Method for preparing high-purity biphenyl dibenzyl chloride through chloromethylation

Abstract

The invention relates to the technical field of organic synthesis, and provides a method for preparing high-purity biphenyl dibenzyl chloride through chloromethylation, which comprises the following steps: mixing paraformaldehyde, acid liquor, biphenyl, a catalyst and cyclohexane to react, drying and refining to obtain biphenyl dibenzyl chloride; the catalyst comprises a bentonite composite catalyst and zinc chloride. According to the technical scheme, the problems of low yield and low purity of biphenyl dibenzyl chloride in related technologies are solved.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation. Background Art

[0002] Biphenyl dibenzyl chloride (also known as: biphenyl dichlorobenzyl) is an important organic synthesis intermediate and is widely used in the fields of medicine, pesticides, polymer materials, etc. The main way to obtain biphenyl dibenzyl chloride is to react with biphenyl, methylating agents, catalysts and other components. Although this method is simple and easy to operate, there are problems such as complex reactions and a large number of by-product impurities in the preparation process. The purity of biphenyl dibenzyl chloride determines the breadth of its application range. Although the purity of the existing biphenyl dibenzyl chloride can be used as a raw material for general chemical synthesis, high-purity biphenyl dibenzyl chloride is required for technical fields such as liquid crystal compounds or polymers. It can be seen that a lot of exploration is needed in the synthesis process to explore a simple and efficient synthesis process, improve the yield and purity of biphenyl dibenzyl chloride, and broaden the scope of further application of biphenyl dibenzyl chloride. Summary of the invention

[0003] The invention provides a method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation, which solves the problem of low yield and purity of biphenyl dibenzyl chloride in the related art.

[0004] The technical solution of the present invention is as follows: The present invention provides a method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation, comprising the following steps: The paraformaldehyde, acid solution, biphenyl, catalyst and cyclohexane are mixed for reaction, dried and refined to obtain biphenyl dibenzyl chloride; The catalyst comprises bentonite composite catalyst and zinc chloride.

[0005] As a further technical solution, the mass of the catalyst is 8% to 15% of the mass of the biphenyl; The mass ratio of the bentonite composite catalyst to zinc chloride is 1-4:7.

[0006] As a further technical solution, the preparation method of the bentonite composite catalyst comprises the following steps: A1. Dissolving a titanium salt in a solvent, adjusting the pH to 1-2, and obtaining a titanium-containing solution; A2. Mix the titanium-containing solution with the cerium salt solution, add bentonite and continue mixing, dry, and calcine to obtain a bentonite composite catalyst.

[0007] In the present invention, when preparing the bentonite composite catalyst, a titanium salt solution is mixed with a cerium salt solution, so that the two metal ions can be evenly distributed, and the catalytic effect is synergistically exerted to form a more stable and more active catalytic active center, thereby improving the reaction selectivity. After the bentonite is added, the active ingredients can be loaded on the porous structure of the bentonite, thereby increasing the specific surface area, increasing the contact probability between the catalyst and the reactant, and improving the purity and yield of diphenyl chloride.

[0008] As a further technical solution, the mass ratio of the titanium salt to the solvent is 1:2-3; The mass ratio of the titanium salt to the cerium salt solution is 1:0.1-0.8; The mass ratio of the bentonite to the titanium salt is 1:2-5; The concentration of the cerium salt solution is 0.04-0.08 mol / L.

[0009] As a further technical solution, the cerium salt in the cerium salt solution includes one or more of cerium nitrate, cerium sulfate, and cerium carbonate.

[0010] As a further technical solution, the titanium salt includes one or both of tetraisopropyl titanate and tetrabutyl titanate.

[0011] As a further technical solution, in step A2, a silver salt solution is also added during the mixing.

[0012] As a further technical solution, the mass ratio of the titanium salt to the silver salt solution is 1:0.2-0.4; The concentration of the silver salt solution is 0.04-0.08 mol / L.

[0013] In the present invention, a silver salt solution is introduced during the preparation of the bentonite composite catalyst, and the bentonite composite catalyst is prepared together with a titanium salt solution and a cerium salt, and is used in the synthesis of biphenyl dibenzyl chloride, thereby further improving the yield of biphenyl dibenzyl chloride.

[0014] As a further technical solution, the refining uses toluene and tert-butyl methyl ether in a mass ratio of 1:9 to 9:1.

[0015] In the present invention, during purification, a mixed solvent of toluene and tert-butyl methyl ether in a mass ratio of 1:9 to 9:1 is used to wash the crude biphenyl dibenzyl chloride, which improves the purity of the product biphenyl dibenzyl chloride compared with the use of toluene or tert-butyl methyl ether alone.

[0016] As a further technical solution, the mass ratio of the paraformaldehyde, acid solution, biphenyl and cyclohexane is 5~8:6:10:12.

[0017] In the present invention, the mass ratio of paraformaldehyde, acid solution, biphenyl and cyclohexane is 5-8:6:10:12. When preparing biphenyl dibenzyl chloride, sufficient formaldehyde groups react with biphenyl to ensure the generation of biphenyl dibenzyl chloride.

[0018] As a further technical solution, during the mixing reaction, the mixture is first mixed at 32-38° C. for 2-3 hours, and then the temperature is raised to 45-50° C. and mixed for 5-6 hours.

[0019] In the present invention, during the mixing reaction, the mixture is first mixed at 32-38° C. for 2-3 hours, and then the temperature is raised to 45-50° C. for 5-6 hours, so that the reactant molecules can be initially contacted in a relatively mild environment and react slowly, which is conducive to orderly interaction between the reactants to form stable intermediate products. As the reaction proceeds, a certain amount of intermediate products accumulates in the system, and the temperature is raised again to increase the kinetic energy of the molecules, accelerate the reaction rate, promote the generation of the product biphenyl dibenzyl chloride, and improve the overall reaction efficiency.

[0020] As a further technical solution, the acid solution includes a hydrochloric acid solution with a mass concentration of 30% to 35%; During the mixed reaction, hydrogen chloride gas is introduced; The molar ratio of the hydrogen chloride gas to the biphenyl is 2-3:1.

[0021] The working principle and beneficial effects of the present invention are: In the present invention, biphenyl dibenzyl chloride is prepared by chloromethylation, wherein, paraformaldehyde, biphenyl and the like are used as raw materials, and under the composite catalysis of a bentonite composite catalyst and zinc chloride, the selectivity and conversion efficiency of the biphenyl dibenzyl chloride product prepared by chloromethylation are improved, thereby improving the purity and yield of the biphenyl dibenzyl chloride. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the following examples and comparative examples, the particle size of bentonite is 400 mesh.

[0024] Example 1 The method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation comprises the following steps: Paraformaldehyde, acid solution, biphenyl, catalyst, and cyclohexane were first mixed at 32°C for 3 hours, then heated to 45°C and mixed for 6 hours. Hydrogen chloride gas (the molar ratio of hydrogen chloride gas to biphenyl was 2:1) was also introduced during the mixing process. The organic phase of the filtrate was filtered, crystallized, dried, and refined (washed with toluene). The solid was dried to obtain biphenyl dibenzyl chloride (yield was 89.6%, purity was 98.8%). The mass ratio of paraformaldehyde, acid solution, biphenyl and cyclohexane was 5:6:10:12, the mass of the catalyst was 8% of the mass of the biphenyl, and the acid solution was a hydrochloric acid solution with a mass concentration of 30%; The catalyst is a bentonite composite catalyst and zinc chloride in a mass ratio of 1:7; Wherein, the preparation method of bentonite composite catalyst comprises the following steps: A1. After dissolving tetrabutyl titanate in ethanol, the pH value is adjusted to 1 to obtain a titanium-containing solution; the mass ratio of tetrabutyl titanate to ethanol is 1:2; A2. Mix the titanium-containing solution with a cerium nitrate solution having a concentration of 0.04 mol / L, add bentonite and continue mixing, dry, and calcine to obtain a bentonite composite catalyst; the mass ratio of tetrabutyl titanate to the cerium nitrate solution is 1:0.1, and the mass ratio of bentonite to tetrabutyl titanate is 1:2.

[0025] Example 2 The method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation comprises the following steps: Paraformaldehyde, acid solution, biphenyl, catalyst and cyclohexane were first mixed at 38°C for 2h, then heated to 50°C and mixed for 5h, hydrogen chloride gas (the molar ratio of hydrogen chloride gas to biphenyl was 3:1) was also introduced during the mixing process, filtered, the organic phase of the filtrate was crystallized, dried, refined (washed with toluene), and the solid was dried to obtain biphenyl dibenzyl chloride (yield was 92.7%, purity was 98.9%); the mass ratio of paraformaldehyde, acid solution, biphenyl and cyclohexane was 8:6:10:12, the mass of the catalyst was 15% of the mass of the biphenyl, and the acid solution was a hydrochloric acid solution with a mass concentration of 35%; The catalyst is a bentonite composite catalyst and zinc chloride in a mass ratio of 4:7; Wherein, the preparation method of bentonite composite catalyst comprises the following steps: A1. After dissolving tetrabutyl titanate in ethanol, the pH value is adjusted to 2 to obtain a titanium-containing solution; the mass ratio of tetrabutyl titanate to ethanol is 1:3; A2. Mix the titanium-containing solution with a cerium nitrate solution having a concentration of 0.08 mol / L, add bentonite and continue mixing, dry, and calcine to obtain a bentonite composite catalyst; the mass ratio of tetrabutyl titanate to the cerium nitrate solution is 1:0.8, and the mass ratio of bentonite to tetrabutyl titanate is 1:5.

[0026] Example 3 The method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation comprises the following steps: The paraformaldehyde, acid solution, biphenyl, catalyst and cyclohexane were first mixed at 35°C for 2.5 hours, then heated to 50°C and mixed for 6 hours. Hydrogen chloride gas (the molar ratio of hydrogen chloride gas to biphenyl was 2:1) was also introduced during the mixing process. The organic phase of the filtrate was filtered, crystallized, dried, and refined (washed with toluene). The solid was dried to obtain biphenyl dibenzyl chloride (yield was 91.1%, purity was 99.0%); the mass ratio of the paraformaldehyde, acid solution, biphenyl and cyclohexane was 6:6:10:12, the mass of the catalyst was 8% of the mass of the biphenyl, and the acid solution was a hydrochloric acid solution with a mass concentration of 35%; The catalyst is a bentonite composite catalyst and zinc chloride in a mass ratio of 3:7; Wherein, the preparation method of bentonite composite catalyst comprises the following steps: A1. After dissolving tetrabutyl titanate in ethanol, the pH value is adjusted to 1 to obtain a titanium-containing solution; the mass ratio of tetrabutyl titanate to ethanol is 1:3; A2. Mix the titanium-containing solution with a cerium nitrate solution having a concentration of 0.05 mol / L, add bentonite and continue mixing, dry, and calcine to obtain a bentonite composite catalyst; the mass ratio of tetrabutyl titanate to the cerium nitrate solution is 1:0.5, and the mass ratio of bentonite to tetrabutyl titanate is 1:3.

[0027] Example 4 The difference between this embodiment and embodiment 3 is that the preparation method of the bentonite composite catalyst comprises the following steps: A1. After dissolving tetrabutyl titanate in ethanol, the pH value is adjusted to 1 to obtain a titanium-containing solution; the mass ratio of tetrabutyl titanate to ethanol is 1:3; A2, mixing the titanium-containing solution with a silver nitrate solution having a concentration of 0.04 mol / L, adding bentonite and continuing to mix, drying, and calcining to obtain a bentonite composite catalyst; the mass ratio of tetrabutyl titanate to the silver nitrate solution is 1:0.5, and the mass ratio of bentonite to tetrabutyl titanate is 1:3; The final yield of the obtained biphenyl dibenzyl chloride is 90.8% and the purity is 99.0%.

[0028] Example 5 The difference between this embodiment and embodiment 3 is that the preparation method of the bentonite composite catalyst comprises the following steps: A1. After dissolving tetrabutyl titanate in ethanol, the pH value is adjusted to 1 to obtain a titanium-containing solution; the mass ratio of tetrabutyl titanate to ethanol is 1:3; A2, the titanium-containing solution is mixed with a cerium nitrate solution with a concentration of 0.05 mol / L and a silver nitrate solution with a concentration of 0.04 mol / L, bentonite is added and continued to mix, dried, and calcined to obtain a bentonite composite catalyst; the mass ratio of tetrabutyl titanate to the cerium nitrate solution is 1:0.5, the mass ratio of bentonite to tetrabutyl titanate is 1:3, and the mass ratio of tetrabutyl titanate to the silver nitrate solution is 1:0.2; The final yield of biphenyl dibenzyl chloride is 94.4% and the purity is 99.2%.

[0029] Example 6 The difference between this embodiment and embodiment 3 is that the preparation method of the bentonite composite catalyst comprises the following steps: A1. After dissolving tetrabutyl titanate in ethanol, the pH value is adjusted to 1 to obtain a titanium-containing solution; the mass ratio of tetrabutyl titanate to ethanol is 1:3; A2, mixing the titanium-containing solution with a 0.05 mol / L cerium nitrate solution and a 0.08 mol / L silver nitrate solution, adding bentonite and continuing to mix, drying, and calcining to obtain a bentonite composite catalyst; the mass ratio of tetrabutyl titanate to the cerium nitrate solution is 1:0.5, the mass ratio of bentonite to tetrabutyl titanate is 1:3, and the mass ratio of tetrabutyl titanate to the silver nitrate solution is 1:0.4; The final yield of the obtained biphenyl dibenzyl chloride is 94.9% and the purity is 99.1%.

[0030] Example 7 The difference between this embodiment and embodiment 6 is that toluene is replaced by tert-butyl methyl ether; The final yield of biphenyl dibenzyl chloride is 94.6% and the purity is 99.1%.

[0031] Example 8 The difference between this embodiment and embodiment 6 is that one tenth of the mass of toluene is replaced by an equal amount of tert-butyl methyl ether; The final yield of biphenyl dibenzyl chloride is 94.4% and the purity is 99.7%.

[0032] Example 9 The difference between this embodiment and embodiment 6 is that nine-tenths of the mass of toluene is replaced by an equal amount of tert-butyl methyl ether; The yield of the finally obtained biphenyl dibenzyl chloride was 95.0% and the purity was 99.9%.

[0033] Comparative Example 1 The difference between this comparative example and Example 3 is that the bentonite composite catalyst is replaced with zinc chloride; The final yield of the obtained biphenyl dibenzyl chloride was 80.0% and the purity was 89.7%.

[0034] Comparative Example 2 The difference between this comparative example and Example 3 is that zinc chloride is replaced by a bentonite composite catalyst; The final yield of the obtained biphenyl dibenzyl chloride is 87.8% and the purity is 90.4%.

[0035] Compared with Comparative Examples 1-2, the yield and purity of biphenyl dibenzyl chloride obtained in Examples 1-9 are higher, indicating that the catalyst uses a bentonite composite catalyst in coordination with zinc chloride to improve the yield and purity of biphenyl dibenzyl chloride.

[0036] Compared with Examples 6 and 7, the purity of the biphenyl dibenzyl chloride obtained in Examples 8 and 9 is higher, indicating that toluene and tert-butyl methyl ether are used as detergents for impurity removal during refining, thereby improving the purity of the biphenyl dibenzyl chloride.

[0037] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation, characterized in that: The following steps are involved: The paraformaldehyde, acid solution, biphenyl, catalyst and cyclohexane are mixed for reaction, dried and refined to obtain biphenyl dibenzyl chloride; The catalyst comprises bentonite composite catalyst and zinc chloride.

2. A method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 1, characterized in that: The mass of the catalyst is 8% to 15% of the mass of the biphenyl; The mass ratio of the bentonite composite catalyst to zinc chloride is 1-4:

7.

3. A method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 1, characterized in that: The preparation method of the bentonite composite catalyst comprises the following steps: A1. Dissolving a titanium salt in a solvent, adjusting the pH to 1-2, and obtaining a titanium-containing solution; A2. Mix the titanium-containing solution with the cerium salt solution, add bentonite and continue mixing, dry, and calcine to obtain a bentonite composite catalyst.

4. A method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 3, characterized in that: The mass ratio of the titanium salt to the solvent is 1:2-3; The mass ratio of the titanium salt to the cerium salt solution is 1:0.1-0.8; The mass ratio of the bentonite to the titanium salt is 1:2-5; The concentration of the cerium salt solution is 0.04-0.08 mol / L.

5. A method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 3, characterized in that: In step A2, a silver salt solution is also added during the mixing.

6. The method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 5, characterized in that: The mass ratio of the titanium salt to the silver salt solution is 1:0.2-0.4; The concentration of the silver salt solution is 0.04-0.08 mol / L.

7. The method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 1, characterized in that: During the refining, toluene and tert-butyl methyl ether are used in a mass ratio of 1:9 to 9:

1.

8. The method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 1, characterized in that: The mass ratio of the paraformaldehyde, acid solution, biphenyl and cyclohexane is 5-8:6:10:

12.

9. The method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 1, characterized in that: During the mixing reaction, the mixture is first mixed at 32-38° C. for 2-3 hours, and then heated to 45-50° C. for 5-6 hours.

10. The method for preparing high-purity biphenyl dibenzyl chloride by chloromethylation according to claim 1, characterized in that: The acid solution comprises a hydrochloric acid solution with a mass concentration of 30% to 35%; During the mixed reaction, hydrogen chloride gas is introduced; The molar ratio of the hydrogen chloride gas to the biphenyl is 2-3:1.