Continuous flow synthesis method of diacetone hydrazone

Abstract

The invention discloses a continuous flow synthesis method of diacetone hydrazone. The method comprises the following steps: S1, acetone and hydrazine hydrate are respectively pumped into a microchannel reactor for a mixed reaction, and the first retention time is 5.6-8.5 s; s2, the mixed liquid flowing out of the micro-channel reactor in the step S1 flows into a tubular reactor connected with the micro-channel reactor in series for continuous reaction, and the second retention time is 200-300 s; and S3, collecting the mixed liquid flowing out of the tubular reactor in the step S2. According to the invention, the micro-channel reactor and the tubular reactor which are sequentially connected in series are adopted for reaction, so that the defects of low efficiency, low purity of the obtained product, safety problem and the like in the traditional batch method are overcome, and the continuous flow synthesis method which is efficient, safe, rapid, economical and easy for large-scale production of diacetone hydrazone is provided.

Description

Technical Field

[0001] The invention relates to a continuous flow synthesis method of diacetone hydrazone. Background Art

[0002] Diacetone hydrazone (4-methyl-3-pentene-2-one hydrazone, acetone azine) is a colorless liquid with a molecular formula of C6H 12 N2, molecular weight is 112.18, stable at room temperature and pressure, sensitive to water and moisture. Diacetone hydrazone is usually prepared using acetone and hydrazine, the reaction process is as follows:

[0003]

[0004] The above-mentioned method for preparing diacetone hydrazone is usually synthesized by a batch method with the participation of other solvents. However, in general batch reactors, there are often defects such as low efficiency, low purity of the obtained product, and safety issues. Therefore, it is of great significance to obtain high-purity diacetone hydrazone with high efficiency without using other solvents. Summary of the invention

[0005] In order to solve the defects of low efficiency, low product purity and safety problems in the traditional batch method for preparing diacetone hydrazone, the present invention adopts a microchannel reactor and a tubular reactor connected in series to carry out the reaction, and provides a continuous flow synthesis method for producing diacetone hydrazone that is efficient, safe, rapid, economical and easy to scale up.

[0006] The present invention adopts the following technical solutions to solve the above technical problems:

[0007] The present invention provides a continuous flow synthesis method of diacetone hydrazone, which is carried out by sequentially connecting a microchannel reactor and a tubular reactor in series, and comprises the following steps:

[0008] S1, introducing acetone and hydrazine hydrate into a microchannel reactor for mixed reaction, wherein the first residence time is 5.6 to 8.5 seconds;

[0009] S2, the mixed solution flowing out of the microchannel reactor in step S1 flows into a tubular reactor connected in series with the microchannel reactor to continue the reaction, wherein the second residence time is 200 to 300 seconds;

[0010] S3, collecting the mixed liquid flowing out of the tubular reactor in step S2.

[0011] In the present invention, the flow rate of the acetone may be 9.20 to 15.12 g / min, preferably 9.96 to 15.12 g / min, such as 9.62 g / min, 10.07 g / min, 10.15 g / min or 12.54 g / min.

[0012] In the present invention, the flow rate of the hydrazine hydrate may be 4.06 to 6.52 g / min, preferably 4.30 to 6.52 g / min, such as 4.18 g / min, 4.74 g / min, 5.25 g / min or 5.29 g / min.

[0013] In the present invention, the first residence time in step S1 refers to the time for the mixing reaction to be carried out in the microchannel reactor, which may be 6.8 s, for example.

[0014] In the present invention, the second residence time in step S2 refers to the time for continuing the reaction in the tubular reactor, for example, it may be 240 seconds.

[0015] In the present invention, the mass percentage of hydrazine in the hydrazine hydrate can be a conventional parameter in the art, preferably 60-80%, for example 70%.

[0016] In the present invention, the method of introducing in step S1 can be conventional in the art, preferably pumping.

[0017] In the present invention, in step S1, the mass ratio of acetone and hydrazine hydrate introduced per unit time is preferably (1.74-2.50):1, more preferably (2.32-2.50):1, for example 2.41:1.

[0018] In the present invention, the temperature of the mixing reaction in step S1 can be a conventional parameter in the art, preferably 25-35°C, such as 30°C.

[0019] In the present invention, the reaction temperature in step S2 can be a conventional parameter in the art, preferably 25-35°C, such as 30°C.

[0020] In the present invention, preferably, step S3 further includes separation and purification of the mixed solution; the separation and purification can be conventional operations in the art, preferably by distillation.

[0021] In the present invention, the microchannel reactor can be a microchannel reactor conventionally used in the art, preferably using a HAC module. The HAC module means that the microchannel reactor is made of a HAC alloy. The HAC module is preferably a 2.4mL HAC module. Among them, "2.4mL" refers to the liquid holding volume of the microchannel reactor, that is, the space inside for reaction is 2.4mL.

[0022] In the present invention, the tubular reactor can be a tubular reactor conventionally used in the art, such as an 85mL 1 / 8″316L tubular reactor. Wherein, “85mL” refers to the liquid holding volume of the tubular reactor, that is, the space inside for reaction is 85mL, “316L” refers to the use of 316L stainless steel material, and “1 / 8″” refers to the outer diameter of the pipe being 1 / 8 inch.

[0023] In certain preferred embodiments, the continuous flow synthesis method of diacetone hydrazone satisfies the following conditions:

[0024] In step S1, the mass ratio of the acetone and hydrazine hydrate introduced per unit time is (2.41-2.50):1, the flow rate of the acetone is 10.07-10.15 g / min, the flow rate of the hydrazine hydrate is 4.06-4.18 g / min, the mass percentage of hydrazine in the hydrazine hydrate is 80%, the first residence time is 8.5 s, and the temperature of the mixed reaction is 25 ° C.;

[0025] In step S2, the second residence time is 300 s, and the reaction temperature is 25°C.

[0026] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0027] The reagents and raw materials used in the present invention are commercially available.

[0028] The positive and progressive effects of the present invention are:

[0029] 1. The present invention provides a continuous flow synthesis method of diacetone hydrazone, which uses acetone and hydrazine hydrate as reaction raw materials, and can synthesize diacetone hydrazone with a purity of more than 96.5% and a yield of more than 85% without using a solvent.

[0030] 2. The synthesis method of the present invention overcomes the defects of the traditional intermittent method such as low efficiency, low purity of the obtained product, and safety issues. By adopting microchannel reactors and tubular reactors connected in series to carry out the reaction, it is efficient, safe, fast, economical, and easy to scale up production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the continuous reaction device for preparing diacetone hydrazone.

[0032] Reference numerals:

[0033] First Pump 3

[0034] Second pump 4

[0035] Microchannel reactor 1

[0036] Tubular Reactor 2

[0037] Receiving tank 5

[0038] First temperature sensor 6

[0039] Second temperature sensor 7

[0040] The third temperature sensor 8

[0041] Fourth temperature sensor 9

[0042] Pressure sensor 10 DETAILED DESCRIPTION

[0043] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0044] The following examples 1-9 and comparative examples 3-6 are Figure 1 The process is carried out in the continuous reaction device shown in the figure, wherein the microchannel reactor 1 adopts a 2.4 ml H C module.

[0045] Example 1

[0046] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 9.96 g / min, the flow rate of hydrazine hydrate is 4.30 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the reaction temperature is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 98.5%, and the yield is 95.3%.

[0047] Example 2

[0048] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 10.07 g / min, the flow rate of hydrazine hydrate is 4.18 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.41:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the reaction temperature is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 98.9%, and the yield is 96.0%.

[0049] Example 3

[0050] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 10.15 g / min, the flow rate of hydrazine hydrate is 4.06 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.50:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the temperature of the reaction is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 98.6%, and the yield is 96.1%.

[0051] Example 4

[0052] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 12.54 g / min, the flow rate of hydrazine hydrate is 5.25 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the first residence time is 6.8 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 240 s, and the reaction temperature is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 98.6%, and the yield is 95.8%.

[0053] Example 5

[0054] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 15.12 g / min, the flow rate of hydrazine hydrate is 6.52 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the first residence time is 5.6 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 200 s, and the reaction temperature is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 98.4%, and the yield is 95.7%.

[0055] Example 6

[0056] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 9.20 g / min, the flow rate of hydrazine hydrate is 5.29 g / min, the mass percentage of hydrazine in hydrazine hydrate is 60%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 1.74:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the temperature of the reaction is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 98.7%, and the yield is 94.9%.

[0057] Example 7

[0058] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 for mixed reaction, wherein the flow rate of acetone is 9.62 g / min, the flow rate of hydrazine hydrate is 4.74 g / min, the mass percentage of hydrazine in hydrazine hydrate is 70%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.03:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the reaction temperature is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the crude diacetone hydrazone is collected with a purity of 98.9% and a yield of 95.1%. After separation, the diacetone hydrazone product is obtained, and the separation is carried out by distillation.

[0059] Example 8

[0060] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 for mixed reaction, wherein the flow rate of acetone is 9.96 g / min, the flow rate of hydrazine hydrate is 4.30 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 30° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the reaction temperature is controlled to be 30° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the crude diacetone hydrazone is collected with a purity of 98.2% and a yield of 95.0%. After separation, the diacetone hydrazone product is obtained, and the separation is carried out by distillation.

[0061] Example 9

[0062] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 for mixed reaction, wherein the flow rate of acetone is 9.96 g / min, the flow rate of hydrazine hydrate is 4.30 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 35° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the reaction temperature is controlled to be 35° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the crude diacetone hydrazone is collected with a purity of 98.6% and a yield of 95.7%. After separation, the diacetone hydrazone product is obtained, and the separation is carried out by distillation.

[0063] Comparative Example 1

[0064] Acetone and hydrazine hydrate are pumped into a tubular reactor for mixed reaction, wherein the flow rate of acetone is 9.96 g / min, the flow rate of hydrazine hydrate is 4.30 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the residence time is 300 s, the temperature of the mixed reaction is 25° C., and the tubular reactor used in this comparative example is consistent with that in the embodiment; the formed mixed solution flows out of the tubular reactor, and the formed mixed solution flows into a receiving tank connected to the tubular reactor, and the purity of the collected diacetone hydrazone is 93.7%, and the yield is 76.4%.

[0065] Comparative Example 2

[0066] Acetone and hydrazine hydrate are pumped into a microchannel reactor for mixed reaction, wherein the flow rate of acetone is 9.96 g / min, the flow rate of hydrazine hydrate is 4.30 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in unit time is 2.32:1, the residence time is 8.5 s, the temperature of the mixed reaction is 25° C., and the microchannel reactor used in this comparative example is consistent with that in the embodiment; the formed mixed solution flows out of the microchannel reactor 1, and the formed mixed solution flows into a receiving tank 5 connected to the microchannel reactor 1, and the purity of the collected diacetone hydrazone is 96.1%, and the yield is 73.2%.

[0067] Comparative Example 3

[0068] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 9.96 g / min, the flow rate of hydrazine hydrate is 4.30 g / min, the mass percentage of hydrazine in hydrazine hydrate is 50%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, the second residence time is 300 s, and the reaction temperature is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 94.5%, and the yield is 71.0%.

[0069] Comparative Example 4

[0070] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively, wherein the flow rate of acetone is 7.26 g / min, the flow rate of hydrazine hydrate is 7.00 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 1.04:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 25° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the temperature of the reaction is controlled to be 25° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 89.0%, and the yield is 53.7%.

[0071] Comparative Example 5

[0072] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 19.92g / min, the flow rate of hydrazine hydrate is 8.60g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the first residence time is 4.25s, the temperature of the mixed reaction is controlled to be 25°C by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 150s, and the reaction temperature is controlled to be 25°C by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 95.1%, and the yield is 83.2%.

[0073] Comparative Example 6

[0074] Acetone and hydrazine hydrate are pumped into the microchannel reactor 1 through the first pump 3 and the second pump 4 respectively for mixed reaction, wherein the flow rate of acetone is 9.96 g / min, the flow rate of hydrazine hydrate is 4.30 g / min, the mass percentage of hydrazine in hydrazine hydrate is 80%, the mass ratio of acetone and hydrazine hydrate pumped in per unit time is 2.32:1, the first residence time is 8.5 s, the temperature of the mixed reaction is controlled to be 15° C. by the first temperature sensor 6, and the pressure sensor 10 is used to detect the pressure at the inlet end of the microchannel reactor; the formed mixed solution flows out of the microchannel reactor 1 and flows into the tubular reactor 2 connected to the microchannel reactor 1 to continue the reaction, wherein the second residence time is 300 s, and the reaction temperature is controlled to be 15° C. by the second temperature sensor 7; the third temperature sensor 8 and the fourth temperature sensor 9 are used to detect the temperature of the material, and the formed mixed solution flows into the receiving tank 5 connected to the tubular reactor 2, and the purity of the collected diacetone hydrazone is 93.0%, and the yield is 81.5%.

[0075] The main parameters involved in the embodiments and comparative examples are shown in Table 1 below:

[0076] Table 1

[0077]

[0078]

[0079] Note: “ / ” in Table 1 means that the condition parameter is not involved in the specific experiment.

[0080] As can be seen from Table 1, compared with Comparative Examples 1-6, the yield and purity of diacetone hydrazone obtained in Examples 1-9 are higher overall, with a yield of 96.1% and a purity of 98.9%, indicating that the method for synthesizing diacetone hydrazone by the continuous flow method of the present invention has a higher synthesis efficiency and the obtained diacetone hydrazone has a higher purity.

[0081] Specifically, the inventors found through experimental research that the use of a microchannel reactor and a tubular reactor connected in series has a great influence on the yield and purity of the obtained diacetone hydrazone. For example, compared with Example 1, the yield and purity of the obtained diacetone hydrazone are lower in Comparative Example 1 using a single tubular reactor; compared with Example 1, the yield and purity of the obtained diacetone hydrazone are lower in Comparative Example 2 using a single microchannel reactor.

[0082] The first residence time and the second residence time have a great influence on the yield and purity of the obtained diacetone hydrazone. For example, compared with Examples 1, 4, and 5, the first residence time and the second residence time in Comparative Example 5 are shorter, and the yield and purity of the obtained diacetone hydrazone are lower.

[0083] The mass ratio of acetone and hydrazine hydrate pumped in per unit time has a certain influence on the yield and purity of the obtained diacetone hydrazone. For example, compared with Example 1, the mass of acetone and hydrazine hydrate pumped in per unit time in Comparative Example 4 is relatively small, and the purity and yield of the obtained diacetone hydrazone are relatively low; in Examples 2 and 3, the mass of acetone and hydrazine hydrate pumped in per unit time is relatively large, and the purity and yield of the obtained diacetone hydrazone are relatively high.

[0084] The mass percentage of hydrazine in hydrazine hydrate has a certain influence on the yield and purity of the obtained diacetone hydrazone. For example, compared with Examples 1, 6, and 7, the mass percentage of hydrazine in hydrazine hydrate in Comparative Example 3 is lower, and the purity and yield of the obtained diacetone hydrazone are lower.

[0085] The temperature of the mixed reaction in the microchannel reactor and the temperature of the reaction in the tubular reactor have a certain influence on the yield and purity of the obtained diacetone hydrazone. For example, compared with Examples 1, 8, and 9, the temperature of the mixed reaction in the microchannel reactor and the temperature of the reaction in the tubular reactor in Comparative Example 6 are lower, and the yield and purity of the obtained diacetone hydrazone are lower.

[0086] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A continuous flow synthesis method for diacetone hydrazone, characterized in that: The method is carried out by sequentially connecting a microchannel reactor and a tubular reactor in series, and comprises the following steps: S1, introducing acetone and hydrazine hydrate into a microchannel reactor for mixed reaction, wherein the first residence time is 5.6 to 8.5 seconds; S2, the mixed solution flowing out of the microchannel reactor in step S1 flows into a tubular reactor connected in series with the microchannel reactor to continue the reaction, wherein the second residence time is 200 to 300 seconds; S3, collecting the mixed liquid flowing out of the tubular reactor in step S2.

2. The continuous flow synthesis method of diacetone hydrazone as claimed in claim 1, characterized in that: In step S1, the flow rate of acetone is 9.20-15.12 g / min, preferably 9.96-15.12 g / min, for example 9.62 g / min, 10.07 g / min, 10.15 g / min or 12.54 g / min; And / or, the flow rate of the hydrazine hydrate is 4.06-6.52 g / min, preferably 4.30-6.52 g / min, for example 4.18 g / min, 4.74 g / min, 5.25 g / min or 5.29 g / min.

3. The continuous flow synthesis method of diacetone hydrazone as claimed in claim 1, characterized in that: In step S1, the first residence time is 6.8s; And / or, in step S2, the second residence time is 240s.

4. The continuous flow synthesis method of diacetone hydrazone as claimed in claim 1, characterized in that: In step S1, the mass percentage of hydrazine in the hydrazine hydrate is 60-80%, for example, 70%.

5. The continuous flow synthesis method of diacetone hydrazone as claimed in claim 1, characterized in that: In step S1, the introduction method is pumping.

6. The continuous flow synthesis method of diacetone hydrazone as claimed in claim 1, characterized in that: In step S1, the mass ratio of acetone and hydrazine hydrate introduced per unit time is (1.74-2.50):1, preferably (2.32-2.50):1, for example 2.03:1 or 2.41:

1.

7. The continuous flow synthesis method of diacetone hydrazone as claimed in claim 1, characterized in that: In step S1, the temperature of the mixed reaction is 25-35°C, for example, 30°C; And / or, in step S2, the reaction temperature is 25-35°C, for example, 30°C.

8. The continuous flow synthesis method of diacetone hydrazone as claimed in claim 1, characterized in that: After step S3, the mixed solution is further separated and purified, and the separation and purification is preferably carried out by distillation.

9. The continuous flow synthesis method of diacetone hydrazone as claimed in claim 1, characterized in that: The microchannel reactor adopts a HAC module.

10. The continuous flow synthesis method of diacetone hydrazone according to claim 1, characterized in that: It meets the following conditions: In step S1, the mass ratio of the acetone and hydrazine hydrate introduced per unit time is (2.41-2.50):1, the flow rate of the acetone is 10.07-10.15 g / min, the flow rate of the hydrazine hydrate is 4.06-4.18 g / min, the mass percentage of hydrazine in the hydrazine hydrate is 80%, the first residence time is 8.5 s, and the temperature of the mixed reaction is 25 ° C.; In step S2, the second residence time is 300 s, and the reaction temperature is 25°C.

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