, the temperature is 45-70 ℃ and the time is 2-5 h.
The temperature of the monoamine for discharging hydrogen sulfide is 100-125 ℃, the temperature of the diamine for discharging hydrogen sulfide is 85-105 ℃, the time is 3-5 h, and the system pressure is regulated by controlling the opening of a vent valve so that the system reaches the reaction temperature;
the temperature of the complete conversion of the monoamine is 115-125 ℃, the temperature of the complete conversion of the diamine is 100-105 ℃, the time is 4-6 h, and the pressure of the system is regulated by closing an emptying valve so as to reach the complete conversion temperature;
the addition reaction section and the complete reaction section adopt gradient heating and utilize a vent valve to slowly release generated hydrogen sulfide, and the pressure of the system is regulated, so that the mild pressure is maintained. The pressure of the invention is not more than 0.2Mpa, and the invention can be produced by adopting a common reaction kettle, thereby avoiding the defects of high equipment requirement, high requirement on the autoclave and high safety risk in the background technology. The gradient temperature rise of the addition reaction stage and the complete reaction stage of the present invention is not limited to, for example: heating the system to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; reducing the opening of the emptying valve to be a semi-closed system, heating to 105 ℃, and preserving heat until the system does not generate hydrogen sulfide gas; heating to 110 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; heating to 120 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 120-125 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to release pressure, then continuing to close the vent valve to preserve heat at 120-125 DEG C
The excessive carbon disulfide can be recycled, and byproduct hydrogen sulfide can be absorbed by alkali to generate sodium sulfide, so that mother liquor can be used without treatment.
The invention adjusts the system pressure by controlling the opening of the vent valve so as to lead the system to reach the reaction temperature, the vent valve is a valve with adjustable size on a pipeline communicated with the absorption tank, when the system discharges a large amount of hydrogen sulfide, the speed of discharging the hydrogen sulfide out of the reaction kettle can be controlled by closing the valve, and the system is maintained to reach a certain pressure, thereby leading the temperature of the reaction system to exceed the boiling point of water and leading the system to reach the required reaction temperature.
The addition reaction section of the invention: and the system is increased to a certain temperature in a close state to discharge most of byproduct hydrogen sulfide. Wherein, the pressure of the system is controlled to be not more than 0.2Mpa in the process of discharging hydrogen sulfide. Complete conversion section: heating the system in a closed state, controlling the pressure of the system to be 0.2Mpa, enabling the intermediate to be completely converted, releasing pressure if the pressure of the system exceeds 0.2Mpa, continuously maintaining the system in the closed state for heat preservation, and ending the reaction if the pressure is not exceeded. When the temperature exceeds 100 ℃, the pressure in the reaction system is the result of the combined action of water vapor and generated hydrogen sulfide, and the pressure and the temperature of the system are controlled by adjusting the valve size of the vent valve to control the discharge speed of the hydrogen sulfide because the boiling point of water is 120 ℃ under the pressure of 0.2Mpa. The hydrogen sulfide discharging section cannot be a totally-enclosed system, the pressure of the system is increased by means of generated hydrogen sulfide so as to reach a temperature higher than the boiling point of water, and meanwhile, the hydrogen sulfide gas can be slowly discharged out of the system so as to prevent the pressure from being excessively high. Most of the hydrogen sulfide in the complete conversion section is discharged, the temperature mainly depends on the pressure of the water vapor of the closed system to ensure that the reaction temperature of the system is higher than the boiling point of water, and once the pressure exceeds 0.2Mpa, the system still releases the hydrogen sulfide, and the reaction is not fully carried out.
According to the invention, water is used as a reaction medium, the system pressure and the reaction temperature are regulated by sectional reaction and gradient heating and by utilizing a vent valve, no catalyst or auxiliary materials are added, the product can realize high yield and high quality, the discharged carbon disulfide can prepare sodium sulfide with better quality through alkali liquor absorption, the mother liquor can be recycled, and the whole process flow realizes safety, high efficiency and no three wastes. The innovation and beneficial effects are as follows:
1. no catalyst or auxiliary materials are added, so that the raw material cost can be saved, the atom utilization rate is improved, the yield is high, and the three wastes are reduced.
2. The temperature and time of each reaction section are strictly controlled by gradient heating, so that the condensation reaction, the elimination reaction, the decomposition reaction and the addition reaction are carried out in each reaction section more fully, excessive carbon disulfide and generated partial hydrogen sulfide in the system are discharged from the system in time, and compared with the direct airtight reaction, the system pressure is lower and is safe and controllable.
3. The pressure and the temperature of the system are regulated and controlled by the vent valve, so that the system can be raised to a temperature exceeding the boiling point of water, the decomposition of ammonium salt is promoted, the generation of products is accelerated, and meanwhile, the generated hydrogen sulfide is discharged from the system in time. In the final stage of reaction, the system is directly changed into a closed system, and the system is raised to a certain high temperature by using higher pressure to promote the complete conversion of the reaction, so that a high-quality product is obtained.
4. The mother liquor in the process can be directly used, and the generated hydrogen sulfide can be absorbed by alkali liquor to prepare sodium sulfide products, so that comprehensive utilization of resources is realized.
Detailed Description
This section will disclose detailed embodiments of the present invention. The embodiments disclosed herein are examples of the invention, which may be embodied in different forms. Therefore, the disclosure's details, including specific structural and functional details, are not intended to limit the invention, but merely to form the basis of the claims. The present invention will now be described with reference to examples and comparative examples.
Example 1
2000L of water and 900kg of aqueous solution of ethylamine with the mass fraction of 70% are added into a kettle, the mixture is stirred for 1h at normal temperature to uniformly mix the system, 650L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the heat is preserved for 2h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 90 ℃ and the required time is 3h. Continuously heating the system to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; reducing the opening of the emptying valve to be a semi-closed system, heating to 105 ℃, and preserving heat until the system does not generate hydrogen sulfide gas; heating to 110 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; heating to 120 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 120-125 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to relieve pressure, then continuing to close the vent valve to preserve heat at 120-125 ℃, if the pressure is not exceeded, ending the reaction. Cooling to below 30-45 ℃, filtering and drying to obtain white powdery product 1, 3-diethyl thiourea, 878kg, yield 95% and melting point 74.8 ℃.
Example two
2000L of the reaction filtrate of the previous batch and 900kg of aqueous solution of ethylamine with the mass fraction of 70% are put into a kettle, the mixture is stirred for 1h at normal temperature to uniformly mix the system, 650L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the temperature is kept for 4h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 90 ℃ and the required time is 3h. Continuously heating the system to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; reducing the opening of the emptying valve to be a semi-closed system, heating to 105 ℃, and preserving heat until the system does not generate hydrogen sulfide gas; heating to 110 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; heating to 120 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 120-125 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to relieve pressure, then continuing to close the vent valve to preserve heat at 120-125 ℃, if the pressure is not exceeded, ending the reaction. Cooling to below 30-45 ℃, filtering and drying to obtain 916.8kg of white powdery product 1, 3-diethyl thiourea, wherein the yield is 99.2%, and the melting point is 75.2 ℃.
Example III
2500L of water and 900kg of n-butylamine are added into the kettle, the mixture is stirred for 1.5h at normal temperature to ensure that the system is uniformly mixed, 600L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the heat is preserved for 2h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 90 ℃ and the required time is 3h. Continuously heating the system to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; reducing the opening of the emptying valve to be a semi-closed system, heating to 105 ℃, and preserving heat until the system does not generate hydrogen sulfide gas; heating to 110 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; heating to 120 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 120-125 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to relieve pressure, then continuing to close the vent valve to preserve heat at 120-125 ℃, if the pressure is not exceeded, ending the reaction. Cooling to below 30-45 ℃, filtering and drying to obtain 1125kg of white powdery product 1, 3-dibutyl thiosemicarbazide, wherein the yield is 97.1 percent and the melting point is 62.1 ℃.
Example IV
2500L of the reaction filtrate of the previous batch and 900kg of n-butylamine are put into the kettle, the mixture is stirred for 1.5h at normal temperature to ensure that the system is uniformly mixed, 600L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the heat is preserved for 2h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 90 ℃ and the required time is 3h. Continuously heating the system to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; reducing the opening of the emptying valve to be a semi-closed system, heating to 105 ℃, and preserving heat until the system does not generate hydrogen sulfide gas; heating to 110 ℃, and preserving heat until the system does not generate hydrogen sulfide gas any more; heating to 120 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 120-125 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to relieve pressure, then continuing to close the vent valve to preserve heat at 120-125 ℃, if the pressure is not exceeded, ending the reaction. Cooling to below 30-45 ℃, filtering and drying to obtain 1145kg of white powdery product 1, 3-dibutyl thiosemicarbazide, wherein the yield is 98.8%, and the melting point is 62.3 ℃.
Example five
2300L of water and 540kg of ethylenediamine are added into the kettle, the mixture is stirred for 0.5h at normal temperature to ensure that the system is uniformly mixed, 675L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the heat is preserved for 1h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 70 ℃ and the required time is 3h. The system is continuously heated to 80 ℃ and is kept warm until the system does not generate hydrogen sulfide gas. Heating to 90 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Reducing the opening of the emptying valve to be a semi-closed system, heating to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 100-102 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to relieve pressure, then continuing to close the vent valve to preserve heat at 103-105 ℃, if the pressure is not exceeded, ending the reaction. Cooling to below 30 ℃, filtering and drying to obtain 893kg of white powdery product tetrahydroimidazole-2-thione, wherein the yield is 97.3%, and the melting point is 197.2 ℃.
Example six
2300L of the previous batch of reaction filtrate and 540kg of ethylenediamine are added into the kettle, the mixture is stirred for 0.5h at normal temperature to ensure that the system is uniformly mixed, 675L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the heat is preserved for 1h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 70 ℃ and the required time is 3h. The system is continuously heated to 80 ℃ and is kept warm until the system does not generate hydrogen sulfide gas. Heating to 90 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Reducing the opening of the emptying valve to be a semi-closed system, heating to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 100-102 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to relieve pressure, then continuing to close the vent valve to preserve heat at 101-103 ℃, if the pressure is not exceeded, ending the reaction. Cooling to below 30 ℃, filtering and drying to obtain 910kg of white powdery product tetrahydroimidazole-2-thione, wherein the yield is 99.1%, and the melting point is 197.8 ℃.
Example seven
Adding 2300L of water and 540kg of 1, 3-propylene diamine into the kettle, stirring for 0.5h at normal temperature to uniformly mix the system, slowly adding 533L of carbon disulfide, controlling the temperature below 45 ℃, and preserving heat for 1h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 70 ℃ and the required time is 3h. The system is continuously heated to 80 ℃ and is kept warm until the system does not generate hydrogen sulfide gas. Heating to 90 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Reducing the opening of the emptying valve to be a semi-closed system, heating to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 103-105 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to relieve pressure, then continuing to close the vent valve to preserve heat at 103-105 ℃, if the pressure is not exceeded, ending the reaction. Cooling to below 30 ℃, filtering and drying to obtain 837kg of white powdery product 3,4,5, 6-4H-2-pyrimidine mercaptan, wherein the yield is 98.9%, and the melting point is 208.4 ℃.
Example eight
Adding 2300L of the previous batch of reaction filtrate and 540kg of 1, 3-propylene diamine into a kettle, stirring for 0.5h at normal temperature to uniformly mix the system, slowly adding 533L of carbon disulfide, controlling the temperature below 45 ℃, and preserving heat for 1h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 70 ℃ and the required time is 3h. The system is continuously heated to 80 ℃ and is kept warm until the system does not generate hydrogen sulfide gas. Heating to 90 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Reducing the opening of the emptying valve to be a semi-closed system, heating to 100 ℃, and preserving heat until the system does not generate hydrogen sulfide gas. Closing the vent valve to make the system become a closed system, heating to 103-105 ℃, preserving heat for 2h, if the system pressure exceeds 0.2Mpa, opening the vent valve to relieve pressure, then continuing to close the vent valve to preserve heat at 103-105 ℃, if the pressure is not exceeded, ending the reaction. Cooling to below 30 ℃, filtering and drying to obtain 842kg of white powdery product 3,4,5, 6-4H-2-pyrimidine mercaptan, wherein the yield is 99.5%, and the melting point is 208.1 ℃.
Comparative example one
2000L of water and 900kg of aqueous solution of ethylamine with the mass fraction of 70% are added into a kettle, the mixture is stirred for 1h at normal temperature to uniformly mix the system, 650L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the heat is preserved for 2h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 90 ℃ and the required time is 3h. Heating to 100-125 deg.c, maintaining for 3 hr and raising the pressure of the system to over 1.2 MPa. Cooling to below 30-45 deg.c, filtering and drying to obtain white or yellow powdered 1, 3-diethyl thiourea 858kg product with yield of 93% and smelting point of 70.2 deg.c.
Comparative example two
2500L of water and 900kg of n-butylamine are added into the kettle, the mixture is stirred for 1.5h at normal temperature to ensure that the system is uniformly mixed, 600L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the heat is preserved for 2h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 90 ℃ and the required time is 3 hours; heating to 110-125 deg.c, maintaining for 3 hr and raising the pressure of the system to over 1.2 MPa. Cooling to below 30 ℃, filtering and drying to obtain 1065.9kg of white or yellow powdery product 1, 3-dibutyl thiosemicarbazide, the yield is 92.1 percent, and the melting point is 59.2 ℃.
Comparative example three
2300L of water and 540kg of ethylenediamine are added into the kettle, the mixture is stirred for 0.5h at normal temperature to ensure that the system is uniformly mixed, 675L of carbon disulfide is slowly added, the temperature is controlled below 45 ℃, and the heat is preserved for 1h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 70 ℃ and the required time is 3h. Heating to 100-120 deg.c, maintaining for 5 hr and system pressure over 0.8MPa. Cooling to below 30deg.C, filtering, and drying to obtain white or light yellow powdery product tetrahydroimidazole-2-thione 844kg, yield 92%, melting point 190.2deg.C.
Comparative example four
Adding 2300L of water and 540kg of 1, 3-propylene diamine into the kettle, stirring for 0.5h at normal temperature to uniformly mix the system, slowly adding 533L of carbon disulfide, controlling the temperature below 45 ℃, and preserving heat for 1h after the addition is finished. Heating to reflux, and recovering excessive carbon disulfide in the system, wherein the system temperature is gradually increased from 46 ℃ to 70 ℃ and the required time is 3h. Heating to 100-120 deg.c, maintaining for 2 hr and over 0.9MPa. Cooling to below 30 ℃, filtering and drying to obtain 770kg of white powdery product 3,4,5, 6-4H-2-pyrimidine mercaptan with the yield of 91% and the melting point of 196.5 ℃.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the invention in any way, and any person skilled in the art may make modifications or alterations to the disclosed technical content to the equivalent embodiments. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (4)
1. A preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as a raw material is characterized in that,
the preparation method comprises the following steps:
(1) Condensation reaction section: mixing primary amine with water, stirring uniformly, controlling the temperature below 45 ℃, dropwise adding carbon disulfide into the solution, and preserving heat after the dropwise adding is finished; the condensation reaction temperature is 20-45 ℃, and the heat preservation time is 0.5-3 h;
the primary amine is monoamine or diamine, the monoamine is n-butylamine, and the corresponding product symmetrical thiourea is 1, 3-dibutyl thiourea; the diamine is ethylenediamine and 1, 3-propylenediamine, and the corresponding symmetrical thiourea products are tetrahydroimidazole-2-thione and 3,4,5, 6-4H-2-pyrimidine mercaptan respectively;
(2) And (3) an elimination reaction section: heating until reflux is carried out to generate elimination reaction and recycling excessive carbon disulfide in the system; in the elimination reaction section, when primary amine is monoamine, the temperature is 45-90 ℃ and the time is 2-5 h; when primary amine is diamine, the temperature is 45-70 ℃ and the time is 2-5 h;
(3) An addition reaction section: the system is increased to a certain temperature in a close state to discharge most of byproduct hydrogen sulfide and carries out nucleophilic addition reaction to generate the product 1, 3-disubstituted symmetrical thiourea, wherein the pressure of the system is controlled to be not more than 0.2Mpa in the process of discharging hydrogen sulfide;
in the addition reaction section, the temperature of monoamine for discharging hydrogen sulfide is 100-125 ℃, and the temperature of diamine for discharging hydrogen sulfide is 85-105 ℃; the time is 3-5 h, and the system pressure is regulated by controlling the opening of the vent valve so that the system reaches the reaction temperature;
(4) Complete conversion section: heating the system in a closed state, controlling the pressure of the system to be 0.2Mpa, and completely converting the intermediate; if the system pressure exceeds 0.2Mpa, releasing pressure, then continuously maintaining the temperature in a closed state, and if the pressure is not exceeded, ending the reaction;
in the complete conversion section, the complete conversion temperature of monoamine is 115-125 ℃, and the complete conversion temperature of diamine is 100-105 ℃; the time is 4-6 hours, and the system pressure is regulated by closing the emptying valve to reach the complete conversion temperature;
(5) And (3) post-reaction treatment: cooling and filtering to obtain the product of the symmetrical thiourea.
2. The method according to claim 1, wherein the mass ratio of primary amine to water is 1:2-1:5, the molar ratio of the carbon disulfide to the monoamine is 1:1-1:2, and the molar ratio of the carbon disulfide to the diamine is 1:0.5-1:1.
3. The method of claim 1, wherein the excess carbon disulfide is recovered and used, and the byproduct hydrogen sulfide is absorbed by alkali to form sodium sulfide, and the mother liquor is used without treatment.
4. The process according to claim 1, wherein the product 1, 3-disubstituted symmetrical thiourea is used as rubber accelerator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210407407.0A CN114702421B (en) | 2022-04-15 | 2022-04-15 | Preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as raw material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210407407.0A CN114702421B (en) | 2022-04-15 | 2022-04-15 | Preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as raw material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114702421A CN114702421A (en) | 2022-07-05 |
| CN114702421B true CN114702421B (en) | 2023-06-30 |
Family
ID=82174619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210407407.0A Active CN114702421B (en) | 2022-04-15 | 2022-04-15 | Preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as raw material |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114702421B (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1910174C3 (en) * | 1969-02-28 | 1974-06-27 | Basf Ag, 6700 Ludwigshafen | Process for the production of N, N * -dialkylthiourest open |
| ZA71441B (en) * | 1970-03-28 | 1971-10-27 | Glanzstoff Ag | Process for the preparation of aliphatically and cycloaliphatically 1,3-di substituted thioureas |
| CN102731357B (en) * | 2012-07-04 | 2014-02-12 | 山东汇海医药化工有限公司 | Preparation method of high purity N,N'-dicyclohexylthiourea |
| CN102862984A (en) * | 2012-09-25 | 2013-01-09 | 科迈化工股份有限公司 | Device and method for recovering surplus carbon bisulfide in rubber vulcanization accelerator diphenylthiourea synthesis process |
| CN104193653A (en) * | 2014-08-07 | 2014-12-10 | 山东汇海医药化工有限公司 | Novel synthesis method of N, N'-dicyclohexylcarbo-diimide |
| CN109369459A (en) * | 2018-10-09 | 2019-02-22 | 淄博天堂山化工有限公司 | Thiourea-uv Method produces N, the method for N '-di-t-butyl carbodiimide |
| CN113929607A (en) * | 2021-10-27 | 2022-01-14 | 鹤壁元昊化工有限公司 | Preparation method of aliphatic asymmetric thiourea compound |
-
2022
- 2022-04-15 CN CN202210407407.0A patent/CN114702421B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN114702421A (en) | 2022-07-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1177944C (en) | Method of producing tungstic acid by closed type hydrochloric acid decompose tunstite | |
| CN109438283B (en) | Synthesis method and device of beta-aminopropionitrile | |
| CN114702421B (en) | Preparation method for synthesizing 1, 3-disubstituted symmetrical thiourea by taking primary amine as raw material | |
| CN109053610B (en) | Environment-friendly clean production process of cyanuric acid | |
| CN112552197B (en) | Kettle type continuous glycine production method | |
| CN110563666B (en) | Preparation method of 2-thiazolidinone | |
| CN113880730B (en) | Industrial method for continuously preparing hexamethylene diisocyanate | |
| CN103601630A (en) | Method utilizing calcium carbide slag and carbon monoxide to synthesize calcium formate | |
| CN110204512A (en) | A kind of technique using phase transfer catalyst direct oxidation production epoxychloropropane | |
| CN114853646A (en) | Method for synthesizing dimethyl dithiodipropionate based on continuous vulcanization reaction | |
| JP2024505087A (en) | Method for ammonolysis of bromoalkanoic acids | |
| CN108484505B (en) | Preparation method of 2-methylimidazole | |
| CN107353236A (en) | A kind of clean method for preparing of thiocarbamide | |
| CN112279795B (en) | Method for continuously producing thiourea by using microchannel reactor | |
| CN112409227B (en) | Method for efficiently synthesizing 3-mercaptopropionic acid | |
| CN112574020B (en) | Preparation method of high-quality 1, 3-cyclohexanedione product | |
| CN111808005A (en) | Continuous synthesis method of 2-chloro-3-isothiocyanic acid-1-propylene | |
| CN111925300B (en) | Synthesis method and device of 4-chloro-2-methoxyimino ethyl acetoacetate | |
| CN217856022U (en) | Reaction device for quickly synthesizing sodium tert-butoxide | |
| CN111909064B (en) | Method for preparing perchloromethylmercaptan by using microchannel reactor | |
| CN109897003B (en) | Method for continuously and rapidly synthesizing 5- (beta-methylmercapto-ethyl) -hydantoin | |
| CN112174829B (en) | Preparation method of dibenzylamine | |
| CN116836068B (en) | Method for continuously producing 3-methylamino-1, 2-propanediol | |
| CN113512063B (en) | Preparation system and method of methyl phosphorus dichloride | |
| CN116003345A (en) | Process method for synthesizing rubber accelerator MBT at normal pressure |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |