Continuous production method of o-aminobenzoic acid

Abstract

The invention relates to the technical field of o-aminobenzoic acid, in particular to a continuous production method of o-aminobenzoic acid, which comprises the following steps: step 1, pumping an aqueous solution of hydroxylamine hydrochloride into a first microchannel reactor, and simultaneously injecting ammonia gas into the first microchannel reactor; step 2, separating reactants in the first micro-channel reactor through a gas-liquid separator, and respectively pumping a separated liquid phase and an alcohol solution of anhydride into a mixing reaction chamber of a second micro-channel reactor for reaction; step 3, pumping a reaction product of the second micro-channel reactor into a mixed reaction chamber of a third micro-channel reactor, pressurizing a gas phase discharged from the first micro-channel reactor, injecting the pressurized gas phase into the mixed reaction chamber of the third micro-channel reactor, and carrying out a reaction; according to the continuous production method of o-aminobenzoic acid, provided by the invention, the reaction yield is increased, the content of organic substances in sewage is reduced, and on the other hand, the emission of ammonia gas is also reduced.

Description

Technical Field

[0001] The invention relates to the technical field of anthranilic acid, and in particular to a continuous production method of anthranilic acid. Background Art

[0002] In recent years, the rapid development of petroleum, chemical, pharmaceutical and printing and dyeing industries has brought serious environmental problems. The large-scale discharge of wastewater containing high-concentration water-soluble aromatic compounds, especially aromatic amphoteric compounds (such as o-aminobenzoic acid) has caused large-scale river water pollution. O-aminobenzoic acid is an important intermediate and raw material for fine chemicals such as dyes, medicines, fragrances and insecticides.

[0003] The synthesis methods of the preparation process of o-aminobenzoic acid include phthalic anhydride method, o-nitrobenzoic acid iron powder reduction method, o-nitroethylbenzene method, etc. Among them, the phthalic anhydride method is the most widely used, but the phthalic anhydride method is generally a batch reaction, its production efficiency is relatively low, and a large amount of ammonia will be discharged during the reaction process, which is easy to cause environmental pollution.

[0004] Therefore, we proposed a continuous production method of anthranilic acid to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a continuous production method of anthranilic acid.

[0006] A continuous production method of anthranilic acid comprises the following steps:

[0007] Step 1, pumping an aqueous solution of hydroxylamine hydrochloride into a first microchannel reactor, and injecting ammonia gas into the first microchannel reactor at the same time, so that the ammonia gas and the aqueous solution of hydroxylamine hydrochloride are fully mixed;

[0008] Step 2, separating the reactants of the first microchannel reactor by a gas-liquid separator, and pumping the separated liquid phase and the alcohol solution of the acid anhydride into the mixing reaction chamber of the second microchannel reactor respectively for reaction;

[0009] Step 3, pumping the reaction product of the second microchannel reactor into the mixing reaction chamber of the third microchannel reactor, and at the same time pressurizing the gas phase discharged from the first microchannel reactor and injecting it into the mixing reaction chamber of the third microchannel reactor to react;

[0010] Step 4, separating the discharge from the third microchannel reactor by a gas-liquid separator, and pumping the liquid phase and the sodium hydroxide solution of sodium hypochlorite into the mixing reaction chamber of the fourth microchannel reactor respectively for reaction;

[0011] Step 5: Add the product of the fourth microchannel reactor into a reactor. When the liquid in the reactor reaches a preset height, add hydrochloric acid into the reactor to adjust the pH to 3-4. Filter and dry the precipitated solid to obtain the product.

[0012] Preferably, in step 1, the molar ratio of hydroxylamine hydrochloride to ammonia per unit time is (0.6-0.9):1, the mass fraction of the solute in the aqueous solution of hydroxylamine hydrochloride is 10%-18%, and the pressure of the ammonia is 0.1-0.5 MPa.

[0013] Preferably, in step 2, the molar ratio of hydroxylamine hydrochloride to acid anhydride per unit time is (1.1-1.5):1, and the mass ratio of acid anhydride to alcohol solution is 1:5-8.

[0014] Preferably, in step 3, the gas phase discharged from the first microchannel reactor is pressurized to 0.2-0.5 MPa and then injected into the mixing reaction chamber of the third microchannel reactor.

[0015] Preferably, in step 4, the molar ratio of sodium hypochlorite to acid anhydride is (1.1-1.5):1, the molar ratio of sodium hypochlorite to sodium hydroxide is (0.9-1.1):1, and the mass fraction of the solute in the sodium hydroxide solution is 20%-30%.

[0016] Preferably, in step 4, before the liquid phase separated in the third microchannel reactor is added to the fourth microchannel reactor, the liquid phase is subjected to reduced pressure distillation to remove the alcohol solution in the liquid phase, and the temperature of the reduced pressure distillation is 50-70° C. and the pressure is (-0.05)-(-0.08) MPa;

[0017] Preferably, the alcohol solution is methanol or ethanol.

[0018] Preferably, in step 5, there are at least two sets of reactors arranged in parallel, and when one of the reactors has finished adding materials, the product of the fourth microchannel reactor is added to the other reactor.

[0019] Preferably, in step 5, before adding hydrochloric acid, the temperature of the reactor is adjusted to 50-80°C.

[0020] Preferably, in step 5, the concentration of hydrochloric acid is 0.5-1.5 mol / L.

[0021] The beneficial effects of the present invention are as follows: in the continuous production method of o-aminobenzoic acid proposed by the present invention, during the reaction process, ammonia is first used as a binding agent for hydroxylamine hydrochloride to ensure that in the subsequent reaction process, hydroxylamine hydrochloride can react normally with acid anhydride, and while hydroxylamine hydrochloride can react with acid anhydride, ammonia water can also react with acid anhydride to generate a part of intermediate products, ammonia discharged from the first microchannel reactor is recovered and injected into the third microchannel reactor, ammonia further reacts with the intermediate product to generate o-formylaminobenzoic acid amine, o-formylaminobenzoic acid amine can smoothly participate in the subsequent reaction, thereby improving the yield of the reaction, while reducing the content of organic matter in sewage, and on the other hand, reducing the emission of ammonia. DETAILED DESCRIPTION

[0022] The present invention will be further explained below in conjunction with specific embodiments.

[0023] A continuous production method of anthranilic acid comprises the following steps:

[0024] Step 1, pumping an aqueous solution of hydroxylamine hydrochloride into a first microchannel reactor, and injecting ammonia gas into the first microchannel reactor at the same time, so that the ammonia gas and the aqueous solution of hydroxylamine hydrochloride are fully mixed;

[0025] Step 2, separating the reactants of the first microchannel reactor by a gas-liquid separator, and pumping the separated liquid phase and the alcohol solution of the acid anhydride into the mixing reaction chamber of the second microchannel reactor respectively for reaction;

[0026] Step 3, pumping the reaction product of the second microchannel reactor into the mixing reaction chamber of the third microchannel reactor, and at the same time pressurizing the gas phase discharged from the first microchannel reactor and injecting it into the mixing reaction chamber of the third microchannel reactor to react;

[0027] Step 4, separating the discharge from the third microchannel reactor by a gas-liquid separator, pumping the liquid phase and the sodium hydroxide solution of sodium hypochlorite into the mixing reaction chamber of the fourth microchannel reactor respectively for reaction, and transporting the gas phase to the tail gas treatment device;

[0028] Step 5: Add the product of the fourth microchannel reactor into a reactor. When the liquid in the reactor reaches a preset height, add hydrochloric acid into the reactor to adjust the pH to 3-4. Filter and dry the precipitated solid to obtain the product.

[0029] The main reaction formula is:

[0030]

[0031]

[0032] Wherein, reaction formula (1) is the main reaction in step 2, reaction formula (2) is the main reaction in step 4, reaction formula (3) is the side reaction in step 2, reaction formula (4) is the main reaction in step 3, reaction formula (5) is the side reaction in step 4, reaction formulas (1) and (2) are the main reactions of the present technical solution, reaction formulas (3), (4) and (5) are the reactions in the present technical solution in order to eliminate excess ammonia and intermediate products, and reaction formulas (3), (4) and (5) are used to improve the yield of the reaction, while reducing the content of organic matter in the sewage and, on the other hand, reducing the emission of ammonia.

[0033] In Example 1, in step 1, the molar ratio of hydroxylamine hydrochloride to ammonia per unit time is 0.6:1, the mass fraction of the solute in the aqueous solution of hydroxylamine hydrochloride is 10%, and the pressure of the ammonia is 0.1 MPa.

[0034] In step 2, the molar ratio of hydroxylamine hydrochloride to acid anhydride per unit time is 1.1:1, and the mass ratio of acid anhydride to alcohol solution is 1:5.

[0035] In step 3, the gas phase discharged from the first microchannel reactor is pressurized to 0.2 MPa and then injected into the mixing reaction chamber of the third microchannel reactor.

[0036] In step 4, the molar ratio of sodium hypochlorite to acid anhydride is 1:1, the molar ratio of sodium hypochlorite to sodium hydroxide is 0.9:1, and the mass fraction of the solute in the sodium hydroxide solution is 20%.

[0037] In step 4, before the liquid phase separated in the third microchannel reactor is added to the fourth microchannel reactor, the liquid phase is subjected to reduced pressure distillation to remove the alcohol solution in the liquid phase, and the temperature of the reduced pressure distillation is 50° C. and the pressure is -0.05 MPa;

[0038] The alcohol solution is methanol.

[0039] In step 5, there are at least two sets of reactors arranged in parallel. When the feeding of one of the reactors is completed, the product of the fourth microchannel reactor is added to the other reactor.

[0040] In step 5, before adding hydrochloric acid, the temperature of the reactor was adjusted to 50°C.

[0041] In step 5, the concentration of hydrochloric acid is 0.5 mol / L.

[0042] In Example 2, in step 1, the molar ratio of hydroxylamine hydrochloride to ammonia per unit time is 0.7:1, the mass fraction of the solute in the aqueous solution of hydroxylamine hydrochloride is 10%-18%, and the pressure of the ammonia is 0.3 MPa.

[0043] Preferably, in step 2, the molar ratio of hydroxylamine hydrochloride to acid anhydride per unit time is 1.2:1, and the mass ratio of acid anhydride to alcohol solution is 1:6.

[0044] Preferably, in step 3, the gas phase discharged from the first microchannel reactor is pressurized to 0.3 MPa and then injected into the mixing reaction chamber of the third microchannel reactor.

[0045] Preferably, in step 4, the molar ratio of sodium hypochlorite to acid anhydride is 1.2:1, the molar ratio of sodium hypochlorite to sodium hydroxide is 1:1, and the mass fraction of the solute in the sodium hydroxide solution is 25%.

[0046] Preferably, in step 4, before the liquid phase separated in the third microchannel reactor is added to the fourth microchannel reactor, the liquid phase is subjected to reduced pressure distillation to remove the alcohol solution in the liquid phase, and the temperature of the reduced pressure distillation is 60° C. and the pressure is -0.06 MPa;

[0047] Preferably, the alcohol solution is ethanol.

[0048] Preferably, in step 5, there are at least two sets of reactors arranged in parallel, and when one of the reactors has finished adding materials, the product of the fourth microchannel reactor is added to the other reactor.

[0049] Preferably, in step 5, before adding hydrochloric acid, the temperature of the reactor is adjusted to 50-80°C.

[0050] Preferably, in step 5, the concentration of hydrochloric acid is 1 mol / L.

[0051] In Example 3, in step 1, the molar ratio of hydroxylamine hydrochloride to ammonia per unit time is 0.9:1, the mass fraction of the solute in the aqueous solution of hydroxylamine hydrochloride is 18%, and the pressure of the ammonia is 0.5 MPa.

[0052] In step 2, the molar ratio of hydroxylamine hydrochloride to acid anhydride per unit time is 1.5:1, and the mass ratio of acid anhydride to alcohol solution is 1:8.

[0053] In step 3, the gas phase discharged from the first microchannel reactor is pressurized to 0.2-0.5 MPa and then injected into the mixing reaction chamber of the third microchannel reactor.

[0054] In step 4, the molar ratio of sodium hypochlorite to acid anhydride is 1.5:1, the molar ratio of sodium hypochlorite to sodium hydroxide is 1.1:1, and the mass fraction of the solute in the sodium hydroxide solution is 20%-30%.

[0055] In step 4, before the liquid phase separated in the third microchannel reactor is added to the fourth microchannel reactor, the liquid phase is subjected to reduced pressure distillation to remove the alcohol solution in the liquid phase, and the temperature of the reduced pressure distillation is 70° C. and the pressure is -0.08 MPa;

[0056] The alcohol solution is ethanol.

[0057] In step 5, there are at least two sets of reactors arranged in parallel. When the feeding of one of the reactors is completed, the product of the fourth microchannel reactor is added to the other reactor.

[0058] In step 5, before adding hydrochloric acid, the temperature of the reactor was adjusted to 80°C.

[0059] In step 5, the concentration of hydrochloric acid is 1.5 mol / L.

[0060] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A continuous production method of anthranilic acid, characterized in that: The following steps are involved: Step 1, pumping an aqueous solution of hydroxylamine hydrochloride into a first microchannel reactor, and injecting ammonia gas into the first microchannel reactor at the same time, so that the ammonia gas and the aqueous solution of hydroxylamine hydrochloride are fully mixed; Step 2, separating the reactants of the first microchannel reactor by a gas-liquid separator, and pumping the separated liquid phase and the alcohol solution of the acid anhydride into the mixing reaction chamber of the second microchannel reactor respectively for reaction; Step 3, pumping the reaction product of the second microchannel reactor into the mixing reaction chamber of the third microchannel reactor, and at the same time pressurizing the gas phase discharged from the first microchannel reactor and injecting it into the mixing reaction chamber of the third microchannel reactor to react; Step 4, separating the discharge from the third microchannel reactor by a gas-liquid separator, and pumping the liquid phase and the sodium hydroxide solution of sodium hypochlorite into the mixing reaction chamber of the fourth microchannel reactor respectively for reaction; Step 5: Add the product of the fourth microchannel reactor into a reactor. When the liquid in the reactor reaches a preset height, add hydrochloric acid into the reactor to adjust the pH to 3-4. Filter and dry the precipitated solid to obtain the product.

2. A continuous production method of anthranilic acid according to claim 1, characterized in that: In the step 1, the molar ratio of hydroxylamine hydrochloride to ammonia per unit time is (0.6-0.9):1, the mass fraction of the solute in the aqueous solution of hydroxylamine hydrochloride is 10%-18%, and the pressure of the ammonia is 0.1-0.5 MPa.

3. A continuous production method of anthranilic acid according to claim 1, characterized in that: In the step 2, the molar ratio of hydroxylamine hydrochloride to acid anhydride per unit time is (1.1-1.5):1, and the mass ratio of acid anhydride to alcohol solution is 1:5-8.

4. A continuous production method of anthranilic acid according to claim 1, characterized in that: In the step 3, the gas phase discharged from the first microchannel reactor is pressurized to 0.2-0.5 MPa and then injected into the mixing reaction chamber of the third microchannel reactor.

5. A continuous production method of anthranilic acid according to claim 1, characterized in that: In step 4, the molar ratio of sodium hypochlorite to acid anhydride is (1.1-1.5):1, the molar ratio of sodium hypochlorite to sodium hydroxide is (0.9-1.1):1, and the mass fraction of the solute in the sodium hydroxide solution is 20%-30%.

6. A continuous production method of anthranilic acid according to claim 5, characterized in that: In the step 4, before the liquid phase separated by the third microchannel reactor is added to the fourth microchannel reactor, the liquid phase is subjected to reduced pressure distillation to remove the alcohol solution in the liquid phase, and the temperature of the reduced pressure distillation is 50-70° C. and the pressure is (-0.05)-(-0.08) MPa; The alcohol solution is methanol or ethanol.

7. A continuous production method of anthranilic acid according to claim 1, characterized in that: In the step 5, there are at least two sets of reactors arranged in parallel, and when one of the reactors has finished adding materials, the product of the fourth microchannel reactor is added to the other reactor.

8. A continuous production method of anthranilic acid according to claim 7, characterized in that: In the step 5, before adding hydrochloric acid, the temperature of the reaction kettle is adjusted to 50-80°C.

9. A continuous production method of anthranilic acid according to claim 7, characterized in that: In step 5, the concentration of hydrochloric acid is 0.5-1.5 mol / L.

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