Continuous preparation method of azo disperse dye
(I) technical field
The invention relates to a preparation method of an azo disperse dye, in particular to a continuous preparation method of the azo disperse dye.
(II) background of the invention
The azo disperse dye is prepared from a diazonium salt and a coupling component through a coupling reaction. Because the diazonium salt has thermal instability and the coupling reaction is an exothermic process, in order to reduce the decomposition of the diazonium salt in a system, the traditional kettle type batch production process usually needs a large amount of ice water to cool to about 0 ℃, and the diazonium salt is added with long time, so that a large amount of cold energy is consumed, the reaction period is prolonged, and the production cost is increased.
In the existing continuous coupling documents, for example, CN102796394A adopts a multistage series kettle type continuous coupling process, and CN105348847A adopts a series loop reactor (including a reaction kettle and an external circulation pipeline) continuous coupling process, because the mass transfer effect of the reaction kettles is poor, side reactions are easy to occur, and the problems of long reaction time, low production efficiency and the like still exist. CN107961755A uses the liquid-liquid jet reactor, first tower reactor and second tower reactor coupling reaction to produce azo dye continuously, has improved the mass transfer effect, but tower reactor temperature can't be controlled accurately, the mass transfer can't reach the best effect.
Disclosure of the invention
The invention aims to provide a continuous preparation method of azo disperse dye, which realizes continuous and efficient preparation of azo disperse dye, and the obtained product has high yield and high purity.
In order to solve the technical problems, the invention adopts the following technical scheme:
a continuous preparation method of azo disperse dye, the equipment adopted by the continuous preparation method comprises a Venturi reactor, a material receiving tank with a flash port, a main fluid circulating pump, a heat exchanger and a crystal conversion kettle, the Venturi reactor, the material receiving tank with the flash port, the main fluid circulating pump and the heat exchanger are connected through pipelines to form a circulating loop I, and the continuous preparation method comprises the following steps:
(1) introducing a main fluid with a certain volume into a material receiving tank with an overflow port, so that the main fluid circularly flows in a circulating loop I, and controlling the temperature of materials in the circulating loop I to be at a temperature suitable for coupling reaction;
(2) continuously feeding the coupling component feed liquid and the diazo liquid into a Venturi reactor according to a certain proportion (as secondary fluid) to perform coupling reaction, continuously feeding the coupling product feed liquid obtained after the reaction into a material receiving tank with a flash port, and allowing the material in the material receiving tank to enter a circulation loop I for circulation, wherein the liquid level in the material receiving tank with the flash port gradually rises along with the continuous feeding of the coupling component feed liquid and the diazo liquid in the Venturi reactor, and then overflowing the material from the flash port;
(3) when the purity of the overflowing material is stable, the coupling product feed liquid overflowing from the overflowing port of the material receiving tank enters a crystal conversion kettle to be heated and converted into crystals, and finally, the azo disperse dye filter cake is obtained by filtering and washing;
and (3) the main fluid is coupling product feed liquid, material overflowing from a flash port or filtrate obtained in the step (3).
The invention greatly shortens the reaction time and obviously improves the production efficiency by utilizing the high-efficiency mass transfer characteristic of the Venturi reactor; meanwhile, the temperature of a reaction system is stabilized by utilizing the self-circulation of the main fluid, so that the energy consumption is reduced; realizes continuous production, and the obtained product has high purity and high yield.
In the coupling component feed solution of the present invention, the coupling component used is an aniline compound commonly used for preparing azo disperse dyes, such as N-ethyl-N-cyanoethylaniline, N-cyanoethyl-N-benzylaniline, N-dicyanoethylaniline, m-acetamido-N, N-diacetoxyethylaniline, m-acetamido-N, N-diethylaniline, 2-methoxy-5-acetamido-N, N-diacetoxyethylaniline, 2-methoxy-5-acetamido-N, N-diallylaniline, etc.
The diazo liquid described in the present invention is a diazonium salt of a diazo component which is common in the preparation of azo disperse dyes, and the diazo component may be aniline, substituted primary aromatic amines or heterocyclic amines, for example aniline substituted with halogen (e.g. chlorine, bromine), nitro, cyano, especially o-chloro-p-nitroaniline, o-bromo-p-nitroaniline, o-cyano-p-nitroaniline, 2, 6-dichloro-4-nitroaniline, 2, 6-dibromo-4-nitroaniline, 2, 6-dicyano-4-nitroaniline, 2, 4-dinitro-6-chloroaniline, 2, 4-dinitro-6-bromoaniline, 2, 4-dinitro-6-cyanoaniline, 6-nitro-2-aminobenzothiazole, 5-nitro-3-aminobenzothiazole or 2-amino-5, 6-dichlorobenzothiazole, 2-amino-6, 7-dichlorobenzothiazole, and the like.
Preferably, the flow rate of the feed liquid in the circulation loop I is controlled to be more than 1.5m/s, and more preferably 1.5 to 3 m/s.
Preferably, in the step (2), the coupling component feed liquid and the diazo liquid are controlled to have a temperature suitable for the coupling reaction by a heat exchanger before entering the Venturi reactor. Preferably, the temperature suitable for the coupling reaction is 0-5 ℃.
Preferably, the molar ratio of the diazo component to the coupling component in the secondary fluid entering the venturi reactor is controlled to be 1: 1.01-1.1, and more preferably 1: 1.01-1.05.
Preferably, in step (2), the coupling liquid is continuously fed into the venturi reactor by a pump, preferably a plunger pump.
Preferably, in step (2), the diazo liquid is sucked into the venturi reactor through a flow limiting device, and more preferably, the flow limiting device is a flow limiting orifice plate or a pump.
Preferably, in step (2), the ratio of the main fluid flow rate to the total flow rate of the secondary fluid diazo liquid and the coupling liquid should be greater than 3, more preferably equal to or greater than 10, and when the ratio is below 3, the main fluid temperature cannot be accurately controlled.
Preferably, the material receiving tank and/or the crystal transferring kettle and/or the pipeline are/is provided with a heat-insulating layer jacket.
In the step (3) of the invention, when the purity of the material overflowing from the material receiving tank is stable, the reaction is at the end point of the reaction. When the reaction system does not reach a steady state, namely the situation that the material overflows from the overflowing port of the material receiving tank but the reaction end point is not reached can occur, the overflowing material can be collected and used for the main fluid of the step (1).
Preferably, the equipment adopted by the continuous preparation method at least comprises two crystal conversion kettles, when the feed liquid in one crystal conversion kettle reaches a certain amount, the other crystal conversion kettle is switched to continue to collect the feed liquid overflowing from the material receiving tank, and the crystal conversion kettle which has collected a certain amount of feed liquid is subjected to temperature rise crystallization.
Compared with the prior art, the continuous preparation method of the azo disperse dye has the beneficial effects that: the invention (1) utilizes the high-efficiency mass transfer characteristic of the Venturi reactor, greatly shortens the reaction time and obviously improves the production efficiency; (2) the temperature of a reaction system is stabilized by utilizing the self-circulation of a main fluid, so that the energy consumption is reduced; (3) realizes continuous production, and the obtained product has high purity and high yield.
(IV) description of the drawings
FIG. 1 shows the equipment used in the continuous preparation method of the present invention, wherein 1 is a coupling component feed liquid storage tank, 2 is a plunger pump, 3 is a coupling liquid inlet, 4 is a diazo liquid storage tank, 5 is a Venturi reactor, 6 is a material receiving tank (with a heat insulating jacket) with a discharge outlet, 7 is a crystal rotating kettle (with a heat insulating jacket), 8 is a main fluid circulating pump, 9-11 are heat exchangers, and 12 is a flow-limiting orifice plate.
(V) detailed description of the preferred embodiments
The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto.
Referring to fig. 1, the apparatus used in the embodiment includes a coupling liquid storage tank 1, a plunger pump 2, a coupling liquid inlet 3, a diazo liquid storage tank 4, a venturi reactor 5, a material receiving tank 6 with a flash port (with a heat-preserving jacket), a crystal-rotating kettle 7 (with a heat-preserving jacket), a main fluid circulation pump 8, heat exchangers 9 to 11, and a restriction orifice plate 12. Venturi reactor 5, take material jar 6, main fluid circulating pump 8, heat exchanger 11 and the coupling liquid of connecing of flash of material mouth and insert 3 and loop through pipe connection and form circulation circuit I, coupling liquid storage tank 1, plunger pump 2, heat exchanger 9 and coupling liquid insert 3 and loop through pipe connection, heavy nitrogen liquid storage tank 4, heat exchanger 10, restricted orifice 12 and venturi reactor 5 loop through pipe connection.
Example 1
(1) 2, 4-dinitro-6-chloroaniline, 98% concentrated sulfuric acid and nitrosyl sulfuric acid are mixed according to a molar ratio of 1: 1.82: 1.025 preparing diazo liquid, cooling to 0 ℃, adding the diazo liquid into a diazo liquid storage tank 4, and starting a heat exchanger 9 (the set temperature is 0 ℃);
(2) mixing m-acetamido-N, N-diethylaniline, a 10% sulfuric acid solution and water according to a molar ratio of 1.02: 0.743: 386 is prepared into coupling component feed liquid, the temperature is reduced to 0 ℃, the coupling component feed liquid is added into a coupling component feed liquid storage tank 1, and a heat exchanger 10 is started (the set temperature is 0 ℃);
(3) starting the plunger pump 2, adding about 3L of coupling component feed liquid into the material receiving tank 6 with the flash port, stopping feeding, starting the pump 8 for circulation, controlling the flow of the main fluid to be 720L/h (the flow rate is 2m/s), and starting the heat exchanger 11 (the set temperature is 0 ℃). When the temperature of the main fluid is slowly reduced to 0 ℃, the flow of the diazo liquid is controlled by using a flow-limiting orifice plate 12 near the Venturi reactor 5, after a proper flow-limiting orifice plate is selected, the feeding of the coupling component liquid is regulated by using a plunger pump 2, and the diazo liquid and the coupling component liquid are mixed according to the diazo component: molar ratio of coupling component 1:1.01 respectively enter a Venturi tube (the feeding amount of diazo liquid is 11.2mL/min, the feeding amount of coupling component liquid is 89.03mL/min), the reacted material continuously enters a material receiving tank 6 with a flash port, and simultaneously, along with the continuous feeding of the coupling component liquid and the diazo liquid in the Venturi reactor, the liquid level in the material receiving tank 6 gradually rises and overflows from the flash port; after the reaction end point is determined (the sampling purity of the overflow port is basically unchanged), the material overflowing from the overflow port of the material receiving tank 6 enters the crystal conversion kettle 7 (two crystal conversion kettles are provided, when one crystal conversion kettle reaches the maximum volume, the other crystal conversion kettle is switched to, and the two crystal conversion kettles are used in turn), the temperature of the crystal conversion kettle 7 is raised to 40 ℃ after the specified liquid level is reached, and the crystal conversion is carried out for 0.5 hour under the condition of heat preservation. Finally, filtering and washing to obtain the azo disperse dye product shown in the formula (1), wherein the purity is 90 percent, and the yield is 96 percent.
Example 2
The filtrate obtained in example 1 was collected, and the procedure of example 1 was followed except that the feed solution of the main fluid coupling product in example 1 was changed to the filtrate, and the other conditions were not changed, to obtain an azo disperse dye product represented by formula (1) with a purity of 90% and a yield of 96%.
Example 3
(1) 2, 4-dinitro-6-chloroaniline, 98% concentrated sulfuric acid and nitrosyl sulfuric acid are mixed according to a molar ratio of 1: 1.82: 1.025 preparing diazo liquid, cooling to 5 ℃, adding the diazo liquid into a diazo liquid storage tank 4, and starting a heat exchanger 9 (the set temperature is 0 ℃);
(2) mixing 2-methoxy-5-acetamido-N, N-diacetoxyethylaniline, 10% sulfuric acid solution and water according to a molar ratio of 1: 1: 252 is prepared into coupling component feed liquid, the temperature is reduced to 0 ℃, the coupling component feed liquid is added into a coupling component feed liquid storage tank 1, and a heat exchanger 10 is started (the set temperature is 0 ℃);
(3) starting the plunger pump 2, adding about 3L of coupling product feed liquid into the material receiving tank 6 with the flash port, stopping feeding, starting the pump 8 for circulation, controlling the flow of the main fluid to be 720L/h (the flow rate is 2m/s), and starting the heat exchanger 11 (the set temperature is 0 ℃). When the temperature of the main fluid is slowly reduced to 0 ℃, controlling the flow of the diazo liquid by utilizing a flow limiting orifice plate flow limiting 12 near the Venturi reactor 5, selecting a proper flow limiting orifice plate, regulating the feeding of the coupling component liquid by using a plunger pump 2, and mixing the diazo liquid and the coupling component liquid according to the diazo component: molar ratio of coupling component 1: 1.02 respectively enters a Venturi tube (the feeding amount of diazo liquid is 22.97mL/min, the feeding amount of coupling component liquid is 171.59mL/min), the reacted material continuously enters a material receiving tank 6 with a flash port, and simultaneously, along with the continuous feeding of the coupling component liquid and the diazo liquid in the Venturi reactor, the liquid level in the material receiving tank 6 gradually rises and overflows from the flash port; after the reaction end point is determined (the sampling purity of the overflow port is basically unchanged), the material overflowing from the overflow port of the material receiving tank 6 enters the crystal conversion kettle 7 (two crystal conversion kettles are provided, when one crystal conversion kettle reaches the maximum volume, the other crystal conversion kettle is switched to, and the two crystal conversion kettles are used in turn), the temperature of the crystal conversion kettle 7 is raised to 40 ℃ after the specified liquid level is reached, and the crystal conversion is carried out for 1 hour under the condition of heat preservation. Finally, filtering and washing to obtain an azo disperse dye product shown in the formula (2), wherein the purity is 91 percent, and the yield is 98 percent.
Example 4
The material overflowing from the material receiving tank 6 overflow port in example 3 was collected, and the procedure of example 3 was followed except that the main fluid coupling product feed liquid in example 3 was changed to the material overflowing from the material receiving tank 6 overflow port in example 3, and other conditions were not changed, to obtain the azo disperse dye product represented by formula (2), which had a purity of 91% and a yield of 98%.
Example 5
The overflow of the material from the overflow port of the material receiving tank 6 in example 3 was collected, and the procedure of example 3 was followed except that the feeding amount of the secondary fluid in example 3 was increased to 1/10 (the feeding amount of the diazo liquid was 141.54mL/min, the feeding amount of the coupling component feed liquid was 1.058L/min) of the main fluid (720L/h), and the other conditions were not changed, to obtain the azo disperse dye product represented by formula (2) with a purity of 90.8% and a yield of 97.5%.
Example 6
The filtrate obtained in example 1 was collected, and the procedure of example 1 was followed except that the flow rate of the main fluid in example 1 was increased to 900L/h (flow rate: 2.5m/s), and the conditions were not changed, to obtain a product of azo disperse dye represented by formula (1), which had a purity of 90.2% and a yield of 96.3%.