Method for preparing tert-butyl peroxypivalate on line through microchannel

Abstract

The invention discloses a method for on-line preparation of tert-butyl peroxypivalate through a micro-channel, and belongs to the technical field of fine chemical synthesis, the method comprises the following steps: continuously preparing tert-butyl peroxypivalate in a micro-channel reactor under the catalysis of sulfuric acid by taking pivalic anhydride and tert-butyl hydroperoxide as raw materials, and after the quenching reaction, carrying out online separation to obtain the tert-butyl peroxypivalate. The microchannel synthesis and online separation technology is adopted, the operation process is simplified, heat and mass transfer in the reaction process is enhanced, the reaction efficiency is improved, and the safe operation condition boundary is widened; the storage amount of unstable organic peroxides is minimized, the reaction retention time is shortened, and compared with a traditional intermittent synthesis process, the safety is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fine chemical synthesis, and particularly relates to a method for on-line preparation of tert-butyl perpivalate in a microchannel. Background Art

[0002] Tert-butyl perpivalate is an organic peroxide and a highly efficient and low-temperature active initiator. Due to its excellent performance in free radical initiation and cross-linking reactions, it is widely used in polymerization processes and other organic synthesis processes. Usually, tert-butyl perpivalate is prepared by the reaction of tert-butyl hydroperoxide and pivaloyl chloride under alkaline conditions. However, tert-butyl perpivalate is very sensitive to temperature and prone to thermal decomposition, and the heat release during the synthesis process is large. The reaction temperature is usually controlled below 20 °C. The fluctuation of temperature may not only affect the quality of the product, but also trigger the thermal decomposition of the product, leading to thermal runaway. Therefore, the precise control of the temperature during its synthesis process is the key to ensuring production quality and safety.

[0003] Chinese Patent CN109678773A discloses a method for preparing tert-butyl peroxy-2-ethylhexanoate. Tert-butyl hydroperoxide and isododecane are mixed and stirred at 10-15 °C for 10-40 min, and then a potassium hydroxide solution and isooctanoyl chloride are simultaneously added dropwise and stirred for another 20-60 min. After standing at 0-5 °C until stratification, the upper organic phase is purified and separated to obtain the target product. This process involves the use of corrosive reagent acyl chloride, and the control of the reaction temperature during the process is required to be high. Subsequent standing separation is needed, and the operation steps are complex and the cycle is long.

[0004] Chinese Patent CN109331871B discloses a method for synthesizing tert-butyl / pentyl peroxycarboxylate. A polyvinyl alcohol composite amino acid catalyst is obtained by polymerizing a spherical polyvinyl alcohol matrix and a composite amino acid. An organic carboxylic acid, tert-butyl / pentyl hydroperoxide, and the polyvinyl alcohol composite amino acid catalyst are added to an organic solvent and stirred for dehydration reaction to synthesize tert-butyl / pentyl peroxycarboxylate. The water generated during the reaction is removed by azeotropic distillation. This process uses acid anhydride instead of highly corrosive acyl chloride, but involves the use and recovery of organic solvents. The reaction time is relatively long, reaching 1-24 h, and water needs to be continuously removed during the reaction process, and the operation is complicated.

[0005] Chinese Patent CN101287704A discloses a method for producing organic peroxides through microreaction technology. Using organic hydroperoxide and acyl chloride as raw materials, peroxycarboxylic acid esters are synthesized under alkaline conditions. The mixing effect of the two-phase reactants is enhanced by a static micro-mixer, and the liquid holdup and reaction residence time are reduced by a micro-reactor. However, in this invention, the temperature control requirements for each raw material and product are different, involving the control of multiple temperature zones and multiple processes, and the operation of the process is complex.

[0006] The above preparation process of peroxycarboxylic acid ester involves the use of strongly corrosive acyl chloride or organic solvents, and requires operations such as static separation. The operation steps are complex and the reaction cycle is long. To ensure production safety, the preparation process needs to strictly control low temperature. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for on-line preparation of tert-butyl peroxy pivalate in a microchannel. The method of the present invention combines a microchannel reactor and an on-line separation technology, strengthens heat and mass transfer, simplifies the process flow, shortens the reaction time, improves the reaction efficiency; and minimizes the inventory of organic peroxides and improves process safety.

[0008] To achieve the above invention purpose, the present invention provides a method for on-line preparation of tert-butyl peroxy pivalate in a microchannel, which includes the following implementation steps: A method for on-line preparation of tert-butyl peroxy pivalate in a microchannel, characterized in that pivalic anhydride and tert-butyl hydroperoxide are used as raw materials, and are continuously prepared in a microchannel reactor under the catalysis of sulfuric acid, and after quenching, the tert-butyl peroxy pivalate is obtained through on-line separation; The microchannel continuous reactor includes a first preheating module, a second preheating module, a reaction module, a quenching module and an on-line separation module; The specific steps are as follows: (1) Add sulfuric acid in a specific proportion to pivalic anhydride to form a premix, and send the pivalic anhydride sulfuric acid premix to the first preheating module for preheating; (2) Send the tert-butyl hydroperoxide solution to the second preheating module for preheating; (3) Send the preheated materials in steps (1) and (2) into the reaction module for mixing reaction by continuous feeding; (4) Send the material in step (3) into the quenching module and mix it with sodium bicarbonate solution for quenching; (5) Send the mixed material in step (4) into the on-line separation module, and the on-line liquid-liquid separator separates the aqueous phase and the organic phase, and the organic phase after separation obtains the tert-butyl peroxy pivalate.

[0009] Further, in step (1), the concentration of the sulfuric acid is 95-98%; the concentration of the pivalic anhydride is not less than 98%.

[0010] Further, in step (1), the dosage of the sulfuric acid is 1-10% of the molar amount of the pivalic anhydride.

[0011] Further, in step (1), for the sulfuric acid and pivalic anhydride premix, add sulfuric acid in a specific proportion to pivalic anhydride, stir for 5-10 min, and keep the temperature at 25-30 °C.

[0012] Further, in step (2), the concentration of the tert-butyl hydroperoxide solution is 70-100%.

[0013] Further, in steps (1) and (2), the preheating temperature is 5-40°C.

[0014] Further, in step (3), the reaction temperature of the pivalic anhydride premix and the tert-butyl hydroperoxide solution in the microchannel reactor is 5-40°C.

[0015] Further, in step (3), the molar ratio of pivalic anhydride to tert-butyl hydroperoxide is (3-1.5):1.

[0016] Further, in step (3), the residence time of the reaction materials in the microchannel reactor is 60-900 s.

[0017] Further, in step (4), the concentration of the sodium bicarbonate is 4 wt%, its temperature is precooled to 0-5°C, and it enters the quenching module by continuous feeding; after the materials in step (3) enter the quenching module, the temperature is reduced to 0-5°C.

[0018] Working principle: In the present invention, sulfuric acid in a specific ratio is added to pivalic anhydride to form a premix, and the pivalic anhydride sulfuric acid premix is sent to preheating module I for preheating; the tert-butyl hydroperoxide solution is sent to preheating module II for preheating; the preheated materials of the pivalic anhydride sulfuric acid premix and the tert-butyl hydroperoxide solution are sent to the reaction module for mixing and reaction by continuous feeding; then the materials are sent to the quenching module and mixed with the sodium bicarbonate solution for quenching; finally, the mixed materials of the signing process are sent to the online separation module, and the water phase and the organic phase are separated by an online liquid-liquid separator, and the organic phase after separation gives the tert-butyl peroxypivalate.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The microchannel reactor can greatly reduce the inventory of organic peroxides, shorten the reaction residence time, which can be reduced to a minimum of 1 min, and improve the reaction efficiency; (2) The enhanced heat and mass transfer effect of the microchannel reactor can achieve precise control of the reaction process temperature, broaden the safety operation temperature boundary, and improve the safety of the reaction system; (3) The application of the online quenching and separation technology can simplify the operation process, quickly reduce the product temperature, and improve the product stability. Brief description of the drawings

[0020] Figure 1 It is a schematic diagram of the composition module of the microchannel reactor used in the present invention. Detailed embodiments

[0021] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be further described through the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not intended to limit the protection scope of the present invention.

[0022] In the following embodiments, the pivalic anhydride is obtained by purchasing from the market with a purity of more than 98%, the tert-butyl hydroperoxide is obtained by purchasing from the market with a purity of 70% (solvent water), and the sulfuric acid is obtained by purchasing from the market with a purity of 95-98%. In the embodiments, the online separation module uses a Zaiput online liquid-liquid separator to separate the aqueous phase and the organic phase, and this separator is also purchased from the market. Example 1

[0023] (1) Prepare a pivalic anhydride sulfuric acid premix, where sulfuric acid:pivalic anhydride = 6.2%, molar ratio. After premixing for 10 minutes, pump it into preheating module 1 and preheat to 8.3 °C.

[0024] (2) Pump the tert-butyl hydroperoxide solution, where pivalic anhydride:tert-butyl hydroperoxide = 2.6:1, molar ratio, into preheating module 2 and preheat to 8.3 °C.

[0025] (3) Subsequently, in the reaction module, the pivalic anhydride sulfuric acid premix and the tert-butyl hydroperoxide solution are mixed and reacted for 863 s at a reaction temperature of 8.3 °C, and finally enter the quenching module to cool down to 0-5 °C.

[0026] (4) After the quenching module discharges, it enters the online separation module, and the aqueous phase and the organic phase are separated by an online liquid-liquid separator. The organic phase is the target product tert-butyl perpivalate.

[0027] (5) Measure the content of the collected organic phase. Through liquid chromatography analysis, the reaction yield is calculated to be 72%. Example 2

[0028] (1) Prepare a pivalic anhydride sulfuric acid premix, where sulfuric acid:pivalic anhydride = 8.3%, molar ratio. After premixing for 10 minutes, pump it into preheating module 1 and preheat to 19.6 °C.

[0029] (2) Pump the tert-butyl hydroperoxide solution, where pivalic anhydride:tert-butyl hydroperoxide = 2.5:1, molar ratio, into preheating module 2 and preheat to 19.6 °C.

[0030] (3) Subsequently, in the reaction module, the pivalic anhydride sulfuric acid premix and the tert-butyl hydroperoxide solution are mixed and reacted for 415 s at a reaction temperature of 19.6 °C, and finally enter the quenching module to cool down to 0-5 °C.

[0031] (4) After the quenching module discharges, it enters the online separation module, and the aqueous phase and the organic phase are separated by an online liquid-liquid separator. The organic phase is the target product tert-butyl perpivalate.

[0032] (5)Measure the content of the collected organic phase. Through liquid chromatography analysis, the reaction yield is calculated to be 68.5%. Example 3

[0033] (1)Prepare a premixed solution of pivalic anhydride and sulfuric acid, where the molar ratio of sulfuric acid to pivalic anhydride is 8.2%. After premixing for 10 minutes, pump it into preheating module 1 and preheat to 29.7 °C.

[0034] (2)Pump a solution of tert-butyl hydroperoxide, where the molar ratio of pivalic anhydride to tert-butyl hydroperoxide is 1.8:1, into preheating module 2 and preheat to 29.7 °C.

[0035] (3)Subsequently, carry out a mixing reaction of the premixed solution of pivalic anhydride and sulfuric acid and the solution of tert-butyl hydroperoxide in the reaction module for 372 s at a reaction temperature of 29.7 °C, and finally enter the quenching module to cool down to 0 - 5 °C.

[0036] (4)After the discharge from the quenching module, enter the online separation module. Separate the aqueous phase and the organic phase through an online liquid-liquid separator. The organic phase is the target product tert-butyl perpivalate.

[0037] (5)Measure the content of the collected organic phase. Through liquid chromatography analysis, the reaction yield is calculated to be 69.9%. Example 4

[0038] (1)Prepare a premixed solution of pivalic anhydride and sulfuric acid, where the molar ratio of sulfuric acid to pivalic anhydride is 4.2%. After premixing for 10 minutes, pump it into preheating module 1 and preheat to 30.3 °C.

[0039] (2)Pump a solution of tert-butyl hydroperoxide, where the molar ratio of pivalic anhydride to tert-butyl hydroperoxide is 2.5:1, into preheating module 2 and preheat to 30.3 °C.

[0040] (3)Subsequently, carry out a mixing reaction of the premixed solution of pivalic anhydride and sulfuric acid and the solution of tert-butyl hydroperoxide in the reaction module for 875 s at a reaction temperature of 30.3 °C, and finally enter the quenching module to cool down to 0 - 5 °C.

[0041] (4)After the discharge from the quenching module, enter the online separation module. Separate the aqueous phase and the organic phase through an online liquid-liquid separator. The organic phase is the target product tert-butyl perpivalate.

[0042] (5)Measure the content of the collected organic phase. Through liquid chromatography analysis, the reaction yield is calculated to be 72.7%. Example 5

[0043] (1) A premix of pivalic anhydride and sulfuric acid, where sulfuric acid:pivalic anhydride = 4.7%, molar ratio. After premixing for 10 min, it is pumped into preheating module 1 and preheated to 35.2 °C.

[0044] (2) A solution of tert-butyl hydroperoxide, where pivalic anhydride:tert-butyl hydroperoxide = 2.9:1, molar ratio. It is pumped into preheating module 2 and preheated to 35.2 °C.

[0045] (3) Subsequently, the premix of pivalic anhydride and sulfuric acid and the solution of tert-butyl hydroperoxide are mixed and reacted in the reaction module for 582 s at a reaction temperature of 35.2 °C, and finally enter the quenching module to cool down to 0 - 5 °C.

[0046] (4) After the discharge from the quenching module, it enters the on-line separation module. The aqueous phase and the organic phase are separated by an on-line liquid-liquid separator, and the organic phase is the target product tert-butyl perpivalate.

[0047] (5) The content of the collected organic phase is measured. By liquid chromatography analysis, the reaction yield is calculated to be 73.9%. Example 6

[0048] (1) A premix of pivalic anhydride and sulfuric acid, where sulfuric acid:pivalic anhydride = 9.7%, molar ratio. After premixing for 10 min, it is pumped into preheating module 1 and preheated to 40 °C.

[0049] (2) A solution of tert-butyl hydroperoxide, where pivalic anhydride:tert-butyl hydroperoxide = 2.7:1, molar ratio. It is pumped into preheating module 2 and preheated to 40 °C.

[0050] (3) Subsequently, the premix of pivalic anhydride and sulfuric acid and the solution of tert-butyl hydroperoxide are mixed and reacted in the reaction module for 60 s at a reaction temperature of 40 °C, and finally enter the quenching module to cool down to 0 - 5 °C.

[0051] (4) After the discharge from the quenching module, it enters the on-line separation module. The aqueous phase and the organic phase are separated by an on-line liquid-liquid separator, and the organic phase is the target product tert-butyl perpivalate.

[0052] (5) The content of the collected organic phase is measured. By liquid chromatography analysis, the reaction yield is calculated to be 69%.

[0053] From the above examples, the beneficial effects of the present invention can be known: (1) The microchannel reactor can significantly reduce the inventory of organic peroxides, shorten the reaction residence time, which can be reduced to as low as 1 min at the lowest, and improve the reaction efficiency; (2) The enhanced heat and mass transfer effect of the microchannel reactor can achieve precise control of the reaction process temperature, broaden the safety operation temperature boundary, and improve the safety of the reaction system; (3) The application of on-line quenching and separation technology can simplify the operation process, rapidly reduce the product temperature and improve the product stability.

Claims

1. A method for on-line preparation of tert-butyl peroxypivalate in a microchannel, characterized in that, Using pivalic anhydride and tert-butyl hydroperoxide as raw materials, continuously prepare in a microchannel reactor under the catalysis of sulfuric acid, and obtain tert-butyl peroxypivalate after quenching through online separation; The microchannel reactor includes a first preheating module, a second preheating module, a reaction module, a quenching module and an online separation module; the specific steps are as follows: (1) Add sulfuric acid with a specific ratio to pivalic anhydride to form a premix, and send the pivalic anhydride-sulfuric acid premix into the first preheating module for preheating; (2) Send the tert-butyl hydroperoxide solution into the second preheating module for preheating; (3) Send the materials preheated in steps (1) and (2) into the reaction module for mixing and reaction by continuous feeding; (4) Send the materials in step (3) into the quenching module and mix with sodium bicarbonate solution for quenching; (5) Send the mixed materials in step (4) into the online separation module, and separate the aqueous phase and the organic phase by an online liquid-liquid separator. After separation, the organic phase obtains the tert-butyl peroxypivalate.

2. The method for on-line preparation of tert-butyl peroxypivalate in a microchannel according to claim 1, characterized in that, In step (1), the concentration of the sulfuric acid is 95-98%; the concentration of the pivalic anhydride is not less than 98%.

3. A method for on-line preparation of tert-butyl peroxypivalate in a microchannel according to claim 1, characterized in that, In step (1), the amount of the sulfuric acid used is 1-10% of the molar amount of the pivalic anhydride.

4. A method for on-line preparation of tert-butyl perpivalate in a microchannel according to claim 1, characterized in that, In step (1), for the sulfuric acid-pivalic anhydride premix, add sulfuric acid with a specific ratio to pivalic anhydride, stir for 5-10 min, and keep the temperature at 25-30 °C.

5. A method for on-line preparation of tert-butyl perpivalate in a microchannel according to claim 1, characterized in that In step (2), the concentration of the tert-butyl hydroperoxide solution is 70-100%.

6. A method for on-line preparation of tert-butyl perpivalate in a microchannel according to claim 1, characterized in that, In steps (1) and (2), the preheating temperature is 5-40 °C.

7. A method for on-line preparation of tert-butyl peroxypivalate in a microchannel according to claim 1, characterized in that, In step (3), the reaction temperature of the pivalic anhydride premix and the tert-butyl hydroperoxide solution in the microchannel reactor is 5-40 °C.

8. A method for on-line preparation of tert-butyl peroxypivalate in a microchannel according to claim 1, characterized in that, In step (3), the molar ratio of pivalic anhydride to tert-butyl hydroperoxide is (3-1.5):

1.

9. A method for on-line preparation of tert-butyl peroxypivalate in a microchannel according to claim 1, characterized in that, In step (3), the reaction residence time of the reaction materials in the microchannel reactor is 60-900 s.

10. A method for on-line preparation of tert-butyl perpivalate in a microchannel according to claim 1, characterized in that, In step (4), the concentration of the sodium bicarbonate is 4 wt%, its temperature is precooled to 0-5 °C, and it enters the quenching module by continuous feeding; the materials in step (4) are cooled to 0-5 °C after entering the quenching module.

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