Method for photo-synthesizing o-dihalogenated compound based on non-corrosive inorganic halide salt

Abstract

The invention discloses a method for photosynthesis of an o-dihalogenated compound by using a non-corrosive inorganic halide salt under the condition of no photoactive agent, and the method comprises the following steps: converting an aromatic olefin compound into an o-dihalogenated compound R-X2 by directly using a metal halide salt under illumination, in which R is an aromatic olefin compound; and X is any one of F, Cl, Br and I. According to the invention, the cheap and safe inorganic halide salt is used as a halogen source to react at normal temperature and normal pressure, a photocatalyst, a halogen simple substance and an oxidizing agent are not required to be additionally added, the selectivity is high, the method is environment-friendly, the existing o-dihalogenated compound synthesis reaction system can be replaced, and the method is suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to a method for synthesizing an ortho-dihalogenated compound, in particular to a method for photosynthesizing a halogenated compound using a non-corrosive inorganic halogen salt, and to a method for photosynthesizing a halogenated compound using a non-corrosive inorganic halogen salt replacing an organic halogen source under conditions without a photocatalyst, and belongs to the technical field of organic synthesis. Background Art

[0002] Light-driven means that light directly promotes chemical reactions, which can achieve the conversion from primary energy to human terminal energy. The energy conversion process is simple and the energy utilization rate is high. The advantages of low energy consumption and green cleaning are in line with the concept of green production and green synthesis, and have received widespread attention in the field of organic synthesis.

[0003] Ortho-dihalogenated compounds are important intermediates for drug synthesis. Currently, the preparation of ortho-dihalogenated compounds often relies on toxic and highly corrosive halogen elements (i.e., Cl 2 Br 2 ) or the use of organic halogen sources (i.e., N-bromosuccinimide, NBS), and the need to introduce strong oxidants into the system, make the production of ortho-dihalogenated compounds more dangerous and also easily cause environmental pollution. In addition, it is necessary to prepare and screen suitable catalysts, making subsequent purification and impurity removal more difficult, and further increasing production costs. Using low-priced and abundant inorganic metal halide salts as halogen sources to achieve light-driven synthesis of ortho-dihalogenated compounds can not only solve the problem of environmental pollution, but also further reduce production costs.

[0004] The prior art uses hydrogen chloride gas as a chlorine source to prepare dichloro compounds, but the chlorine source used in the reaction is toxic and harmful hydrogen chloride gas, which needs to be refluxed under high temperature conditions, which is complicated to operate, dangerous in production conditions, and takes a long time to react. The prior art uses inorganic metals as halogen sources to prepare chloro compounds, but the reaction can only produce monohalogenated compounds, and cannot obtain ortho-dihalogenated compounds, and the method requires a photoactive reagent.

[0005] In summary, the current ortho-dihalogenated compounds still have the problems of strong halogen source corrosiveness, complicated operation, unstable halogen source, etc., which are not conducive to large-scale industrial production. Therefore, the new method research of efficiently, greenly and economically synthesizing ortho-dihalogenated compounds has very important value. Using cheap and readily available inorganic metal halogen salts to synthesize ortho-dihalogenated compounds is beneficial to the application of this method in actual production. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a green, environmentally friendly and efficient method for synthesizing vicinal dihalogenated compounds based on inorganic metal halide salts replacing halogen elements in the air without photocatalyst conditions.

[0007] The present invention adopts the following technical solution: A method for photosynthesizing vicinal dihalogenated compounds based on non-corrosive inorganic halogen salts comprises the following steps: in the presence of an acid, using metal halogen salts and aromatic olefin compounds as raw materials, subjecting the vicinal dihalogenated compounds to light-induced reactions; the aromatic olefin compounds contain terminal olefin groups.

[0008] A method for continuous photosynthesis of ortho-dihalogenated compounds based on non-corrosive inorganic halogen salts comprises the following steps: (1) In the presence of acid, metal halide and aromatic olefin compounds are used as raw materials and light is irradiated to react; (2) Then add metal halide and react with light; (3) Repeat step (2) to synthesize an ortho-dihalogenated compound; The aromatic olefin compound contains a terminal olefin group.

[0009] In the present invention, the structure of the aromatic olefin compound is shown in the following formula:

[0010] The structure of the ortho-dihalogenated compound is shown below:

[0011] In the above chemical structure, R is 1, 2, 3, 4 or 5 substituents connected to the benzene ring, each of which is independently hydrogen, halogen, C1-C10 alkyl or alkenyl or alkynyl, C6-C20 aryl, -CF 3 , -C(=O)OH and -C(=O); R 1 , R 2 is halogen, preferably, R 1 , R 2 is the same halogen, such as any one of F, Cl, Br, and I.

[0012] In the present invention, the metal halide salt is a non-corrosive inorganic halide salt, and its chemical formula is MXn, wherein M is a metal and X is a halogen; preferably, M is any one or more mixtures of transition metals of the III-VIII subgroups, such as manganese, copper, nickel, iron, and cobalt, X is any one of F, Cl, Br, and I, and n is a non-zero integer. Preferably, the metal halide salt is a non-corrosive transition metal halide salt, one or a combination of manganese chloride, cupric chloride, nickel chloride, ferrous chloride, cobalt chloride, manganese bromide, cupric bromide, nickel bromide, ferrous bromide, and cobalt bromide.

[0013] In the present invention, the acid is H 2 SO 4 , HNO 3 , HCl, HClO4 CF 3 COOH, CH 3 COOH, H 2 C 2 O 4 , HCOOH or a combination of several thereof.

[0014] In the present invention, the illumination is 0.01-100 W xenon lamp, LED, halogen lamp or mercury lamp irradiation, and the wavelength of the illumination is 300-1100 nm; the temperature of the illumination reaction is -50°C to 100°C, preferably 20-50°C, such as room temperature; the time is 1 h to 24 h, preferably 1 h to 15 h, more preferably 1 h to 10 h, further preferably 1 h to 5 h, and further preferably 1 h to 3 h.

[0015] Preferably, the present invention can realize continuous photosynthesis of ortho-dihalogenated compounds based on non-corrosive inorganic halogen salts by only using light without heating.

[0016] In the present invention, the photoreaction is carried out in the presence of a solvent; the solvent comprises N , N - one or more of dimethylformamide, dimethyl sulfoxide, acetonitrile, n-hexane, 1,4-dioxane, cyclohexane, and ethyl acetate.

[0017] In the present invention, during the light irradiation reaction, the concentration of the acid is 0 to 30 μL / mL, the concentration of the metal halide is 50 to 150 mg / mL, and the concentration of the aromatic olefin compound is 5 to 50 mM.

[0018] The present invention discloses a method for photosynthesizing ortho-dihalogenated compounds based on non-corrosive inorganic halogen salts replacing organic halogen sources, the method comprising the following steps: under light, using metal halogen salts, acids, and organic solvents to convert aromatic olefin compounds into ortho-dihalogenated compounds R`-X 2 , wherein R' is the structure after the double bond of the terminal group of the aromatic olefin compound is opened, and X is any one of the halogens F, Cl, Br, and I.

[0019] In the above technical solution, the wavelength of the light is 300 to 1100 nm, preferably visible light.

[0020] In the above technical solution, the solvent is N , N - one or a combination of dimethylformamide, dimethyl sulfoxide, acetonitrile, n-hexane, 1,4-dioxane, cyclohexane, ethyl acetate.

[0021] In the above technical scheme, in the method for continuously photosynthesizing ortho-dihalogenated compounds based on non-corrosive inorganic halide salts, after step (2) is completed, the metal halide salt is separated, and then acid and aromatic olefin compounds are added as raw materials to carry out step (3) to continuously synthesize ortho-dihalogenated compounds.

[0022] Specifically, the method for photosynthesizing an ortho-dihalogenated compound based on a non-corrosive inorganic halogen salt comprises the following steps: (1) adding a metal halide, an acid, and an aromatic olefin compound into a solvent and performing ultrasonic dispersion to obtain a mixed solution; (2) reacting the mixed solution under 1 to 10 W light at -50 to 100° C. for 1 to 24 hours; (3) After centrifugation, the separated organic phase is dried and concentrated to obtain the ortho-dihalogenated compound.

[0023] Wherein, in the mixed solution, the concentration of the acid is 5-30 μL / mL, the concentration of the metal halide is 70-120 mg / mL, and the concentration of the aromatic olefin compound is 15-30 mM.

[0024] The light source can be a xenon lamp, LED, halogen lamp or mercury lamp with a power of 0.01-100 W.

[0025] Wherein, the reaction temperature is controlled by ice bath, water bath or oil bath.

[0026] The method for photosynthesizing ortho-dihalogenated compounds based on non-corrosive inorganic halogen salts of the present invention is schematically shown as follows:

[0027] The method for photosynthesizing vicinal dihalogenated compounds based on non-corrosive inorganic halogen salts described in the present invention is a method for light-driven continuous synthesis of vicinal dihalogenated compounds. Importantly, the method does not contain an organic halogen source and a photocatalyst; in particular, the method of the present invention does not require the additional addition of a photoactive agent (also called a photocatalyst) and can be light-driven continuous synthesis of vicinal dihalogenated compounds in the air.

[0028] In the present invention, the method for light-driven continuous synthesis of ortho-dihalogenated compounds comprises the steps of continuously adding metal halide salts to continuously synthesize ortho-dihalogenated compounds. Specifically, after step (2) is completed, inorganic halide salts are continuously added, and step (2) is repeated to continuously synthesize ortho-dihalogenated compounds without adding new metal halide salts; the inorganic halide salts used are cheap halide salts, such as MnCl 2 , CuCl 2 , NiCl 2 , FeCl 2 , CoCl 2 , MnBr 2 , CuBr 2, NiBr 2 , FeBr 2 ,CoBr 2 One or a combination of the following.

[0029] The method for light-driven continuous synthesis of halogenated compounds based on inorganic halogen salts replacing halogen elements of the present invention can achieve dihalogenation of hydrocarbon compounds to obtain corresponding halogenated compounds, has high selectivity, low light-driven cost, and is green and pollution-free, which is beneficial for the stable and efficient use of this reaction system in industrial organic synthesis to release its high economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the time kinetic curve of styrene chlorination reaction.

[0031] Figure 2 This is the gas chromatogram of the products obtained from the chlorination reaction of styrene.

[0032] Figure 3 The mass spectrum of the product obtained from the chlorination reaction of styrene and the standard NIST mass spectrum.

[0033] Figure 4 This is the H NMR spectrum of dichlorostyrene.

[0034] Figure 5 This is the carbon NMR spectrum of dichlorostyrene.

[0035] Figure 6 Time kinetic curve of styrene bromination reaction.

[0036] Figure 7 This is the gas chromatogram of the product obtained from the bromination reaction of styrene.

[0037] Figure 8 The mass spectrum of the product obtained from the bromination reaction of styrene and the standard NIST mass spectrum.

[0038] Fig. 9 To continuously generate the yield and selectivity of dichlorostyrene. DETAILED DESCRIPTION

[0039] The present invention discloses a method for continuously synthesizing ortho-dihalogenated compounds by light induction based on inorganic metal halide salts replacing organic halogen sources under the condition of no photocatalyst. Under light and in air, aromatic olefin compounds can be continuously converted into ortho-dihalogenated compounds, and the halogens are F, Cl, Br, and I.

[0040] In the present invention, metal halide and aromatic olefin compounds are used as raw materials in the presence of acid and solvent, and light is irradiated in air to synthesize ortho-dihalogenated compounds; no other reagents are required, no photocatalyst needs to be added, and the reaction conditions are simple.

[0041] In a specific embodiment of the present invention, in the inorganic metal halide MXn, M is any one or more of the metals of the main groups I-III and the subgroups I-VIII. Preferably, M is any one of Mn, Cu, Ni, Fe, and Co. n is a non-zero integer, preferably 1 to 3. X is any one of F, Cl, Br, and I. Preferably, the inorganic metal halide is selected from MnCl 2 , CuCl 2 , NiCl 2 , FeCl 2 , CoCl 2 , MnBr 2 , CuBr 2 , NiBr 2 , FeBr 2 , CoBr 2 One or a combination of the following.

[0042] The above-mentioned method for light-driven continuous synthesis of ortho-dihalogenated compounds based on inorganic metal halide replacing halogen element under the condition of no photocatalyst comprises the following steps: (a) adding metal halide, acid, and aromatic olefin compound to a solvent for ultrasonic dispersion to obtain a mixed solution; (b) stirring the mixture under 0.01-100 W light irradiation and controlling the reaction temperature to -50-100 ℃, preferably room temperature; (c) centrifuging the mixed phase, drying and concentrating the separated organic phase to obtain the halogenated compound. Further, after step (b) is completed, an inorganic metal halide is added and the step is repeated, and step (c) is performed after the final reaction is completed to achieve light-driven continuous synthesis of ortho-dihalogenated compounds.

[0043] In a specific embodiment of the present invention, the intensity of the illumination is achieved by a xenon lamp, LED, halogen lamp or mercury lamp with a wavelength of 300-1100 nm and a light source power of 0.01-100 W.

[0044] In one embodiment of the present invention, the acid is H 2 SO 4 , HNO 3 , HCl, HClO 4 CF 3 COOH, CH 3 COOH, H 2 C 2 O 4 , HCOOH or a combination of them, with a concentration of 5-25 μL / mL.

[0045] In one embodiment of the present invention, the reaction temperature is controlled by an ice bath, a water bath or an oil bath.

[0046] The technical progress of the present invention is illustrated by specific experiments below. The raw materials involved are all existing products. The specific preparation operations and performance tests are all conventional techniques. Unless otherwise specified, the reaction is carried out in air under light without additional heating. During the experiment, the yield of the target product is determined by gas chromatography. Embodiment 1

[0047] This example provides a method for light-driven synthesis of halogenated compounds based on inorganic halogen salts replacing halogen elements under the condition of no photocatalyst, comprising the following steps: (1) 1.5 mmol of FeCl 2 , 2 mL of acetonitrile, 20 mM styrene, and 15 μL of concentrated hydrochloric acid (37%) were mixed evenly and then ultrasonically dispersed to obtain a suspension; (2) The dispersed suspension was heated at 0.35 W (0.07 W / cm 2 ) under the irradiation of LED light simulating sunlight, the reaction was stirred for 2 h under room temperature and air conditions; then the obtained organic phase was dried and concentrated to obtain dichlorostyrene:

[0048] (3) After the liquid at the end of the reaction was separated from the inorganic halide in the reaction system by centrifugation, the supernatant was taken and analyzed by gas chromatography for the conversion rate of the reactants and the yield of the target product. The final experimental results showed that the yield of dichlorostyrene was 85% and the selectivity was 95%.

[0049] Figure 1 This is the time kinetic curve of the chlorination reaction of styrene to form dichlorostyrene. The complete reaction was achieved in 120 min. The yield of dichlorostyrene was 85% and the selectivity was 95%. Figure 2 This is the gas chromatogram of the products obtained from the chlorination reaction of styrene. Figure 3 The mass spectrum of the product obtained from the chlorination reaction of styrene and the standard NIST mass spectrum. Figure 4 as well as Figure 5 These are the carbon and hydrogen spectra of the products obtained from the chlorination reaction of styrene.

[0050] The existing technology is based on FeCl 3 As an inorganic metal chlorine source, dichlorostyrene is prepared. However, FeCl 3 It is highly corrosive and environmentally unfriendly, and the reaction needs to be carried out in an argon atmosphere, and the reaction time is as long as 10 hours. The present invention solves the problems of the prior art, and uses inorganic metal halide salts to replace halogen elements in the light-driven synthesis of ortho-dihalogenated compounds. After 2 hours of illumination in the air, the yield of dichlorostyrene can be 85% and the selectivity can be 95%.

[0051] Comparative Example 1 In this comparative example, FeCl 3 Preparation of dichlorostyrene as an inorganic metal chlorine source, referring to Example 1, except that: in step (1), 1.5 mmol of FeCl 2 Change to 1.5 mmol FeCl 3 6H 2 O, 15 μL concentrated hydrochloric acid was omitted, and the rest were the same. Finally, the gas chromatograph test and analysis showed that the yield of dichlorostyrene was 61% and the selectivity was 62%. Embodiment 2

[0052] This example provides a method for light-driven synthesis of ortho-dihalogenated compounds based on inorganic halogen salts replacing halogen elements under the condition of no photocatalyst, referring to Example 1, except that: 1.5 mmol of FeCl in step (1) 2 Change to 1 mmol FeBr 2 , 15 μL concentrated hydrochloric acid was changed to 30 μL hydrobromic acid (48 wt.%), and the rest remained the same. Finally, the yield of dibromostyrene was 78% and the selectivity was 98% when analyzed by gas chromatography.

[0053]

[0054] Figure 6 This is the time kinetic curve of the bromination reaction of styrene to form dibromostyrene. The complete reaction was achieved in 120 min. The yield of dibromostyrene was 78% and the selectivity was 98%.

[0055] Figure 7 This is the gas chromatogram of the product obtained from the bromination reaction of styrene. Figure 8 The mass spectrum of the product obtained from the bromination reaction of styrene and the standard NIST mass spectrum. Embodiment 3

[0056] This example provides a method for light-driven synthesis of ortho-dihalogenated compounds based on inorganic halogen salts replacing halogen elements under the condition of no photocatalysis, referring to Example 1, except that: in step (1), 1.5 mmol of FeCl 2 Change to 1 mmol FeBr 2 , 15 μL concentrated hydrochloric acid was changed to 50 μL hydrobromic acid, and finally the gas chromatograph test analysis showed that the yield of dibromostyrene was 85% and the selectivity was 93%. Embodiment 4

[0057] This example provides a method for light-driven synthesis of ortho-dihalogenated compounds based on replacing halogen elements with inorganic halogen salts, referring to Example 1, except that styrene in step (1) is replaced with 4-chlorostyrene, and the rest is the same. Finally, the gas chromatograph test and analysis show that the yield of 4-chlorodichlorostyrene is 90% and the selectivity is 91%.

[0058]

[0059] Comparative Example 2 In this comparative example, FeCl 3 Preparation of 4-chlorodichlorostyrene as an inorganic metal chlorine source, referring to Example 4, except that: in step (1), 1.5 mmol of FeCl 2 Change to 1.5 mmol FeCl 3 6H 2 O, 15 μL concentrated hydrochloric acid was omitted, and the rest were the same. Finally, the gas chromatograph was used to test and analyze the generated 4-chlorodichlorostyrene with a yield of 48% and a selectivity of 60%. Embodiment 5

[0060] This example provides a method for the continuous synthesis of ortho-dihalogenated compounds based on inorganic halogen salts replacing halogen elements under the condition of no photocatalyst. Referring to Example 1, the difference is that: in step (3), after the liquid after the reaction is separated from the inorganic halogen salt, 20 mM styrene acetonitrile solution and 15 μL concentrated hydrochloric acid (37%) are added to the inorganic halogen salt to achieve the continuous production of ortho-dihalogenated compounds, and the rest is the same. This system can achieve continuous production of ortho-dihalogenated compounds for multiple times. The yield and selectivity of dichlorostyrene generated by gas chromatography are as follows: Fig. 9 As shown, the yield and conversion rate can be maintained after five consecutive syntheses, which is beyond the expectations of those skilled in the art.

[0061] Previously, our research group used metal halide salts and photoactive agents to convert hydrocarbon or nitrile compounds into halogenated compounds RX. However, continuous synthesis could not be achieved if the photoactive agent was omitted. The present invention solves this technical problem by using inorganic metal halide light to drive the continuous synthesis of o-dihalogenated compounds. After 2 hours of illumination in the air, a technical effect of 85% dichlorostyrene yield and 95% selectivity can be achieved. Moreover, the yield and conversion rate can be maintained for multiple consecutive syntheses, which is beyond the expectations of those skilled in the art. Embodiment 6

[0062] This example provides a method for light-driven synthesis of ortho-dihalogenated compounds based on inorganic halogen salts replacing halogen elements under conditions without photocatalysts, referring to Example 1, except that: in step (1), 15 μL of concentrated hydrochloric acid (37%) is replaced by 30 μL of concentrated sulfuric acid (98%), and the rest is the same. Finally, the gas chromatograph test and analysis show that the yield of dichlorostyrene is 89% and the selectivity is 75%. Embodiment 7

[0063] This example provides a method for light-driven synthesis of ortho-dihalogenated compounds based on inorganic halogen salts replacing halogen elements under conditions without photocatalysts, referring to Example 1, except that: in step (1), 15 μL of concentrated hydrochloric acid (37%) is replaced by 15 μL of concentrated nitric acid (98%), and the rest is the same. Finally, the gas chromatograph test and analysis show that the yield of dichlorostyrene is 19% and the selectivity is 20%. Embodiment 8

[0064] This example provides a method for light-driven synthesis of ortho-dihalogenated compounds based on inorganic halogen salts replacing halogen elements under the condition of no photocatalysis, referring to Example 1, except that: in step (1), FeCl 2 Change to CuCl 2 , the rest were the same, and finally the gas chromatograph test analysis showed that the yield of dichlorostyrene was 43% and the selectivity was 61%. Embodiment 9

[0065] This example provides a method for light-driven synthesis of ortho-dihalogenated compounds based on inorganic halogen salts replacing halogen elements under the condition of no photocatalysis, referring to Example 1, except that: in step (1), FeCl 2 To CoCl 2 , the rest were the same, and finally the gas chromatograph test and analysis showed that the yield of dichlorostyrene was 30% and the selectivity was 49%. Embodiment 10

[0066] This example provides a method for light-driven synthesis of ortho-dihalogenated compounds based on inorganic halogen salts replacing halogen elements under the condition of no photocatalysis, referring to Example 1, except that: in step (1), FeCl 2 Changed to NiCl 2 , the rest were the same, and finally the gas chromatograph test analysis showed that the yield of dichlorostyrene was 25% and the selectivity was 34%.

[0067] Comparative Example 3 This comparative example refers to Example 1, except that no light irradiation was performed, and an ortho-dihalogenated compound could not be obtained.

[0068] Comparative Example 4 This comparative example refers to Example 1, except that no inorganic halogen salt is added, and an ortho-dihalogenated compound cannot be obtained.

[0069] Comparative Example 5 This comparative example refers to Example 1, except that: no acid is added, and the yield of dichlorostyrene is 64% and the selectivity is 90% on the basis of achieving a one-time synthesis of the ortho-dihalogenated compound; however, continuous synthesis cannot be achieved.

[0070] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for photosynthesizing ortho-dihalogenated compounds based on non-corrosive inorganic halogen salts, characterized in that: The method comprises the following steps: in the presence of acid, using metal halide and aromatic olefin compounds as raw materials, subjecting them to light irradiation reaction to synthesize an ortho-dihalogenated compound; the aromatic olefin compound contains a terminal olefin group.

2. A method for continuous photosynthesis of ortho-dihalogenated compounds based on non-corrosive inorganic halogen salts, characterized in that: The following steps are involved: (1) In the presence of acid, metal halide and aromatic olefin compounds are used as raw materials and light is irradiated to react; (2) Then add metal halide and react with light; (3) Repeat step (2) to synthesize an ortho-dihalogenated compound; The aromatic olefin compound contains a terminal olefin group.

3. The method according to claim 1 or 2, characterized in that: The structure of the aromatic olefin compound is shown below: ； The structure of the ortho-dihalogenated compound is shown below: ； In the above chemical structure, R is 1, 2, 3, 4 or 5 substituents connected to the benzene ring, each of which is independently any one of hydrogen, halogen, and C1-C10 alkyl; R1 and R2 are halogen.

4. The method according to claim 1 or 2, characterized in that The metal halide salt is a non-corrosive transition metal halide salt; the acid is one or more of H2SO4, HNO3, HCl, HClO4, CF3COOH, CH3COOH, H2C2O4, and HCOOH.

5. The method according to claim 1 or 2, characterized in that: The wavelength of the light is 300-1100 nm; the temperature of the light reaction is -50°C-100°C, and the time is 1 h-24 h; the light reaction is carried out in the presence of a solvent and in the air.

6. The method according to claim 5, characterized in that The solvent includes N , N - one or more of dimethylformamide, dimethyl sulfoxide, acetonitrile, n-hexane, 1,4-dioxane, cyclohexane, and ethyl acetate.

7. The method according to claim 1 or 2, characterized in that: During the light irradiation reaction, the concentration of the acid is 0 to 30 μL / mL, the concentration of the metal halide is 50 to 150 mg / mL, and the concentration of the aromatic olefin compound is 5 to 50 mM.

8. The method according to claim 1 or 2, characterized in that The light is 0.01~100W xenon lamp, LED, halogen lamp or mercury lamp.

9. The method according to claim 1 or 2, characterized in that: The method does not contain an organic halogen source and a photocatalyst.

10. The application of metal halide salts and aromatic olefin compounds as raw materials in the synthesis of ortho-dihalogenated compounds by photoreaction.

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