Energy-saving and environment-friendly production process of o-nitro-p-tert-butylphenol

Abstract

The invention relates to the technical field of organic synthesis, and provides an energy-saving and environment-friendly production process of o-nitro-p-tert-butylphenol, which comprises the following steps: in a stirring state, adding a catalyst into a dilute nitric acid solution, continuously adding p-tert-butylphenol according to a feeding rate of 300-400kg / h, and mixing and reacting for 3-5 hours to obtain a mixed solution; and standing the mixed solution for 30-45 minutes, separating liquid, washing a lower-layer phase with water, standing for 20-40 minutes, separating liquid to obtain a lower-layer product, namely an o-nitro-p-tert-butylphenol crude product, and distilling and purifying under vacuum reduced pressure to obtain the o-nitro-p-tert-butylphenol. The production process disclosed by the invention is simple to operate, free of addition of a solvent, energy-saving, environment-friendly and high in production safety, meanwhile, water can be recycled and reused, coordinated development of economic benefits and environmental benefits is realized, and the obtained o-nitro-p-tert-butylphenol is high in yield and purity and has a relatively good application value.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis technology, and specifically relates to an energy-saving and environment-friendly production process of o-nitro-p-tert-butylphenol. Background Art

[0002] Nitration is a chemical process that introduces nitro groups into organic compound molecules. Nitro compounds play an important role in many fields, including explosives manufacturing, dye synthesis, solvent production, and pharmaceutical development. In addition, nitro compounds also serve as key intermediates in synthetic chemistry. They can be converted into derivatives such as nitroso compounds, amines, azo compounds, and hydrazines through a series of reduction reactions. These derivatives can further participate in chemical reactions to generate a variety of nitrogen-containing compounds with important application value. In particular, tert-butylphenol can be converted into its ortho-derivative, ortho-nitro-tert-butylphenol, through nitration. This conversion process is of great significance in organic synthesis.

[0003] As a key chemical intermediate, o-nitro-p-tert-butylphenol usually appears as yellow crystals or oily transparent liquids in its pure form, and plays a vital role in the field of chemical synthesis. At present, there are two main process routes for the synthesis of o-nitro-p-tert-butylphenol. One is the concentrated nitric acid nitration method, in which p-tert-butylphenol is dissolved in a solvent, and then concentrated nitric acid solution is gradually added for nitration; however, the solubility of p-tert-butylphenol in the solvent is not ideal, which not only requires the consumption of a large amount of solvent, but also makes the subsequent purification process cumbersome. The second is the mixed acid nitration method, in which p-tert-butylphenol is nitrated in a mixed acid environment, which has reached the level of industrial production; but the use of mixed acid will reduce the purity of the product, which is not conducive to high-quality production.

[0004] In general, traditional chemical synthesis processes are often accompanied by environmental pollution or product quality problems. The development of clean and environmentally friendly production methods is an important issue in the current chemical industry. The research on the synthesis process of o-nitro-p-tert-butylphenol is based on this concept and aims to achieve the coordinated development of economic and environmental benefits.

[0005] Chinese patent CN 109896960 A discloses a method for synthesizing o-nitro-p-tert-butylphenol, wherein p-tert-butylphenol is added in batches to a 25-35wt% dilute nitric acid solution under stirring, reacted at 10-30°C for 3-5h, separated and washed with alkali to obtain o-nitro-p-tert-butylphenol. This invention has the advantages of simple process, high yield, low pollution, and suitability for scale-up production. However, the reaction temperature range is large, and it is difficult to ensure that the reaction maintains a high yield. Experiments show that the yield is less than 86%.

[0006] Therefore, there is an urgent need for an energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, which can not only simplify the process but also achieve a high yield. Summary of the invention

[0007] In view of the existing technical problems, the purpose of the present invention is to provide an energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol. The production process of the present invention is simple to operate, does not need to add solvent, is energy-saving and environmentally friendly, has high production safety, and water can be recycled and reused, achieving the coordinated development of economic benefits and environmental benefits. The obtained o-nitro-p-tert-butylphenol has a high yield and high purity, and has good application value.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] The present invention provides an energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol, comprising the following steps:

[0010] S1. Under stirring, a catalyst was added to a dilute nitric acid solution, and p-tert-butylphenol was continuously added at a feed rate of 300-400kg / h, and the mixture was reacted for 3-5h to obtain a mixed solution;

[0011] S2. The mixed solution obtained in step S1 is allowed to stand for 30-45 minutes and then separated. The lower phase is washed with water and allowed to stand for 20-40 minutes for separation. The lower product obtained is crude o-nitro-p-tert-butylphenol, which is purified by distillation under vacuum to obtain o-nitro-p-tert-butylphenol.

[0012] The reaction mechanism and effects of the present invention are as follows:

[0013] 1. The present invention can ensure that the nitration reaction is complete within the reaction time by controlling the amount of the dilute nitric acid solution; and at the same time, avoid the decrease in product purity caused by unreasonable concentration of the dilute nitric acid solution.

[0014] 2. The present invention strictly controls the molar ratio of p-tert-butylphenol to dilute nitric acid to ensure complete nitration reaction and improve purity, while avoiding waste of raw materials and saving energy and protecting the environment.

[0015] 3. The present invention strictly controls the temperature of the nitration reaction to ensure the smooth progress of the reaction while avoiding excessively fast reaction rate caused by excessive temperature, which may cause production safety problems; in addition, the temperature of the nitration reaction will also affect the purity of o-nitro-p-tert-butylphenol.

[0016] 4. The present invention combines 3,5-diisopropyl o-hydroxybenzoic acid with carbon nanotubes to form a catalyst, and controls the reaction rate by controlling the mass ratio of the catalyst to p-tert-butylphenol to avoid excessive reaction and explosion. On the one hand, as p-tert-butylphenol reacts with dilute nitric acid, the system temperature continues to rise, and high temperature conditions increase the occurrence of oxidation side reactions and generate nitrophenol by-products. Carbon nanotubes, due to their unique nanostructure and excellent physical properties, can effectively improve heat exchange rate and heat dissipation efficiency, improve the yield and purity of the product, and improve safety.

[0017] On the other hand, the introduction of 3,5-diisopropyl o-hydroxybenzoic acid can control the reaction rate while ensuring the yield and purity. The molecule of 3,5-diisopropyl o-hydroxybenzoic acid is relatively large, which provides steric hindrance during the nitration process, hindering the attack of nitric acid on p-tert-butylphenol, thereby slowing down the nitration rate; at the same time, 3,5-diisopropyl o-hydroxybenzoic acid is a strong electron donating group, which may affect the electron density of p-tert-butylphenol through the conjugation effect, reduce its nucleophilicity to the nitrating agent, and slow down the reaction rate; in addition, 3,5-diisopropyl o-hydroxybenzoic acid competes with p-tert-butylphenol for the active sites in the dilute nitric acid solution, reducing the direct contact between p-tert-butylphenol and dilute nitric acid, thereby slowing down the nitration rate, but at the same time, the amount of catalyst added is strictly controlled, and the accessible sites of 3,5-diisopropyl o-hydroxybenzoic acid are limited, making it difficult for the reaction to produce other nitro products related to it.

[0018] Furthermore, due to the stability of its carrier, the catalyst is easier to separate and recover after the reaction, which helps to reduce costs and environmental impact, and achieve coordinated development of economic and environmental benefits.

[0019] 5. The present invention uses water washing to neutralize the excess dilute nitric acid in the reaction system, thereby reducing other polynitration products, and the water can be recycled, making the reaction process more environmentally friendly.

[0020] 6. The present invention maintains a specific stirring rate throughout the reaction. In the initial stage of the nitration reaction, the role of stirring is particularly critical. At this time, the density difference between the reactants is large, resulting in uneven mixing, and the reaction process is accompanied by the rapid release of a large amount of heat. In order to effectively solve the challenges of mass transfer and heat transfer, the nitration reaction is promoted by maintaining a specific stirring rate. In addition, stopping stirring or intermittent stirring is very dangerous and is likely to cause serious safety accidents.

[0021] In some embodiments, the mass ratio of p-tert-butylphenol to catalyst in step S1 is 1:(0.005-0.01).

[0022] In some embodiments, the mass fraction of the dilute nitric acid solution in step S1 is 18-25%.

[0023] In some embodiments, the molar ratio of p-tert-butylphenol to the dilute nitric acid in the dilute nitric acid solution in step S1 is 1:(1.1-1.4).

[0024] Preferably, the molar ratio of p-tert-butylphenol to the dilute nitric acid in the dilute nitric acid solution in step S1 is 1:(1.2-1.3).

[0025] In some embodiments, the temperature of the mixing reaction in step S1 is 28-30°C.

[0026] In some embodiments, the stirring rate in step S1 is 200-500 r / min.

[0027] In some embodiments, the method for preparing the catalyst in step S1 comprises the following steps:

[0028] (1) adding carbon nanotubes, concentrated nitric acid solution and concentrated sulfuric acid solution into a reaction kettle, heating under reflux in an oil bath at 100-120° C. for 1-1.5 h, repeatedly filtering and rinsing with deionized water until neutral, and drying to obtain acidified carbon nanotubes;

[0029] (2) The acidified carbon nanotubes obtained in step (1) are added to deionized water for ultrasonic dispersion, and a dimethyl sulfoxide solution of 3,5-diisopropyl o-hydroxybenzoic acid and N,N'-dicyclohexylcarbodiimide are added, heated to 30-50° C., stirred for reaction for 12-16 hours, centrifuged, washed, and dried to obtain a catalyst.

[0030] In some embodiments, the mass fraction of the concentrated nitric acid solution in step (1) is 58-70%, and the mass fraction of the concentrated sulfuric acid solution is 92-98%.

[0031] In some embodiments, the ratio of the carbon nanotubes, concentrated nitric acid solution and concentrated sulfuric acid solution in step (1) is (35-45) g: 0.5 L: (1.5-2.5) L.

[0032] In some embodiments, the mass ratio of the acidified carbon nanotubes to 3,5-diisopropyl-o-hydroxybenzoic acid in step (2) is (2-4):1.

[0033] In some embodiments, the yield of the produced o-nitro-p-tert-butylphenol is not less than 95%, and the purity is not less than 98%.

[0034] In some embodiments, the production process uses an internal titanium alloy coil containing deep well water for cooling throughout the process.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The production process of the present invention is simple to operate, does not require the addition of solvents, is energy-saving and environmentally friendly, has high production safety, and water can be recycled and reused, thereby achieving coordinated development of economic benefits and environmental benefits. The yield of the obtained o-nitro-p-tert-butylphenol is not less than 90%, and the purity is not less than 98%, thereby having good application value.

[0037] 2. The present invention controls the amount of dilute nitric acid solution and coordinates the molar ratio of p-tert-butylphenol to dilute nitric acid to ensure that the nitration reaction is complete within the reaction time and avoid a decrease in product purity.

[0038] 3. The present invention strictly controls the temperature of the nitration reaction to ensure the smooth progress of the reaction while avoiding excessively high temperature causing a too fast reaction rate and causing safety problems.

[0039] 4. The present invention controls the reaction rate by controlling the mass ratio of the catalyst to p-tert-butylphenol to avoid overly fast reaction and explosion. On the one hand, carbon nanotubes can effectively improve the heat exchange rate and heat dissipation efficiency due to their unique nanostructure and excellent physical properties, thereby improving the yield and purity of the product while improving safety. On the other hand, the introduction of 3,5-diisopropyl o-hydroxybenzoic acid can control the reaction rate while ensuring the yield and purity, and strictly control the amount of catalyst added, and the accessible sites of 3,5-diisopropyl o-hydroxybenzoic acid are limited, so that the reaction is not easy to produce by-products.

[0040] 5. The present invention maintains a specific stirring rate throughout the reaction, which promotes the smooth progress of the nitration reaction and improves safety. DETAILED DESCRIPTION

[0041] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, rather than to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0042] According to the ratios of the raw materials and the preparation methods specified in the following examples and comparative examples, o-nitro-p-tert-butylphenol was produced.

[0043] In order to facilitate those skilled in the art to implement the present invention, the sources of some raw materials in the embodiments and comparative examples are described as follows:

[0044] Carbon nanotubes: purchased from Shanghai Lishuo Composite Materials Technology Co., Ltd.;

[0045] Other raw materials are not specially specified and can be purchased from the market.

[0046] Preparation Example 1

[0047] The preparation method of catalyst A comprises the following steps:

[0048] (1) 4 kg of carbon nanotubes, 50 L of 68 wt% concentrated nitric acid solution and 200 L of 98 wt% concentrated sulfuric acid solution were added to a reaction kettle, refluxed in an oil bath at 110° C. for 1 h, repeatedly filtered and rinsed with deionized water until neutral, and dried at 105° C. for 3 h to obtain acidified carbon nanotubes;

[0049] (2) Dispersing 4 kg of 3,5-diisopropyl o-hydroxybenzoic acid in 10 L of dimethyl sulfoxide to obtain a dimethyl sulfoxide solution of 3,5-diisopropyl o-hydroxybenzoic acid for later use; adding 3 kg of the acidified carbon nanotubes obtained in step (1) into 6 L of deionized water for ultrasonic dispersion for 15 min, adding 3.75 kg of the dimethyl sulfoxide solution of 3,5-diisopropyl o-hydroxybenzoic acid and 0.5 kg of N,N'-dicyclohexylcarbodiimide, heating to 40°C, stirring for reaction for 14 h, centrifuging, washing with deionized water three times, and drying at 70°C for 5 h to obtain catalyst A.

[0050] Preparation Example 2

[0051] The preparation method of catalyst B is the same as that of Preparation Example 1, except that in step (1), 5.5 kg of carbon nanotubes, 50 L of 68 wt% concentrated nitric acid solution and 200 L of 98 wt% concentrated sulfuric acid solution are added to a reactor, refluxed in an oil bath at 110°C for 1 h, repeatedly filtered and rinsed with deionized water until neutral, and dried at 105°C for 3 h to obtain acidified carbon nanotubes.

[0052] Preparation Example 3

[0053] The preparation method of catalyst C is the same as that of Preparation Example 1, except that in step (2), the amount of dimethyl sulfoxide solution of 3,5-diisopropyl o-hydroxybenzoic acid added is 6.25 kg.

[0054] Example 1

[0055] An energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol comprises the following steps:

[0056] S1. At a speed of 350r / min, keep stirring continuously, add 1kg of catalyst A to 358.95kg of 22wt% dilute nitric acid solution, add 150kg of p-tert-butylphenol continuously at a feeding rate of 350kg / h, control the temperature to 29°C, mix and react for 4h to obtain a mixed solution;

[0057] S2. The mixed solution obtained in step S1 was allowed to stand for 40 minutes and then separated. The lower phase was washed with water and then allowed to stand for 30 minutes for separation. The lower product obtained was crude o-nitro-p-tert-butylphenol, which was purified by distillation under vacuum until there was no solvent to obtain o-nitro-p-tert-butylphenol.

[0058] Example 2

[0059] An energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol comprises the following steps:

[0060] S1. At a speed of 200r / min, keep stirring continuously, add 0.75kg of catalyst A to 277.2kg of 25wt% dilute nitric acid solution, add 150kg of p-tert-butylphenol continuously at a feeding rate of 300kg / h, control the temperature to 28°C, mix and react for 3h to obtain a mixed solution;

[0061] S2. The mixed solution obtained in step S1 was allowed to stand for 30 minutes and then separated. The lower phase was washed with water and then allowed to stand for 20 minutes for separation. The lower product obtained was crude o-nitro-p-tert-butylphenol, which was purified by distillation under vacuum until there was no solvent to obtain o-nitro-p-tert-butylphenol.

[0062] Example 3

[0063] An energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol comprises the following steps:

[0064] S1. At a speed of 500r / min, keep stirring continuously, add 1.5kg of catalyst A to 490kg of 18wt% dilute nitric acid solution, add 150kg of p-tert-butylphenol continuously at a feed rate of 400kg / h, control the temperature to 30°C, mix and react for 5h to obtain a mixed solution;

[0065] S2. The mixed solution obtained in step S1 was allowed to stand for 45 minutes and then separated. The lower phase was washed with water and then allowed to stand for 40 minutes for separation. The lower product obtained was crude o-nitro-p-tert-butylphenol, which was purified by distillation under vacuum until there was no solvent to obtain o-nitro-p-tert-butylphenol.

[0066] Example 4

[0067] An energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, the specific implementation method is the same as that of Example 1, except that an equal amount of catalyst B is used to replace catalyst A.

[0068] Example 5

[0069] An energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, the specific implementation method is the same as that of Example 1, except that an equal amount of catalyst C is used to replace catalyst A.

[0070] Example 6

[0071] An energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, the specific implementation method is the same as that of Example 1, except that the added amount of catalyst A is 1.8 kg.

[0072] Example 7

[0073] An energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, the specific implementation method is the same as that of Example 1, except that the mass fraction of dilute nitric acid is 30%.

[0074] Example 8

[0075] An energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, the specific implementation method is the same as that of Example 1, except that the added amount of 22wt% dilute nitric acid solution is 286.36kg.

[0076] Example 9

[0077] An energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, the specific implementation method is the same as that of Example 1, except that the temperature of the mixed reaction is 24°C.

[0078] Comparative Example 1

[0079] An energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, the specific implementation method is the same as that of Example 1, except that catalyst A is not added.

[0080] Effect evaluation:

[0081] The o-nitro-p-tert-butylphenol synthesized in the above Examples 1-9 and Comparative Example 1 was tested, and the content of the product was determined using a gas chromatograph. The specific results are shown in Table 1.

[0082] Table 1

[0083]

[0084]

[0085] From the results in Table 1, it can be seen that the yield of o-nitro-p-tert-butylphenol prepared in Examples 1-3 is greater than 95%, and the purity of o-nitro-p-tert-butylphenol is also greater than 98%, which has good production value.

[0086] Compared with Example 1, in Example 4, the material ratio of carbon nanotubes, concentrated nitric acid solution and concentrated sulfuric acid solution was changed during the preparation of the catalyst, so that the effect of acidifying the carbon nanotubes became worse, which was not conducive to the combination of 3,5-diisopropyl o-hydroxybenzoic acid and carbon nanotubes, and the catalytic effect was reduced, thereby reducing its yield and purity.

[0087] Compared with Example 1, when preparing the catalyst, the mass ratio of the acidified carbon nanotubes and 3,5-diisopropyl-2-hydroxybenzoic acid was changed, so that the reaction was incomplete within the reaction time, thereby affecting the yield and purity.

[0088] Compared with Example 1, Example 6 changes the mass ratio of p-tert-butylphenol to the catalyst, which affects the reaction rate and further affects the yield and purity.

[0089] Compared with Example 1, Example 7 increases the concentration of dilute nitric acid, which makes the reaction too fast, thereby resulting in reduced yield and purity.

[0090] In Example 8, compared with Example 1, the molar ratio of p-tert-butylphenol to the dilute nitric acid in the dilute nitric acid solution is changed, and the reaction is not complete within the reaction time, thereby affecting the yield and purity.

[0091] Compared with Example 1, Example 9 changes the temperature of the mixed reaction, which greatly slows down the reaction rate, thereby affecting the yield and purity.

[0092] Compared with Example 1, in Comparative Example 1, no catalyst A was added, and the reaction rate was too fast, thereby affecting the yield and purity.

[0093] The above is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present application. Although the present application is disclosed as above in the preferred embodiment, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. An energy-saving and environmentally friendly production process for o-nitro-p-tert-butylphenol, characterized in that: The following steps are included: S1. Under stirring, a catalyst was added to a dilute nitric acid solution, and p-tert-butylphenol was continuously added at a feed rate of 300-400kg / h, and the mixture was reacted for 3-5h to obtain a mixed solution; S2. The mixed solution obtained in step S1 is allowed to stand for 30-45 minutes and then separated. The lower phase is washed with water and allowed to stand for 20-40 minutes for separation. The lower product obtained is crude o-nitro-p-tert-butylphenol, which is purified by distillation under vacuum to obtain o-nitro-p-tert-butylphenol.

2. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 1, characterized in that: The mass ratio of p-tert-butylphenol to catalyst in step S1 is 1:(0.02-0.1).

3. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 1, characterized in that: The mass fraction of the dilute nitric acid solution in step S1 is 18-25%.

4. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 3, characterized in that: The molar ratio of p-tert-butylphenol to the dilute nitric acid in the dilute nitric acid solution in step S1 is 1:(1.1-1.4).

5. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 1, characterized in that: The temperature of the mixed reaction in step S1 is 28-30°C.

6. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 1, characterized in that: The method for preparing the catalyst in step S1 comprises the following steps: (1) adding carbon nanotubes, concentrated nitric acid solution and concentrated sulfuric acid solution into a reaction kettle, heating under reflux in an oil bath at 100-120° C. for 1-1.5 h, repeatedly filtering and rinsing with deionized water until neutral, and drying to obtain acidified carbon nanotubes; (2) The acidified carbon nanotubes obtained in step (1) are added to deionized water for ultrasonic dispersion, and a dimethyl sulfoxide solution of 3,5-diisopropyl o-hydroxybenzoic acid and N,N'-dicyclohexylcarbodiimide are added, heated to 30-50° C., stirred for reaction for 12-16 hours, centrifuged, washed, and dried to obtain a catalyst.

7. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 6, characterized in that: The mass fraction of the concentrated nitric acid solution in step (1) is 58-70%, and the mass fraction of the concentrated sulfuric acid solution is 92-98%.

8. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 7, characterized in that: The material ratio of the carbon nanotubes, concentrated nitric acid solution and concentrated sulfuric acid solution in step (1) is (35-45) g: 0.5 L: (1.5-2.5) L.

9. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 6, characterized in that: The mass ratio of the acidified carbon nanotubes to 3,5-diisopropyl o-hydroxybenzoic acid in step (2) is (2-4):

1.

10. The energy-saving and environmentally friendly production process of o-nitro-p-tert-butylphenol according to claim 1, characterized in that: The yield of the produced o-nitro-p-tert-butylphenol is not less than 95%, and the purity is not less than 98%.

Images