A method for preparing an organic peroxide

Abstract

This invention provides a method for preparing organic peroxides. The method involves reacting an organic alcohol or organic ketone with hydrogen peroxide in a microchannel reactor under the catalysis of concentrated sulfuric acid to obtain the organic peroxide. This invention utilizes a microchannel reactor for the synthesis of organic peroxides; the reaction of an organic alcohol with hydrogen peroxide and concentrated sulfuric acid yields organic peroxides with the corresponding structures. Furthermore, the use of a microchannel reactor avoids the harmful effects of excessive exothermic reactions, significantly shortens the reaction time, and allows for continuous reaction, effectively improving the yield.

Description

Technical Field

[0001] This invention belongs to the field of materials chemistry, and specifically relates to a method for preparing organic peroxides. Background Technology

[0002] Organic peroxides generally refer to organic compounds containing -OO-peroxy functional groups, formed by replacing hydrogen atoms in hydrogen peroxide with organic groups such as alkyl, acyl, and aromatic groups. They are characterized by decomposition upon heating above a certain temperature, producing oxygen-containing free radicals, and are unstable and easily decomposed. In chemical production, organic peroxides are mainly used as polymerization initiators and catalysts for synthetic resins. In the field of polymer materials, they can be used as initiators for free radical polymerization, grafting reactions, crosslinking agents for rubber and plastics, curing agents for unsaturated polyesters, and molecular weight and molecular weight distribution regulators in the preparation of spinning-grade polypropylene. Polluted air in the environment can produce peroxyacyl nitrate compounds through free radical reactions under light, which are particulate types of photochemical oxidants.

[0003] In the field of polymer materials, organic peroxides are used as initiators for free radical polymerization, initiators for grafting reactions, crosslinking agents for rubber and plastics, curing agents for unsaturated polyesters, and molecular weight and molecular weight distribution regulators in the preparation of spinning-grade polypropylene. Organic peroxides are sources of free radicals for the following applications: ① initiators for free radical polymerization and copolymerization of vinyl and diene monomers; ② vulcanizing agents for thermosetting resins; ③ crosslinking agents for elastomers and polyethylene.

[0004] Besides the aforementioned polymer materials industry, organic peroxides are used as photoinitiators and sensitizers in the film industry, in photosensitive polymers, photosensitive resins, etc., and are also commonly used in the production of epoxy resins. In medical materials, organic peroxides, combined with drugs, form initiators used to synthesize drug delivery matrices (such as microspheres, microcapsules, and drug films). In organic synthesis, organic peroxides are mainly used as oxidants and epoxidants. Additionally, organic peroxides are also used in medical devices and food disinfection, and in the textile, paper, and other daily chemical industries as bleaching agents, decolorizing agents, bactericides, and cleaning agents.

[0005] The decomposition temperature of an organic peroxide at an effective rate largely determines its application. Other important factors include cost, solubility, safety, efficiency, the type of free radicals generated, the necessity of cryogenic storage and transportation, compatibility with the production system, potential impact on the product, and the ability to be activated. Organic peroxides can decompose at controlled rates at high or room temperature to generate reactive free radicals.

[0006] All organic peroxides are thermally unstable, and their decomposition accelerates with increasing temperature. A common quantitative method for determining the reactivity of organic peroxides is by measuring their half-life, which is the time required for a given amount of peroxide to decompose to half its initial amount at a specific temperature. Currently, half-life data for commercial organic peroxides are available on computer floppy disks. A suitable peroxide can be selected for a given polymerization or process condition using a computer menu program.

[0007] These free radicals can be added to unsaturated vinyl monomers such as styrene, vinyl chloride, or methyl methacrylate to initiate polymerization reactions. Some free radicals also attack polymers such as polyethylene (PE) to generate free radicals on the chain. When two such polymer free radicals combine, a cross-linked structure is formed. Currently, organic peroxides are generally synthesized using organic alcohols and hydrogen peroxide in the presence of concentrated sulfuric acid. However, the raw materials used in this reaction are highly hazardous (strong oxidizing agents, easily corrosive, and explosive). Summary of the Invention

[0008] To reduce the risk, this invention provides a method for preparing organic peroxides. The technical solution involves reacting an organic alcohol or organic ketone with hydrogen peroxide in a microchannel reactor under the catalysis of concentrated sulfuric acid to obtain the organic peroxide. The concentrated sulfuric acid is an aqueous solution of sulfuric acid with a mass fraction greater than or equal to 70%.

[0009] In some implementations, the reaction temperature is 0-80°C.

[0010] In some implementations, the reaction pressure is atmospheric pressure.

[0011] In some implementations, the microchannel reaction time is 10-60 min.

[0012] In some embodiments, the organic alcohol or organic ketone is in an equivalent ratio of 1:0.5-2.5 to the hydrogen peroxide.

[0013] In some embodiments, the concentrated sulfuric acid comprises more than 45% of the mixture; the mixture consists of the organic alcohol or ketone, the hydrogen peroxide, and the concentrated sulfuric acid. That is, the percentage of sulfuric acid in the mixture is more than 45%.

[0014] In some embodiments, the organic alcohol is selected from one or more of 2,5-dimethyl-2,5-hexanediol, 1,4-dihydroxy-diisopropylbenzene, tert-butanol, and their derivatives; the organic ketone is selected from one or more of butanone and its homologues. Homologues of butanol include acetone and pentanone.

[0015] In some embodiments, the organic peroxide is 2,5-dimethyl-2,5-bis(tert-butadiene)hexane; the specific preparation method is as follows: 2,5-dimethyl-2,5-hexanediol is dissolved in hydrogen peroxide, and then passed into a microchannel reactor together with concentrated sulfuric acid. After the reaction, a solid is precipitated. The solid is separated and dissolved in tert-butanol, and then reacted with concentrated sulfuric acid to obtain the final product.

[0016] In some embodiments, the organic peroxide is di-tert-butylperoxide hexane; the specific preparation method is as follows: tert-butanol and hydrogen peroxide are introduced into a microchannel reactor together with concentrated sulfuric acid in a certain proportion. After the reaction, the system separates into phases, and the resulting oil phase is di-tert-butylperoxide.

[0017] In some embodiments, the organic peroxide is bis-tert-butylperoxyisopropylbenzene; the preparation method is as follows: tert-butanol and hydrogen peroxide are introduced into a microchannel reactor together with concentrated sulfuric acid in a certain proportion. After the reaction, the system is separated into phases, and the resulting oil phase is tert-butylperoxyisopropylbenzene. The oil phase is then mixed with bis-tert-butylperoxyisopropylbenzene and introduced into a microchannel reactor together with concentrated sulfuric acid to obtain bis-tert-butylperoxyisopropylbenzene.

[0018] In some embodiments, the organic peroxide is 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane; its preparation method is as follows: butanone and hydrogen peroxide are introduced into a microchannel reactor together with concentrated sulfuric acid in a certain proportion. After the reaction, the system separates into phases, and the resulting oil phase is 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane.

[0019] Microreactors, microstructured reactors, and microchannel reactors refer to chemical reactions that can be completed within a lateral dimension of less than 1 mm. The most typical example of this structure is the microchannel. Microreactors are a discipline in the field of microfabrication engineering, and these devices (such as micro heat exchangers) also involve some physical reactions. These microreactors are typically continuous fluid reactors (as opposed to batch reactors). Compared with conventional reaction equipment, microreactors have advantages in many aspects, not only in heat exchange efficiency, reaction rate, yield, safety, stability, monitorability, on-site / on-demand production, but also in enabling more precise production control.

[0020] This invention utilizes a microchannel reactor to synthesize organic peroxides. Organic alcohols are reacted with hydrogen peroxide and concentrated sulfuric acid to obtain organic peroxides with corresponding structures. Furthermore, the use of a microchannel reactor avoids the hazards of excessive exothermic reactions, significantly shortens the reaction time, and allows the reaction to proceed continuously, effectively improving the yield.

[0021] The present invention has the following advantages over traditional processes:

[0022] 1. The reaction process is simple. Compared with traditional methods for synthesizing organic peroxides, the method involved in this invention can avoid the harm caused by a large amount of exothermic reaction due to the characteristics of the microchannel reactor. It can carry out the reaction directly at a higher temperature and the reaction time is short.

[0023] 2. High production efficiency: Microchannel reactors can carry out continuous reactions, reducing pretreatment and posttreatment steps and saving overall reaction time.

[0024] 3. High safety factor: The microchannel reactor has a small liquid holdup and accurate temperature control, ensuring the safety of the production process. Detailed Implementation

[0025] To make the technical means, inventive features, achieved objectives and effects of the invention readily understandable, the invention is described below with reference to specific embodiments. However, the invention is not limited to the examples described below. In the following embodiments, the flow rate introduced into the microchannel reactor is 0.1-50 ml / min, preferably 0.1-20 ml / min.

[0026] Comparative Example 1

[0027] 97g of hydrogen peroxide was added to a flask, and 63g of concentrated sulfuric acid was slowly added at 0℃, followed by 14.6g of 2,5-dimethyl-2,5-hexanediol. The reaction was carried out at 15℃, and after 3 hours, a large amount of white solid precipitated. The solid was filtered and washed with water to obtain 2,5-dimethyl-2,5-peroxyhexanediol with a yield of 98%. 1.45g of 2,5-dimethyl-2,5-peroxyhexanediol was added to a mixed solution (7.8g tert-butanol / 4.2g concentrated sulfuric acid / 2g water), and the temperature was raised to 40℃ for reaction. After 2 hours, the reaction system separated into phases. The upper oil phase was collected and washed with anhydrous sodium carbonate to obtain 2,5-dimethyl-2,5-bis(tert-butperoxy)hexane with a yield of 77%.

[0028] Example 1

[0029] 14.6 g of 2,5-dimethyl-2,5-hexanediol was dissolved in 97 g of hydrogen peroxide. The solution was then introduced into a microchannel reactor at 40 °C and a 2:1 ratio with concentrated sulfuric acid. The residence time was 20 min, resulting in the precipitation of a large amount of white solid. This solid was filtered to obtain 2,5-dimethyl-2,5-peroxyhexanediol. The obtained 2,5-dimethyl-2,5-peroxyhexanediol was dissolved in a mixed solution (7.8 g tert-butanol / 4.2 g concentrated sulfuric acid / 2 g water). The solution was heated to 40 °C and introduced into the microchannel reactor. After 15 min, the reaction system underwent phase separation. This separation was performed using a continuous phase oil-water separator to obtain 2,5-dimethyl-2,5-bis(tert-butperoxy)hexane with a yield of 98%.

[0030] Comparative Example 2

[0031] 31.4 g of concentrated sulfuric acid was gradually added to 13.6 g of hydrogen peroxide (30%) at 0 °C, followed by the gradual addition of 20 g of tert-butanol. The reaction was controlled at 30 °C for 3 h. The reaction system was divided into two phases. The upper oil phase was washed with anhydrous sodium carbonate to obtain di-tert-butyl peroxide with a yield of 98%.

[0032] Example 2

[0033] 20g of tert-butanol and 13.6g of hydrogen peroxide were mixed and fed into a microchannel reactor at a ratio of 1:1 with 32g of concentrated sulfuric acid at 60℃. After 20 minutes, a two-phase mixture was obtained. The mixture was separated by a continuous phase oil-water separator. The oil phase was di-tert-butyl peroxide, with a yield of 99%.

[0034] Comparative Example 3

[0035] At 0°C, 5g of concentrated sulfuric acid was gradually added to 10g of hydrogen peroxide (35%), followed by 5g of tert-butanol. The mixture was heated to 30°C and reacted for 3 hours to obtain a phase-separated liquid. The upper oil phase was collected and washed with anhydrous sodium carbonate to obtain peroxytert-butanol with a yield of 99%. 0.5g of peroxytert-butanol was then mixed with 0.5g of α,α-dihydroxy-1,4-diisopropylbenzene and dissolved in 10ml of tetrahydrofuran. 6g of concentrated sulfuric acid was gradually added at 0°C. After the addition was complete, the mixture was heated to 40°C and reacted for 2 hours to obtain a white turbid liquid. After filtration, bis-tert-butylperoxyisopropylbenzene was obtained with a yield of 66%.

[0036] Example 3

[0037] Peroxytert-butanol and α,α-dihydroxy-1,4-diisopropylbenzene were mixed at a mass ratio of 1:1. 10g of the mixture was dissolved in 40g of tetrahydrofuran. The mixture was then fed into a microchannel reactor at a ratio of 10:1 with concentrated sulfuric acid at 60℃. After 30min, a white turbid liquid was obtained. After filtration, bis-tert-butylperoxyisopropylbenzene was obtained with a yield of 85%.

[0038] Comparative Example 4

[0039] 4.9 g of concentrated sulfuric acid was slowly added to 11.4 g of hydrogen peroxide (30%) at 0 °C, followed by the addition of 1.5 g of butanone. The reaction was carried out at 40 °C for 3 h to obtain a phase-separated system. The oil phase was collected and washed with anhydrous sodium carbonate to obtain 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane with a yield of 82%.

[0040] Example 4

[0041] A mixture of concentrated sulfuric acid and butanone (4.9 g concentrated sulfuric acid / 1.5 g butanone) and 11.4 g hydrogen peroxide were introduced into a microchannel reactor at a ratio of 1:2 at 60 °C. After 20 min, a phase-separated system was obtained. The system was separated using a continuous phase oil-water separator. The oil phase was collected to obtain 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane with a yield of 94%.

[0042] Comparative Example 5

[0043] 20g of tert-butanol was mixed with 13.6g of hydrogen peroxide. At 60℃, 32g of concentrated sulfuric acid was added dropwise to the mixture at a rate of 6ml / min. After 3 minutes, the mixture boiled and exploded. The solution turned reddish-brown and produced a coke-like substance.

[0044] Comparative Example 6

[0045] 20g of tert-butanol and 13.6g of hydrogen peroxide were mixed and fed into a microchannel reactor at a ratio of 2:1 with 16g of concentrated sulfuric acid at 60℃. After 20 minutes, a two-phase mixture was obtained. The mixture was separated using a continuous phase oil-water separator. The oil phase was tert-butyl peroxide, with a yield of 30%, and the target product could not be obtained.

[0046] Comparative Example 7

[0047] 20g of tert-butanol was mixed with 13.6g of hydrogen peroxide and fed into a microchannel reactor at 95℃ with 32g of concentrated sulfuric acid in a 1:1 ratio. After 20 minutes, a reddish-brown liquid was obtained, but the target product could not be obtained.

[0048] In this invention, the target product cannot be obtained when the sulfuric acid concentration is below 45% (i.e., the percentage of sulfuric acid in the mixture is below 45%) or the reaction temperature exceeds 80°C. For example, Comparative Examples 6 and 7 represent the cases where the sulfuric acid concentration is reduced to outside the range and the temperature is increased to outside the range, respectively, based on Example 2.

[0049] This invention also specifies requirements for reaction time (microchannel reaction time: 10-60 min) and the ratio of organic alcohol or ketone to hydrogen peroxide (equivalent ratio: 1:0.5-2.5). While reactions occurring outside the specified time will not cause deviations in the synthesis process, they will affect its economics, i.e., impact yield and / or consume excessive time. Similarly, while the ratio of organic alcohol or ketone to hydrogen peroxide will not lead to qualitative differences in the target product, it has a significant impact on reaction conversion rate and economics.

[0050] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing an organic peroxide, characterized in that, The organic peroxide was synthesized by reacting organic ketones with hydrogen peroxide in a microchannel reactor under the catalysis of concentrated sulfuric acid. At a reaction temperature of 60°C, a mixture of 4.9 g concentrated sulfuric acid and 1.5 g butanone was introduced into the microchannel reactor at a ratio of 1:2 with 11.4 g hydrogen peroxide. After 20 min, a phase-separated system was obtained. The system was separated using a continuous phase oil-water separator, and the oil phase was collected to obtain 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane.