Preparation method of halogenated aryl compound

Abstract

The invention discloses a preparation method of a halogenated aryl compound, which comprises the following steps: by taking lignin or a lignin model compound as a raw material, carrying out halogenation depolymerization reaction in the presence of a halogenating reagent and a solvent to obtain the halogenated aryl compound. According to the method, the first halogenation depolymerization reaction of the lignin model compound and real lignin is realized, the polysubstituted aryl halide can be prepared by taking the lignin or the lignin model compound as a raw material, and the method is low in cost, simple in operation and reaction conditions, green and renewable in raw material, high in depolymerization efficiency and wide in lignin universality.

Description

Technical Field

[0001] The invention relates to a method for preparing a halogenated aryl compound. Background Art

[0002] Halogenated aromatic compounds (or aromatic halides) are indispensable chemical raw materials in academic research and industrial production. At present, aromatic halides are mainly produced by halogenation of aromatic hydrocarbons produced by catalytic reforming and steam cracking of petroleum and coal. However, these routes that rely on fossil resources have problems such as complex preparation, numerous processes, high energy consumption, and environmental pollution. Therefore, the development of efficient and green production processes using renewable biomass as raw materials has received widespread attention, which is in line with the trend of environmental friendliness and sustainable development.

[0003] Lignin is the most abundant aromatic structural resource on earth and is the most promising alternative for the production of functionalized aromatic compounds. The conversion of lignin into high-value aromatic chemicals through the depolymerization of lignin bonds has been widely studied, and these conditions usually require composite / precious metal catalysts, high temperatures, and high pressure reaction conditions. Under these depolymerization systems, only simple oxygen-containing aromatic molecules can be obtained, such as phenol, aromatic ketones, phenylpropane, benzoic acid, and phenylpropanol. The introduction of heteroatoms other than C, H, and O during the depolymerization of lignin can construct more diverse functionalized aromatics, further enrich the types of lignin products, and make lignin more efficient in value-added.

[0004] The depolymerization and functionalization methods of lignin units reported in the literature can only prepare aromatic molecules containing heteroatoms (S, N, Si). However, due to the complex three-dimensional structure and low reactivity of real lignin, these methods are mostly limited to lignin model compounds, and are often extremely inefficient when treating real lignin. There are two main problems: (1) pretreatment processes, such as oxidation of natural lignin or in situ modification of N atoms, are necessary steps to construct reactive sites; (2) the introduction of functional groups with rich conversion capabilities is extremely limited, and simultaneous depolymerization and functionalization in a simple reaction system is still extremely challenging. Therefore, it is of great significance to convert lignin into aromatic compounds with more functions and wider applications. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for preparing a halogenated aromatic compound, realizes the first halogenated depolymerization reaction of a lignin model compound and real lignin, and can prepare polysubstituted aromatic halides (such as polysubstituted aromatic bromides and chlorides) using lignin or a lignin model compound as a raw material. The method of the present invention has low cost, simple operation and reaction conditions, green and renewable raw materials, high depolymerization efficiency and wide lignin universality, and solves the defects of the prior art that the raw materials for the preparation of brominated and chlorinated aromatic compounds are non-renewable and unsustainable, the depolymerization efficiency of lignin functional groups is low, and the value of depolymerization products is not high.

[0006] According to a first aspect of the present invention, a method for preparing a halogenated aromatic compound is provided, the method comprising using lignin or a lignin model compound as a raw material, and carrying out a halogenated depolymerization reaction in the presence of a halogenating agent and a solvent to obtain a halogenated aromatic compound.

[0007] In some embodiments, the lignin is selected from softwood lignin and / or hardwood lignin.

[0008] In some embodiments, the lignin is selected from one or more of larch lignin, Scots pine lignin, red pine lignin, fir lignin, poplar lignin, birch lignin, and beech lignin.

[0009] In some embodiments, the halogenated aryl compound includes a brominated aryl compound and / or a chlorinated aryl compound.

[0010] In some embodiments, the halogenated aromatic compound prepared using the lignin as a raw material includes one or more of the following compounds:

[0011]

[0012] In some embodiments, the halogenated aromatic compound prepared using the softwood lignin as a raw material includes one or more of the following compounds:

[0013]

[0014] In some embodiments, the halogenated aromatic compound prepared using the hardwood lignin as a raw material includes one or more of the following compounds:

[0015]

[0016] In some embodiments, the lignin model compound has a structure as shown in Formula I:

[0017]

[0018] R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 Each is independently selected from hydrogen, C1-C6 alkoxy, C1-C6 alkyl, halogen, hydroxyl; R6 is selected from hydrogen or hydroxymethyl.

[0019] In some embodiments, R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 Each is independently selected from hydrogen or C1-C6 alkoxy.

[0020] In some embodiments, R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 Not at the same time as hydrogen.

[0021] In some embodiments, R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 Each is independently selected from hydrogen or methoxy.

[0022] In some embodiments, R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 In the embodiment, at least one of R2, R3 and R4 is a methoxy group, and R9 and R 11 At least one of them is a methoxy group and the rest are hydrogen.

[0023] In some embodiments, the lignin model compound is selected from:

[0024]

[0025] In some embodiments, the halogenated aromatic compound prepared using the lignin model compound as a raw material includes the following compounds:

[0026]

[0027] In some embodiments, the halogenating agent is selected from one or more of N-chlorosuccinimide (NCS) and N-bromosuccinimide (NBS).

[0028] In some embodiments, the solvent comprises a first solvent selected from 2,2,2-trifluoroethanol and / or hexafluoroisopropanol.

[0029] In some embodiments, the solvent further comprises a second solvent, and the second solvent is selected from one or more of ethyl acetate, methyl acetate, DMSO, 1,4-dioxane, and acetone.

[0030] In some embodiments, the volume ratio of the first solvent to the second solvent is 1:(0.1-10), for example, 1:0.1, 1:0.2, 1:0.5, 1:0.8, 1:1, 1:2, 1:5, 1:10 or any value therebetween.

[0031] In some preferred embodiments, the volume ratio of the first solvent to the second solvent is 1:(0.5-2), preferably 1:(0.8-1.2), for example 1:1.

[0032] In some embodiments, the concentration of the lignin in the solvent is 5-100 g / L, preferably 10-50 g / L.

[0033] In some specific embodiments, the concentration of the lignin in the solvent is 5 g / L, 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 80 g / L, 100 g / L or any value therebetween.

[0034] In some embodiments, the concentration of the lignin model compound in the solvent is 0.05-0.5M, preferably 0.05-0.2M.

[0035] In some specific embodiments, the concentration of the lignin model compound in the solvent is 0.05 M, 0.1 M, 0.15 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M or any value therebetween.

[0036] In some embodiments, the concentration of the halogenating agent in the solvent is 0.05-5M, preferably 0.1-2M.

[0037] In some embodiments, the concentration of the halogenating agent in the solvent is 0.05 M, 0.1 M, 0.15 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M or any value therebetween.

[0038] In some embodiments, when the raw material is a lignin model compound, the concentration of the halogenating agent in the solvent is 0.1-1M, preferably 0.2-0.8M.

[0039] In some specific embodiments, when the raw material is a lignin model compound, the concentration of the halogenating agent in the solvent is 0.1 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M, 0.6 M, 0.8 M or any value therebetween.

[0040] In some embodiments, the concentration of the halogenating agent in the solvent is 0.05-5M, preferably 0.1-2M.

[0041] In some embodiments, the concentration of the halogenating agent in the solvent is 0.05 M, 0.1 M, 0.5 M, 1 M, 1.5 M, 2 M, 3 M, 4 M, 5 M or any value therebetween.

[0042] In some embodiments, the mass ratio of the lignin to the halogenating agent is 1:(0.2-50), preferably 1:(0.5-20).

[0043] In some specific embodiments, the mass ratio of the lignin to the halogenating agent is 1:0.2, 1:0.5, 1:1, 1:5, 1:10, 1:15, 1:20, 1:30, 1:40, 1:50 or any value therebetween.

[0044] In some embodiments, the molar ratio of the lignin model compound to the halogenating agent is 1:(1-20), preferably 1:(2-10).

[0045] In some specific embodiments, the molar ratio of the lignin model compound to the halogenating agent is 1:1, 1:2, 1:4, 1:1:5, 1:6, 1:8, 1:10, 1:15, 1:20 or any value therebetween.

[0046] In some embodiments, the reaction temperature of the halogenation depolymerization reaction is 10-120°C, preferably 15-100°C.

[0047] In some specific embodiments, the reaction temperature of the halogenated depolymerization reaction is 10°C, 15°C, 20°C, 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or any value therebetween.

[0048] In some embodiments, when the raw material is lignin, the reaction temperature of the halogenated depolymerization reaction is 10-40° C., preferably 15-30° C. In some specific embodiments, when the raw material is lignin, the reaction temperature of the halogenated depolymerization reaction is 10° C., 15° C., 20° C., 25° C., 30° C., 40° C. or any value therebetween.

[0049] In some embodiments, when the raw material is a lignin model compound, the reaction temperature of the halogenated depolymerization reaction is 10-120° C., preferably 25-100° C. In some specific embodiments, when the raw material is a lignin model compound, the reaction temperature of the halogenated depolymerization reaction is 10° C., 15° C., 20° C., 25° C., 30° C., 40° C., 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., 110° C., 120° C. or any value therebetween.

[0050] In some embodiments, the halogenation depolymerization reaction time is 8-80 hours, preferably 12-72 hours.

[0051] In some specific embodiments, the halogenation depolymerization reaction time is 8 h, 10 h, 15 h, 20 h, 30 h, 40 h, 50 h, 60 h, 700 h, 80 h or any value therebetween.

[0052] In some embodiments, when the raw material is lignin, the time of the halogen depolymerization reaction is 60-80 hours, for example, 64 hours, 68 hours, 72 hours, 76 hours, etc.

[0053] In some embodiments, when the raw material is a lignin model compound, the time of the halogenated depolymerization reaction is 8-20 hours, for example, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, etc.

[0054] According to a second aspect of the present invention, there is provided a halogenated aromatic compound obtained by the preparation method described in the first aspect.

[0055] According to the third aspect of the present invention, there is provided the use of the halogenated aromatic compound obtained by the preparation method described in the first aspect in the synthesis of organic compounds, drug synthesis, and the preparation of polymer materials and optoelectronic materials.

[0056] The method of the present invention realizes the first halogenation depolymerization reaction of lignin model compounds and real lignin, and can prepare multi-substituted aromatic halides using lignin or lignin model compounds as raw materials. The halogenation depolymerization is initiated by the electrophilic reaction of bromine or chloride cations in the halogenation reagent to the benzene ring of lignin, wherein the activation of the halogenation reagent by 2,2,2-trifluoroethanol / or hexafluoroisopropanol through hydrogen bonding is the key to the reaction. The method of the present invention has simple and mild reaction conditions, in-situ efficient depolymerization and halogenation of lignin, cheap and readily available sources of chlorine and bromination reagents, high selectivity and high efficiency of C(sp 2 )-C(sp 3 ) bond breaking, etc., and can efficiently depolymerize and halogenate lignin from a variety of wood sources, showing excellent reactivity and system compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A gas chromatography-mass spectrometry test spectrum of brominated depolymerization products according to some embodiments of the present application is shown.

[0058] Figure 2 A gas chromatography-mass spectrometry test spectrum of a chlorinated depolymerization product according to some embodiments of the present application is shown. DETAILED DESCRIPTION

[0059] The present invention will be further described below by means of specific examples, but the scope of the present invention is not limited thereto.

[0060] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0061] Example 1 Preparation of aryl bromide compounds from lignin

[0062] The steps for preparing aromatic bromide compounds from lignin are as follows: 100 mg of larch lignin, N-bromosuccinimide (NBS) and trifluoroethanol (TFE) were added to a 10 mL Schlenk tube and stirred for 72 hours. The reactions were carried out in different solvents and reaction temperatures, as shown in Table 1 below.

[0063] After the reaction was completed, 10 mL of ethyl acetate was added and the insoluble matter was removed by centrifugation. The supernatant was dried by spin drying, an internal standard (n-octadecane) was added, and the yield was determined by gas chromatography-mass spectrometry, and the molecular weight distribution was determined by gel permeation chromatography (GPC).

[0064] The structure of the bromination depolymerization product is as follows:

[0065]

[0066] 1 H NMR (500MHz, CDCl3) δ7.18(s,1H),7.06(s,1H),5.58(s,1H),3.88(s,3H); 13 CNMR (126MHz, CDCl3) δ146.45,145.57,119.15,115.50,115.36,113.79,56.36.

[0067] The yield results are shown in Table 1 below.

[0068] Table 1

[0069] experiment Temperature(℃) Solvent (4 mL) NBS(mmol) Yield (wt%) 15 TFE 3 0.112 1 25 TFE 3 0.177 50 TFE 3 0.035 2 80 TFE 3 0.047 5 100 TFE / acetone (1:1) 3 0.031 6 100 TFE / 1,4-dioxane (1:1) 3 0.010 8 25 TFE 2 0.064 9 25 TFE 5 0.104

[0070] Example 2 Preparation of aromatic chloride compounds from lignin

[0071] The steps for preparing aromatic chloride compounds from lignin are as follows: 100 mg of larch lignin, N-chlorosuccinimide (NCS) and trifluoroethanol were added to a 10 mL Schlenk tube. The mixture was stirred for 72 hours. The reactions were carried out in different solvents and reaction temperatures, as shown in Table 2 below.

[0072] After the reaction was completed, 10 mL of ethyl acetate was added and the insoluble matter was removed by centrifugation. The supernatant was dried by spin drying, and an internal standard (n-octadecane) was added. The yield was determined by gas chromatography-mass spectrometry, and its molecular weight distribution was determined by GPC. The structure of the chlorinated depolymerization product is as follows:

[0073]

[0074] 1 H NMR (500MHz, CDCl3) δ6.06 (s, 1H), 3.95 (s, 3H); 13 C NMR (126MHz, CDCl3) δ145.85,143.37,128.35,126.40,124.03,119.35,61.36.

[0075] The yield results are shown in Table 2 below.

[0076] Table 2

[0077] experiment Temperature(℃) Solvent (4 mL) NCS(mmol) Yield (wt%) 1 25 TFE 1 0.311 2 60 TFE 1 0.442 3 80 TFE 1 0.455 4 100 TFE 1 0.553 5 100 TFE / methyl acetate (1:1) 1 0.309 6 100 TFE / 1,4-dioxane (1:1) 1 1.864 8 100 TFE / 1,4-dioxane (1:1) 0.5 2.069 9 100 TFE / 1,4-dioxane (1:1) 2 2.274 10 100 TFE / 1,4-dioxane (1:1) 3 2.054 11 100 TFE / 1,4-dioxane (1:1) 4 2.691

[0078] Example 3

[0079] Different types of lignin were used to prepare aromatic bromide compounds.

[0080] The steps for preparing the aryl bromide compound are as follows: 100 mg of lignin, N-bromosuccinimide (NBS) and trifluoroethanol (4.0 mL) were added to a 10 mL Schlenk tube and the reaction was stirred at 100° C. for 72 hours.

[0081] After the reaction was completed, 10 mL of ethyl acetate was added and the insoluble matter was removed by centrifugation. The supernatant was dried by spin drying, an internal standard (n-octadecane) was added, and the yield was determined by gas chromatography-mass spectrometry, and the molecular weight distribution was determined by GPC.

[0082] The insoluble matter was washed three times with water to remove the NH compounds generated by debromination of the chlorination reagent. The obtained solid was dried and weighed in an oven at 100°C, which was recorded as the mass of insoluble matter. The insoluble matter is the highly polymerized lignin produced during the reaction, which is difficult to dissolve, has extremely low reaction activity, and cannot be used. The mass of the insoluble matter is used to reflect the degree of depolymerization of the reaction. The higher the degree of depolymerization, the less insoluble matter.

[0083] The results of yield and insoluble matter mass are shown in Table 3. The gas chromatography-mass spectrometry test spectrum of lignin bromide depolymerization product is shown in Table 3. Figure 1 shown.

[0084] The depolymerization product of bromination is or A mixture of

[0085] 1 H NMR (500MHz, CDCl3) δ7.18(s,1H),7.06(s,1H),5.58(s,1H),3.88(s,3H); 13 C NMR (126MHz, CDCl3) δ146.45,145.57,119.15,115.50,115.36,113.79,56.36.

[0086] 1H NMR (500MHz, CDCl3) δ5.78 (s, 1H), 3.92 (s, 6H); 13 C NMR (126MHz, CDCl3) δ145.62,142.92,117.69,116.23,60.98.

[0087] Table 3

[0088]

[0089] Example 4

[0090] Different types of lignin were used to prepare aromatic chloride compounds.

[0091] The steps for preparing the aryl chloride compound are as follows: 100 mg of lignin, N-chlorosuccinimide (NCS) (1 mmol) and trifluoroethanol / 1,4-dioxane (1:1, 4.0 mL) were added to a 10 mL Schlenk tube and the reaction was stirred at room temperature for 72 hours.

[0092] After the reaction was completed, 10 mL of ethyl acetate was added and the insoluble matter was removed by centrifugation. The supernatant was dried by spin drying, an internal standard (n-octadecane) was added, and the yield was determined by gas chromatography-mass spectrometry, and the molecular weight distribution was determined by GPC.

[0093] The insoluble matter was washed three times with water to remove the NH compounds generated after dechlorination by the chlorination reagent. The obtained solid was dried and weighed in an oven at 100°C, which was recorded as the mass of insoluble matter. The insoluble matter is the highly polymerized lignin produced during the reaction, which is difficult to dissolve, has extremely low reaction activity, and cannot be used. The mass of the insoluble matter is used to reflect the degree of depolymerization of the reaction. The higher the degree of depolymerization, the less insoluble matter.

[0094] The results of yield and insoluble matter mass are shown in Table 4. The gas chromatography-mass spectrometry test spectrum of lignin chlorination depolymerization product is shown in Table 4. Figure 2 shown.

[0095] The depolymerization product of bromination is or A mixture of

[0096] 1 H NMR (500MHz, CDCl3) δ6.06 (s, 1H), 3.95 (s, 3H); 13 C NMR (126MHz, CDCl3) δ145.85,143.37,128.35,126.40,124.03,119.35,61.36.

[0097] 1 H NMR (500MHz, CDCl3) δ5.79 (s, 1H), 3.94 (s, 6H); 13 C NMR (126MHz, CDCl3) δ143.63,142.63,123.40,122.88,61.19.

[0098] Table 4

[0099]

[0100]

[0101] Example 5 Preparation of aryl bromide compounds from lignin model compounds

[0102] Different types of lignin model compounds were used to prepare bromine.

[0103] Preparation of aryl bromide compounds from lignin model compounds Steps: In a 10 mL reaction bottle, add lignin model compound (0.2 mmol, 1 equivalent), N-bromosuccinimide (NBS) (0.9 mmol, 4.5 equivalents) and trifluoroethanol (2.0 mL). The reaction was stirred at room temperature for 12 hours. After the reaction was completed, the reaction mixture was filtered with a thin layer of silica gel (100-200 mesh) and the solvent was removed by rotary evaporation. The residue was purified by column chromatography on 300-400 mesh silica gel with a petroleum ether / ethyl acetate gradient eluent to obtain the target product. The results are shown in Table 5.

[0104] Table 5

[0105]

[0106]

[0107] in,

[0108] 1 H NMR (500MHz, CDCl3) δ7.06 (s, 2H), 3.86 (s, 6H); 13C NMR (126MHz, CDCl3) δ148.90,115.93,114.79,56.30.

[0109] 1 H NMR (500MHz, CDCl3) δ9.86 (t, J = 0.9 Hz, 1H), 7.13 (s, 1H), 7.04 (s, 1H), 4.60 (d, J = 0.9 Hz, 2H), 3.87 (s, 3H); 13 C NMR(126MHz, CDCl3)δ198.28,149.52,146.96,119.32,117.19,116.84,114.74,74.23,56.33.IR(ATR)ν(cm -1 )=2929,2848,1735,1589,1495,1438,1356,1250,1207,1179,1061,1027,911,852,809,735.HRMS:m / z(ESI-TOF)C9H8Br2O3[M+H] + : Theoretical value 324.8892, measured value 324.8887.

[0110] 1 H NMR (500MHz, CDCl3) δ9.85 (t, J = 1.0Hz, 1H), 7.42 (d, J = 9.0Hz, 2H), 6.79 (d, J = 8.9Hz, 2H), 4.56 (d, J = 1.1Hz, 2H); 13 C NMR(126MHz, CDCl3)δ198.54,156.74,132.63,116.39,114.32,72.81.IR(ATR)ν(cm -1 )=2919,2887,1775,1712,1587,1486,1466,1376,1285,1242,1043,1006,818,721.HRMS:m / z(ESI-TOF)C8H7BrO2[M+NH4] + : Theoretical value 231.9967, measured value 231.9970.

[0111] 1 H NMR (500MHz, CDCl3) δ9.43 (s, 1H), 7.28 (s, 1H), 7.21 (s, 1H), 5.37 (d, J = 3.1Hz, 1H), 5.21 (d, J = 3.1Hz, 1H), 3.81 (s, 3H);13 C NMR(126MHz, CDCl3)δ186.24,157.35,150.79,142.67,126.11,120.95,117.79,114.86,108.97,56.37.IR(ATR)ν(cm -1 )=2923,2846,2256,1703,1623,1583,1486,1436,1351,1310,1257,1178,1108,1029,970,909,855,732,644.HRMS:m / z(ESI-TOF)C 10 H8Br2O3[M+H] + : Theoretical value 336.8892, measured value 336.8887.

[0112] 1 H NMR (500MHz, CDCl3) δ9.45 (s, 1H), 7.49 (d, J = 8.8Hz, 2H), 6.94 (d, J = 8.8Hz, 2H), 5.44 (d, J = 2.8Hz, 1H), 5.36 (d, J = 2.9Hz, 1H); 13 C NMR(126MHz, CDCl3)δ186.83,158.24,153.73,133.03,121.78,117.77,110.47.IR(ATR)ν(cm -1 )=2924,2885,2143,1711,1622,1582,1484,1469,1375,1312,1222,1071,1046,1011,965,911,735,651.HRMS:m / z(ESI-TOF)C9H7BrO2[M+H] + : Theoretical value 226.9702, measured value 226.9710.

[0113] 1 H NMR (500MHz, CDCl3) δ7.40 (s, 1H), 6.79 (d, J = 9.0Hz, 2H), 3.78 (s, 4H); 13 C NMR (126MHz, CDCl3) δ158.75,132.27,115.78,112.83,55.42.

[0114] 1H NMR (500MHz, CDCl3) δ9.84(t,J=1.1Hz,1H),7.16(dd,J=2.6,0.7Hz,1H),6.85-6.83(m,2H),4.53(d,J=1.1Hz,2H),3.86(s,3H); 13 C NMR(126MHz, CDCl3)δ198.82,151.92,151.31,120.23,114.37,112.74,112.20,73.51,56.78.IR(ATR)ν(cm -1 )=2989,2838,2502,2072,1737,1600,1574,1494,1440,1374,1273,1241,1093,1043,848,807,752.HRMS:m / z(ESI-TOF)C9H9BrO3[M+H] + : Theoretical value 244.9807, measured value 244.9805.

[0115] 1 H NMR (500MHz, CDCl3) δ3.93 (s, 3H), 3.90 (s, 6H); 13 C NMR (126MHz, CDCl3) δ151.70,146.98,122.11,116.84,61.38,61.12.

[0116] Example 6 Preparation of aromatic chloride compounds from lignin model compounds

[0117] Different types of lignin model compounds were used to prepare aromatic chloride compounds.

[0118] Preparation of aryl chloride compounds from lignin model compounds: In a 10 mL reaction bottle, add lignin model compound (0.2 mmol, 1 equivalent), N-chlorosuccinimide (NCS) (0.8 mmol, 4 equivalents) and trifluoroethanol (2.0 mL). The reaction was stirred at room temperature for 12 hours.

[0119] After the reaction was completed, the reaction mixture was filtered through a thin layer of silica gel (100-200 mesh), and the solvent was removed by rotary evaporation. The residue was purified by column chromatography on 300-400 mesh silica gel using a petroleum ether / ethyl acetate gradient eluent to obtain the target product. The results are shown in Table 6.

[0120] Table 6

[0121]

[0122] in,

[0123] 1 H NMR (500MHz, CDCl3) δ3.92 (s, 6H); 13 C NMR (126MHz, CDCl3) δ149.87,128.20,127.55,61.30.

[0124] 1 H NMR (500MHz, CDCl3) δ9.92 (t, J = 1.1 Hz, 1H), 4.64 (d, J = 1.0 Hz, 2H), 3.92 (s, 3H); 13 C NMR(126MHz, CDCl3)δ197.67,149.33,148.38,129.20,128.78,127.95,127.15,77.77,61.64.IR(ATR)ν(cm -1 )=3389,2944,2887,2837,2794,2247,1728,1538,1453,1403,1369,1350,1222 ,1072,1023,976,909,882,817,763,731.HRMS:m / z(ESI-TOF)C9H6Cl4O3[M+H] + : Theoretical value 304.9114, measured value 304.9114.

[0125] Although some exemplary embodiments of the present application have been illustrated and described, the present application is not limited to the disclosed embodiments. On the contrary, those skilled in the art will recognize that some modifications and changes may be made to the described embodiments without departing from the spirit and scope of the present application as described in the appended claims.

Claims

1. A method for preparing a halogenated aromatic compound, comprising using lignin or a lignin model compound as a raw material, carrying out a halogenation depolymerization reaction in the presence of a halogenating agent and a solvent to obtain a halogenated aromatic compound.

2. The preparation method according to claim 1, characterized in that: The lignin is selected from softwood lignin and / or hardwood lignin; Preferably, the lignin is selected from one or more of larch lignin, Scots pine lignin, red pine lignin, fir lignin, poplar lignin, birch lignin and beech lignin.

3. The preparation method according to claim 2, characterized in that: The halogenated aryl compound includes a brominated aryl compound and / or a chlorinated aryl compound; Preferably, the halogenated aromatic compound prepared using the lignin as a raw material includes one or more of the following compounds:

4. The preparation method according to claim 1, characterized in that: The lignin model compound has a structure as shown in Formula I: R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 Each is independently selected from hydrogen, C1-C6 alkoxy, C1-C6 alkyl, halogen, hydroxyl; R6 is selected from hydrogen or hydroxymethyl; Preferably, R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 Each is independently selected from hydrogen or C1-C6 alkoxy; preferably, R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 are not hydrogen at the same time; preferably, R1, R2, R3, R4, R5, R7, R8, R9, R 10 , R 11 Each is independently selected from hydrogen or methoxy.

5. The preparation method according to claim 1, characterized in that: The lignin model compound is selected from:

6. The preparation method according to claim 4 or 5, characterized in that: The halogenated aryl compound includes a brominated aryl compound and / or a chlorinated aryl compound; Preferably, the halogenated aromatic compounds prepared using the lignin model compound as a raw material include the following compounds:

7. The preparation method according to any one of claims 1 to 6, characterized in that: The halogenating agent is selected from one or more of N-chlorosuccinimide and N-bromosuccinimide; and / or The solvent comprises a first solvent selected from 2,2,2-trifluoroethanol and / or hexafluoroisopropanol; and / or The solvent further comprises a second solvent, wherein the second solvent is selected from one or more of ethyl acetate, methyl acetate, DMSO, 1,4-dioxane, and acetone; Preferably, the volume ratio of the first solvent to the second solvent is 1:(0.1-10), preferably 1:(0.5-2).

8. The preparation method according to claim 7, characterized in that: The concentration of the lignin in the solvent is 5-100 g / L, preferably 10-50 g / L; and / or The concentration of the lignin model compound in the solvent is 0.05-0.5 M, preferably 0.05-0.2 M; and / or The concentration of the halogenating agent in the solvent is 0.05-5M, preferably 0.1-2M; and / or The mass ratio of the lignin to the halogenating agent is 1:(1-50), preferably 1:(1-20); and / or The molar ratio of the lignin model compound to the halogenating agent is 1:(0.2-20), preferably 1:(0.5-10).

9. The preparation method according to any one of claims 1 to 8, characterized in that: The reaction temperature of the halogenated depolymerization reaction is 10-120°C, preferably 15-100°C; and / or The halogenation depolymerization reaction time is 8-80 hours, preferably 12-72 hours.

10. Use of the halogenated aromatic compound obtained by the preparation method according to any one of claims 1 to 9 in the synthesis of organic compounds, drug synthesis, and the preparation of polymer materials and optoelectronic materials.

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