Process for the preparation of tert-butyl peroxy maleate

Abstract

This invention belongs to the field of acyclic compound technology, specifically relating to a method for preparing tert-butyl maleate peroxide. A tert-butyl hydrogen peroxide aqueous solution is added to deionized water and mixed, stirred, and cooled to obtain a mixed solution. Under stirring, liquid alkali and sodium nitrate are added sequentially to the mixed solution. After the addition is complete, stirring continues to produce reaction solution I. Under stirring, maleic anhydride is added to reaction solution I. After the addition is complete, stirring continues to produce reaction solution II. Under stirring, acid is added to reaction solution II. After the addition is complete, stirring continues to produce reaction solution III. Reaction solution III is washed with deionized water and filtered to obtain crude tert-butyl maleate peroxide. The crude tert-butyl maleate peroxide is washed and dried to obtain tert-butyl maleate peroxide. This invention does not use organic solvents, is environmentally friendly and cost-effective, and can increase the product yield to over 93%.

Description

Technical Field

[0001] This invention belongs to the field of acyclic compound technology, specifically relating to a method for preparing tert-butyl maleate peroxide. Background Technology

[0002] tert-butyl peroxide (TBPMA) has the molecular formula C8H. 12 O5, belonging to the ester-based organic peroxide class, is a highly efficient free radical polymerization initiator. It can be used as a curing agent for unsaturated polyester resins and a vulcanizing agent for silicone rubber, as well as in the polymerization of acrylic acid or monomers containing acrylic acid. Tert-butyl maleate peroxide has an accelerated decomposition temperature of 60℃. It is chemically reactive and easily decomposes upon heating, friction, or contact with reducing agents, releasing oxygen and free radicals, posing a risk of combustion or explosion.

[0003] Chinese patent CN117756689A discloses a method for synthesizing high-purity tert-butyl maleate peroxide. The method uses tert-butyl hydrogen peroxide, potassium hydroxide solution, and isododecane as raw materials. The reaction solution is continuously stirred and the reaction mixture is reserved for the next step. In the previous step, a certain amount of maleic anhydride is added to the reaction solution under controlled temperature and feeding rate, followed by water in a certain proportion to the reaction solution. The mixture is stirred and washed continuously. After the reaction is complete, the mixture is filtered to obtain crude tert-butyl maleate peroxide. The crude product is then neutralized and washed with sodium hydroxide, potassium hydroxide, or sodium carbonate until neutral. The solid is then separated by filtration and dried to obtain high-purity tert-butyl maleate peroxide. This patent requires a large amount of the organic solvent isododecane, resulting in high production costs and environmental unfriendliness. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing tert-butyl maleate peroxide, which is easy to operate, has a high product yield, is environmentally friendly, and is suitable for industrial applications.

[0005] The preparation method of tert-butyl maleate peroxide according to the present invention includes the following steps:

[0006] (1) Add tert-butyl hydrogen peroxide aqueous solution to deionized water, mix, stir and cool to obtain a mixed solution;

[0007] (2) Under stirring conditions, liquid alkali and sodium nitrate were added to the mixed solution in sequence. After the addition was completed, the reaction was stirred to obtain reaction solution I.

[0008] (3) Under stirring conditions, maleic anhydride was added to reaction solution I. After the addition was complete, the reaction was stirred to obtain reaction solution II.

[0009] (4) Under stirring conditions, acid is added to reaction solution II. After the addition is complete, the reaction is stirred to obtain reaction solution III.

[0010] (5) Add deionized water to reaction solution III for washing, filter, and obtain crude tert-butyl maleate peroxide;

[0011] (6) The crude tert-butyl maleate peroxide was washed and dried to obtain tert-butyl maleate peroxide.

[0012] In step (1), the concentration of the tert-butyl hydrogen peroxide aqueous solution is 50-99 wt.%, and the cooling temperature is 0-5℃.

[0013] In step (1), the mass ratio of tert-butyl hydrogen peroxide aqueous solution to deionized water is 1:1 to 10.

[0014] In step (2), the liquid alkali is an aqueous solution of sodium hydroxide or potassium hydroxide, the concentration of the liquid alkali is 20-50 wt.%, the mass of sodium nitrate is 1-5% of the mass of the liquid alkali, and the mass ratio of the liquid alkali to the aqueous solution of tert-butyl hydrogen peroxide in step (1) is 0.68-3.4:1.

[0015] In step (2), the temperature is 0-5℃, and the total addition time of liquid alkali and sodium nitrate is 10-30 min; the temperature of the stirring reaction is 5-10℃, and the stirring reaction time is 10-30 min.

[0016] In step (3), add the product at a temperature of 15-20°C for 10-30 minutes; stir the product at a temperature of 0-35°C for 30-300 minutes.

[0017] In step (3), the mass ratio of maleic anhydride to liquid alkali in step (2) is 1:1.13 to 2.94.

[0018] In step (4), the acid is one of sulfuric acid, hydrochloric acid or nitric acid, the concentration of the acid is 25-70 wt.%, the mass ratio of the acid to the tert-butyl hydrogen peroxide aqueous solution in step (1) is 0.33-1.7:1, the addition time is 5-30 min, the addition temperature is 0-35℃, the stirring reaction time is 20-30 min, and the stirring reaction temperature is 0-35℃.

[0019] In step (5), the washing time is 10 to 30 minutes and the washing temperature is 0 to 15°C.

[0020] In step (6), the washing is carried out with alkaline solution and deionized water. The alkaline solution is an aqueous solution of sodium bicarbonate with a concentration of 5 wt.% to saturation. The washing is performed 2 to 3 times. After washing, the pH value of the crude tert-butyl maleate peroxide is 7 to 8.

[0021] The reaction principle of this invention is as follows:

[0022] A mixture of tert-butyl hydrogen peroxide aqueous solution and deionized water forms a low-temperature mixed solution. Liquid alkali is then added to react with the tert-butyl hydrogen peroxide, generating a metal peroxide intermediate (tert-butyl peroxide sodium / potassium salt). Maleic anhydride is then added. Under alkaline conditions, maleic anhydride undergoes nucleophilic ring-opening, with hydroxide ions acting as nucleophiles to attack the carbonyl carbon atom of maleic anhydride, forming a tetrahedral intermediate. Subsequently, acyl-oxygen bond cleavage occurs, generating a monosodium / potassium maleate intermediate. Upon contact with the monosodium / potassium maleate intermediate, the metal peroxide intermediate preferentially attacks the carboxylic acid group, which is more acidic and more positively charged due to the electron delocalization of the conjugated system, resulting in nucleophilic addition and elimination reactions to generate peroxytert-butyl maleate monosodium / potassium salt. Adding a certain amount of acid allows for reaction with the peroxytert-butyl maleate monosodium / potassium salt to obtain the product, tert-butyl maleate peroxide.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. Base (activates the substrate and maintains an alkaline environment): tert-butyl hydroperoxide (TBHP) is a weakly acidic peroxide that can undergo partial deprotonation under alkaline conditions to generate tert-butyl peroxide anion ((CH3)3COO). - The oxygen atom of this negative ion exhibits stronger nucleophilicity and oxidizing properties. Simultaneously, the addition of liquid alkali to maintain the alkalinity of the system prevents the decomposition of TBHP in an acidic environment, thus improving raw material utilization. Furthermore, while the cyclic anhydride structure in maleic anhydride molecules possesses some electrophilicity, its own reactivity is relatively low. Alkali reacts with maleic anhydride in a nucleophilic ring-opening reaction, generating a monosodium / potassium maleate intermediate. The electron delocalization effect of the carboxyl anion in this intermediate enhances the electron cloud density of the double bond, significantly increasing its nucleophilicity. This makes it more readily reacted with the oxygen atom in the metal peroxide intermediate (tert-butyl peroxide sodium / potassium salt) to generate peroxytert-butyl maleate monosodium / potassium salt, which, upon further reaction with acid, generates tert-butyl maleate peroxide.

[0025] 2. Sodium nitrate (promotes oxidation cycle and electron transfer): Under alkaline conditions, nitrate ions (NO3) - It has certain oxidizing properties and can accept electrons from the double bond in the sodium / potassium maleate intermediate, thus being reduced to nitrite (NO2). - Meanwhile, TBHP's peroxide anions ((CH3)3COO) - As a strong oxidizing agent, it can oxidize NO2. - Re-oxidized to NO3 - , forming NO3 - →NO2 - →NO3 - The "cycle" accelerates the electron transfer between the sodium / potassium maleate intermediate and the metal peroxide intermediate, lowering the activation energy of the reaction and making it easier to proceed; the Na in the reaction system+ / K + It can form an ion pair (K) with the negative ion intermediate generated in the reaction. + / Na + · - OOC-CH=CH-COOH and K + / Na + · - The electrostatic interaction of the ion pairs (OOC(CH3)3) stabilizes the reaction transition state (peroxytert-butylmaleic acid monosodium / potassium salt formed by the combination of sodium / potassium maleate intermediate and metal peroxide intermediate), further lowering the reaction energy barrier and increasing the reaction rate.

[0026] Liquid alkali activates the substrate and maintains an alkaline environment. Sodium nitrate promotes oxidation cycle and electron transfer under alkaline conditions, accelerating the reaction rate. The two work synergistically to achieve the linkage of "substrate activation-electron transfer-environment regulation", ultimately achieving efficient synthesis of tert-butyl maleate peroxide.

[0027] 3. No organic solvents are added in this invention, which is environmentally friendly and cost-effective, while increasing the product yield to over 93%. Detailed Implementation

[0028] The present invention will be further described below with reference to embodiments.

[0029] Example 1

[0030] (1) Add 11.47g of deionized water to the reactor, then add 11.47g of 80wt.% tert-butyl hydrogen peroxide aqueous solution and mix. Stir and cool to 0℃ to obtain a mixed solution.

[0031] (2) Under stirring conditions, 12.18g of 35wt.% sodium hydroxide aqueous solution and 0.13g of sodium nitrate were added to the mixed solution in sequence at a temperature of 0-5℃. The total addition time of sodium hydroxide aqueous solution and sodium nitrate was 10min. After the addition was completed, the reaction was stirred at 5-10℃ for 30min to obtain reaction solution I.

[0032] (3) Under stirring conditions, 10.71 g of maleic anhydride was added to reaction solution I at a temperature of 15-20°C for 20 min. After the addition was completed, the reaction was stirred at 20°C for 180 min to obtain reaction solution II.

[0033] (4) Under stirring conditions, 3.83 g of 70 wt.% sulfuric acid was added dropwise to reaction solution II at a temperature of 20-25°C for 5 min. After the addition was completed, the reaction was stirred at 20°C for 30 min to obtain reaction solution III.

[0034] (5) Add 90g of deionized water to reaction solution III and wash for 10min at 0-15℃. Filter to obtain crude tert-butyl maleate peroxide.

[0035] (6) The crude tert-butyl maleate peroxide was washed three times with a 5 wt.% sodium bicarbonate aqueous solution and deionized water until pH=7, and dried to obtain the tert-butyl maleate peroxide product. The content of tert-butyl maleate peroxide was tested to be 98.6 wt.% and the product yield was 93.23%.

[0036] Example 2

[0037] (1) Add 51.03g of deionized water to the reactor, then add 18.35g of 50wt.% tert-butyl hydrogen peroxide aqueous solution and mix. Stir and cool to 5℃ to obtain a mixed solution.

[0038] (2) Under stirring conditions, 12.63g of 50wt.% sodium hydroxide aqueous solution and 0.63g of sodium nitrate were added to the mixed solution in sequence at a temperature of 0-5℃. The total addition time of sodium hydroxide aqueous solution and sodium nitrate was 30min. After the addition was completed, the reaction was stirred at 5-10℃ for 10min to obtain reaction solution I.

[0039] (3) Under stirring conditions, 10.71 g of maleic anhydride was added to reaction solution I at a temperature of 15-20°C for 30 min. After the addition was completed, the reaction was stirred at 35°C for 30 min to obtain reaction solution II.

[0040] (4) Under stirring conditions, 15.2 g of 36 wt.% hydrochloric acid was added dropwise to reaction solution II at a temperature of 30-35°C for 20 min. After the addition was completed, the mixture was stirred at 35°C for another 20 min to obtain reaction solution III.

[0041] (5) Add 90g of deionized water to reaction solution III and wash for 20min at 0-15℃. Filter to obtain crude tert-butyl maleate peroxide.

[0042] (6) The crude tert-butyl maleate peroxide was washed twice with saturated sodium bicarbonate aqueous solution and deionized water until pH=8, and dried to obtain the tert-butyl maleate peroxide product. The content of tert-butyl maleate peroxide was tested to be 99.1 wt.% and the product yield was 93.6%.

[0043] Example 3

[0044] (1) Add 92.7g of deionized water to the reactor, then add 9.27g of 99wt.% tert-butyl hydrogen peroxide aqueous solution and mix. Stir and cool to 3℃ to obtain a mixed solution.

[0045] (2) Under stirring conditions, 31.4 g of 20 wt.% potassium hydroxide aqueous solution and 0.50 g of sodium nitrate were added to the mixed solution in sequence. The addition temperature was 0-5℃. The total addition time of potassium hydroxide aqueous solution and sodium nitrate was 20 min. After the addition was completed, the reaction was stirred at 5-10℃ for another 20 min to obtain reaction solution I.

[0046] (3) Under stirring conditions, 10.71 g of maleic anhydride was added to reaction solution I at a temperature of 15-20°C for 10 min. After the addition was completed, the reaction was stirred at 0°C for 300 min to obtain reaction solution II.

[0047] (4) Under stirring conditions, 15.7g of nitric acid with a concentration of 25wt.% was added dropwise to reaction solution II at a temperature of 0-5℃ for 30min. After the addition was completed, the reaction was stirred at 0℃ for 25min to obtain reaction solution III.

[0048] (5) Add 90g of deionized water to reaction solution III and wash for 30min at 0-15℃. Filter to obtain crude tert-butyl maleate peroxide.

[0049] (6) The crude tert-butyl maleate peroxide was washed three times with a 7 wt.% sodium bicarbonate aqueous solution and deionized water until pH=7.5 to obtain the tert-butyl maleate peroxide product. The content of tert-butyl maleate peroxide was tested to be 98.8 wt.% and the product yield was 93.39%.

[0050] Comparative Example 1

[0051] Sodium nitrate was not added, and the other steps were the same as in Example 1. The content of tert-butyl maleate peroxide was measured to be 75.8 wt.%, and the product yield was 78.16%.

Claims

1. A method for preparing tert-butyl maleate peroxide, characterized in that... Includes the following steps: (1) Add tert-butyl hydrogen peroxide aqueous solution to deionized water, mix, stir and cool to obtain a mixed solution; (2) Under stirring conditions, liquid alkali and sodium nitrate were added to the mixed solution in sequence. After the addition was completed, the reaction was stirred to obtain reaction solution I. (3) Under stirring conditions, maleic anhydride was added to reaction solution I. After the addition was complete, the reaction was stirred to obtain reaction solution II. (4) Under stirring conditions, acid is added to reaction solution II. After the addition is complete, the reaction is stirred to obtain reaction solution III. (5) Add deionized water to reaction solution III for washing, filter, and obtain crude tert-butyl maleate peroxide; (6) The crude tert-butyl maleate peroxide was washed and dried to obtain tert-butyl maleate peroxide; In step (1), the concentration of the tert-butyl hydrogen peroxide aqueous solution is 50–99 wt.%. In step (2), the mass of sodium nitrate is 1-5% of the mass of liquid alkali, the liquid alkali is an aqueous solution of sodium hydroxide or potassium hydroxide, the concentration of the liquid alkali is 20-50 wt.%, and the mass ratio of the liquid alkali to the aqueous solution of tert-butyl hydrogen peroxide in step (1) is 0.68-3.4:

1. In step (3), the mass ratio of maleic anhydride to liquid alkali in step (2) is 1:1.13 to 2.94; In step (4), the acid is one of sulfuric acid, hydrochloric acid or nitric acid, and the concentration of the acid is 25 to 70 wt.%. The mass ratio of the acid to the tert-butyl hydrogen peroxide aqueous solution in step (1) is 0.33 to 1.7:

1.

2. The method for preparing tert-butyl maleate peroxide according to claim 1, characterized in that... In step (1), the cooling temperature is 0 to 5℃.

3. The method for preparing tert-butyl maleate peroxide according to claim 1, characterized in that... In step (1), the mass ratio of tert-butyl hydrogen peroxide aqueous solution to deionized water is 1:1 to 10.

4. The method for preparing tert-butyl maleate peroxide according to claim 1, characterized in that... In step (2), the temperature is 0-5℃, and the total addition time of liquid alkali and sodium nitrate is 10-30 min; the temperature of the stirring reaction is 5-10℃, and the stirring reaction time is 10-30 min.

5. The method for preparing tert-butyl maleate peroxide according to claim 1, characterized in that... In step (3), the temperature is 15-20℃ and the addition time is 10-30 min; the temperature for stirring the reaction is 0-35℃ and the stirring time is 30-300 min.

6. The method for preparing tert-butyl maleate peroxide according to claim 1, characterized in that... In step (4), the addition time is 5 to 30 minutes, the addition temperature is 0 to 35°C, the stirring reaction time is 20 to 30 minutes, and the stirring reaction temperature is 0 to 35°C.

7. The method for preparing tert-butyl maleate peroxide according to claim 1, characterized in that... In step (5), the washing time is 10 to 30 minutes and the washing temperature is 0 to 15°C.

8. The method for preparing tert-butyl maleate peroxide according to claim 1, characterized in that... In step (6), the washing is carried out with alkaline solution and deionized water. The alkaline solution is an aqueous solution of sodium bicarbonate with a concentration of 5 wt.% to saturation. The washing is performed 2 to 3 times. After washing, the pH value of the crude tert-butyl maleate peroxide is 7 to 8.