Method for preparing m-diisopropylbenzene peroxide through oxidation of m-diisopropylbenzene

Abstract

The invention provides a method for preparing m-diisopropylbenzene peroxide through oxidation of m-diisopropylbenzene. According to the invention, poly (N-isopropylacrylamide)-block-perfluorooctyl acrylate is prepared, the poly (N-isopropylacrylamide)-block-perfluorooctyl acrylate is added in the oxidation reaction process of m-diisopropylbenzene so as to promote the mixing of oil and water phases and further promote the oxidation reaction, and after the reaction is finished, the oil-water phase separation can be rapidly carried out, so that the smooth proceeding of the subsequent separation process is facilitated. The method is simple to operate and has an excellent application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing m-diisopropylbenzene peroxide by oxidation of m-diisopropylbenzene, belonging to the field of chemical preparation. Background Technology

[0002] m-Dipropylbenzene hydroperoxide (DHP) is a peroxide obtained by the oxidation of m-dipropylbenzene (m-DIPB). It can be used as a free radical reaction initiator, oxidant, and organic synthesis intermediate. Currently, it is used industrially in the production of α,α'-dihydroxy-diisopropylbenzene (DC) and resorcinol.

[0003] The current mainstream method for preparing m-diisopropylbenzene hydroperoxide (DHP) is to oxidize m-diisopropylbenzene with an oxygen-containing gas (such as air), as shown in the following reaction formula:

[0004]

[0005] This reaction is a free radical reaction, and the product is a peroxide. At the same time, some excessive oxidation reactions will occur, generating acidic substances and phenolic substances. Phenolic substances will inhibit the free radical reaction, causing the oxidation reaction to fail to proceed normally. Therefore, a low concentration of NaOH solution is usually added during the reaction to maintain the alkalinity of the reaction solution and ensure that the oxidation reaction proceeds smoothly.

[0006] The reactant diisopropylbenzene is insoluble in water, and the reaction solution is an oil-water two-phase mixture. Better mixing of the oil and water during the reaction is beneficial for its progress, while rapid and efficient phase separation of the oil and water after the reaction is desired to facilitate subsequent separation processes. Therefore, solving the problem of strong mixing and rapid phase separation of the oil-water two-phase mixture is a key technical challenge.

[0007] US Patent 3933921A discloses a method for producing hydroperoxides by oxidizing aromatic hydrocarbons having at least one tertiary carbon atom with oxygen or oxygen-containing gas in the presence of an alkaline aqueous solution. This method uses vigorous mechanical mixing to thoroughly emulsify and mix the oil and water phases, thereby accelerating the reaction. However, this method involves a complex mechanical mixing structure, and the invention does not address the issue of oil and water phase separation after the reaction. Therefore, finding an efficient way to solve the problem of vigorous mixing and rapid phase separation of the two phases is of great significance. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing m-diisopropylbenzene peroxide by oxidation of m-diisopropylbenzene. This method can effectively solve the problems of efficient mixing of oil and water phases and rapid phase separation after the reaction.

[0009] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0010] A method for preparing m-diisopropylbenzene peroxide by oxidation of m-diisopropylbenzene includes the following steps:

[0011] 1) Add m-diisopropylbenzene, NaOH aqueous solution, and poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate to the reactor, and stir and heat.

[0012] 2) Introduce air and apply pressure to carry out the oxidation reaction;

[0013] 3) After the reaction is complete, cool down to allow the oil and water to separate into two phases.

[0014] In a preferred embodiment of the present invention, the concentration of the NaOH aqueous solution in step 1) is 0.1-2 wt%, preferably 0.2-1 wt%. The mass ratio of m-diisopropylbenzene to the NaOH aqueous solution is 10:1 to 4:1; the amount of poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate added is 0.001-0.02% of the mass of m-diisopropylbenzene, preferably 0.002-0.01%.

[0015] The structural formula of the poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate in this invention is shown below:

[0016]

[0017] Where n = 35–45, m = 5–15, and p = 2–5.

[0018] As a preferred embodiment of the present invention, step 1) the preparation method of poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate includes the following steps:

[0019] a. Synthesis of poly(N-isopropylacrylamide) (PNIPAM) macromolecular chain transfer agent: Using N-isopropylacrylamide (NIPAM) as the raw material, 4-cyano-4-(phenylthiocarboxylthio)valerate (CPDB) as the RAFT (chain transfer) reagent, azobisisobutyronitrile (AIBN) as the initiator, and anhydrous dioxane as the solvent, the molar ratio of NIPAM:CPDB:AIBN:dioxane was 1:0.01~0.02:0.001~0.01:2~5 for polymerization. The reaction was carried out in an oil bath at 65~75℃ with stirring for 5~7 hours, followed by liquid nitrogen freezing. The reaction was terminated by opening the tube to expose air. After precipitation, centrifugation, drying, and purification, PNIPAM was obtained. n -CPDB; Specific operation: The reaction solution is added dropwise to cold diethyl ether (200mL, -20 to -10℃) to precipitate, centrifuged (8000 to 10000 rpm, 5 to 20 min), the precipitation is repeated 3 to 5 times, and vacuum dried for 12 to 36 hours to obtain a white solid.

[0020] b. Block copolymerization and disulfide bond introduction: Add PNIPAM to the reactor.n -CPDB, FOA (Perfluorooctyl acrylate), BADSDP (Dithiodimethylbis(ethane-2,1-diyl)diacrylate), AIBN, PNIPAM (Fluorobenzene) n The molar ratio of -CPDB:FOA:BADSDP:AIBN is 0.2–0.4:1:0.03–0.05:0.004–0.01. The concentration of FOA in the fluorobenzene solvent is 0.2–1 mol / L. After deoxygenation, the mixture is sealed. After reacting at 60–70°C for 16–20 hours, the mixture is frozen with liquid nitrogen and the reaction is terminated by exposure to air. The reaction solution is filtered through a PTFE membrane and purified by dialysis to obtain the product. The reaction solution is filtered through a 0.45 μm PTFE membrane to remove insoluble matter and dialyzed (molecular weight cutoff 3 kDa, deionized water, 24–48 hours, water changed 6–10 times).

[0021] As a preferred embodiment of the present invention, step 1) involves heating to 50-120°C, preferably 70-90°C.

[0022] As a preferred embodiment of the present invention, the pressure in step 2) is 1-10 barG, preferably 2-5 barG.

[0023] As a preferred embodiment of the present invention, the reaction time in step 2) is 10-30h, preferably 15-25h.

[0024] As a preferred embodiment of the present invention, in step 3), the temperature is lowered to 10-40°C, preferably 20-30°C.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] Poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate is a temperature-responsive reversible phase-change surfactant. At high temperatures (>32°C), the PNIPAM chains dehydrate and shrink, exposing an amphiphilic block structure. The perfluorooctyl group forms a weak "fluorine-hydrocarbon" interaction with the hydrocarbon oil phase, reducing the interfacial tension (down to <1mN / m) and forming a stable microemulsion. At low temperatures (<25°C), the PNIPAM chains rehydrate and extend, encapsulating the perfluorooctyl segments. The molecules self-assemble into "core-shell" micelles (the core is a perfluoro chain, and the shell is PNIPAM), detaching from the interface. The interfacial tension recovers to >15mN / m, resulting in rapid stratification. Based on the above-mentioned unique properties, this substance can promote oil-water mixing (emulsification) at high temperatures and automatically promote oil-water separation (demulsification) at low temperatures. Adding poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate during the oxidation reaction of m-diisopropylbenzene can achieve the purpose of promoting oil-water mixing and accelerating the reaction at normal reaction temperatures. After the reaction is completed and the temperature is lowered, it can play a demulsification role, realizing the rapid separation of the oil and water phases. Detailed Implementation

[0027] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0029] Unless otherwise specified, the raw materials and reagents used in the embodiments and comparative examples of this invention were all purchased from commercially available sources.

[0030] Product content test method:

[0031] High performance liquid chromatography: Shimadzu LC-20AT, operating conditions: column: Waters XSelect HSS T3 5μm×4.6mm×250mm, detection wavelength: 233nm, mobile phase: acetonitrile / water (containing 0.1% phosphoric acid) = 35 / 65, elution mode: isocratic elution, flow rate: 1.0mL / min, column temperature: 30℃, injection volume: 10μL.

[0032] Example

[0033] Example 1: Preparation of poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate

[0034] 1. Main reagents

[0035] monomer:

[0036] N-Isopropylacrylamide (NIPAM, ≥99%), MERCK Ltd.

[0037] Perfluorooctyl acrylate (FOA, ≥95%), Shanghai Aladdin Biochemical Technology Co., Ltd.

[0038] RAFT (chain transfer) reagent: 4-cyano-4-(phenylthiocarbamoylthio)valerate (CPDB, ≥98%), Beijing Innocare Technology Co., Ltd.

[0039] Initiator: Azobisisobutyronitrile (AIBN, ≥98%), Beijing Innocare Technology Co., Ltd.

[0040] Crosslinking agent: 2,2-dithiodiethanol diacrylate (BADSDP, 36837-96-4, containing disulfide bonds, ≥95%), Shanghai Maclean Biochemical Technology Co., Ltd.

[0041] Solvents: anhydrous dioxane, fluorobenzene (anhydrous grade), diethyl ether (AR grade).

[0042] 2. Instruments

[0043] Schlenk reaction tubes (pressure resistant), constant temperature oil bath, magnetic stirrer, dialysis bags (MWCO 3kDa), freeze dryer.

[0044] Inert gas system (N2 / Ar doublet), GPC (THF as mobile phase), nuclear magnetic resonance spectrometer ( 1 H / 19 F NMR).

[0045] Step-by-step synthesis process

[0046] Step 1: Synthesis of PNIPAM macromolecular chain transfer agent

[0047] Reaction system setup:

[0048] Add the following to the Schlenk tube:

[0049] NIPAM (22.6g)

[0050] CPDB (560mg)

[0051] AIBN (33mg)

[0052] Anhydrous dioxane (100 mL).

[0053] Oxygen was removed by three cycles of "freezing-vacuuming-nitrogen purging" (operating conditions for the three cycles: 1. Freezing stage temperature: -50℃, 3 hours; 2. Vacuuming stage: vacuum degree below 10Pa for 10 minutes; 3. Nitrogen purging stage: nitrogen flow rate 10L / h for 10 minutes, then restored to a slightly positive pressure of 0.101MPa. Repeat three cycles, oxygen residue <0.1%), and then sealed.

[0054] Polymerization reaction:

[0055] The reaction was carried out in a 70℃ oil bath with stirring for 6 hours (conversion rate >90%). 1 (The olefin peak disappeared as monitored by H NMR). Reaction equation:

[0056] n NIPAM + CPDB + (catalytic amount) AIBN → PNIPAM n -CPDB

[0057] Termination: Liquid nitrogen freezing, opening the tube to expose air.

[0058] purification:

[0059] The reaction solution was added dropwise into cold diethyl ether (2000 mL, -20 °C) to precipitate, and then centrifuged (8000 rpm, 5 min).

[0060] The precipitation was repeated three times, and the product was dried under vacuum for 24 hours to obtain a white solid (yield 85%).

[0061] Characterization: GPC measurement showed Mn≈5000Da, PDI=1.18; 1 1H NMR (CDCl3) confirmed the terminal thioester peak (δ 7.2-7.4 ppm).

[0062] Step 2: Block copolymerization and disulfide bond introduction

[0063] Reaction system:

[0064] Add the following to the Schlenk tube:

[0065] PNIPAM n -CPDB(10g)

[0066] Perfluorooctyl acrylate (FOA) (4.8g)

[0067] BADSDP (92 mg) of 2,2-dithiodiethanol diacrylate

[0068] AIBN (6.6mg)

[0069] Fluorobenzene (50mL)

[0070] Seal after deoxygenation.

[0071] Segment aggregation:

[0072] React at 65℃ for 18 hours (FOA conversion ~80%, via...) 19 (F NMR monitoring).

[0073] Termination: Liquid nitrogen freezing, followed by exposure to air.

[0074] PNIPAM n -S2NO2C 13 H 13 +m FOA+p BADSDP→PNIPAM n -*b*-[P(FOA m -stat-BADSDP p )]-S2NO2C 13 H 13

[0075] purification:

[0076] The reaction solution was filtered through a 0.45μm PTFE membrane to remove insoluble matter.

[0077] Dialysis (MWCO 3kDa, deionized water, 48 hours, 6 water changes).

[0078] Freeze-drying yielded a white, fluffy powder (yield ~78%).

[0079] Characterization and Validation:

[0080] GPC analysis: Using PMMA standard and THF as mobile phase, Mn = 10.2 kDa and PDI = 1.28 were measured.

[0081] Nuclear magnetic resonance:

[0082] 1 1H NMR (CDCl3): δ1.1ppm (PNIPAM-CH3), δ4.8ppm (-OCH2-of FOA), δ2.7ppm (ortho-disulfide bond).

[0083] 19 F NMR (CDCl3): -81ppm (CF3), -122ppm (CF2).

[0084] LCST test: 1 wt% aqueous solution, dynamic light scattering (DLS) showed a sudden increase in particle size (50 nm → 300 nm) at 32 °C.

[0085] Examples 2-5: Preparation of m-diisopropylbenzene Peroxide by Oxidation of m-Diisopropylbenzene

[0086] Add m-diisopropylbenzene, NaOH solution, and poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate to a 100ml pressure-resistant reactor. Stir at 500rpm, heat and automatically control the temperature, insert a bottom tube to introduce air (flow rate 100ml / min), react for 20h, analyze the composition of the reaction product by liquid chromatography, and calculate the yield.

[0087] The reaction conditions and results for each embodiment are shown in the table below:

[0088]

[0089]

[0090] Comparative Example 1

[0091] The oxidation of m-diisopropylbenzene was carried out in a 100ml pressure-resistant reactor under automatic temperature control and a stirring speed of 500rpm. Air was introduced through the bottom tube (flow rate 100ml / min) and the reaction was carried out for 20 hours. The composition of the reaction product was analyzed by liquid chromatography, and the yield was calculated. In Example 2, the poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate was replaced with the conventional emulsifier stearic acid, while all other conditions remained unchanged.

[0092]

[0093]

[0094] Comparative Example 2

[0095] The oxidation of m-diisopropylbenzene was carried out in a 100ml pressure-resistant reactor under automatic temperature control and a stirring speed of 500rpm. Air was introduced through the bottom tube (flow rate 100ml / min) and the reaction was carried out for 20 hours. The composition of the reaction product was analyzed by liquid chromatography, and the yield was calculated. Except for the absence of emulsifiers, all other conditions were the same as in Example 2.

[0096]

[0097] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing m-diisopropylbenzene peroxide by oxidation of m-diisopropylbenzene, comprising the following steps: 1) Add m-diisopropylbenzene, NaOH aqueous solution, and poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate to the reactor, and stir and heat. 2) Introduce air and apply pressure to carry out the oxidation reaction; 3) After the reaction is complete, cool down to allow the oil and water to separate into two phases; The structure of the poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate is as follows: Where n = 35–45, m = 5–15, and p = 2–5.

2. The method as described in claim 1, characterized in that, Step 1) The preparation method of poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate includes the following steps: a. Synthesis of poly(N-isopropylacrylamide) (PNIPAM) macromolecular chain transfer agent: Using N-isopropylacrylamide (NIPAM) as the raw material, 4-cyano-4-(phenylthiocarbamoylthio)valerate (CPDB) as the RAFT (chain transfer) reagent, azobisisobutyronitrile (AIBN) as the initiator, and anhydrous dioxane as the solvent, The polymerization reaction was carried out with a molar ratio of NIPAM:CPDB:AIBN:dioxane of 1:0.01~0.02:0.001~0.01:2~5. The reaction was carried out by stirring in an oil bath at 65~75℃ for 5~7 hours, followed by liquid nitrogen freezing. The reaction was terminated by opening the tube to expose air. After precipitation, centrifugation, drying and purification, PNIPAM was obtained. n -CPDB; Specific operation: The reaction solution is added dropwise to cold diethyl ether (200mL, -20 to -10℃) to precipitate, centrifuged (8000 to 10000 rpm, 5 to 20 min), the precipitate is dried under vacuum for 12 to 36 hours to obtain a white solid. b. Block copolymerization and disulfide bond introduction: Add PNIPAM to the reactor. n -CPDB, FOA (Perfluorooctyl acrylate), BADSDP (Dithiodimethylbis(ethane-2,1-diyl)diacrylate), AIBN, PNIPAM (Fluorobenzene) n The molar ratio of -CPDB:FOA:BADSDP:AIBN is 0.2–0.4:1:0.03–0.05:0.004–0.

01. The concentration of FOA in the fluorobenzene solvent is 0.2–1 mol / L. After deoxygenation, the mixture is sealed. After reacting at 60–70°C for 16–20 hours, the mixture is frozen with liquid nitrogen and the reaction is terminated by exposure to air. The reaction solution is filtered through a PTFE membrane and purified by dialysis to obtain the product. The reaction solution is filtered through a 0.45 μm PTFE membrane to remove insoluble matter and dialyzed (molecular weight cutoff 3 kDa, deionized water, 24–48 hours, water changed 6–10 times).

3. The method as described in claim 1 or 2, characterized in that, In step 1), the concentration of the NaOH aqueous solution is 0.1-2 wt%, preferably 0.2-1 wt%; and / or, the mass ratio of m-diisopropylbenzene to the NaOH aqueous solution is 10:1 to 4:1; the amount of poly(N-isopropylacrylamide)-block-perfluorooctyl acrylate added is 0.001-0.02% of the mass of m-diisopropylbenzene, preferably 0.002-0.01%.

4. The method according to any one of claims 1-3, characterized in that, Step 1) Heat to 50-120℃, preferably 70-90℃.

5. The method according to any one of claims 1-4, characterized in that, The pressure in step 2) is 1-10 barG, preferably 2-5 barG; and / or the reaction time in step 2) is 10-30 h, preferably 15-25 h.

6. The method according to any one of claims 1-5, characterized in that, In step 3), the temperature is lowered to 10-40℃, preferably 20-30℃.

7. The m-diisopropylbenzene peroxide prepared by the method according to any one of claims 1-6.

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