CN118085602B - Method for continuously synthesizing pigment orange 16 by utilizing micro-channel reaction device - Google Patents

Abstract

The invention discloses a method for continuously synthesizing pigment orange 16 by utilizing a micro-channel reaction device. Dissolving 3', 3-dimethoxy benzidine dihydrochloride in water, adding hydrochloric acid and sodium nitrite to react to generate diazonium salt solution as a first homogeneous solution; excess coupling component is reacted: respectively dissolving N-acetoacetanilide, 2-methyl-N-acetoacetanilide and 2, 4-dimethyl-N-acetoacetanilide in aqueous solution of sodium acetate and sodium hydroxide to prepare a second homogeneous solution, a third homogeneous solution and a fourth homogeneous solution; sodium acetate was dissolved in water to make a fifth homogeneous solution. And preheating the first, second, third, fourth and fifth homogeneous solutions by adopting a advection pump, conveying the preheated solutions into a cross microchannel reactor and a stainless steel coil pipe for mixing reaction, then heating the mixed solution to 70 ℃ for crystal transformation, and then cooling the mixed solution and collecting the product. And filtering, drying and purifying the collected crude product suspension to obtain the pigment orange 16 product.

Description

A method for continuously synthesizing pigment orange 16 using a microchannel reaction device

Technical Field

The invention relates to the field of organic synthesis, and in particular to a method for continuously synthesizing pigment orange 16 by using a microchannel reaction device.

Background Art

Pigment Orange 16 is one of the important disazo pigments and is widely used in many fields such as dyeing, printing, spraying and plastic manufacturing.

At present, the synthesis of pigment orange 16 mainly adopts the batch synthesis method in a kettle, that is, 3', 3-dimethoxybenzidine dihydrochloride is used as a raw material, and sodium nitrite is directly reacted in a large amount of hydrochloric acid aqueous solution to generate 3', 3-dimethoxybenzidine didiazonium salt, and then the diazonium salt solution is passed into the kettle of N-acetoacetanilide sodium acetate solution for coupling reaction, and then a surfactant is added, followed by filtration and drying. This type of method has the following disadvantages in actual operation: 1) The reaction substrate is temperature sensitive and needs to be reacted below 35°C, and temperature is a more sensitive indicator in the kettle reaction. If it is not properly adjusted, the diazonium salt will decompose, causing danger and reducing the product quality; 2) The reaction repeatability is poor, and the product color is closely related to the pH of the reaction and the ratio of the coupling ligand. If the reaction conditions cannot be accurately controlled, the color of the product of the same process may be greatly different, which will increase the complexity and risk of the production process. 3) The required amount of reactants and solvents is large, which greatly increases the production cost and pollutes the environment. Therefore, developing a new method and process route for preparing and regulating Pigment Orange 16 has become one of the most important topics in this field.

Micro-reaction continuous synthesis process refers to the process of continuously producing chemicals and drugs in micro-reactor pipes with sizes of micrometers and millimeters. The continuous flow microchannel reaction device has good heat and mass transfer performance and low liquid holdup, which can achieve precise control of reaction conditions to a certain extent. It is safe, environmentally friendly, efficient, controllable reaction conditions and low energy consumption.

Summary of the invention

In view of the deficiencies of the above-mentioned prior art, the present invention provides a method for continuously synthesizing Pigment Orange 16 using a microchannel reaction device. The method uses a microchannel reaction device to transform the kettle synthesis process, which originally requires a long time, has complicated steps, and is difficult to control reaction conditions, into a continuous synthesis process, and uses a pump unit composed of five horizontal flow pumps to achieve functions such as continuous synthesis of products and online regulation of product color. The process is simple, the reaction cycle is shortened, it is environmentally friendly, the regulation is precise, the safety is high, and no other surfactants are required, and it has great potential in later industrial applications.

In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

The present invention first provides a method for continuously synthesizing pigment orange 16 using a microchannel reaction device, comprising the following steps:

1) dissolving 3',3-dimethoxybenzidine dihydrochloride in deionized water, and adding hydrochloric acid and sodium nitrite to synthesize a diazonium salt solution as a first homogeneous solution; dissolving N-acetoacetanilide in a deionized aqueous solution of sodium acetate and sodium hydroxide to prepare a second homogeneous solution; dissolving 2-methyl-N-acetoacetanilide in a deionized aqueous solution of sodium acetate and sodium hydroxide to prepare a third homogeneous solution; dissolving 2,4-dimethyl-N-acetoacetanilide in a deionized aqueous solution of sodium acetate and sodium hydroxide to prepare a fourth homogeneous solution; and dissolving sodium acetate in deionized water to prepare a fifth homogeneous solution;

2) pumping the first homogeneous solution, the second homogeneous solution, the third homogeneous solution, the fourth homogeneous solution and the fifth homogeneous solution into a microchannel reaction device for mixed reaction, and adjusting the flow ratio of the second, third and fourth homogeneous solutions and the flow rate of the fifth homogeneous solution to achieve the control of the color light of the pigment orange product;

3) collecting the suspension slurry flowing out of the microchannel reaction device, and filtering and drying the suspension slurry to obtain the product Pigment Orange 16.

As a preferred solution of the present invention, the microchannel reaction device in step 2) includes a preheating section, a reaction section, a crystallization section and a cooling section connected by pipelines; the preheating section includes a coupling component mixing preheating delay pipeline, a sodium acetate component preheating delay pipeline and a diazonium salt component preheating delay pipeline, and the preheating temperature range is 7.5°C to 22.5°C; the reaction section includes a cross-shaped micromixer and a reaction coil, the three inlets of the cross-shaped micromixer are respectively connected to the coupling component mixing preheating delay pipeline, the sodium acetate component preheating delay pipeline and the diazonium salt component preheating delay pipeline, the outlet of the cross-shaped micromixer is connected to the reaction coil, and the temperature range of the reaction section is 0°C to 30°C; the crystallization section and the cooling section are both coils, the temperature range of the crystallization section is 70°C to 75°C, and the temperature range of the cooling section is 10°C to 20°C; the preheating section, the reaction section, the crystallization section and the cooling section are all temperature controlled by a constant temperature water bath.

As a preferred scheme of the present invention, in the step 2), the second homogeneous solution, the third homogeneous solution and the fourth homogeneous solution are merged into a flow channel and then enter the coupling component mixing preheating delay pipeline for preheating; the flow rate range of the second homogeneous solution, the third homogeneous solution and the fourth homogeneous solution is 0ml/min to 20ml/min, and the total flow rate after the second homogeneous solution, the third homogeneous solution and the fourth homogeneous solution are merged is controlled to be 15 to 60ml/min.

As a preferred scheme of the present invention, in the step 2), the first homogeneous solution enters the diazonium salt component preheating delay pipeline for preheating, and the flow rate of the first homogeneous solution is consistent with the total flow rate after the second homogeneous solution, the third homogeneous solution and the fourth homogeneous solution are combined; the fifth homogeneous solution enters the sodium acetate component preheating delay pipeline for preheating, and the flow rate adjustment range of the fifth homogeneous solution is 1.5ml/min to 10ml/min.

The online regulation of the red and yellow light of the pigment orange product is achieved by regulating the flow rates of the second homogeneous solution, the second homogeneous solution, the fourth homogeneous solution and the fifth homogeneous solution. When the flow rate of the fifth homogeneous solution is adjusted to ≤5mL/min, the coupling reaction medium is acidic, and the synthesized products are all red light, and the red light intensity of the products synthesized by different coupling component compositions is different; if the flow rate of the second homogeneous solution is increased, the red light hue presented by the product is enhanced, and the yellow light hue is weakened. If the flow rate of the fourth homogeneous solution is increased, the red light hue presented by the product is weakened, and the yellow light hue is enhanced. If the flow rate of the third homogeneous solution is adjusted, the color light effect presented by the product is between the above two. When the flow rate of the fifth homogeneous solution is adjusted to >5mL/min, preferably when the flow rate of the fifth homogeneous solution is adjusted to >8mL/min, the coupling reaction medium is alkaline, and the synthesized products are all yellow light, and the yellow light intensity of the products synthesized by different coupling component compositions is different. If the flow rate of the second homogeneous solution is increased, the yellow light hue presented by the product will be weakened, and the red light hue will be enhanced. If the flow rate of the fourth homogeneous solution is increased, the yellow light tone of the product will be enhanced and the red light tone will be weakened. If the flow rate of the third homogeneous solution is adjusted, the color light effect presented by the product will be between the above two.

As a preferred solution of the present invention, in step 3), rapid qualitative filter paper is used for suction filtration and oven drying is performed at a drying temperature of 70°C to 90°C.

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

1) The present invention uses a microreactor to carry out continuous coupling reaction, avoids the use of a large amount of solvent, has mild reaction conditions, simple post-treatment, reduces the generation of a large amount of three wastes, and is environmentally friendly.

2) A one-step continuous synthesis process is used to replace the original kettle synthesis process which requires a long time and has complicated steps. The process is simple, the reaction cycle is short, and the safety is high;

3) A cross-shaped micromixer is used for material mixing. The three fluids are mixed quickly and efficiently in the micromixer, and a uniform reaction state is reached instantly. The reaction efficiency is high and it is easy to scale up. In addition, the continuous reaction is easy to monitor and control the reaction process, which can achieve precise regulation of the reaction conditions during the synthesis of the Pigment Orange 16 product, and at the same time achieve online precise control of the color light.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a process for continuously synthesizing Pigment Orange 16 using a microchannel reaction apparatus according to the present invention.

In the figure, 1, the first homogeneous solution; 2, the second homogeneous solution; 3, the third homogeneous solution; 4, the fourth solution; 5, the fifth homogeneous solution; 6, the polytetrafluoroethylene advection pump; 7, the first stainless steel advection pump; 8, the second stainless steel advection pump; 9, the third stainless steel advection pump; 10, the fourth stainless steel advection pump; 11, the coupling component mixing preheating delay pipeline; 12, the sodium acetate component preheating delay pipeline; 13, the diazonium salt component preheating delay pipeline; 14, the reaction coil; 15, the crystallization delay pipeline; 16, the cooling delay pipeline; 17, the constant temperature circulation cold trap; 18, the constant temperature water bath; 19, the constant temperature circulation cold trap; 20, the cross-shaped micro mixer; 21, the product collection device.

DETAILED DESCRIPTION

The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

The present invention provides a method for continuously synthesizing pigment orange 16 using a microchannel reaction device, comprising the following steps:

1) dissolving 3',3-dimethoxybenzidine dihydrochloride in deionized water, and adding hydrochloric acid and sodium nitrite to synthesize a diazonium salt solution as a first homogeneous solution; dissolving N-acetoacetanilide in a deionized aqueous solution of sodium acetate and sodium hydroxide to prepare a second homogeneous solution; dissolving 2-methyl-N-acetoacetanilide in a deionized aqueous solution of sodium acetate and sodium hydroxide to prepare a third homogeneous solution; dissolving 2,4-dimethyl-N-acetoacetanilide in a deionized aqueous solution of sodium acetate and sodium hydroxide to prepare a fourth homogeneous solution; and dissolving sodium acetate in deionized water to prepare a fifth homogeneous solution;

2) pumping the first homogeneous solution, the second homogeneous solution, the third homogeneous solution, the fourth homogeneous solution and the fifth homogeneous solution into a microchannel reaction device for mixed reaction, and adjusting the flow ratio of the second, third and fourth homogeneous solutions and the flow rate of the fifth homogeneous solution to achieve the control of the color light of the pigment orange product;

3) collecting the suspension slurry flowing out of the microchannel reaction device, and filtering and drying the suspension slurry to obtain the product Pigment Orange 16.

In the method of the present invention, the red-yellow light of the pigment orange product is online regulated by regulating the flow rates of the second, third, and fourth homogeneous solutions and regulating the flow rate of the fifth homogeneous solution. When the flow rate of the fifth homogeneous solution of the base is adjusted to ≤5 mL/min, the coupling reaction medium is acidic, and the synthesized products at this time all show red light, and the red light intensity of the products synthesized by different coupling component compositions is different. If the flow rate of the second homogeneous solution is increased, the red light hue presented by the product is enhanced and the yellow light hue is weakened. If the flow rate of the fourth homogeneous solution is increased, the red light hue presented by the product is weakened and the yellow light hue is enhanced. If the flow rate of the third homogeneous solution is adjusted, the color light effect presented by the product is between the above two.

When the flow rate of the fifth homogeneous solution is adjusted to >5mL/min, preferably the flow rate of the fifth homogeneous solution is >8mL/min, the coupling reaction medium is alkaline, and the synthesized products at this time are all yellow light, and the yellow light intensity of the products synthesized by different coupling component compositions is different. If the flow rate of the second homogeneous solution is increased, the yellow light hue presented by the product will become weaker and the red light hue will be enhanced. If the flow rate of the fourth homogeneous solution is increased, the yellow light hue presented by the product will be enhanced and the red light hue will be weakened. If the flow rate of the third homogeneous solution is adjusted, the color light effect presented by the product is between the above two.

Example 1: Referring to FIG. 1 , the method of the present invention is used to continuously synthesize Pigment Orange 16, as follows:

Using deionized water as solvent, a 0.0550 mol/L 3', 3-dimethoxybenzidine dihydrochloride solution was prepared, hydrochloric acid was added dropwise at a molar ratio of 14:1 to 3', 3-dimethoxybenzidine dihydrochloride, 30% wt sodium nitrite was added dropwise at a molar ratio of 2.4:1 to 3', 3-dimethoxybenzidine dihydrochloride, and a diazotization reaction was performed to generate a first homogeneous solution 1; using deionized water as solvent, a 0.0755 mol/L N-acetoacetanilide solution was prepared, sodium acetate was added to adjust its concentration to 0.76 mol/L, sodium hydroxide was added to adjust its concentration to 0.23 mol/L, and a second homogeneous solution 2 was prepared; using deionized water as solvent, a concentration of 0.0755 mol/L was prepared. 2-methyl N-acetoacetanilide solution, sodium acetate is added to adjust its concentration to 0.76 mol/L, sodium hydroxide is added to adjust its concentration to 0.23 mol/L, and the third homogeneous solution 3 is prepared; deionized water is used as solvent to prepare a 0.0755 mol/L 2,4-dimethyl-N-acetoacetanilide solution, sodium acetate is added to adjust its concentration to 0.76 mol/L, sodium hydroxide is added to adjust its concentration to 0.23 mol/L, and the fourth homogeneous solution 4 is prepared; deionized water is used as solvent to prepare a sodium acetate solution with a concentration of 3.8 mol/L as the fifth homogeneous solution 5;

In this embodiment, the first homogeneous solution 1 is pumped by a tetrafluoroethylene advection pump 6, the second homogeneous solution 2 is pumped by a first stainless steel advection pump 7, the third homogeneous solution 3 is pumped by a second stainless steel advection pump 8, the fourth homogeneous solution 4 is pumped by a third stainless steel advection pump 9, and the fifth homogeneous solution 5 is pumped by a fourth stainless steel advection pump 10; the flow rate of the first homogeneous solution is set to 20ml/min, the flow rate of the second homogeneous solution is set to 20ml/min, the flow rate of the third homogeneous solution is set to 0ml/min, the flow rate of the fourth homogeneous solution is set to 0ml/min, and the flow rate of the fifth homogeneous solution is set to 1.5ml/min; the first homogeneous solution passes through the diazonium salt component preheating coil 13 at a flow rate of 20ml/min; the second, third and fourth homogeneous solutions pass through the coupling component preheating mixing coil 11 at flow rates of 20ml/min, 0ml/min and 0ml/min respectively; the fifth homogeneous solution passes through the sodium acetate component preheating coil 12 at a flow rate of 1.5ml/min;

In this embodiment, the preheating section includes three 316L stainless steel tubes with an inner diameter of 2mm, a volume of 9 to 10mL, and a preheating temperature range of 7.5°C to 22.5°C; the reaction section is composed of a cross-shaped micromixer 20 and a 316L stainless steel reaction coil 14, the dispersion scale range of the micromixer 20 is 250 to 750μm, the inner diameter of the stainless steel reaction coil 14 is 4mm, the volume range is 18 to 20mL, and the temperature range of the reaction section is 0°C to 30°C; the crystallization section is composed of a 316L stainless steel coil with an inner diameter of 4mm, a volume range of 58 to 60mL, and a crystallization section temperature range of 70°C to 75°C; the cooling section is composed of a 316L stainless steel coil with an inner diameter of 4mm, a volume range of 9 to 10mL, and a cooling section temperature range of 10°C to 20°C. The above-mentioned parts are all connected by stainless steel pipes with an inner diameter of 2mm, and a low-temperature constant temperature water bath is used for temperature control.

The three solutions in the coupling component mixing preheating delay pipeline, the sodium acetate component preheating delay pipeline and the diazonium salt component preheating delay pipeline are transported to the micro mixer 20 and then start the mixing reaction through the stainless steel reaction coil 14, wherein the coupling component mixing preheating delay pipeline, the sodium acetate component preheating delay pipeline, the diazonium salt component preheating delay pipeline, the coupling reaction delay pipeline and the micro mixer 20 are placed in a constant temperature circulation cold trap 17, the temperature is controlled at 17.5°C, and the dispersion scale of the micro mixer 20 is 250μm. After that, the reaction liquid enters the crystallization section, which is placed in a constant temperature water bath 18, the temperature is controlled at 70°C, and then enters the cooling section, which is placed in a constant temperature circulation cold trap 19, the temperature is controlled at 15°C. The reaction products are collected at the outlet of the microreactor system, and the collected product A is processed and measured by a colorimeter to obtain the product color value; the flow rate of the second homogeneous solution is adjusted to 0 ml/min, the flow rate of the third homogeneous solution is adjusted to 20 ml/min, the flow rate of the fourth homogeneous solution is adjusted to 0 ml/min, and the flow rate of the fifth homogeneous solution is adjusted to remain unchanged. The reaction products are collected by the product collecting device 21 at the outlet of the microreactor system, and the collected product B is processed and measured by a colorimeter to obtain the product color value. The flow rate of the second homogeneous solution is adjusted to 0 ml/min, the flow rate of the third homogeneous solution is adjusted to 0 ml/min, the flow rate of the fourth homogeneous solution is adjusted to 20 ml/min, and the flow rate of the fifth homogeneous solution is adjusted to remain unchanged. The reaction products are collected at the outlet of the microreactor system, and the collected product C is processed and measured by a colorimeter to obtain the product color value. The color value of the synthetic product was compared with that of the commercially available product. The results are shown in Table 1. Products A-C are all reddish, among which product A has the strongest red light and the weakest yellow light, product C has the weakest red light and the strongest yellow light, and product B is in between the two.

Table 1. Comparison of color value between synthetic pigment orange products and commercially available pigment orange products

Product No. L(Light and Dark) a(red and green) b(yellow-blue) △L △a △b Commercially available samples 49.04 63.60 46.85 / / / A 50.32 61.23 40.34 +1.28 -2.37 -6.51 B 52.17 55.42 41.78 +3.13 -8.18 -5.07 C 50.54 58.45 44.67 +1.50 -5.15 -2.18

Example 2: Referring to FIG. 1 , the method of the present invention is used to continuously synthesize Pigment Orange 16, as follows:

Using deionized water as solvent, prepare a 0.0550 mol/L 3', 3-dimethoxybenzidine dihydrochloride solution, add hydrochloric acid at a molar ratio of 15:1 to 3', 3-dimethoxybenzidine dihydrochloride, add 30% wt sodium nitrite at a molar ratio of 3', 3-dimethoxybenzidine dihydrochloride at a ratio of 3:1 to generate a first homogeneous solution 1; using deionized water as solvent, prepare a 0.0755 mol/L N-acetoacetanilide solution, add sodium acetate to adjust its concentration to 0.76 mol/L, add sodium hydroxide to adjust its concentration to 0.23 mol/L, and prepare a second homogeneous solution 2; using deionized water as solvent, prepare a concentration of 0.0755 mol/L 2-methyl N-acetoacetanilide solution, sodium acetate is added to adjust its concentration to 0.76 mol/L, sodium hydroxide is added to adjust its concentration to 0.23 mol/L, and the third homogeneous solution 3 is prepared; deionized water is used as solvent to prepare a 0.0755 mol/L 2,4-dimethyl-N-acetoacetanilide solution, sodium acetate is added to adjust its concentration to 0.76 mol/L, sodium hydroxide is added to adjust its concentration to 0.23 mol/L, and the fourth homogeneous solution 4 is prepared; deionized water is used as solvent to prepare a sodium acetate solution with a concentration of 3.8 mol/L as the fifth homogeneous solution 5;

In this embodiment, the first homogeneous solution 1 is pumped by a tetrafluoroethylene advection pump 6, the second homogeneous solution 2 is pumped by a first stainless steel advection pump 7, the third homogeneous solution 3 is pumped by a second stainless steel advection pump 8, the fourth homogeneous solution 4 is pumped by a third stainless steel advection pump 9, and the fifth homogeneous solution 5 is pumped by a fourth stainless steel advection pump 10; the flow rate of the first homogeneous solution is set to 20ml/min, the flow rate of the second homogeneous solution is set to 20ml/min, the flow rate of the third homogeneous solution is set to 0ml/min, the flow rate of the fourth homogeneous solution is set to 0ml/min, and the flow rate of the fifth homogeneous solution is set to 10ml/min; the first homogeneous solution passes through the diazonium salt component preheating coil 13 at a flow rate of 20ml/min; the second, third and fourth homogeneous solutions pass through the coupling component preheating mixing coil 11 at flow rates of 20ml/min, 0ml/min and 0ml/min respectively; the fifth homogeneous solution passes through the sodium acetate component preheating coil 12 at a flow rate of 10ml/min;

In this embodiment, the preheating section includes three 316L stainless steel tubes with an inner diameter of 2mm, a volume of 9 to 10mL, and a preheating temperature range of 7.5°C to 22.5°C; the reaction section is composed of a cross-shaped micromixer and a 316L stainless steel coil, the dispersion scale range of the micromixer is 250 to 750μm, the inner diameter of the stainless steel coil is 4mm, the volume range is 18 to 20mL, and the temperature range of the reaction section is 0°C to 30°C; the crystallization section is composed of a 316L stainless steel coil with an inner diameter of 4mm, a volume range of 58 to 60mL, and the temperature range of the crystallization section is 70°C to 75°C; the cooling section is composed of a 316L stainless steel coil with an inner diameter of 4mm, a volume range of 9 to 10mL, and a cooling section temperature range of 10°C to 20°C. The above-mentioned parts are all connected by stainless steel pipes with an inner diameter of 2mm, and a low-temperature constant temperature water bath is used for temperature control.

The three solutions in the coupling component mixing preheating delay pipeline, the sodium acetate component preheating delay pipeline and the diazonium salt component preheating delay pipeline are transported to the micro mixer 20 and then start the mixing reaction through the stainless steel reaction coil 14, wherein the coupling component mixing preheating delay pipeline, the sodium acetate component preheating delay pipeline, the diazonium salt component preheating delay pipeline, the coupling reaction delay pipeline and the micro mixer 20 are placed in a constant temperature circulation cold trap 17, the temperature is controlled at 17.5°C, and the dispersion scale of the micro mixer 20 is 750μm. After that, the reaction liquid enters the crystallization section, which is placed in a constant temperature water bath 18, and the temperature of the temperature control zone is controlled at 75°C, and then enters the cooling section, which is placed in a constant temperature circulation cold trap 19, and the temperature of the temperature control zone is controlled at 15°C. The reaction products are collected at the outlet of the microreactor system, and the collected product D is treated and then measured by a colorimeter to obtain a product color value; the flow rate of the second homogeneous solution is adjusted to 14 ml/min, the flow rate of the third homogeneous solution is adjusted to 0 ml/min, the flow rate of the fourth homogeneous solution is adjusted to 6 ml/min, and the flow rate of the fifth homogeneous solution is adjusted to remain unchanged. The reaction products are collected at the outlet of the microreactor system, and the collected product E is treated and then measured by a colorimeter to obtain a product color value; the flow rate of the second homogeneous solution is adjusted to 7 ml/min n, the flow rate of the third homogeneous solution was adjusted to 0 ml/min, the flow rate of the fourth homogeneous solution was adjusted to 13 ml/min, and the flow rate of the fifth homogeneous solution was adjusted to remain unchanged. The reaction products were collected at the outlet of the microreactor system, and the collected product F was treated and the product color value was measured by a colorimeter. The color value of the synthetic product was compared with that of the commercially available product. The results are shown in Table 2. Products D-F all tended to be yellowish, among which product D had the strongest red light and the weakest yellow light, product F had the weakest red light and the strongest yellow light, and product E was between the two.

Table 2. Comparison of color value between synthetic pigment orange products and commercially available pigment orange products

Product No. L(Light and Dark) a(red and green) b(yellow-blue) △L △a △b Commercially available samples 49.04 63.60 46.85 / / / D 52.52 58.55 55.19 +3.48 -5.05 +8.13 E 55.68 55.41 57.62 +6.64 -8.19 +10.77 F 51.57 52.39 61.35 +2.53 -11.21 +14.5

Comparative Example 1: Pigment Orange 16 was produced intermittently using a conventional reactor, as follows:

Add 7g (0.022mol) of 3',3-dimethoxybenzidine dihydrochloride to a 1000ml three-necked flask, add 30g (0.31mol) of hydrochloric acid (36-38%wt), add 400ml of deionized water, cool to 0-5°C, drop 23.6g (0.05mol) of 30%wt sodium nitrite solution, keep warm for 40min, add activated carbon, stir for 10min and filter to obtain a diazonium salt solution. Add 8.7g (0.050mol) of N-acetyl acetanilide to a 3000ml three-necked flask, add 50.0g (0.61mol) of sodium acetate, add 4.0g (0.10mol) of sodium hydroxide, add 600ml of deionized water, add 5g (0.013mol) of Turkish red oil; build a mechanical stirring device, set the mechanical stirring speed to 360rpm, keep warm at 17.5°C, stir and dissolve to make a coupling component solution. The diazonium salt component solution was added below the surface of the coupling component solution within 30 minutes, and the product slurry was kept warm and stirred for 15 minutes, then heated to 70°C, heated under reflux for 2 hours, the heating was turned off, and the temperature was cooled to room temperature and filtered. The filter cake was washed with deionized water to pH = 7, the oven was set to 90°C, and the filter cake was dried for 12 hours to obtain the product. The product color value L = 50.31, a = 58.88, b = 55.19 was measured by a colorimeter, and the product color was yellowish.

Comparative Example 2: Pigment Orange 16 was produced intermittently using a conventional reactor, as follows:

In a 1000ml three-necked flask, add 7g (0.022mol) of 3',3-dimethoxybenzidine dihydrochloride, add 30g (0.31mol) of hydrochloric acid (36-38%wt), add 400ml of deionized water, cool to 0-5°C, add 23.6g (0.05mol) of 30%wt sodium nitrite solution dropwise, keep warm for 40min, add activated carbon, stir for 10min and filter to obtain a diazonium salt solution. Add 10.3g (0.050mol) of 2,4-dimethyl-N-acetoacetanilide, 36.6g (0.61mol) of acetic acid, 12.5g (0.15mol) of sodium acetate, 600ml of deionized water, and 5g (0.013mol) of Turkish red oil to a 3000ml three-necked flask; set a mechanical stirring device, set the mechanical stirring speed to 360rpm, keep warm at 17.5℃, stir and dissolve to make a coupling component solution. Add the diazonium salt component solution below the liquid surface of the coupling component solution within 30min to obtain a product slurry, keep warm and stir for 15min, then heat to 70℃, heat under reflux for 2h, turn off the heating, cool to room temperature and filter, wash the filter cake with deionized water to pH=7, set the oven temperature to 90℃, and dry the filter cake for 12h to obtain the product. The color value of the product measured by a colorimeter is L=47.37, a=53.35, b=46.85, and the color of the product is reddish.

In Example 1-2, the continuous production process of the pigment orange 16 product from synthesis to crystallization is realized by a micro-reactor, the pH of the reaction medium can be accurately controlled, the reaction efficiency is high, and the reaction time is short. Comparative Example 1-2 uses a traditional kettle process to synthesize reddish and yellowish pigment products, which has a long reaction cycle, difficult to control reaction conditions, and difficult to achieve continuous online adjustment of product color light.

The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims (9)

1. A method for continuously synthesizing pigment orange 16 by using a microchannel reactor, comprising the steps of:

1) Dissolving 3', 3-dimethoxy benzidine dihydrochloride in deionized water, adding hydrochloric acid and sodium nitrite to react and synthesize diazonium salt solution as a first homogeneous solution; dissolving acetoacetanilide in deionized water solution of sodium acetate and sodium hydroxide to prepare a second homogeneous solution; dissolving 2-methyl-N-acetoacetanilide in deionized water solution of sodium acetate and sodium hydroxide to prepare a third homogeneous solution; dissolving 2, 4-dimethyl-N-acetoacetanilide in deionized water solution of sodium acetate and sodium hydroxide to prepare a fourth homogeneous solution; dissolving sodium acetate in deionized water to prepare a fifth homogeneous solution;

2) Pumping the first homogeneous solution, the second homogeneous solution, the third homogeneous solution, the fourth homogeneous solution and the fifth homogeneous solution into a microchannel reaction device for mixing reaction; the color light of the pigment orange 16 product is regulated and controlled by regulating the flow rate proportion of the second, third and fourth homogeneous solutions and the flow rate of the fifth homogeneous solution; the micro-channel reaction device comprises a preheating section, a reaction section, a crystal transformation section and a cooling section which are connected through pipelines; the preheating section comprises a coupling component mixing preheating delay pipeline, a sodium acetate component preheating delay pipeline and a diazonium salt component preheating delay pipeline, and the preheating temperature range is 7.5-22.5 ℃; the reaction section comprises a cross-shaped micromixer and a reaction coil, three inlets of the cross-shaped micromixer are respectively communicated with a coupling component mixing and preheating delay pipeline, a sodium acetate component preheating delay pipeline and a diazonium salt component preheating delay pipeline, an outlet of the cross-shaped micromixer is communicated with the reaction coil, and the temperature range of the reaction section is 0-30 ℃; the crystal transformation section and the cooling section are coiled tubes, the temperature range of the crystal transformation section is 70-75 ℃, and the temperature range of the cooling section is 10-20 ℃; the preheating section, the reaction section, the crystal transformation section and the cooling section are all subjected to temperature control through a constant-temperature water bath;

3) And collecting suspension slurry flowing out of the micro-channel reaction device, and carrying out suction filtration and drying treatment on the suspension slurry to obtain the product pigment orange 16.

2. The method for continuously synthesizing pigment orange 16 according to claim 1, wherein the concentration of 3', 3-dimethoxy benzidine dihydrochloride in the step 1) is in the range of 0.0513 to 0.0552mol/L after being dissolved in deionized water; the mol ratio of the added hydrochloric acid to the 3', 3-dimethoxy benzidine dihydrochloride is (13-15): 1, a step of; the mole ratio of the added sodium nitrite to the 3', 3-dimethoxy benzidine dihydrochloride is (2-3): 1.

3. The method for continuously synthesizing pigment orange 16 according to claim 1, wherein the concentration of the acetoacetanilide in the second homogeneous solution in the step 1) ranges from 0.1104 to 0.1200mol/L; the concentration range of the sodium acetate in the second homogeneous solution is 0.75-0.77 mol/L; the concentration of sodium hydroxide in the second homogeneous solution ranges from 0.21 to 0.25mol/L.

4. The method for continuously synthesizing pigment orange 16 according to claim 1, wherein the concentration of 2-methyl-acetoacetanilide in the third homogeneous solution in the step 1) ranges from 0.1104 to 0.1200mol/L; the concentration range of the sodium acetate in the third homogeneous solution is 0.75-0.77 mol/L; the concentration range of the sodium hydroxide in the third homogeneous solution is 0.21-0.25 mol/L.

5. The method for continuously synthesizing pigment orange 16 according to claim 1, wherein the concentration of 2, 4-dimethyl-acetoacetanilide in the fourth homogeneous solution in the step 1) ranges from 0.1104 to 0.1200mol/L; the concentration range of the sodium acetate in the fourth homogeneous solution is 0.75-0.77 mol/L; the concentration range of the sodium hydroxide in the fourth homogeneous solution is 0.21-0.25 mol/L.

6. The method for continuously synthesizing pigment orange 16 according to claim 1, wherein the concentration of sodium acetate in the fifth homogeneous solution in the step 1) is 3.60 to 4.00mol/L.

7. The method for continuously synthesizing pigment orange 16 according to claim 1, wherein in the step 2), the second homogeneous solution, the third homogeneous solution and the fourth homogeneous solution are converged in one flow passage and then enter a coupling component mixing and preheating delay pipeline for preheating; the flow rates of the second homogeneous phase solution, the third homogeneous phase solution and the fourth homogeneous phase solution are all in the range of 0ml/min to 20ml/min, and the total flow rate after the second homogeneous phase solution, the third homogeneous phase solution and the fourth homogeneous phase solution are converged is controlled to be 15 ml/min to 60ml/min.

8. The method for continuously synthesizing pigment orange 16 according to claim 1, wherein in the step 2), the first homogeneous solution enters a diazonium salt component preheating delay line for preheating, and the flow rate of the first homogeneous solution is consistent with the total flow rate after the second homogeneous solution, the third homogeneous solution and the fourth homogeneous solution are combined; the fifth homogeneous solution enters a sodium acetate component preheating delay pipeline for preheating, and the flow speed adjusting range of the fifth homogeneous solution is 1.5 ml/min-10 ml/min.

9. The method for continuously synthesizing pigment orange 16 according to claim 1, wherein in the step 3), the rapid qualitative filter paper is used for suction filtration and an oven is used for drying, and the drying temperature is 70-90 ℃.