Used for benzene NO 2 Polymerizable triphenylboron Lewis acid catalysts for the nitration to nitrobenzene, their preparation methods and applications

Abstract

A type of benzene NO 2 Polymerizable triphenylboron Lewis acid catalysts for the nitration to nitrobenzene, their preparation methods, and applications. Polymerizable triphenylboron Lewis acid catalysts can be prepared via a Friedel-Crafts reaction between triphenylboron and dichloroethane. Using polymerizable triphenylboron Lewis acid as a catalyst, NO... 2 Nitrifying agent, O 2 Using dichloroethane as an oxidant and dichloroethane as a solvent, benzene nitration to nitrobenzene can be achieved at 0-50℃ and 0.1-3 MPa pressure. After the reaction, the catalyst can be recovered and reused through filtration. Compared with existing nitration methods, this invention provides a clean production process for benzene nitration that is weakly exothermic, low-corrosion, and low-pollution.

Description

Polymerizable triphenylboron Lewis acid catalysts for the nitration of benzene (NO2) to nitrobenzene, their preparation methods and applications Technical Field

[0001] This invention relates to a polymeric triphenylboron Lewis acid catalyst, its preparation, and a method for nitrifying benzene NO2 to produce nitrobenzene, belonging to the field of fine chemicals. Background Technology

[0002] Nitrobenzene is an important chemical raw material, used in the preparation of aniline, benzidine, azobenzene, etc. Currently, the industrial production of nitrobenzene employs a mixed acid nitration method, using a mixed acid system composed of sulfuric acid and nitric acid as a catalyst and nitrating agent to nitrate benzene. For example, patent CN102516082A reports a method for preparing nitrobenzene by reacting benzene with a mixed acid system containing 3-30% nitric acid, 50-80% sulfuric acid, and 10-25% water; patent US4091042 reports a method for producing nitrobenzene by nitrating benzene with a mixed acid system (HNO3 3.0-7.5 wt%, H2SO4 58.5-66.5 wt%, H2O 28-37 wt%) at 80-120℃, achieving a conversion rate of 98%. Although the above-mentioned method of nitration using mixed acid has a fast reaction rate and good selectivity, it has problems such as strong exothermic reaction, strong corrosiveness of mixed acid, and poor process safety, which pose a huge challenge to the environment and safe production.

[0003] To address the environmental and safety issues associated with traditional mixed acid nitration, the use of nitrogen oxides (NOx) as nitrating agents has garnered increasing attention. While currently reported catalytic systems demonstrate good catalytic performance for toluene, the inertness of benzene compared to toluene, coupled with the fact that NO2 is more inert than N2O4 and N2O5 among nitrogen oxides, results in less than ideal NO2 nitration of benzene. For instance, Chem. Commun. (2000, 1571–1572) reported a method using β-zeolite as a catalyst and NO2 as the nitrating agent for toluene nitration, achieving 100% toluene conversion, but only 55% benzene conversion under the same reaction conditions and with double the reaction time. The method reported in e-EROS Encyclopedia of Reagents for Organic Synthesis (2009, 1-9) even requires a high temperature of 171°C to achieve NO2 nitration of benzene.

[0004] There has been no good solution for achieving efficient NO2 nitration of benzene under mild conditions and obtaining nitrobenzene with high selectivity. Summary of the Invention

[0005] The present invention aims to provide a novel polymeric triphenylboron Lewis acid catalyst, and to utilize it to achieve efficient nitration of benzene NO2 under mild conditions and obtain nitrobenzene with high selectivity (Figure 1). This method can overcome the problems of low benzene conversion and high reaction temperature in existing methods.

[0006] The main technical solution of the present invention is a polymeric triphenylboron Lewis acid catalyst, characterized in that the catalyst is prepared by reacting aluminum trichloride or ferric trichloride with triphenylboron, wherein the mass ratio of aluminum trichloride or ferric trichloride to triphenylboron in the catalyst is 5:1-0.5:1.

[0007] The present invention also provides a method for preparing the above-mentioned polymeric triphenylboron Lewis acid catalyst, characterized in that the catalyst preparation includes the following steps: adding triphenylboron, dichloroethane, aluminum trichloride or ferric chloride to a pressure-resistant reactor; after the reaction is completed, adding methanol to quench the reaction; and performing Soxhlet extraction with dichloromethane. The resulting solid is the polymeric triphenylboron Lewis acid catalyst.

[0008] As a further feasible approach, the catalyst used in the above-described method for preparing polymeric triphenylboron Lewis acid catalyst is aluminum trichloride or ferric trichloride.

[0009] The present invention provides a method for producing nitrobenzene by nitration of benzene with a polymeric triphenylboron Lewis acid catalyst using NO2, characterized by the following steps: adding benzene, solvent, polymeric triphenylboron Lewis acid catalyst, and NO2 to a pressure-resistant reactor, introducing oxygen, and carrying out the reaction under vigorous stirring; after the reaction is completed, removing unreacted NO2 under reduced pressure to obtain a nitrobenzene solution.

[0010] As a further feasible approach, the above-mentioned method for producing nitrobenzene by nitration of benzene NO2 involves a mass ratio of polymeric triphenylboronic Lewis acid to benzene of 0.005:1-0.1:1.

[0011] As a further feasible approach, the above-mentioned method for producing nitrobenzene by nitration of benzene with NO2 can be implemented with a mass ratio of NO2 to benzene of 1:1 to 20:1.

[0012] The above-mentioned method for producing nitrobenzene by nitration of benzene NO2 can be further implemented by using benzene, dichloromethane, chloroform, dichloroethane, or trichloroethane as solvents.

[0013] The above-described method for producing nitrobenzene by nitration of benzene with NO2, as a further feasible approach, involves a reaction temperature of -10 to 50°C. o C.

[0014] The above-mentioned method for producing nitrobenzene by nitration of benzene with NO2, as a further feasible option, uses an oxygen pressure of 0.1-3 MPa.

[0015] As a further feasible approach to the above-mentioned method of producing nitrobenzene by nitration of benzene NO2, the catalyst can be recovered and reused by filtration after the reaction is completed.

[0016] Compared with existing methods for producing nitrobenzene by benzene nitration, this invention provides a clean production process for nitrobenzene that is less corrosive and has higher safety. Attached Figure Description

[0017] Figure 1 is a diagram of the reaction process for the production of nitrobenzene from benzene NO2 using a polymeric triphenylboron Lewis acid catalyst in the embodiment.

[0018] Figure 2 is a schematic diagram of the synthesis method and structure of the polymeric triphenylboronic Lewis acid catalyst in the embodiment.

[0019] Figure 3 is an EDS-Mapping diagram of the catalyst synthesized in the examples.

[0020] Figure 4 is an elemental distribution diagram of the catalyst synthesized in the example. Detailed Implementation

[0021] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Variations are included within the scope of the present invention without departing from its general spirit. Example 1

[0022] Catalyst preparation: 10.0 g triphenylborane, 100 mL dichloroethane, and 30.0 g aluminum trichloride were added to a 500 mL pressure-resistant reactor, and the mixture was heated at 80 °C. o The reaction was carried out at C for 24 hours. Then the temperature was lowered to 50°C. o C, slowly add 200 mL of methanol to quench the reaction. Stir for 2 h to remove aluminum trichloride. At 55 °C... o The reaction mixture was subjected to Soxhlet extraction with dichloromethane at C, and the resulting solid was dried to obtain 8.9 g of polymeric triphenylboron Lewis acid catalyst.

[0023] The characterization results of the obtained catalyst are shown in Figures 3 and 4. Figure 3 shows that C, B, and Cl elements are uniformly distributed on the catalyst surface. Figure 4 shows that C accounts for 84.96%, B for 12.11%, and Cl for 1.30%. Example 2

[0024] In a 100 mL pressure-resistant reactor, 3.0 g benzene, 20.0 g 1,2-dichloroethane, 15.0 g NO2, and 0.03 g of polymeric triphenylboron Lewis acid catalyst were added sequentially. After purging with 1.0 MPa of oxygen, the mixture was stirred vigorously at 0°C for 8 hours. After the reaction was complete, unreacted NO2 was removed under reduced pressure to obtain a nitrobenzene solution. Gas chromatography analysis of the reaction solution showed a benzene conversion of 86.1% and a nitrobenzene selectivity of 99.3%.

[0025] Examples 3-7

[0026] Similar to Example 1, a polymeric triphenylboron Lewis acid catalyst was synthesized using a different method. Then, benzene NO2 nitration to nitrobenzene was carried out using a method similar to Example 2, and the results are shown in Table 1.

[0027] .

[0028] Examples 8-10

[0029] Similar to Example 2, different amounts of catalyst were used to catalyze the nitration of benzene NO2 to produce nitrobenzene, and the results are shown in Table 2.

[0030] .

[0031] Examples 11-13

[0032] Similar to Example 2, different amounts of NO2 were used to nitrate benzene, and the results are shown in Table 3.

[0033] .

[0034] Examples 14-17

[0035] Similar to Example 2, nitrobenzene was produced by nitration of benzene with NO2 using different solvents, and the results are shown in Table 4.

[0036] .

[0037] Examples 18-20

[0038] Similar to Example 2, nitrobenzene was produced by nitration of benzene with NO2 at different temperatures, and the results are shown in Table 5.

[0039] .

[0040] Examples 21-23

[0041] Similar to Example 2, nitrobenzene was produced by nitration of benzene with NO2 under different pressures, and the results are shown in Table 6.

[0042] Example 24

[0043] Catalyst recovery and reuse: Similar to Example 2, after the reaction is completed, the polymeric triphenylboron Lewis acid catalyst is obtained by filtration and separation (recovery).

[0044] In a 100 mL pressure-resistant reactor, 3.0 g benzene, 20.0 g 1,2-dichloroethane, 15.0 g NO2, and 0.03 g of polymeric triphenylboron Lewis acid catalyst (recovered) were added sequentially. After purging with 1.0 MPa of oxygen, the reaction was carried out at 0°C with vigorous stirring for 8 h. After the reaction was complete, unreacted NO2 was removed under reduced pressure to obtain a nitrobenzene solution. Gas chromatography analysis of the reaction solution showed a benzene conversion of 86.0% and a nitrobenzene selectivity of 99.2%.

[0045] Analysis of the data from the above embodiments shows that, compared to existing mixed acid nitration processes, the present invention, using NO2 as a nitrating agent to nitrate benzene to nitrobenzene, has advantages such as mild reaction conditions, low exothermic reaction, and low material corrosivity. Compared to existing NO2 nitration processes, the method provided by the present invention achieves efficient benzene NO2 nitration under mild conditions and obtains nitrobenzene with high selectivity.

Claims

1. The application of a polymeric triphenylboron Lewis acid catalyst in the nitration of benzene (NO2) to nitrobenzene, characterized in that... The catalyst is prepared by ferric chloride and triphenylboron, and the mass ratio of ferric chloride to triphenylboron in the catalyst is 5:1-0.5:

1. The method for using the polymeric triphenylboron Lewis acid catalyst to nitrobenzene by nitration of benzene with NO2 includes the following steps: adding benzene, solvent, polymeric triphenylboron Lewis acid catalyst, and NO2 to a pressure-resistant reactor, introducing oxygen, and carrying out the reaction under vigorous stirring at a reaction temperature of -10-50℃. After the reaction is completed, removing unreacted NO2 under reduced pressure to obtain a nitrobenzene solution.

2. The application according to claim 1, characterized in that... The catalyst preparation includes the following steps: adding triphenylborane, dichloroethane, and ferric chloride to a pressure-resistant reactor; after the reaction is completed, adding methanol to quench the reaction; and performing Soxhlet extraction with dichloromethane. The resulting solid is the polymeric triphenylborane Lewis acid catalyst.

3. The application according to claim 2, characterized in that... Ferric chloride is used as a catalyst in the synthesis of polymeric triphenylboronic Lewis acid.

4. The application according to claim 1, characterized in that... The solvent is benzene, dichloromethane, chloroform, dichloroethane, or trichloroethane.

5. The application according to claim 1, characterized in that... When benzene is nitrated with NO2 to produce nitrobenzene, the mass ratio of polymeric triphenylboronic Lewis acid to benzene is 0.005:1-0.1:

1.

6. The application according to claim 1, characterized in that... When benzene is nitrated with NO2 to produce nitrobenzene, the mass ratio of NO2 to benzene is 1:1 to 20:1.

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