A polyethyleneimine type ammonium salt ionic liquid and its preparation method and application

Abstract

The present invention discloses a polyethyleneimine type ammonium salt ionic liquid, wherein the ammonium salt ionic liquid is prepared from polyethyleneimine and a corresponding protonic acid, wherein the anion in the ammonium salt comes from the anion in the protonic acid and is selected from HSO4 ‑ 、HSO4(H2SO4) ‑ 、HSO4(H2SO4)2 ‑ CF3SO3 ‑ 、CH3SO3 ‑ and R'‑C6H4SO3 ‑ An anion in the ammonium salt ionic liquid, wherein R' is an alkyl group; the cation in the ammonium salt ionic liquid is an ammonium cation formed from polyethyleneimine, and in the ammonium salt ionic liquid, the molar ratio of nitrogen atom to protonic acid is 1:(1-3). The ionic liquid prepared by the method of the present invention exhibits stronger catalytic activity in acid-catalyzed reactions. The ionic liquid synthesized by the present invention can achieve a conversion rate of over 90% when catalyzing the nitration of aromatic hydrocarbons to produce a mononitro product.

Description

Technical Field

[0001] The present invention relates to the fields of organic chemical synthesis technology and green catalysis, in particular to a polyethyleneimine type ammonium salt ionic liquid and a preparation method thereof. Background Art

[0002] Acid catalysts are indispensable in the modern chemical industry and are widely used in representative synthetic routes such as nitration, esterification, and alkylation. Currently, industrial acid-catalyzed processes, especially esterification and aromatic nitration, frequently utilize inorganic acid catalysts such as hydrochloric acid, sulfuric acid, and phosphoric acid to enhance reaction activity. However, this also causes equipment corrosion, high separation and recovery costs, and difficulty in reuse. Consequently, the resulting waste acid requires significant amounts of alkali neutralization, and the added alkali neutralization and inorganic salt removal steps consume additional raw materials and energy.

[0003] In order to cope with the shortcomings of traditional inorganic acid catalysts, the development of green and efficient new catalysts has become a trend. Acidic ionic liquid catalysts have the characteristics of low vapor pressure and low volatility, relatively simple synthesis process, and can be recycled after separation and recovery and water removal.

[0004] Imidazolium ionic liquids are the most common and earliest commercialized One of the acidic ionic liquids. D. Gong et al. successfully synthesized room temperature ionic liquid [Hmim]HSO4 using methylimidazole and sulfuric acid as raw materials (Asian Journal of Chemistry, Vol. 22, No. 8, 6413-6416). 10 Using [min](OTf) as a catalyst to nitrate the substrate benzene, near-theoretical yields of nitrobenzene were obtained. However, this method is limited by the nitration of some of the catalyst itself. Furthermore, due to the high cost and toxicity of imidazole precursors, large-scale industrial production is currently unavailable, resulting in a limited market supply.

[0005] CN1772739A discloses a method for synthesizing ionic liquids in one step by replacing imidazole with lactam, which simplifies the reaction and reduces the cost of raw materials. The ionic liquid synthesized by this method has a low Hammett acid strength H0 = 4.54-5.03 (using methyl yellow as an indicator) and a low catalytic activity.

[0006] CN105732439A, CN101648894A, and CN101348487A first perform sulfonyl functionalization of polyamines, and then add a stoichiometric equivalent of acid to protonate to obtain high-acidity ionic liquids. Sulfonate quaternary ammonium salt acidic ionic liquids embody the powerful designability of ionic liquids, but the disadvantage of this method is that the functionalization step of the polyamines requires the addition of an ylide that is many times the amine equivalent, which increases raw material consumption, prolongs the synthesis process, and easily introduces impurities, weakening the process advantage of ionic liquids that are easy to synthesize. Therefore, it is very necessary to find low-cost, efficient ionic liquids. Summary of the Invention

[0007] In response to the problems existing in the prior art, the present invention provides a polyethyleneimine-type ammonium salt ionic liquid, a preparation method and application thereof. Starting from polyethyleneimine, by adding an appropriate amount of protonic acid, under specific experimental conditions, an ammonium salt ionic liquid is constructed with ammonium radicals formed by polyethyleneimine as cations and anions derived from anions in the protonic acid.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A polyethyleneimine type ammonium salt ionic liquid, characterized in that

[0010] The ammonium salt ionic liquid is prepared from polyethyleneimine and the corresponding protonic acid (HA), and the anion in the ammonium salt comes from the anion in the protonic acid (A - ), selected from HSO4 - 、HSO4(H2SO4) - 、HSO4(H2SO4)2 - CF3SO3 - 、CH3SO3 - and R'-C6H4SO3 - wherein R' is an alkyl group; the cation in the ammonium salt ionic liquid is an ammonium cation formed by polyethyleneimine, and in the ammonium salt ionic liquid, the molar ratio of nitrogen atoms to proton acid is 1:(1-3);

[0011] The structure of the polyethyleneimines (PEI) is shown in the following formula I:

[0012]

[0013] In formula I, x and y are not zero at the same time and x+y≥4, R is selected from H, C1-C12 alkyl, and z = 1 to 15, and At least one of .

[0014] The structural formula of formula I shows that the main chain structure of polyethyleneimine includes two structural units: At least one of, when comprising two structural units, It can be at least one of random copolymerization, block copolymerization, and alternating copolymerization; when the main chain structure of polyethyleneimine includes When the structural unit is formed, the R substituent in the structure can be H, C1-C12 alkyl, and z = 1 to 15, and At least one of the following, in the same polyethyleneimine product When there are two or more R substituents in The units may be at least one of random copolymerization, block copolymerization, and alternating copolymerization.

[0015] The ammonium salt ionic liquid of the present invention can be labeled as [polyethyleneimine][HA] x’ , x' is the molar ratio of proton acid to nitrogen atom in polyethyleneimine, x'=1-3, HA is proton acid, and the proton acid can be H2SO4 (which can form HSO4 - 、HSO4(H2SO4) - or HSO4(H2SO4)2 - anion), CF3SO3H, CH3SO3H and R'-C6H4SO3H.

[0016] The polyethyleneimine of the present invention can be a single compound or polymer or a mixture of multiple compounds or polymers.

[0017] In the above ionic liquid, as a preferred embodiment, R' is CH3, C 12 H 25 Isoalkyl, R'-C6H4SO3 - Preferably p-R'-C6H4SO3 - .

[0018] As a preferred embodiment of the above ionic liquid, in Formula I, x=0-230, y=0-230, and x+y≥4; preferably, x=0-100, y=0-100, and x+y≥4.

[0019] As a preferred embodiment of the above ionic liquid, the Mn of the polyethyleneimine is 400-13000.

[0020] In the above ionic liquid, as a preferred embodiment, the polyethyleneimine is selected from at least one of CAS Nos. 9002-98-6, 25987-06-8, 106899-94-9, and 68130-97-2.

[0021] As a preferred embodiment of the above-mentioned ionic liquid, the polyethyleneimine is selected from EPOMIN polyethyleneimine produced by Nippon Shokubai or Lupasol polyethyleneimine produced by BASF.

[0022] As a preferred embodiment of the above ionic liquid, in the formula I, x=0 and y=4-100, more preferably x+y=7-100; preferably, the polyethyleneimine is selected from one of CAS Nos. 4067-16-7 and 112-57-2.

[0023] As a preferred embodiment, the above-mentioned ionic liquid has the following structural formula of polyethyleneimine:

[0024] Wherein Mn is 500-11000;

[0025] Preferably, the CAS number of the polyethyleneimine is 25987-06-8 or 9002-98-6.

[0026] As a preferred embodiment of the above ionic liquid, in the formula I, R is one of C1-C12 alkyl groups, and Mn is 6000-10000; preferably, the CAS of the polyethyleneimine is 26913-07-5.

[0027] In the present invention, the anion of the ionic liquid is hydrogen sulfate hydrogen bonded to sulfuric acid, that is, HSO4 (H2SO4) - , or HSO4(H2SO4)2 - Compared with traditional bisulfate anions, bisulfate hydrogen bonded to sulfuric acid is more acidic, more active and stable, and is more unique when paired with polyethyleneimine type cations.

[0028] The polyethyleneimine ammonium salt ionic liquid has the characteristics of low melting point, low viscosity and strong fluidity. The melting point can be as low as -50°C and the viscosity can be as low as 5500cp at 25°C.

[0029] The present invention also provides a method for preparing the above-mentioned ionic liquid, which adopts the following technical solution:

[0030] A method for preparing the above-mentioned polyethyleneimine type ammonium salt ionic liquid,

[0031] Add an appropriate amount of protonic acid to polyethyleneimine, and after the reaction, obtain an ionic liquid in which ammonium cations formed by polyethyleneimine and anions of protonic acid are coordinated; the anions are selected from HSO4 (H2SO4) - 、HSO4(H2SO4)2 - 、HSO4 - CF3SO3 -、CH3SO3 - and R'-C6H4SO3 - An anion in, wherein R' is an alkyl group; the molar equivalent ratio of the protonic acid to the nitrogen atoms in the polyethyleneimine is 3:1 to 1:1.

[0032] In the above preparation method, as a preferred embodiment, the preparation method specifically comprises the following steps:

[0033] Step 1: Add the polyethyleneimine into a reactor equipped with a stirring device and a condensing reflux device, start stirring, and set the speed to 100-1000 rpm, preferably 400-800 rpm;

[0034] Step 2: Add the protonic acid into the reactor of step 1 in batches over 30-60 minutes, and control the temperature in the reactor to be between 0-30°C. After the addition is completed, stir at 0-30°C for 2-3 hours to obtain a viscous ionic liquid.

[0035] In the above preparation method, as a preferred embodiment, when the anion of the ammonium salt ionic liquid is hydrogen sulfate hydrogen bonded sulfuric acid, that is, HSO4 (H2SO4) - , or HSO4(H2SO4)2 - When, the preparation method comprises:

[0036] Step 1: Add polyethyleneimine to a reactor equipped with a stirring device and a condensing reflux device, start stirring, and set the speed to 400-1000 rpm;

[0037] Step 2: Place the reactor in the above step 1 in an ice water bath, and slowly add 93-98% sulfuric acid dropwise over 30-60 minutes. During the addition of sulfuric acid, the temperature in the reaction vessel is controlled between 0-30°C. After the addition is completed, stirring is continued at 0-30°C for 2-3 hours, and stirring is stopped to obtain the polyethylene polyammonium hydrogen sulfate hydrogen-bonded sulfate room temperature ionic liquid.

[0038] The present invention also provides a use of the above-mentioned polyethyleneimine ammonium salt ionic liquid or the polyethyleneimine ammonium salt ionic liquid obtained by the above-mentioned preparation method as a catalyst in the field of industrial acid-catalyzed reactions, wherein the industrial acid-catalyzed reaction includes a nitration reaction; preferably, the nitration reaction is an aromatic hydrocarbon nitration reaction.

[0039] In the above application, as a preferred embodiment, the polyethyleneimine type ammonium salt ionic liquid is used to catalyze the nitration reaction of aromatic hydrocarbons, wherein the aromatic hydrocarbons include benzene, substituted benzenes or aromatic hydrocarbons having a structure represented by formula V, wherein the substituted benzenes are selected from monosubstituted, disubstituted and polysubstituted groups. Preferably, the structure of the substituted benzenes is selected from one of the following structures:

[0040]

[0041] In the formula II, X is selected from one of halogen, alkyl, halogen-substituted alkyl, alkoxy, and amide. Preferably, X is selected from F, Cl, Br, I, CF3, CH3, OCH3, C2H5, C4H9, C 10 H 21 、C 12 H 25 、C 18 H 37 and one of NHCOCH3;

[0042] In the formula III or IV, X is selected from one of halogen, alkyl, and alkoxy, preferably, X is selected from one of F, Cl, CH3, and OCH2CH2O; X in the formula III and formula IV is the same or different.

[0043] The structure of Formula V is:

[0044] Wherein A is O, CH2 or S.

[0045] The method for using the polyethyleneimine ammonium salt ionic liquid to catalyze the nitration reaction of aromatic hydrocarbons comprises: mixing aromatic hydrocarbons as substrates with the polyethyleneimine ammonium salt ionic liquid and nitric acid to carry out the aromatic hydrocarbon nitration reaction; cooling after the reaction is completed, standing and stratifying, separating a lower aqueous ionic liquid layer and an upper organic phase containing the nitration product; washing the upper organic phase to neutrality, and removing the detergent to obtain the nitration product.

[0046] Furthermore, the mass ratio of substrate to ionic liquid is 1:1 to 3;

[0047] Furthermore, the temperature of the nitration reaction is 50 to 80°C;

[0048] Furthermore, the nitration reaction time is 1 to 20 hours;

[0049] Further, the molar ratio of nitric acid to substrate is 1 to 2:1;

[0050] Furthermore, the aqueous ionic liquid layer can be reused after evaporation to remove water;

[0051] Furthermore, the nitric acid concentration is above 65%;

[0052] Further, after the reaction is completed, the temperature is cooled to 40-50°C;

[0053] Furthermore, the nitration product is mainly a mononitro product.

[0054] The ionic liquid synthesized using the technical solution of the present invention is liquid at room temperature. On the one hand, the ionic liquid has the characteristics of low viscosity and strong fluidity; on the other hand, the ionic liquid is a protonated ionic liquid with a high acid value, which can make the receptor protonation more complete and show stronger catalytic activity in acid-catalyzed reactions.

[0055] Compared with the prior art, the technical solution adopted by the present invention has the following beneficial technical effects:

[0056] (1) The ionic liquids of the present invention have low melting points, low viscosity, and high fluidity. Due to their low melting point, these ionic liquids are liquid at room temperature, meaning they can be fully mixed with reactants as catalysts even without heating. Furthermore, their high fluidity significantly enhances the degree of mixing between the reactants and the ionic liquid, which helps to increase the conversion rate of the primary reaction.

[0057] (2) The ionic liquids of the present invention are all synthetic compounds not found in nature. They are novel ionic liquids synthesized by the inventors through careful theoretical design, repeated experimental exploration, and experimentation with different reaction conditions. These ionic liquids can be used in nitration reactions, esterification reactions, alkylation reactions, condensation reactions, oxidation reactions, and the like.

[0058] (3) Industrial acid catalysis, especially for the nitration of aromatic hydrocarbons, often uses inorganic acid catalysts such as hydrochloric acid, sulfuric acid, and phosphoric acid to enhance reaction activity. However, this also causes equipment corrosion, high regeneration costs after separation and recovery, and low reuse rates. Consequently, the waste acid produced requires a large amount of alkali neutralization. The additional alkali neutralization and inorganic salt removal steps consume additional raw materials and energy. The ionic liquids of the present invention are novel, green catalysts with low vapor pressure and low volatility, a relatively simple synthesis process, and can be recycled after separation and recovery, with the addition of water.

[0059] (4) The ionic liquid prepared by the method of the present invention is a protonated ionic liquid. As a catalyst, it has a higher acid value, can make the receptor protonated more completely, and exhibits stronger catalytic activity in acid-catalyzed reactions.

[0060] (5) Unlike lower amines such as triethylamine and tripropylamine, polyethyleneimine has an adjustable molecular weight and better side chain modifiability. The production process of polyethyleneimine is mature, inexpensive, and the market supply is sufficient. The ionic liquid of the present invention has low cost and high catalytic efficiency.

[0061] (6) The ionic liquid synthesized in the present invention has a high yield of mononitro products when catalyzing the nitration reaction of aromatic hydrocarbons. In addition to the mononitro products, other by-products in the product are very rare or even undetectable, and the substrate conversion rate can reach more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is the NMR spectrum of the ionic liquid prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0063] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the specific embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other implementations obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0064] In the present invention, % unless otherwise specified is % by mass.

[0065] Example 1

[0066] Select a polyethyleneimine with the following structure:

[0067]

[0068] The polyethyleneimine has an average Mw of 25,000 as measured by LS method and an average Mn of 10,000 as measured by GPC method, CAS: 9002-98-6, and is a commercially available product.

[0069] 20 g of polyethyleneimine (CAS: 9002-98-6, 0.465 mol N equivalent) was weighed into a 100 mL four-necked flask. 139.4 g of 98% sulfuric acid (1.395 mol) was slowly added dropwise over 40 minutes while stirring in an ice bath (500 rpm). After the addition was complete, the mixture was stirred and reacted at room temperature for 2 hours to obtain a yellow-brown viscous ionic liquid with the composition of [polyethyleneimine][H2SO4]3, i.e., the anion of the ionic liquid was HSO4(H2SO4)2 - The yield is 99.2%. The ionic liquid is numbered 1-1. The nuclear magnetic spectrum of the ionic liquid is as follows Figure 1 .

[0070] The ionic liquid was prepared by replacing 98% sulfuric acid with 99% methanesulfonic acid as follows:

[0071] 20 g of polyethyleneimine (CAS: 9002-98-6, 0.465 mol N equivalent, which is a mixture of polyethyleneimines of different molecular weights) was weighed into a 100 mL four-necked flask. Under ice-bath stirring (speed of 500 rpm), 135.4 g of 99% methanesulfonic acid (1.395 mol) was slowly added dropwise over 40 minutes. After the addition was complete, the reaction was continued with stirring at room temperature for 2 hours to obtain a yellow-brown viscous ionic liquid with a composition of [polyethyleneimine][CH3SO3H]3, that is, the anion of the ionic liquid is CH3SO3(CH3SO3H)3 - The yield was 99.2%. The ionic liquid was numbered 1-2.

[0072] The ionic liquid was prepared by replacing 99% methanesulfonic acid with 99% trifluoromethanesulfonic acid as follows:

[0073] 20 g of polyethyleneimine (CAS: 9002-98-6, 0.465 mol N equivalent, which is a mixture of polyethyleneimines of different molecular weights) was weighed into a 100 mL four-necked flask. Under ice-bath stirring (500 rpm), 211.5 g of 99% methanesulfonic acid (1.395 mol) was slowly added dropwise over 40 minutes. After the addition was complete, the mixture was stirred at room temperature for 2 hours to obtain a yellow-brown viscous ionic liquid with the composition of [polyethyleneimine][CF3SO3H]3, i.e., the anion of the ionic liquid was CF3SO3(CF3SO3H)3 - The yield was 99.2%. The ionic liquids were numbered 1-3.

[0074] Example 2

[0075] Select a polyethyleneimine with the following structure:

[0076]

[0077] The average Mw determined by LS method is ∼800, and the average Mn determined by GPC method is ∼600. The CAS number is 25987-06-8, and it is a commercially available product.

[0078] Polyethyleneimine (CAS No. 25987-06-8) (20 g, 0.465 mol N equivalent, which is a mixture of polyethyleneimines of different molecular weights) was weighed into a 100 mL four-necked flask. Under ice bath stirring (speed of 500 rpm), 139.4 g of 98% sulfuric acid (1.395 mol) was slowly added dropwise over 40 minutes. After the addition was complete, the reaction was continued with stirring at room temperature for 2 hours to obtain a yellow-brown viscous ionic liquid with a composition of [polyethyleneimine][H2SO4]3, that is, the anion of the ionic liquid was HSO4(H2SO4)2 - The yield was 99%. This ionic liquid was numbered 2-1.

[0079] The ionic liquid was prepared by replacing 98% sulfuric acid with 99% methanesulfonic acid as follows:

[0080] 20 g of polyethyleneimine (CAS: 25987-06-8, 0.465 mol N equivalent, which is a mixture of polyethyleneimines of different molecular weights) was weighed into a 100 mL four-necked flask. Under ice-bath stirring (500 rpm), 135.4 g of 99% methanesulfonic acid (1.395 mol) was slowly added dropwise over 40 minutes. After the addition was complete, the mixture was stirred at room temperature for 2 hours to obtain a yellow-brown viscous ionic liquid with a composition of [polyethyleneimine][CH3SO3]3, i.e., the anion of the ionic liquid was CH3SO3(CH3SO3H)3 - The yield was 99.2%. This ionic liquid was numbered 2-2.

[0081] The ionic liquid was prepared by replacing 99% methanesulfonic acid with 99% trifluoromethanesulfonic acid as follows:

[0082] 20 g of polyethyleneimine (CAS: 25987-06-8, 0.465 mol N equivalent, which is a mixture of polyethyleneimines of different molecular weights) was weighed into a 100 mL four-necked flask. Under ice-bath stirring (500 rpm), 211.5 g of 99% methanesulfonic acid (1.395 mol) was slowly added dropwise over 40 minutes. After the addition was complete, the mixture was stirred at room temperature for 2 hours to obtain a yellow-brown viscous ionic liquid with the composition of [polyethyleneimine][CF3SO3H]3, i.e., the anion of the ionic liquid was CF3SO3(CF3SO3H)3 - The yield was 99.2%. This ionic liquid was numbered 2-3.

[0083] Example 3

[0084] A polyethyleneimine type ammonium salt ionic liquid, wherein the structure of the polyethyleneimine is as follows:

[0085] The average Mn was determined by SEC to be ~8100, CAS: 26913-07-5. The synthesis method can be found in the literature: (1) Hanneke ML Lambermont-Thijs et al., Linear poly(alkyl ethylene imine) with varying side chain length: synthesis and physical properties, Polym. Chem., 2010, 1, 747–754. (2) Hoque, J.; Akkapeddi, P.; Yadav, V.; Manjunath, GB; Uppu, DSSM; Konai, MM; Yarlagadda, V.; Sanyal, K.; Haldar, J. Broad spectrum antibacterial and antifungal polymeric paint materials: synthesis, structure-activity relationship, and membrane-active mode of action. ACS Appl. Mater. Interfaces 2015, 7, 1804-1815.

[0086] A certain amount of polyethyleneimine (nitrogen content 25.6 wt %; the following molar amount calculations are based on the actual number of moles of nitrogen element; this is a mixture of polyethyleneimines of different molecular weights) was weighed into a 100 mL four-necked flask. A certain amount of 98% sulfuric acid (see Table 1 below) was slowly added dropwise over 40 minutes while stirring in an ice bath (500 rpm). After the addition was complete, the reaction was continued with stirring at room temperature for 2 hours to obtain the corresponding yellow-brown viscous ionic liquid product, whose composition was [polyethyleneimine][H2SO4] x' (See Table 1 below).

[0087] Table 1 Preparation of [Polyethyleneimine] [H2SO4] in Example 3 x' Experimental conditions and yields

[0088] Example Polyethyleneimine (g) Sulfuric acid (g) <![CDATA[[Polyethyleneimine][H2SO4] x' > Yield (%) 3-1 11.4 62.5 x'＝3 99.5 3-2 11.4 41.7 x'＝2 99.6 3-3 11.4 20.8 x'＝1 99.2

[0089] When x'=1, the anion of the ionic liquid is HSO4 - ; When x'=2, the anion of the ionic liquid is HSO4 (H2SO4) - ; When x'=3, the anion of the ionic liquid is HSO4(H2SO4)2 - .

[0090] The yellow-brown viscous ionic liquid product in Example 3-1, whose composition is [polyethyleneimine][H2SO4]3, was taken to test the viscosity of the ionic liquid at different temperatures, as shown in Table 2 below.

[0091] Table 2 Viscosity of [polyethyleneimine][H2SO4]3 prepared in Example 3 at different temperatures

[0092]

[0093] Similarly, 98% sulfuric acid was replaced with 99% methanesulfonic acid.

[0094] A certain amount of polyethyleneimine (nitrogen content 25.6 wt%) was weighed into a 100 mL four-necked flask. Under ice-bath stirring (500 rpm), a certain amount of 99% methanesulfonic acid was slowly added dropwise over 40 minutes. The specific amount is shown in Table 3 below. After the addition was complete, the reaction was continued with stirring at room temperature for 2 hours to obtain the corresponding yellow-brown viscous ionic liquid product, whose composition is [polyethyleneimine][CH3SO3H] x' (See Table 3 below).

[0095] Table 3 Preparation of [Polyethyleneimine] [CH3SO3H] in Example 3 x' Experimental conditions and yields

[0096]

[0097] When x'=1, the anion of the ionic liquid is CH3SO3 - ; When x'=2, the anion of the ionic liquid is CH3SO3(CH3SO3H) - ; When x'=3, the anion of the ionic liquid is CH3SO3(CH3SO3H)2 - .

[0098] 99% methanesulfonic acid was replaced with 99% trifluoromethanesulfonic acid.

[0099] A certain amount of polyethyleneimine (nitrogen content 25.6 wt%) was weighed into a 100 mL four-necked flask. Under ice-bath stirring (500 rpm), a certain amount of 99% trifluoromethanesulfonic acid was slowly added dropwise over 40 minutes. The specific amount is shown in Table 4 below. After the addition was complete, the reaction was continued with stirring at room temperature for 2 hours to obtain the corresponding yellow-brown viscous ionic liquid product, whose composition is [polyethyleneimine][CF3SO3H] x' (See Table 4 below).

[0100] Table 4 Preparation of [Polyethyleneimine] [CF3SO3H] in Example 3 x' Experimental conditions and yields

[0101]

[0102] When x'=1, the anion of the ionic liquid is CF3SO3 - ; When x'=2, the anion of the ionic liquid is CF3SO3(CF3SO3H) - When x'=3, the anion of the ionic liquid is CF3SO3(CF3SO3H)2 - .

[0103] Example 4

[0104] 20 g of EPOMIN (Japan Catalyst) polyethyleneimine, product model SP-003 (nitrogen content 21 wt %, molar amounts calculated below are based on the actual number of moles of nitrogen element, CAS 106899-94-9) was weighed and placed in a 100 mL four-necked flask. With stirring in an ice bath (500 rpm), 31.61 g of 93% sulfuric acid was slowly added dropwise over 30 minutes. After the addition was complete, the reaction was continued with stirring at room temperature for 2 hours to obtain a yellow-brown viscous ionic liquid with the composition of [polyethyleneimine][H2SO4], and the yield was 99.0%.

[0105] Still using the polyethyleneimine of this example, under the same reaction conditions, the amount of 93% sulfuric acid was increased to 63.23 g and 94.84 g to obtain the corresponding ionic liquids, whose compositions were [polyethyleneimine][H2SO4]2 and [polyethyleneimine][H2SO4]3, respectively, with a yield of 99.0%.

[0106] The ionic liquid was prepared by varying the sulfuric acid concentration: 20 g of polyethyleneimine SP-003 (CAS: 106899-94-9, nitrogen content 21 wt%) from EPOMIN (Japan Shokubai) was weighed and placed in a 100 mL four-necked flask. While stirring in an ice bath, 30.0 g of 98% sulfuric acid was slowly added dropwise over 40 minutes. After the addition was complete, the reaction was continued with stirring at room temperature for 2 hours to obtain a yellow-brown viscous ionic liquid with the composition [EPOMIN SP-003][H2SO4], numbered 4-1, and a yield of 99.2%.

[0107] 98% sulfuric acid was replaced with 99% methanesulfonic acid. Still using 20g of the polyethyleneimine of this example, under the same reaction conditions, the amounts of 99% methanesulfonic acid used were 29.1g, 58.2g, and 87.4g, respectively, to obtain the corresponding ionic liquids, whose compositions were [polyethyleneimine][CH3SO3H], [polyethyleneimine][CH3SO3H]2, and [polyethyleneimine][CH3SO3H]3, respectively, with yields of 99.0%. [Polyethyleneimine][CH3SO3H]3 was numbered 4-2.

[0108] Similarly, 98% sulfuric acid was replaced with 99% trifluoromethanesulfonic acid. Still using 20 g of the polyethyleneimine of this example, under the same reaction conditions, the amounts of 99% trifluoromethanesulfonic acid used were 45.5 g, 91 g, and 150 g, respectively, to obtain the corresponding ionic liquids, whose compositions were [polyethyleneimine][CF3SO3H], [polyethyleneimine][CF3SO3H]2, and [polyethyleneimine][CF3SO3H]3, respectively, with yields of 99.0%. [Polyethyleneimine][CF3SO3H]3 was numbered 4-3.

[0109] Example 5

[0110] Different polyethyleneimine oligomers (see Table 5 for details) were quantitatively weighed into a 100 mL four-necked flask. 98% sulfuric acid was slowly added dropwise over 40 minutes while stirring in an ice bath (500 rpm). After the addition was complete, the mixture was stirred and reacted at room temperature for 2 hours to obtain a brown viscous ionic liquid with the composition of [polyethyleneimine oligomer][H2SO4] x' , x'=1~3, x' is the molar ratio of H2SO4 to the nitrogen atom in the polyethyleneimine oligomer, and is numbered as shown in Table 5 below.

[0111] Table 5 Preparation of [Polyethyleneimine Oligomer] [H2SO4] in Example 5 x' Experimental conditions and yields

[0112]

[0113] The following describes the value of the novel ionic liquids of the present invention in the nitration reaction of aromatic hydrocarbons using specific embodiments. It should be understood that the described embodiments represent only a portion of the present invention, and are not exhaustive. The nitration reaction in the examples is generally described as follows: add the ionic liquid and nitric acid, heat to 70-80°C, add the substrate, and proceed with the nitration reaction. In each example and comparative example, when adjusting the nitric acid concentration for testing, the actual amount of nitric acid used was adjusted to achieve a 1:1 molar ratio of substrate to pure nitric acid. The ortho-to-para ratio in the present invention refers to the molar ratio of ortho-to-para-product, the conversion rate is the molar percentage of substrate converted to product in the nitration reaction, and the yield is the percentage of the actual molar amount of the mononitrated product to the theoretical molar amount. The present invention achieves a high yield of the mononitrated product, with minimal or even undetectable byproducts other than the mononitrated product. Therefore, the conversion rate and yield are essentially identical, with the difference between the two being less than 1%.

[0114] Example 6

[0115] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 1-1 prepared in Example 1 and 21.2 g of 95% nitric acid were added. The mixture was heated to 70-80°C, and 36 g of chlorobenzene was added to carry out the nitration reaction of chlorobenzene. After 11 hours of reaction, the mixture was cooled to 40-50°C, allowed to stand and separate into layers. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene. The chlorobenzene conversion rate exceeded 95%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.0. The aqueous ionic liquid layer was evaporated to remove water and could be reused.

[0116] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 1-1 prepared in Example 1 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 6. The specific reaction conditions are shown in Table 6:

[0117] Table 6 Example 1-1 Nitration of chlorobenzene catalyzed by [polyethyleneimine][H2SO4]3 ionic liquid

[0118]

[0119] Example 7

[0120] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 1-2 prepared in Example 1 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction of chlorobenzene. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase was essentially the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.1. The aqueous ionic liquid layer was evaporated and reused.

[0121] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 1-2 prepared in Example 1 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 7. The specific reaction conditions are shown in Table 7:

[0122] Table 7 Example 1-2 Nitration of chlorobenzene catalyzed by [polyethyleneimine][CH3SO3H]3 ionic liquid

[0123]

[0124] Example 8

[0125] To a four-necked flask equipped with a reflux condenser, 50.4 g of ionic liquid 1-3 prepared in Example 1 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 95%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.1. The aqueous ionic liquid layer was evaporated and reused.

[0126] The examples of catalyzing the nitration of chlorobenzene by the ionic liquids 1-3 prepared in Example 1 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 8. The specific reaction conditions are shown in Table 8:

[0127] Table 8 Example 1-3 [Polyethyleneimine][CF3SO3H]3 ionic liquid catalyzed nitration of chlorobenzene

[0128]

[0129] Example 9

[0130] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 2-1 prepared in Example 1 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to initiate the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 95%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.0. The aqueous ionic liquid layer was evaporated and reused.

[0131] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 2-1 prepared in Example 2 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 9. The specific reaction conditions are shown in Table 9:

[0132] Table 9 Example 2-1 Nitration of chlorobenzene catalyzed by [polyethyleneimine][H2SO4]3 ionic liquid

[0133]

[0134] Example 10

[0135] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 2-2 prepared in Example 2 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.0. The aqueous ionic liquid layer was evaporated and reused.

[0136] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 2-2 prepared in Example 2 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 10. The specific reaction conditions are shown in Table 10:

[0137] Table 10 Example 2-2 Nitration of chlorobenzene catalyzed by [polyethyleneimine][CH3SO3H]3 ionic liquid

[0138]

[0139] Example 11

[0140] To a four-necked flask equipped with a reflux condenser, 50.4 g of ionic liquid 2-3 prepared in Example 2 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.0. The aqueous ionic liquid layer was evaporated and reused.

[0141] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 2-3 prepared in Example 2 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 10. The specific reaction conditions are shown in Table 11:

[0142] Table 11 Example 2-3 Nitration of chlorobenzene catalyzed by [polyethyleneimine][CF3SO3H]3 ionic liquid

[0143]

[0144] Example 12

[0145] To a four-necked flask equipped with a reflux condenser, 36.0 g of the ionic liquid prepared in Example 3-1 and 25.3 g of 95% nitric acid were added. The mixture was heated to 70-80°C and 30 g of benzene was added to initiate the nitration reaction. After 8 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower layer, containing water, of the ionic liquid was separated, and the upper organic phase, containing nitrobenzene, was separated. The vapor phase of the upper organic phase was analyzed for product, revealing a mononitrobenzene content of 95.2% and a dinitrobenzene content of 0.1%.

[0146] The examples of catalytic nitration of benzene by ionic liquid 3-1 and nitric acid at other concentrations can be similarly carried out by the general method mentioned in the examples. The specific reaction conditions are shown in Table 12:

[0147] Table 12 Example 3-1 Nitration of benzene catalyzed by [polyethyleneimine][H2SO4]3 ionic liquid

[0148]

[0149]

[0150] Note: The contents in Table 12 are the contents of the corresponding substances in the upper organic phase.

[0151] Example 13

[0152] To a four-necked flask equipped with a reflux condenser, 28.0 g of the ionic liquid prepared in Example 3-1 and 16.5 g of 68% nitric acid were added, heated to 70-80°C, and 20.0 g of chlorobenzene was added to carry out the nitration reaction. After 12 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for stratification. The lower aqueous ionic liquid layer was separated, and the upper organic phase was essentially mononitrochlorobenzene. The chlorobenzene conversion was 96%. Gas analysis of the upper organic phase revealed a mononitrochlorobenzene content of 95% and a dinitrochlorobenzene content of 0.05%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.3. The aqueous ionic liquid layer was evaporated to remove water and could be reused.

[0153] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid prepared in Example 3-1 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 13. The specific reaction conditions are shown in Table 13:

[0154] Table 13 Example 3-1 Nitration of chlorobenzene catalyzed by [polyethyleneimine][H2SO4]3 ionic liquid

[0155]

[0156] Note: The contents in Table 13 are the contents of the corresponding substances in the upper organic phase.

[0157] Example 14

[0158] To a four-necked flask equipped with a reflux condenser, 42.0 g of the ionic liquid prepared in Example 3-1 and 30.5 g of 68% nitric acid were added, followed by heating to 70-80°C. Then, 30.0 g of toluene was added to initiate the toluene nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer separated, while the upper organic phase consisted primarily of mononitrotoluene, achieving a toluene conversion exceeding 95%. Liquid chromatography analysis of the product revealed an o-toluene ratio of 2.1. The aqueous ionic liquid layer was evaporated and reused.

[0159] The examples of catalyzing the nitration of toluene by the ionic liquid prepared in Example 3-1 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 14. The specific reaction conditions are shown in Table 14:

[0160] Table 14 Example 3-1 Nitration of toluene catalyzed by [polyethyleneimine][H2SO4]3 ionic liquid

[0161]

[0162] Example 15

[0163] To a four-necked flask equipped with a reflux condenser, 48.0 g of the ionic liquid prepared in Example 3-1 and 18.9 g of 68% nitric acid were added, followed by heating to 70-80°C. Then, 30.0 g of o-dichlorobenzene was added to initiate a nitration reaction. After 12 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer separated, while the upper organic phase, consisting primarily of mononitro-o-dichlorobenzene, achieved a conversion rate exceeding 94%. The aqueous ionic liquid layer could be reused after evaporation.

[0164] The examples of catalyzing the nitration of o-dichlorobenzene by the ionic liquid prepared in Example 3-1 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 15. The specific reaction conditions are shown in Table 15:

[0165] Table 15 Example 3-1 Nitration of o-dichlorobenzene catalyzed by [polyethyleneimine][H2SO4]3 ionic liquid

[0166] Example Substrate / ionic liquid weight ratio Nitric acid(%) Temperature Reaction time Conversion rate (%) 15-1 1:1.6 65 70-80 12h 94.1 15-2 1:1.6 68 70-80 12h 94.2 15-3 1:1.6 95 70-80 11h 96.2 15-4 1:1.6 98 70-80 11h 97.0

[0167] Example 16

[0168] To a four-necked flask equipped with a reflux condenser, 48.0 g of the ionic liquid prepared in Example 3-1 and 26.2 g of 68% nitric acid were added, followed by heating to 70-80°C. Then, 30.0 g of o-xylene was added to initiate a nitration reaction. After 8 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer separated, while the upper organic phase, consisting primarily of mononitro o-xylene, achieved a conversion rate exceeding 94%. The aqueous ionic liquid layer could be reused after evaporation.

[0169] The examples of catalyzing the nitration of o-xylene by the ionic liquid prepared in Example 3-1 at other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 16. Here, as shown in Table 16:

[0170] Table 16 Example 3-1 Nitration of o-xylene catalyzed by [polyethyleneimine][H2SO4]3 ionic liquid

[0171] Example Substrate / ionic liquid weight ratio Nitric acid (%) Temperature Reaction time Conversion Rate % 16-1 1:1.6 65 70-80 8h 95.1 16-2 1:1.6 68 70-80 8h 95.2 16-3 1:1.6 95 70-80 7h 96.5 16-4 1:1.6 98 70-80 7h 96.8

[0172] Example 17

[0173] The results of the nitration reactions of the ionic liquid 3-1 described in Example 3 with other aromatic hydrocarbons and substituted aromatic hydrocarbons are summarized in Table 17 below. The raw material amounts, reaction parameters, and post-treatment conditions not listed in the table are the same as those in Example 16, for example, the molar ratio of pure nitric acid to the nitration substrate is 1:1.

[0174] Table 17 Example 3-1 Nitration of aromatic hydrocarbons catalyzed by [polyethyleneimine] [H2SO4]3 ionic liquid

[0175]

[0176]

[0177] Note: “ / ” in Table 17 represents “or”.

[0178] Example 18

[0179] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 3-3 prepared in Example 3 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.2. The aqueous ionic liquid layer was evaporated and reused.

[0180] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 3-3 prepared in Example 3 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 18. The specific conditions are shown in Table 18:

[0181] Table 18 Example 3-3 Nitration of chlorobenzene catalyzed by [polyethyleneimine] [H2SO4] ionic liquid

[0182]

[0183] Example 19

[0184] To a four-necked flask equipped with a reflux condenser, 50.4 g of ionic liquid 3-6 prepared in Example 3 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.2. The aqueous ionic liquid layer was evaporated and reused.

[0185] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 3-6 prepared in Example 3 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 19. The specific conditions are shown in Table 19:

[0186] Table 19 Nitration of chlorobenzene catalyzed by ionic liquid 3-6 in Example 3

[0187] Example Substrate / ionic liquid weight ratio Nitric acid Temperature Reaction time Conversion Rate % Neighbor comparison 19-1 1:1.4 65％ 70-80 12h 95.0 2.2 19-2 1:1.4 68％ 70-80 12h 95.0 2.2 19-3 1:1.4 95％ 70-80 11h 95.2 2.2 19-4 1:1.4 98％ 70-80 11h 95.2 2.2

[0188] Example 20

[0189] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 3-9 prepared in Example 3 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.2. The aqueous ionic liquid layer was evaporated and reused.

[0190] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 3-9 prepared in Example 3 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 20. The specific conditions are shown in Table 20:

[0191] Table 20 Nitration of chlorobenzene catalyzed by ionic liquid 3-9 in Example 20

[0192] Example Substrate / ionic liquid weight ratio Nitric acid Temperature Reaction time Conversion Rate % Neighbor comparison 20-1 1:1.4 65％ 70-80 12h 95.0 2.1 20-2 1:1.4 68％ 70-80 12h 95.0 2.1 20-3 1:1.4 95％ 70-80 11h 95.1 2.2 20-4 1:1.4 98％ 70-80 11h 95.1 2.2

[0193] Example 21

[0194] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 4-1 prepared in Example 4 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.1. The aqueous ionic liquid layer was evaporated and reused.

[0195] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 4-1 prepared in Example 4 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 21. The specific conditions are shown in Table 21:

[0196] Table 21 Nitration of chlorobenzene catalyzed by ionic liquid 4-1 in Example 4

[0197] Example Substrate / ionic liquid weight ratio Nitric acid Temperature Reaction time Conversion Rate % Neighbor comparison 21-1 1:1.4 65％ 70-80 12h 95.0 2.1 21-2 1:1.4 68％ 70-80 12h 95.0 2.1 21-3 1:1.4 95％ 70-80 11h 95.2 2.1 21-4 1:1.4 98％ 70-80 11h 95.2 2.1

[0198] Example 22

[0199] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 4-2 prepared in Example 4 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.1. The aqueous ionic liquid layer was evaporated and reused.

[0200] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 4-2 prepared in Example 4 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 22. The specific conditions are shown in Table 22:

[0201] Table 22 Nitration of chlorobenzene catalyzed by ionic liquid 4-2 in Example 22

[0202] Example Substrate / ionic liquid weight ratio Nitric acid Temperature Reaction time Conversion Rate % Neighbor comparison 22-1 1:1.4 65％ 70-80 12h 95.0 2.0 22-2 1:1.4 68％ 70-80 12h 95.0 2.0 22-3 1:1.4 95％ 70-80 11h 95.1 2.1 22-4 1:1.4 98％ 70-80 11h 95.1 2.1

[0203] Example 23

[0204] To a four-necked flask equipped with a reflux condenser, 50.4 g of the ionic liquid 4-3 prepared in Example 4 and 21.2 g of 95% nitric acid were added, heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase consisted primarily of the product, mononitrochlorobenzene, with a conversion rate exceeding 94%. Liquid chromatography analysis of the product revealed an o-to-to ratio of 2.1. The aqueous ionic liquid layer was evaporated and reused.

[0205] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid 4-3 prepared in Example 4 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 23. The specific conditions are shown in Table 23:

[0206] Table 23 Nitration of chlorobenzene catalyzed by ionic liquid 4-3 in Example 23

[0207] Example Substrate / ionic liquid weight ratio Nitric acid Temperature Reaction time Conversion Rate % Neighbor comparison 23-1 1:1.4 65％ 70-80 12h 95.0 2.0 23-2 1:1.4 68％ 70-80 12h 95.0 2.0 23-3 1:1.4 95％ 70-80 11h 95.1 2.1 23-4 1:1.4 98％ 70-80 11h 95.1 2.1

[0208] Example 24

[0209] To a four-necked flask equipped with a reflux condenser, 51.0 g of the ionic liquid product from Example 5-3 and 21.2 g of 95% nitric acid (1.0 eq.) were added sequentially. The mixture was heated to 70-80°C, and 36.0 g of chlorobenzene was added to carry out the nitration of chlorobenzene. After the reaction, the mixture was cooled to 40-50°C, allowed to stand, and the layers separated. The lower aqueous ionic liquid layer was separated, and the upper organic phase was essentially mononitrochlorobenzene, with a conversion rate of greater than 97%.

[0210] Liquid chromatography analysis of the product showed an o-to-concentration ratio of 2.3. The aqueous ionic liquid layer was evaporated under reduced pressure and then reused.

[0211] The examples of catalyzing the nitration of chlorobenzene by the ionic liquid prepared in Example 5-3 under other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 24. The specific conditions are shown in Table 24:

[0212] Table 24 Example 5-3 Nitration of chlorobenzene catalyzed by [pentaethylenehexamine][H2SO4]3 ionic liquid

[0213] Example Substrate / ionic liquid weight ratio Nitric acid(%) Temperature Reaction time Conversion Rate % Neighbor comparison 24-1 1:1.4 65 70-80 12h 97.2 2.3 24-2 1:1.4 68 70-80 12h 97.4 2.3 24-3 1:1.4 95 70-80 11h 98.4 2.3 24-4 1:1.4 98 70-80 11h 98.5 2.3

[0214] Example 25

[0215] To a four-necked flask equipped with a reflux condenser, 42.0 g of the ionic liquid prepared in Example 5-3 and 30.5 g of 68% nitric acid were added, heated to 70-80°C, and 30.0 g of toluene was added to carry out the toluene nitration reaction. After the reaction, the flask was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer was separated, and the upper organic phase was essentially mononitrotoluene, with a conversion rate exceeding 97%. Liquid chromatography analysis of the product revealed an o-toluene ratio of 2.4. The aqueous ionic liquid layer was evaporated and reused.

[0216] The examples of catalyzing the nitration of toluene with the ionic liquid prepared in Example 5-3 and nitric acid at other concentrations can be similarly carried out using the general method mentioned in Example 25. The specific conditions are shown in Table 25:

[0217] Table 25 Example 5-3 Nitration of toluene catalyzed by [pentaethylenehexamine][H2SO4]3 ionic liquid

[0218] Example Substrate / ionic liquid weight ratio Nitric acid(%) Temperature Reaction time Conversion Rate % Neighbor comparison 26-1 1:1.4 65 70-80 11h 94.4 2.4 26-2 1:1.4 68 70-80 11h 94.4 2.4 26-3 1:1.4 95 70-80 10h 95.4 2.4 26-4 1:1.4 98 70-80 10h 96.2 2.4

[0219] Example 26

[0220] The results of the nitration reactions of the ionic liquid 5-3 described in Example 5 with other aromatic hydrocarbons and substituted aromatic hydrocarbons are summarized in Table 26 below. The raw material dosage relationships, reaction parameters, and post-treatment conditions not listed in the table are the same as those in Example 25, for example, the molar ratio of pure nitric acid to the nitration substrate is 1:1.

[0221] Table 26 Example 5-3 Nitration of aromatic hydrocarbons catalyzed by [pentaethylenehexamine][H2SO4]3 ionic liquid

[0222]

[0223]

[0224] Note: “ / ” in Table 26 represents “or”.

[0225] Example 27

[0226] To a four-necked flask equipped with a reflux condenser, 28.0 g of the ionic liquid prepared in Examples 5-6 and 11.8 g of 95% nitric acid were added, followed by heating to 70-80°C. Then, 20.0 g of chlorobenzene was added to initiate the nitration of chlorobenzene. After 12 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer separated, while the upper organic phase, consisting primarily of mononitrochlorobenzene, exhibited a conversion rate exceeding 96%. Liquid chromatography analysis revealed an o-to-to ratio of 2.3. The aqueous ionic liquid layer was evaporated and reused.

[0227] The examples of catalyzing the nitration of chlorobenzene by the ionic liquids prepared in Examples 5-6 at other concentrations of nitric acid can be similarly carried out by the general method mentioned in Example 27. The specific conditions are shown in Table 27:

[0228] Table 27 Example 5-6 Nitration of chlorobenzene catalyzed by [tetraethylenepentamine][H2SO4]3 ionic liquid

[0229]

[0230]

[0231] Example 28

[0232] To a four-necked flask equipped with a reflux condenser, 42.0 g of the ionic liquid prepared in Examples 5-6 and 30.5 g of 68% nitric acid were added, followed by heating to 70-80°C. Then, 30.0 g of toluene was added to initiate the toluene nitration reaction. After 11 hours of reaction, the mixture was cooled to 40-50°C and allowed to stand for separation. The lower aqueous ionic liquid layer separated, while the upper organic phase, consisting primarily of mononitrotoluene, exhibited a conversion rate exceeding 95%. Liquid chromatography analysis of the product revealed an o-toluene ratio of 2.4. The aqueous ionic liquid layer was evaporated and reused.

[0233] The examples of catalyzing the nitration of toluene with the ionic liquids prepared in Examples 5-6 and nitric acid at other concentrations can be similarly carried out using the general method mentioned in Example 28. The specific conditions are shown in Table 28:

[0234] Table 28 Example 5-6 Nitration of toluene catalyzed by [tetraethylenepentamine][H2SO4]3 ionic liquid

[0235] Example Substrate / ionic liquid weight ratio Nitric acid (%) Temperature Reaction time Conversion Rate % Neighbor comparison 28-1 1:1.4 65 70-80 11h 96 2.4 28-2 1:1.4 68 70-80 11h 96.6 2.4 28-3 1:1.4 95 70-80 10h 97 2.4 28-4 1:1.4 98 70-80 10h 97.5 2.4

[0236] Example 29

[0237] The results of the nitration reactions of ionic liquids 5-6 described in Example 5 with other aromatic hydrocarbons and substituted aromatic hydrocarbons are summarized in Table 29 below. The raw material amounts, reaction parameters, and post-treatment conditions not listed in the table are the same as those in Example 28, for example, the molar ratio of pure nitric acid to the nitration substrate is 1:1.

[0238] Table 29 Example 5-6 [Tetraethylenepentamine][H2SO4]3 ionic liquid catalyzed nitration of aromatic hydrocarbons

[0239]

[0240]

[0241]

[0242] Note: “ / ” in Table 29 represents “or”.

[0243] The ionic liquid used in the following comparative examples is N,N-tetramethylethylenediamine sulfate, i.e. [N,N-tetramethylethylenediamine][H2SO4]3. The specific preparation method is shown in Example 3-1, that is, the raw material polyethyleneimine in Example 3-1 is replaced by N,N-tetramethylethylenediamine.

[0244] Comparative Example 1

[0245] To a four-necked flask equipped with a reflux condenser, add 36.0g of ionic liquid (N,N-tetramethylethylenediamine sulfate, molar ratio of cationic nitrogen element:sulfuric acid = 1:3) and 25.3g of 95% nitric acid. Heat to 70-80°C, then add 30g of benzene to initiate the nitration reaction. After 8 hours of reaction, cool to 40-50°C, allow to stand, and separate the lower aqueous ionic liquid layer. The upper organic phase, nitrobenzene, is separated. Gas analysis of the upper organic phase reveals a mononitrobenzene content of 87.1% and a dinitrobenzene content of 5.3%.

[0246] Examples of nitration of benzene catalyzed by [N,N-tetramethylethylenediamine][H2SO4]3 ionic liquid and nitric acid at other concentrations can be similarly carried out using the general method mentioned in Comparative Example 1. The specific conditions are shown in Table 30:

[0247] Table 30 Nitration of benzene catalyzed by N,N-tetramethylethylenediamine sulfate ionic liquid

[0248]

[0249] Note: The contents in Table 30 are the contents of the corresponding substances in the upper organic phase.

[0250] Comparing the results of Example 12 with Comparative Example 1 shows that when sulfate ionic liquids formed from different ammonium ions are used to catalyze the nitration reaction of benzene, the nitration products exhibit essential differences. The nitrobenzene product obtained using the ionic liquid Example 3-1 [polyethyleneimine][H2SO4]3 of the present invention as the catalyst has a higher mononitrobenzene content of over 95%, with minimal dinitrobenzene contamination. In contrast, the nitrobenzene product obtained using the N,N-tetramethylethylenediamine sulfate ionic liquid as the catalyst has a mononitrobenzene content of only approximately 87%, with over 5% dinitrobenzene contamination. The ionic liquids of the present invention exhibit higher selectivity for the mononitration reaction.

[0251] Comparative Example 2

[0252] To a four-necked flask equipped with a reflux condenser, add 28.0g of ionic liquid (N,N-tetramethylethylenediamine sulfate, molar ratio of cationic nitrogen to sulfuric acid = 1:3) and 16.5g of 68% nitric acid. Heat to 70-80°C, then add 20g of chlorobenzene to initiate the nitration reaction. After 12 hours of reaction, cool to 40-50°C, allow to stand, and separate the lower aqueous ionic liquid layer. The upper organic phase, representing nitrochlorobenzene, is separated. Gas analysis of the upper organic phase reveals a mononitrochlorobenzene content of 88.3% and a dinitrochlorobenzene content of 3.8%.

[0253] The examples of nitration of chlorobenzene catalyzed by [N,N-tetramethylethylenediamine][H2SO4]3 ionic liquid and nitric acid at other concentrations can be similarly carried out using the general method mentioned in Comparative Example 2. The specific conditions are shown in Table 31:

[0254] Table 31 Nitration of chlorobenzene catalyzed by N,N-tetramethylethylenediamine sulfate ionic liquid

[0255]

[0256] Note: The contents in Table 31 are the contents of the corresponding substances in the upper organic phase.

[0257] Comparison of the results in Example 13 and Comparative Example 2 reveals that when sulfate ionic liquids formed from different ammonium ions are used to catalyze the nitration reaction of chlorobenzene, the nitration products exhibit substantial differences. The nitrochlorobenzene product obtained using the ionic liquid Example 3-1 [polyethyleneimine][H2SO4]3 of the present invention as the catalyst exhibits a higher mononitrochlorobenzene content of over 95%, with minimal dinitrochlorobenzene contamination. In contrast, the nitrochlorobenzene product obtained using the N,N-tetramethylethylenediamine sulfate ionic liquid as the catalyst exhibits only approximately 89% mononitrochlorobenzene content, with a dinitrochlorobenzene contamination content of 3.8%. The ionic liquids of the present invention exhibit higher selectivity for the mononitration reaction.

Claims

1. A polyethyleneimine type ammonium salt ionic liquid as a catalyst in the field of industrial acid catalysis reaction, characterized in that: The ammonium salt ionic liquid is prepared from polyethyleneimine and the corresponding protonic acid, and the anion in the ammonium salt ionic liquid comes from the anion in the protonic acid, selected from HSO4 - 、HSO4(H2SO4) - 、HSO4(H2SO4)2 - CF3SO3 - 、CH3SO3 - and R'-C6H4SO3 - An anion in which R' is an alkyl group; the cation in the ammonium salt ionic liquid is an ammonium cation formed by polyethyleneimine, and in the ammonium salt ionic liquid, the molar ratio of nitrogen atoms to proton acid is 1: (1 to 3); The structure of the polyethyleneimine is shown in the following formula I: , Formula Ⅰ In formula I, x and y are not zero at the same time and x+y≥4, R is selected from H, C1-C12 alkyl, And z = 1~15, and At least one of; The industrial acid-catalyzed reaction is a nitration reaction, and the nitration reaction is a nitration reaction of aromatic hydrocarbons catalyzed by the polyethyleneimine type ammonium salt ionic liquid.

2. The application of the polyethyleneimine type ammonium salt ionic liquid as a catalyst in the field of industrial acid catalysis reaction according to claim 1, characterized in that: The aromatic hydrocarbon is selected from benzene or substituted benzene, and the substituted benzene is selected from one of monosubstituted, disubstituted and polysubstituted.

3. The application of the polyethyleneimine type ammonium salt ionic liquid as a catalyst in the field of industrial acid catalysis reaction according to claim 2, characterized in that: The structure of the substituted benzene is selected from one of the following structures: , formula II; , formula III; , Formula IV; In the formula II, X is selected from one of halogen, alkyl, halogen-substituted alkyl, alkoxy, and amide; In the formula III or IV, X is selected from halogen, alkyl, and alkoxy; and X in the formula III and IV is the same or different.

4. The application of the polyethyleneimine type ammonium salt ionic liquid as a catalyst in the field of industrial acid catalysis reaction according to claim 3, characterized in that: In the formula II, X is selected from F, Cl, Br, I, CF3, CH3, OCH3, C2H5, C4H9, C 10 H 21 、C 12 H 25 、C 18 H 37 and one of NHCOCH3; In the formula III or IV, X is selected from one of F, Cl and CH3.

5. The application of the polyethyleneimine type ammonium salt ionic liquid as a catalyst in the field of industrial acid catalysis reaction according to claim 2, characterized in that: The structure of the substituted benzene is shown in Formula V: , Formula V, wherein A is O, CH2 or S.

6. The use of the polyethyleneimine type ammonium salt ionic liquid according to claim 1 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: The R' is CH3 or C 12 H 25 ; and / or, x=0~230, y=0~230, and x+y≥4; And / or, the Mn of the polyethyleneimine is 400-13000.

7. The use of the polyethyleneimine type ammonium salt ionic liquid according to claim 6 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: x = 0~100, y = 0~100, and x+y ≥ 4.

8. The use of the polyethyleneimine type ammonium salt ionic liquid according to claim 1 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: The polyethyleneimine is selected from at least one of CAS Nos. 9002-98-6, 25987-06-8, 106899-94-9, and 68130-97-2.

9. The use of the polyethyleneimine type ammonium salt ionic liquid according to claim 1 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: The polyethyleneimine is selected from EPOMIN polyethyleneimine produced by Nippon Shokubai or Lupasol polyethyleneimine produced by BASF.

10. Use of the polyethyleneimine type ammonium salt ionic liquid according to claim 1 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: In the formula I, x=0 and y=4~100.

11. Use of the polyethyleneimine type ammonium salt ionic liquid according to claim 10 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: In the formula I, x=0 and y=7~100.

12. Use of the polyethyleneimine type ammonium salt ionic liquid according to claim 1 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: The polyethyleneimine is selected from one of CAS Nos. 4067-16-7 and 112-57-2.

13. Use of the polyethyleneimine type ammonium salt ionic liquid according to claim 1 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: The structural formula of the polyethyleneimine is as follows: , where Mn is 500-11000.

14. Use of the polyethyleneimine type ammonium salt ionic liquid according to claim 1 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: In the formula I, R is one of C1~C12 alkyl groups, and Mn is 6000-10000.

15. Use of the polyethyleneimine type ammonium salt ionic liquid according to claim 1 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: The CAS number of the polyethyleneimine is 26913-07-5.

16. Use of the polyethyleneimine type ammonium salt ionic liquid according to any one of claims 1 to 15 as a catalyst in the field of industrial acid-catalyzed reactions, characterized in that: The preparation method of the polyethyleneimine type ammonium salt ionic liquid is as follows: Add an appropriate amount of protonic acid to polyethyleneimine, and after the reaction, obtain an ionic liquid in which ammonium cations formed by polyethyleneimine and anions of protonic acid are coordinated; the anions are selected from HSO4 (H2SO4) - 、HSO4(H2SO4)2 - 、HSO4 - CF3SO3 - 、CH3SO3 - and R'-C6H4SO3 - An anion in, wherein R' is an alkyl group; the molar equivalent ratio of the protonic acid to the nitrogen atoms in the polyethyleneimine is 3:1 to 1:

1.

17. Use of the polyethyleneimine type ammonium salt ionic liquid according to claim 16 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: The method for preparing the polyethyleneimine type ammonium salt ionic liquid specifically comprises the following steps: Step 1: Add polyethyleneimine to a reactor equipped with a stirring device and a condensing reflux device, start stirring, and set the speed to 100-1000 rpm; Step 2: Add the protonic acid into the reactor of step 1 in batches over 30-60 minutes, and control the temperature in the reactor to be between 0-30°C. After the addition is completed, stir at 0-30°C for 2-3 hours to obtain a viscous ionic liquid.

18. Use of the polyethyleneimine type ammonium salt ionic liquid according to claim 17 as a catalyst in the field of industrial acid catalysis reaction, characterized in that: In step 1, the speed is set to 400-800 rpm.

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