Process for the preparation of alkylbenzenes containing substituents

Abstract

The present application relates to a kind of preparation method of substituted alkylbenzene.The method includes: substituted aromatic ketone flows through catalyst bed and is reacted, the catalyst bed includes: hydrogenation catalytic bed and intramolecular dehydration catalytic bed of alternative arrangement, and the first section and the last section of the catalyst bed are hydrogenation catalytic bed;The reaction is carried out in the presence of non-alcohol solvent.The present application is in the presence of non-alcohol solvent, using substituted aromatic ketone is synthesized in the catalyst bed with hydrogenation catalytic bed and intramolecular dehydration catalytic bed of alternative arrangement, and the first section and the last section of the catalyst bed are hydrogenation catalytic bed, substituted alkylbenzene, with the advantages of high reactant conversion, high selectivity of product substituted aromatic ketone, simple post-processing.

Description

Technical Field

[0001] This invention relates to a method for preparing alkylbenzenes containing substituents. Background Technology

[0002] Substituent-containing alkylbenzenes are important fine chemicals and synthetic intermediates with wide applications in pharmaceuticals, pesticides, food, and synthetic materials. Their preparation methods mainly include natural separation, alkylaniline diazotization hydrolysis, alkylbenzene chlorination hydrolysis, and phenol alkylation. Among these, natural separation is increasingly being replaced by chemical synthesis methods due to limited resources and complex processes. The alkylaniline diazotization hydrolysis method uses large amounts of sulfuric acid, causing severe equipment corrosion, and requires significant alkali neutralization after the reaction, thus it is gradually being phased out. The alkylbenzene chlorination hydrolysis method is highly polluting and is now largely obsolete. The phenol alkylation method often yields a mixture of three ethyl-substituted phenols, reducing product selectivity and increasing separation costs. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of low reactant conversion rate, low product selectivity, and high process cost in existing technologies for preparing substituted alkylbenzenes, and to provide a method for preparing substituted alkylbenzenes with high reactant conversion rate, high selectivity of substituted alkylbenzenes, and low process cost.

[0004] To achieve the above objectives, the present invention provides a method for preparing a substituted alkylbenzene, the method comprising:

[0005] A substituent-containing aromatic ketones are reacted by passing through a catalyst bed, the catalyst bed comprising: alternating hydrogenation catalyst beds and intramolecular dehydration catalyst beds, wherein the first and last sections of the catalyst bed are both hydrogenation catalyst beds;

[0006] The reaction is carried out in the presence of a non-alcoholic solvent.

[0007] Through the above technical solution, the present invention has the following advantages:

[0008] This invention utilizes substituted aromatic ketones in the presence of non-alcoholic solvents to synthesize substituted alkylbenzenes in a catalyst bed with alternating hydrogenation and intramolecular dehydration catalyst beds, wherein the first and last sections of the catalyst bed are hydrogenation catalyst beds. This method has the advantages of high reactant conversion, high selectivity for substituted aromatic ketones as products, and simple post-processing.

[0009] For example, the method of the present invention for preparing ethylphenol achieves a 100% conversion rate of the reactant hydroxyacetophenone, a selectivity of 99.2% for ethylphenol, and can be applied to continuous production. Detailed Implementation

[0010] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0011] This invention provides a method for preparing a substituted alkylbenzene, the method comprising:

[0012] A substituent-containing aromatic ketones are reacted by passing through a catalyst bed comprising alternating hydrogenation catalyst beds and intramolecular dehydration catalyst beds, wherein the first and last sections of the catalyst bed are both hydrogenation catalyst beds; the reaction is carried out in the presence of a non-alcohol solvent.

[0013] According to a preferred embodiment of the present invention, the packing volume ratio of the hydrogenation catalyst bed and the intramolecular dehydration catalyst bed in two adjacent sections is 1-10:1.

[0014] This invention utilizes substituted aromatic ketones in the presence of non-alcoholic solvents to synthesize substituted alkylbenzenes in a catalyst bed with alternating hydrogenation and intramolecular dehydration catalyst beds, wherein the first and last sections of the catalyst bed are hydrogenation catalyst beds. This method has the advantages of high reactant conversion, high selectivity for substituted aromatic ketones as products, and simple post-processing.

[0015] In this invention, as long as the objective of the invention can be achieved, the number of hydrogenation catalytic bed segments and intramolecular dehydration catalytic bed segments in the catalyst bed is not particularly limited. According to a preferred embodiment of the invention, the catalyst bed includes 2-4 hydrogenation catalytic bed segments and 1-2 intramolecular dehydration catalytic bed segments. By adopting the aforementioned preferred embodiment, the reactant conversion rate and the selectivity of the product containing substituents, aromatic ketones, can be further improved.

[0016] According to a preferred embodiment of the present invention, the catalyst bed comprises two hydrogenation catalyst beds and one intramolecular dehydration catalyst bed.

[0017] In this invention, the installation method of the catalyst bed can be a conventional choice in the art. According to a preferred embodiment of the invention, the catalyst bed is installed in two fixed-bed reactors connected in series. The first fixed-bed reactor is filled with a hydrogenation catalyst bed, and the second fixed-bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed. The outlet of the first fixed-bed reactor is connected to the inlet of the intramolecular dehydration catalyst bed of the second fixed-bed reactor.

[0018] According to a preferred embodiment of the present invention, the volume ratio of the hydrogenation catalyst bed packed in the first fixed-bed reactor, the hydrogenation catalyst bed packed in the second fixed-bed reactor, and the intramolecular dehydration catalyst bed packed in the second fixed-bed reactor is preferably 1-10:1-10:1.

[0019] In this invention, the fixed-bed reactor can be a conventional choice in the art. According to a preferred embodiment of this invention, the fixed-bed reactor is a trickle-bed reactor.

[0020] In this invention, the catalyst of the hydrogenation catalytic bed can be a conventional choice in the art. According to a preferred embodiment of this invention, the catalyst of the hydrogenation catalytic bed is one or more of copper-based catalysts, palladium-based catalysts, platinum-based catalysts, nickel-based catalysts, and ruthenium-based catalysts.

[0021] According to a preferred embodiment of the present invention, the copper-based catalyst contains 10-40% by weight of copper and 60-90% by weight of a support.

[0022] According to a preferred embodiment of the present invention, the support for the copper-based catalyst is selected from one or more of alumina, silicon-based materials and titanium dioxide; preferably silicon-based materials; more preferably silicon dioxide.

[0023] By employing the catalyst of the aforementioned preferred hydrogenation catalytic bed, the present invention can further improve the reactant conversion rate and the selectivity of the product containing substituent aromatic ketones.

[0024] In this invention, the catalyst of the intramolecular dehydration catalytic bed can be a conventional choice in the art. According to a preferred embodiment of the invention, the catalyst of the intramolecular dehydration catalytic bed is a resin and / or molecular sieve, preferably one or more of A36 ion exchange resin, A25 ion exchange resin, Hβ molecular sieve, USY molecular sieve, and Hmor molecular sieve. By employing the aforementioned preferred catalyst of the intramolecular dehydration catalytic bed, this invention can further improve the reactant conversion rate and the selectivity of the product containing substituents, aromatic ketones.

[0025] In this invention, there are no particular limitations on the conditions under which the substituent-containing aromatic ketones react in the catalyst bed. According to a preferred embodiment of the invention, the reaction is carried out in the presence of a solvent.

[0026] In this invention, the non-alcoholic solvent can be a conventional choice in the art. According to a preferred embodiment of the invention, the non-alcoholic solvent is selected from one or more of toluene, chlorobenzene, ethyl acetate, N,N-dimethylformamide, 1,4-dioxane, dimethyl sulfoxide, and tetrahydrofuran. By employing the aforementioned preferred method, the reactant conversion rate and the selectivity of the substituted aromatic ketone product can be further improved.

[0027] According to a preferred embodiment of the present invention, the reaction conditions include a temperature of 20-250°C, preferably 70-200°C.

[0028] According to a preferred embodiment of the present invention, the reaction conditions include: a pressure of atmospheric pressure - 10 MPa, preferably atmospheric pressure - 4 MPa.

[0029] According to a preferred embodiment of the present invention, the reaction conditions include a liquid space velocity of 0.01-50 h⁻¹. -1 Preferably 0.1-5h -1 .

[0030] By employing the aforementioned preferred reaction conditions, this invention can further improve the reactant conversion rate and the selectivity of the product containing substituent aromatic ketones.

[0031] According to a preferred embodiment of the present invention, the substituted alkylbenzene has a structural formula represented by chemical formula a or chemical formula b.

[0032]

[0033]

[0034] R2 can be selected from H, alkyl, methoxy, ester, nitro, or hydroxyl groups from C1 to C6;

[0035] R1 and R3 are independently selected from alkyl groups of C1 to C6 and aryl groups of C6 to C9;

[0036] X is selected from one of F, Cl, Br, and I.

[0037] The present invention will be described in detail below through embodiments.

[0038] Example 1

[0039] Two trickle bed reactors connected in series are used. The first trickle bed reactor is filled with a hydrogenation catalyst bed with a catalyst loading of 5 ml. The second trickle bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the first trickle bed reactor is connected to the inlet of the intramolecular dehydration catalyst bed of the second trickle bed reactor.

[0040] The catalyst in the hydrogenation catalytic bed is 28% Cu / SiO2, and the catalyst in the intramolecular dehydration catalytic bed is A36 ion exchange resin. Initially, reduction was carried out at 280°C, H2 flow rate of 45 ml / min, and N2 flow rate of 155 ml / min for 20 h. Then, the first trickle bed reactor was cooled to 120°C, and the second trickle bed reactor was cooled to 170°C. The H2 flow rate was adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone tetrahydrofuran solution to 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a 100% conversion of hydroxyacetophenone and a 99.2% selectivity for p-ethylphenol.

[0041] Example 2

[0042] Two trickle bed reactors connected in series are used. The first trickle bed reactor is filled with a hydrogenation catalyst bed with a catalyst loading of 5 ml. The second trickle bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the first trickle bed reactor is connected to the inlet of the intramolecular dehydration catalyst bed of the second trickle bed reactor.

[0043] The catalyst in the hydrogenation catalytic bed is 10% Cu / SiO2, and the catalyst in the intramolecular dehydration catalytic bed is A36 ion exchange resin. Initially, reduction is carried out at 280℃, H2 flow rate of 45 ml / min, and N2 flow rate of 155 ml / min for 20 h. Then, the first trickle bed reactor is cooled to 70℃, and the second trickle bed reactor is cooled to 70℃. The H2 flow rate is adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone dimethyl sulfoxide solution is 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a 100.0% conversion of hydroxyacetophenone and a 97.5% selectivity for p-ethylphenol.

[0044] Example 3

[0045] Two trickle bed reactors connected in series are used. The first trickle bed reactor is filled with a hydrogenation catalyst bed with a catalyst loading of 5 ml. The second trickle bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the first trickle bed reactor is connected to the inlet of the intramolecular dehydration catalyst bed of the second trickle bed reactor.

[0046] The catalyst in the hydrogenation catalytic bed is 40% Cu / SiO2, and the catalyst in the intramolecular dehydration catalytic bed is A36 ion exchange resin. Initially, reduction is carried out at 280℃, H2 flow rate of 45 ml / min, and N2 flow rate of 155 ml / min for 20 h. Then, the first trickle bed reactor is cooled to 200℃, and the second trickle bed reactor is cooled to 200℃. The H2 flow rate is adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone N,N-dimethylformamide solution is set to 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a 100% conversion of hydroxyacetophenone and a 95.1% selectivity for p-ethylphenol.

[0047] Example 4

[0048] Three trickle bed reactors connected in series were used. The first trickle bed reactor was filled with a hydrogenation catalyst bed with a catalyst loading of 5 ml. The second trickle bed reactor was filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the first trickle bed reactor was connected to the inlet of the intramolecular dehydration catalyst bed of the second trickle bed reactor. The third trickle bed reactor was filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the second trickle bed reactor was connected to the inlet of the intramolecular dehydration catalyst bed of the third trickle bed reactor.

[0049] The catalyst in the hydrogenation catalytic bed is 28% Cu / SiO2, and the catalyst in the intramolecular dehydration catalytic bed is A36 ion exchange resin. Initially, reduction was carried out at 280°C, H2 flow rate of 45 ml / min, and N2 flow rate of 155 ml / min for 20 h. Then, the first trickle bed reactor was cooled to 120°C, and the second trickle bed reactor was cooled to 170°C. The H2 flow rate was adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone tetrahydrofuran solution to 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a 100% conversion of hydroxyacetophenone and a selectivity of 86.3% for p-ethylphenol.

[0050] Example 5

[0051] Two bubbling bed reactors connected in series are used. The first bubbling bed reactor is filled with a hydrogenation catalyst bed with a catalyst loading of 5 ml. The second bubbling bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the first bubbling bed reactor is connected to the inlet of the intramolecular dehydration catalyst bed of the second bubbling bed reactor.

[0052] The catalyst in the hydrogenation catalytic bed is 28% Cu / SiO2, and the catalyst in the intramolecular dehydration catalytic bed is A36 ion exchange resin. Initially, reduction was carried out at 280°C, H2 flow rate of 45 ml / min, and N2 flow rate of 155 ml / min for 20 h. Then, the first bubbling bed reactor was cooled to 120°C, and the second bubbling bed reactor was cooled to 170°C. The H2 flow rate was adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone tetrahydrofuran solution to 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a 100% conversion of hydroxyacetophenone and a selectivity of 87.9% for p-ethylphenol.

[0053] Example 6

[0054] Two trickle bed reactors connected in series are used. The first trickle bed reactor is filled with a hydrogenation catalyst bed with a catalyst loading of 5 ml. The second trickle bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the first trickle bed reactor is connected to the inlet of the intramolecular dehydration catalyst bed of the second trickle bed reactor.

[0055] The catalyst in the hydrogenation catalytic bed is 5% Cu / SiO2, and the catalyst in the intramolecular dehydration catalytic bed is A36 ion exchange resin. Initially, reduction is carried out at 280℃, H2 flow rate of 45 ml / min, and N2 flow rate of 155 ml / min for 20 h. Then, the first trickle bed reactor is cooled to 120℃, and the second trickle bed reactor is cooled to 170℃. The H2 flow rate is adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone tetrahydrofuran solution to 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a 100.0% conversion of hydroxyacetophenone and a selectivity of 87.5% for p-ethylphenol.

[0056] Comparative Example 1

[0057] Two trickle bed reactors connected in series were used. Both trickle bed reactors were filled with hydrogenation catalyst beds, with catalyst loading amounts of 5 ml and 5 ml, respectively.

[0058] The catalyst in the hydrogenation catalytic bed is 28% Cu / SiO2. Initially, reduction is carried out at 280°C, with an H2 flow rate of 45 ml / min and an N2 flow rate of 155 ml / min for 20 h. Then, the first trickle bed reactor is cooled to 120°C, and the second trickle bed reactor is cooled to 170°C. The H2 flow rate is adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone tetrahydrofuran solution to 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a conversion rate of 84.6% for hydroxyacetophenone and a selectivity of 68.5% for p-ethylphenol.

[0059] Comparative Example 2

[0060] Two trickle bed reactors connected in series are used. The first trickle bed reactor is filled with a hydrogenation catalyst bed with a catalyst loading of 5 ml. The second trickle bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the first trickle bed reactor is connected to the inlet of the hydrogenation catalyst bed of the second trickle bed reactor.

[0061] The catalyst in the hydrogenation catalytic bed is 28% Cu / SiO2, and the catalyst in the intramolecular dehydration catalytic bed is A36 ion exchange resin. Initially, reduction was carried out at 280°C, H2 flow rate of 45 ml / min, and N2 flow rate of 155 ml / min for 20 h. Then, the first trickle bed reactor was cooled to 120°C, and the second trickle bed reactor was cooled to 170°C. The H2 flow rate was adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone tetrahydrofuran solution to 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a conversion rate of 95.1% for hydroxyacetophenone and a selectivity of 71.4% for p-ethylphenol.

[0062] Comparative Example 3

[0063] Two trickle bed reactors connected in series are used. The first trickle bed reactor is filled with a hydrogenation catalyst bed with a catalyst loading of 5 ml. The second trickle bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed with catalyst loadings of 5 ml and 2.5 ml, respectively. The outlet of the first trickle bed reactor is connected to the inlet of the intramolecular dehydration catalyst bed of the second trickle bed reactor.

[0064] The catalyst in the hydrogenation catalytic bed is 28% Cu / SiO2, and the catalyst in the intramolecular dehydration catalytic bed is A36 ion exchange resin. Initially, reduction was carried out at 280°C, H2 flow rate of 45 ml / min, and N2 flow rate of 155 ml / min for 20 h. Then, the first trickle bed reactor was cooled to 120°C, and the second trickle bed reactor was cooled to 170°C. The H2 flow rate was adjusted to 65 ml / min, the N2 flow rate to 0 ml / min, the pressure to 1 MPa, and the liquid hourly space velocity (LHSV) of the 5% hydroxyacetophenone isopropanol solution to 0.2 h⁻¹. -1 GC analysis of the reacted sample showed a conversion rate of 90.5% for hydroxyacetophenone and a selectivity of 75.2% for p-ethylphenol.

[0065] In summary, this invention achieves a 100% conversion rate of the reactant hydroxyacetophenone, a selectivity of over 85% for ethylphenol, and can be applied to continuous production.

[0066] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a substituted alkylbenzene, characterized in that, The method includes: A substituent-containing aromatic ketones are reacted by passing through a catalyst bed comprising alternating hydrogenation catalytic beds and intramolecular dehydration catalytic beds, wherein the first and last sections of the catalyst bed are both hydrogenation catalytic beds; the reaction is carried out in the presence of a non-alcohol solvent; The catalyst bed comprises 2-4 hydrogenation catalyst beds and 1-2 intramolecular dehydration catalyst beds; The packing volume ratio of the hydrogenation catalyst bed and the intramolecular dehydration catalyst bed in two adjacent sections is 1-10:1; The catalyst bed is installed in two or three fixed-bed reactors connected in series.

2. The preparation method according to claim 1, wherein, The catalyst bed comprises two hydrogenation catalyst beds and one intramolecular dehydration catalyst bed.

3. The preparation method according to claim 1, wherein, The catalyst bed is installed in two fixed-bed reactors connected in series. The first fixed-bed reactor is filled with a hydrogenation catalyst bed, and the second fixed-bed reactor is filled with a hydrogenation catalyst bed and an intramolecular dehydration catalyst bed. The outlet of the first fixed-bed reactor is connected to the inlet of the intramolecular dehydration catalyst bed of the second fixed-bed reactor.

4. The preparation method according to claim 3, wherein, The volume ratio of the hydrogenation catalyst bed packed in the first fixed-bed reactor, the hydrogenation catalyst bed packed in the second fixed-bed reactor, and the intramolecular dehydration catalyst bed packed in the second fixed-bed reactor is 1-10:1-10:

1.

5. The preparation method according to claim 3, wherein, The fixed-bed reactor is a trickle-bed reactor.

6. The preparation method according to claim 1, wherein, The catalyst in the hydrogenation catalytic bed is one or more of the following: copper-based catalyst, palladium-based catalyst, platinum-based catalyst, nickel-based catalyst, and ruthenium-based catalyst.

7. The preparation method according to claim 6, wherein, The copper-based catalyst contains 10-40% by weight of copper and 60-90% by weight of a support.

8. The preparation method according to claim 7, wherein, The carrier is selected from one or more of alumina, silicon-based materials, and titanium dioxide.

9. The preparation method according to claim 8, wherein, The carrier is a silicon-based material.

10. The preparation method according to claim 9, wherein, The carrier is silicon dioxide.

11. The preparation method according to claim 1, wherein, The catalyst in the intramolecular dehydration catalytic bed is a resin and / or a molecular sieve.

12. The preparation method according to claim 11, wherein, The catalyst in the intramolecular dehydration catalytic bed is one or more of A36 ion exchange resin, A25 ion exchange resin, Hβ molecular sieve, USY molecular sieve and Hmor molecular sieve.

13. The preparation method according to claim 1, wherein, The non-alcoholic solvent is selected from one or more of toluene, chlorobenzene, ethyl acetate, N,N-dimethylformamide, 1,4-dioxane, dimethyl sulfoxide, and tetrahydrofuran.

14. The preparation method according to claim 1, wherein, The conditions for the reaction include: Temperature 20-250℃; and / or Pressure is atmospheric pressure to 10 MPa; and / or Liquid space velocity is 0.01-50 h⁻¹ -1 .

15. The preparation method according to claim 14, wherein, The conditions for the reaction include: Temperatures of 70-200℃; and / or Pressure is atmospheric pressure to 4 MPa; and / or The liquid space velocity is 0.1-5 h⁻¹. -1 .

16. The preparation method according to claim 1, wherein, The substituted alkylbenzene has the structural formula shown in chemical formula a or chemical formula b. Chemical formula a; Chemical formula b; R2 is selected from H, C1~C6 alkyl, methoxy, ester, nitro, and hydroxyl groups; R1 and R3 are independently selected from alkyl groups of C1 to C6 and aryl groups of C6 to C9; X is selected from one of F, Cl, Br, and I.

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