A preparation method of tris(p-dimethylaminophenyl)methane

Abstract

The present invention relates to a method for preparing tris(p-dimethylaminophenyl)methane, comprising the following steps: reacting an alkoxymethane of formula 1 and N,N-dimethylaniline of formula 2 in an organic solvent at 20-80 °C under the action of a Lewis acid catalyst, and obtaining tris(p-dimethylaminophenyl)methane of formula 3 after the reaction is complete. The reaction route is as follows: wherein R is an alkyl group containing 1-5 carbon atoms. By using the method of the present invention, the reaction conversion rate is above 80%, and the content of the finished product obtained after post-treatment reaches above 99%. This process can meet the requirements of industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and particularly relates to a preparation method of tris(p-dimethylaminophenyl)methane. Background Art

[0002] Tris(p-dimethylaminophenyl)methane (LCV) (colorless crystal violet) is mainly used in the dye industry and is the colorless parent body of methyl violet. It can be used as an analytical reagent or a photosensitive material in the film industry.

[0003] The reported synthetic methods of tris(p-dimethylaminophenyl)methane (LCV) usually use p-dimethylaminobenzaldehyde and N,N-dimethylaniline as starting materials for preparation, such as in the literature Synthetic Communications Vol.33, No.11, pp.1885 - 1889, 2003; Tetrahedron Letters 46(2005)1119 - 1122; International Journal of ChemTech Research Vol.1, No.3, pp.452 - 456; Patent US4394314, CN201010506103.7 provides theoretical and practical basis for the development and utilization of tris(p-dimethylaminophenyl)methane (LCV) photosensitizer. However, in these traditional synthetic methods, there are disadvantages such as high reaction temperature, long reaction time, low reaction conversion rate, low crude product content requiring repeated refining, and serious environmental pollution, which limit the application of tris(p-dimethylaminophenyl)methane (LCV) photosensitizer. Summary of the Invention

[0004] To solve the above technical problems, the object of the present invention is to provide a preparation method of tris(p-dimethylaminophenyl)methane. By using the method of the present invention, the reaction conversion rate is above 80%, and the content of the finished product obtained after post-treatment reaches more than 99%. This process can meet the requirements of industrial production.

[0005] The present invention provides a preparation method of tris(p-dimethylaminophenyl)methane, comprising the following steps:

[0006] React alkoxymethane of formula 1 and N,N-dimethylaniline of formula 2 in an organic solvent at 20 - 80°C under the action of a Lewis acid catalyst. After the reaction is complete, tris(p-dimethylaminophenyl)methane of formula 3 is obtained. The reaction route is as follows:

[0007]

[0008] Wherein, R is an alkyl group containing 1 - 5 carbon atoms.

[0009] Further, the organic solvent is methanol, ethanol, isopropanol, butanol, toluene, tetrahydrofuran, dioxane or DMF.

[0010] Further, the dosage of the organic solvent is 3 - 10 times that of N,N - dimethylaniline, preferably 4 - 6 times.

[0011] Further, the molar ratio of alkoxymethane to N,N - dimethylaniline is 1:3 - 1:6, preferably 1:3 - 1:4.

[0012] Further, the Lewis acid catalyst is AlCl3, BF3, SbCl5, FeBr3, FeCl3, SnCl4, TiCl4 or ZnCl2.

[0013] Further, the mass of the Lewis acid catalyst is 1% - 5% of the mass of N,N - dimethylaniline, preferably 1% - 3%.

[0014] Using the Lewis acid catalyst can ensure that the reaction has good yield and selectivity.

[0015] Preferably, the reaction temperature is 40 - 60 °C.

[0016] Further, the reaction time is 1 - 10 hours, preferably 3 - 5 hours.

[0017] Preferably, R is methyl.

[0018] Further, after the reaction is complete, it further includes the steps of filtering the product, purifying with toluene and drying.

[0019] By means of the above - mentioned scheme, the present invention has at least the following advantages:

[0020] (1) The preparation process of the present invention is simple, the process flow is short, and the three wastes are less, which is beneficial to environmental protection and suitable for industrial production;

[0021] (2) In the preparation process of the present invention, solvents and other auxiliary materials can be recycled and reused, reducing the production cost and realizing green production;

[0022] (3) In the preparation process of the present invention, the solvents, catalysts and other auxiliary materials used have a wide selection range and are all common substances, which is convenient for production selection;

[0023] (4) In the preparation process of the present invention, the temperature is low, the reaction is mild, the conversion rate and yield are high, the quality is stable, and the content is high.

[0024] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following is a detailed description with the preferred embodiments of the present invention as follows. Detailed Embodiments

[0025] The following further describes in detail the specific implementation manners of the present invention in combination with embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0026] Example 1

[0027] In a 250 ml three-necked flask, 36.3 g (0.3 mol) of N,N-dimethylaniline, 12.7 g (0.12 mol) of trimethoxymethane, 0.24 g of AlCl3 catalyst, and 90 g of methanol were successively added, heated to 45 °C, reacted for 3 hours, cooled to 25 °C, and the crude product was obtained by suction filtration. The crude product was refined with 50 g of toluene, dried, and 36.6 g of the product was obtained, with a yield of 98.12% and an HPLC content of 99.63%. Elemental analysis: Cal: C 80.39, H 8.37, N 11.25 Found: C 80.37, H 8.35, N 11.28; ESI: 373.51.

[0028] Example 2

[0029] In a 250 ml three-necked flask, 42.4 g (0.35 mol) of N,N-dimethylaniline, 12.7 g (0.12 mol) of trimethoxymethane, 0.25 g of BF3 catalyst, and 90 g of methanol were successively added, heated to 45 °C, reacted for 3 hours, cooled to 25 °C, and the crude product was obtained by suction filtration. The crude product was refined with 50 g of toluene, dried, and 36.6 g of the product was obtained, with a yield of 84.1% and an HPLC content of 99.65%. Elemental analysis: Cal: C 80.39, H 8.37, N 11.25 Found: C 80.36, H 8.36, N 11.28; ESI: 373.52.

[0030] Example 3

[0031] In a 250 ml three-necked flask, 48.4 g (0.4 mol) of N,N-dimethylaniline, 12.7 g (0.12 mol) of trimethoxymethane, 0.23 g of SbCl5 catalyst, and 90 g of dioxane were successively added, heated to 50 °C, reacted for 4 hours, cooled to 25 °C, and the crude product was obtained by suction filtration. The crude product was refined with 50 g of toluene, dried, and 36.3 g of the product was obtained, with a yield of 81.1% and an HPLC content of 99.71%. Elemental analysis: Cal: C 80.39, H 8.37, N 11.25 Found: C 80.36, H 8.37, N 11.28; ESI: 373.51.

[0032] Example 4

[0033] In a 250 ml three-necked flask, 42.4 g (0.35 mol) of N,N-dimethylaniline, 12.7 g (0.12 mol) of trimethoxymethane, 0.24 g of FeBr3 catalyst, and 90 g of dioxane were successively added. The mixture was heated to 50 °C and reacted for 4 hours. After cooling to 25 °C, the crude product was obtained by suction filtration. The crude product was refined with 50 g of toluene, dried, and 36.7 g of the product was obtained, with a yield of 84.34% and an HPLC content of 99.68%. Elemental analysis: Cal: C 80.39, H 8.37, N 11.25; Found: C 80.37, H 8.39, N 11.28; ESI: 373.50.

[0034] Example 5

[0035] In a 250 ml three-necked flask, 54.4 g (0.45 mol) of N,N-dimethylaniline, 12.7 g (0.12 mol) of trimethoxymethane, 0.26 g of FeCl3 catalyst, and 90 g of tetrahydrofuran were successively added. The mixture was heated to 55 °C and reacted for 5 hours. After cooling to 25 °C, the crude product was obtained by suction filtration. The crude product was refined with 50 g of toluene, dried, and 36.6 g of the product was obtained, with a yield of 81.95% and an HPLC content of 99.72%. Elemental analysis: Cal: C 80.39, H 8.37, N 11.25; Found: C 80.34, H 8.35, N 11.28; ESI: 373.53.

[0036] Example 6

[0037] In a 250 ml three-necked flask, 36.3 g (0.3 mol) of N,N-dimethylaniline, 12.7 g (0.12 mol) of trimethoxymethane, 0.25 g of ZnCl2 catalyst, and 90 g of tetrahydrofuran were successively added. The mixture was heated to 55 °C and reacted for 5 hours. After cooling to 25 °C, the crude product was obtained by suction filtration. The crude product was refined with 50 g of toluene, dried, and 36.7 g of the product was obtained, with a yield of 98.4% and an HPLC content of 99.63%. Elemental analysis: Cal: C 80.39, H 8.37, N 11.25; Found: C 80.37, H 8.35, N 11.26; ESI: 373.51.

[0038] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing tris(p-dimethylaminophenyl)methane, characterized in that, It includes the following steps: In a 250 ml three-necked flask, 36.3 g of N,N-dimethylaniline, 12.7 g of trimethoxymethane, 0.24 g of AlCl3 catalyst, and 90 g of methanol were successively added. It was heated to 45 °C and reacted for 3 hours, then cooled to 25 °C. The crude product was obtained by suction filtration. The crude product was refined with 50 g of toluene, dried, and 36.6 g of the product was obtained, with an HPLC content of 99.63%.

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