Preparation method of 4, 6-diamino resorcinol hydrochloride crystal
By using a continuous tube reactor in the preparation of 4,6-diamino-resorcinol hydrochloride crystals, adjusting the reactor size and process conditions, the problem of different crystal particles in the prior art is solved, the controllability of particle size and narrowing of distribution is achieved, and the quality of PBO fibers is improved.
Patent Information
- Application Number
- CN202311365435.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-20
- Publication Date
- 2025-04-22
AI Technical Summary
In the preparation of 4,6-diaminoisosorcinol hydrochloride crystals, the mass transfer and heat transfer effect are poor and the reaction time is long, resulting in different crystal particles, which affects the subsequent polymerization and spinning process, thereby affecting the quality of PBO fibers.
A continuous tubular reactor is used to control the size and distribution of crystal particles by adjusting the size and process conditions of the reactor. The specific steps include pumping the 4,6-diaminoisosorcinol hydrochloride solution and hydrochloric acid into the tubular reactor in proportion, controlling the temperature of the salt-forming reaction to react to the salt, and separating the material from the tubular reactor through solid-liquid and drying to obtain 4,6-diaminoisosorcinol hydrochloride crystals.
This method can effectively control the size of 4,6-diamino-resorcinol hydrochloride crystal particles. Under the optimization conditions, the mass fraction of the crystals with the target particle size is >92.0%, which improves the quality of PBO fibers.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of fine chemicals, and specifically relates to a method for preparing 4,6-diaminoresorcinol hydrochloride crystals. Background Art
[0002] Poly(p-phenylene benzobisoxazole) is a high-performance fiber that has been used in military, aerospace and other fields. 4,6-Diaminoresorcinol hydrochloride is one of the important monomers for the synthetic fiber poly(p-phenylene benzobisoxazole).
[0003] At present, the main process for preparing 4,6-diaminoresorcinol hydrochloride is to use trichlorobenzene as raw material through nitration, hydrolysis, hydrogenation, crystallization and other processes. The crystallization process is generally completed in a tank reactor, which has poor mass and heat transfer effects, long reaction time, and uneven material distribution. Therefore, the prepared 4,6-diaminoresorcinol hydrochloride crystal particles are of different sizes, which affects the subsequent polymerization and spinning processes, thereby affecting the quality of PBO fibers.
[0004] The continuous flow tubular reactor has good mass and heat transfer effects, stable process conditions, and good crystallization effects. By changing the reactor size and process conditions, the crystal particle size and distribution can be controlled. Summary of the invention
[0005] The purpose of the present invention is to provide a method for preparing 4,6-diaminoresorcinol hydrochloride crystals. The purpose of controlling the size and distribution of crystal particles is achieved by selecting the size of a continuous tubular reactor and related process conditions.
[0006] The main technical scheme of the present invention is a method for preparing 4,6-diaminoresorcinol hydrochloride crystals, which is characterized in that a 4,6-diaminoresorcinol hydrochloride solution and hydrochloric acid are pumped into a tubular reactor in proportion, stay in the reactor, control the temperature of the salt-forming reaction to react and form salt, separate the material coming out of the tubular reactor into a solid by solid-liquid separation, and dry the solid to obtain 4,6-diaminoresorcinol hydrochloride crystals.
[0007] Generally, the preparation method of the present invention comprises the following steps: (1) adding crude 4,6-diaminoresorcinol hydrochloride crystals into a reaction kettle, adding a solvent, and heating to dissolve to obtain a 4,6-diaminoresorcinol hydrochloride solution; (2) Prepare hydrochloric acid of a certain concentration; (3) using pumps to respectively deliver 4,6-diaminoresorcinol hydrochloride solution and hydrochloric acid into a tubular reactor of a certain diameter in proportion, allowing the solution to stay in the tubular reactor for a period of time to react and form salts, and controlling the temperature of the salt-forming reaction by introducing a medium at a certain temperature into the jacket of the tubular reactor; (4) The material coming out of the tubular reactor is subjected to solid-liquid separation to obtain a solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals.
[0008] Preferably, in step (1), the mass ratio of the solvent to the crude 4,6-diaminoresorcinol hydrochloride crystals is (5-15):1, preferably (8-10):1.
[0009] Preferably, the solvent is selected from methanol, ethanol, water or a mixture thereof, preferably water.
[0010] Preferably, the dissolution temperature in step (1) is 40-100°C, preferably 90-100°C.
[0011] Preferably, the mass concentration of the hydrochloric acid is 15-30%, preferably 25-30%.
[0012] Preferably, the diameter of the tubular reactor is 1-20 mm, preferably 6-10 mm.
[0013] Preferably, the inner tube of the tubular reactor is a tantalum tube, a Hastelloy tube or a carbon steel tube lined with polytetrafluoroethylene, preferably a Hastelloy tube.
[0014] Preferably, in step (3), the residence time of the material in the tubular reactor is 1-5 min; the salt-forming reaction temperature is 40-80°C, preferably 45-55°C.
[0015] Preferably, the molar ratio of the 4,6-diaminoresorcinol hydrochloride solution to the hydrogen chloride contained in the hydrochloric acid is 1:(2.0-8.0), preferably 1:(3.2-4.4).
[0016] Compared with the prior art, the preparation method of the present invention has controllable 4,6-diaminoresorcinol hydrochloride crystal particle size and narrow distribution. The preparation method of the present invention can effectively control the 4,6-diaminoresorcinol hydrochloride crystal particle size, and under optimized conditions, the mass fraction of crystals with a target particle size can be greater than 92.0%. Implementation
[0017] The present invention is further described below by way of examples, but is not limited to these examples. Example 1
[0018] Add 500g of crude 4,6-diaminoresorcinol hydrochloride crystals to the reactor, add 5000g of water, heat to 90℃, stir and dissolve; prepare hydrochloric acid containing 25% mass fraction of hydrogen chloride; use pumps to send 4,6-diaminoresorcinol solution and hydrochloric acid into a Hastelloy tubular reactor with a diameter of 10mm, adjust the flow of the two pumps so that the molar ratio of hydrogen chloride to 4,6-diaminoresorcinol is 3.2:1, and stay in the reaction tube for 5min. Adjust the temperature of the temperature control medium of the reaction tube so that the reaction temperature is 55℃. The material coming out of the tubular reactor is separated into solid and liquid to obtain solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals. The crystal size of 4,6-diaminoresorcinol hydrochloride was measured by sieving, and the result showed that the mass fraction of crystals with d≤0.1mm was 2.1%, the mass fraction of crystals with 0.1<d≤0.5mm was 5.7%, the mass fraction of crystals with 0.5<d≤1.0mm was 91.3%, and the mass fraction of crystals with d>1mm was 0.9%. Example 2
[0019] Add 500g of crude 4,6-diaminoresorcinol hydrochloride crystals to the reactor, add 5000g of water, heat to 90℃, stir and dissolve; prepare hydrochloric acid containing 30% mass fraction of hydrogen chloride; use pumps to send 4,6-diaminoresorcinol solution and hydrochloric acid into a Hastelloy tubular reactor with a diameter of 10mm, adjust the flow of the two pumps so that the molar ratio of hydrogen chloride to 4,6-diaminoresorcinol is 3.2:1, and stay in the reaction tube for 5 minutes. Adjust the temperature of the temperature control medium of the reaction tube so that the reaction temperature is 45℃. The material coming out of the tubular reactor is separated from the solid to obtain a solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals. The crystal size of 4,6-diaminoresorcinol hydrochloride was measured by sieving, and the result showed that the mass fraction of crystals with d≤0.1mm was 3.2%, the mass fraction of crystals with 0.1<d≤0.5mm was 20.4%, the mass fraction of crystals with 0.5<d≤1.0mm was 73.8%, and the mass fraction of crystals with d>1mm was 2.6%. Example 3
[0020] Add 500g of crude 4,6-diaminoresorcinol hydrochloride crystals to the reactor, add 4000g of water, heat to 95℃, stir and dissolve; prepare hydrochloric acid containing 30% mass fraction of hydrogen chloride; use pumps to send 4,6-diaminoresorcinol solution and hydrochloric acid into a Hastelloy tubular reactor with a diameter of 10mm, adjust the flow of the two pumps so that the molar ratio of hydrogen chloride to 4,6-diaminoresorcinol is 4.4:1, and stay in the reaction tube for 5min. Adjust the temperature of the temperature control medium of the reaction tube so that the reaction temperature is 55℃. The material coming out of the tubular reactor is separated into solid and liquid to obtain solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals. The crystal size of 4,6-diaminoresorcinol hydrochloride was measured by sieving, and the result showed that the mass fraction of crystals with d≤0.1mm was 2.9%, the mass fraction of crystals with 0.1<d≤0.5mm was 55.6%, the mass fraction of crystals with 0.5<d≤1.0mm was 41.1%, and the mass fraction of crystals with d>1mm was 0.4%. Example 4
[0021] Add 500g of crude 4,6-diaminoresorcinol hydrochloride crystals to the reactor, add 4000g of water, heat to 92°C, stir and dissolve; prepare hydrochloric acid containing 28% of hydrogen chloride by mass; use pumps to send 4,6-diaminoresorcinol solution and hydrochloric acid into a Hastelloy tubular reactor with a diameter of 8mm, adjust the flow of the two pumps so that the molar ratio of hydrogen chloride to 4,6-diaminoresorcinol is 3.6:1, and stay in the reaction tube for 4 minutes. Adjust the temperature of the temperature control medium of the reaction tube to make the reaction temperature 50°C. The material coming out of the tubular reactor is separated from the solid to obtain a solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals. The crystal size of 4,6-diaminoresorcinol hydrochloride was measured by sieving, and the result showed that the mass fraction of crystals with d≤0.1mm was 1.7%, the mass fraction of crystals with 0.1<d≤0.5mm was 46.2%, the mass fraction of crystals with 0.5<d≤1.0mm was 50.2%, and the mass fraction of crystals with d>1mm was 1.9%. Example 5
[0022] Add 500g of crude 4,6-diaminoresorcinol hydrochloride crystals to the reactor, add 4500g of water, heat to 92°C, stir and dissolve; prepare hydrochloric acid containing 28% of hydrogen chloride by mass; use pumps to send 4,6-diaminoresorcinol solution and hydrochloric acid into a Hastelloy tubular reactor with a diameter of 6mm, adjust the flow of the two pumps so that the molar ratio of hydrogen chloride to 4,6-diaminoresorcinol is 3.8:1, and stay in the reaction tube for 2 minutes. Adjust the temperature of the temperature control medium of the reaction tube so that the reaction temperature is 48°C. The material coming out of the tubular reactor is separated from the solid to obtain a solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals. The crystal size of 4,6-diaminoresorcinol hydrochloride was measured by sieving, and the result showed that the mass fraction of crystals with d≤0.1mm was 1.0%, the mass fraction of crystals with 0.1<d≤0.5mm was 60.5%, the mass fraction of crystals with 0.5<d≤1.0mm was 37.1%, and the mass fraction of crystals with d>1mm was 1.4%. Example 6
[0023] Add 500g of crude 4,6-diaminoresorcinol hydrochloride crystals to the reactor, add 4250g of water, heat to 98°C, stir and dissolve; prepare hydrochloric acid containing 28% of hydrogen chloride by mass; use pumps to send 4,6-diaminoresorcinol solution and hydrochloric acid into a Hastelloy tubular reactor with a diameter of 6mm, adjust the flow of the two pumps so that the molar ratio of hydrogen chloride to 4,6-diaminoresorcinol is 3.4:1, and stay in the reaction tube for 5 minutes. Adjust the temperature of the temperature control medium of the reaction tube so that the reaction temperature is 50°C. The material coming out of the tubular reactor is separated into a solid by solid-liquid separation, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals. The crystal size of 4,6-diaminoresorcinol hydrochloride was measured by sieving, and the result showed that the mass fraction of crystals with d≤0.1mm was 1.6%, the mass fraction of crystals with 0.1<d≤0.5mm was 17.1%, the mass fraction of crystals with 0.5<d≤1.0mm was 80.3%, and the mass fraction of crystals with d>1mm was 1.0%. Example 7
[0024] Add 500g of crude 4,6-diaminoresorcinol hydrochloride crystals to the reactor, add 4000g of water, heat to 98°C, stir and dissolve; prepare hydrochloric acid containing 30% mass fraction of hydrogen chloride; use pumps to send 4,6-diaminoresorcinol solution and hydrochloric acid into a Hastelloy tubular reactor with a diameter of 6mm, adjust the flow of the two pumps so that the molar ratio of hydrogen chloride to 4,6-diaminoresorcinol is 4.4:1, and stay in the reaction tube for 1min. Adjust the temperature of the temperature control medium of the reaction tube so that the reaction temperature is 45°C. The material coming out of the tubular reactor is separated from the solid to obtain a solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals. The crystal size of 4,6-diaminoresorcinol hydrochloride was measured by sieving, and the result showed that the mass fraction of crystals with d≤0.1mm was 0.7%, the mass fraction of crystals with 0.1<d≤0.5mm was 92.1%, the mass fraction of crystals with 0.5<d≤1.0mm was 5.4%, and the mass fraction of crystals with d>1mm was 1.8%. Comparative Example
[0025] Add 500g of crude 4,6-diaminoresorcinol hydrochloride crystals to the reactor, add 4000g of water, heat to 98°C, and stir to dissolve; prepare hydrochloric acid containing 30% mass fraction of hydrogen chloride; take a certain volume of hydrochloric acid with a mass fraction of 30, so that the molar ratio of hydrogen chloride to 4,6-diaminoresorcinol is 4.4:1. Under stirring conditions, add the above hydrochloric acid to the reactor, control the dropping time to 2h, and stop stirring. Adjust the refrigerant temperature in the reactor jacket to cool the material in the reactor to 45°C, and control the cooling time to 2h. The cooled material is separated by solid-liquid separation to obtain a solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals. The crystal size of 4,6-diaminoresorcinol hydrochloride was measured by sieving, and the result showed that the mass fraction of crystals with d≤0.1mm was 10.2%, the mass fraction of crystals with 0.1<d≤0.5mm was 40.9%, the mass fraction of crystals with 0.5<d≤1.0mm was 35.7%, and the mass fraction of crystals with d>1mm was 13.2%.
[0026] The preparation method of the present invention can effectively control the particle size of 4,6-diaminoresorcinol hydrochloride crystals. Under optimized conditions, the mass fraction of crystals with a target particle size can be greater than 92.0%. Application Examples
[0027] Example 7: 500 g of the product of the comparative example was subjected to degassing, prepolymerization, postpolymerization and spinning under the same material ratio and process conditions to obtain PBO fibers.
[0028] The measurement results of PBO fiber indexes are shown in Table 1
[0029] It can be seen from the data in the above table that the performance of the PBO fiber obtained by polymerizing the 4,6-diaminoresorcinol hydrochloride crystals prepared by the preparation method of the present invention is better than that of the existing products.
Claims
1. A method for preparing 4,6-diaminoresorcinol hydrochloride crystals, characterized in that The 4,6-diaminoresorcinol hydrochloride solution and hydrochloric acid are pumped into a tubular reactor in proportion, stay in the reactor, and the temperature of the salt-forming reaction is controlled to react and form salt. The material coming out of the tubular reactor is separated from the solid to obtain a solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals.
2. The preparation method according to claim 1, characterized in that The following steps are involved: (1) adding crude 4,6-diaminoresorcinol hydrochloride crystals into a reaction kettle, adding a solvent, and heating to dissolve to obtain a 4,6-diaminoresorcinol hydrochloride solution; (2) Prepare hydrochloric acid of a certain concentration; (3) using pumps to respectively deliver 4,6-diaminoresorcinol hydrochloride solution and hydrochloric acid into a tubular reactor of a certain diameter in proportion, allowing the solution to stay in the tubular reactor for a period of time to react and form salts, and controlling the temperature of the salt-forming reaction by introducing a medium at a certain temperature into the jacket of the tubular reactor; (4) The material coming out of the tubular reactor is subjected to solid-liquid separation to obtain a solid, and the solid is dried to obtain 4,6-diaminoresorcinol hydrochloride crystals.
3. The preparation method according to claim 2, characterized in that In step (1), the mass ratio of the solvent to the crude 4,6-diaminoresorcinol hydrochloride crystals is (5-15):1, preferably (8-10):
1.
4. The preparation method according to claim 2 or 3, characterized in that The solvent is selected from methanol, ethanol, water or a mixture thereof, preferably water.
5. The preparation method according to claim 2, characterized in that The dissolution temperature in step (1) is 40-100°C, preferably 90-100°C.
6. The preparation method according to claim 1 or 2, characterized in that The mass concentration of hydrochloric acid is 15-30%, preferably 25-30%.
7. The preparation method according to claim 1 or 2, characterized in that The diameter of the tubular reactor is 1-20 mm, preferably 6-10 mm.
8. The preparation method according to claim 1, 2 or 7, characterized in that The inner tube of the tubular reactor is a tantalum tube, a Hastelloy tube or a carbon steel tube lined with polytetrafluoroethylene, preferably a Hastelloy tube.
9. The preparation method according to claim 1 or 2, characterized in that In step (3), the residence time of the material in the tubular reactor is 1-5 min; the salt-forming reaction temperature is 40-80°C, preferably 45-55°C.
10. The preparation method according to claim 1 or 2, characterized in that The molar ratio of the 4,6-diaminoresorcinol hydrochloride solution to the hydrogen chloride contained in the hydrochloric acid is 1:(2.0-8.0), preferably 1:(3.2-4.4).