Method for preparing 2,2'-di(trifluoromethyl)-4,4'-benzidine

Abstract

The invention relates to a method for preparing 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl capable of being used as a liquid crystal material from 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl by reduction reaction. According to the specific technical scheme, the method comprises the following steps: carrying out coupling reaction of 2-bromo-5-nitrobenzotrifluoride in the presence of a transition metal (Pd, Cu, Ni) catalyst to obtain 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl; and catalyzing by a Cu oxide or metal Pa in the hydrogen atmosphere to obtain 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl. The process for preparing 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl has the advantages of less emission of the three wastes and high yield.

Description

technical field

[0001] The present invention relates to the preparation of 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl which can be used as liquid crystal and other raw materials through reduction reaction The preparation method of base)-4,4'-diaminobiphenyl. Background technique

[0002] The preparation method of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl currently has the rearrangement reaction of 3,3'-bis(trifluoromethyl)diphenylhydrazine, and 3, 3'-bis(trifluoromethyl)diphenylhydrazine is prepared by m-nitrobenzotrifluoride in an alkaline solution of Zn powder (Journal of polymer Science Part A: Polymer Chemistry 1999, volume 37, pages 937-957; and See the Chinese invention application whose patent application number is 200480044354.0 and publication number is CN101102992A). However, the process disclosed in this patent application has a large amount of solvent used—for example, the mass ratio of m-nitrobenzotrifluoride to solvent is 1:7.6, and the use of Zn and...

Examples

Embodiment 1

[0020] Under nitrogen atmosphere, 270g (1mol) of 2-bromo-5-nitrobenzotrifluoride, 254g (4mol) of Cu powder and 1L of N,N-dimethylformamide after anhydrous treatment were heated to 155°C for 10 hours , lower the temperature to 120°C and filter, and wash the filter cake with 200ml of N,N-dimethylformamide at a temperature of 100°C. N,N-dimethylformamide was recovered under reduced pressure (110° C. / 3 mmHg), with a recovery rate of 92%, and 300 ml of methanol was added for recrystallization to obtain 123.5 g of yellow crystals, with a yield of 65%. (Melting point: 143-145°C).

[0021] Take 760g (2mol) of 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl, 100g of 10% Pd / C (water content 30%), 2L of methanol, under 1MP hydrogen pressure in React at room temperature for 10 hours. After the reaction, the clear liquid was poured out, and 1.5 L of solvent was recovered by concentration. The crude product obtained by filtration at room temperature was recrystallized from 700 ml of methan...

Embodiment 2

[0023] Under nitrogen atmosphere, 270g (1mol) of 2-bromo-5-nitrobenzotrifluoride, 127g (2mol) of Cu powder and 1L of N,N-dimethylformamide after anhydrous treatment were heated at 155°C for 10 hours. Cool down to 120°C and filter, and wash the filter cake with 200ml of N,N-dimethylformamide at a temperature of 100°C. N,N-dimethylformamide was recovered under reduced pressure (110°C / 3mmHg), with a recovery rate of 92%, and 300ml of methanol was added for recrystallization to obtain 102.6 g of yellow crystals, with a yield of 54% (melting point: 143-145°C).

[0024] Take 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl 760g (2mol), 5%Pd / C (water content 30%) 200g, methanol 2L, under 1MP hydrogen pressure in React at room temperature for 10 hours. After the reaction, the clear liquid was poured out, and 1.5 L of solvent was recovered by concentration. The crude product obtained by filtration at room temperature was recrystallized from 700 ml of methanol to obtain 375 g of white so...

Embodiment 3

[0026] Under nitrogen atmosphere, 270g (1mol) of 2-bromo-5-nitrobenzotrifluoride, 318g (5mol) of Cu powder and 1L of N,N-dimethylformamide after anhydrous treatment were heated at 155°C for 10 hours. Cool down to 120°C and filter, and wash the filter cake with 200ml of N,N-dimethylformamide at a temperature of 100°C. N,N-dimethylformamide was recovered under reduced pressure (110°C / 3mmHg), the recovery rate was 91%, and 300 ml of methanol was added for recrystallization to obtain 125.4 g of yellow crystals, with a yield of 66% (mp 143-145°C).

[0027] Take 760g (2mol) of 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl, 240g of copper oxide, and 2L of methanol, and react at 100°C for 15 hours under 7MP hydrogen pressure. After the reaction, the clear liquid was poured out, and 1.5 L of solvent was recovered by concentration. The crude product obtained by filtration at room temperature was recrystallized from 700 ml of methanol to obtain 450 g of a white solid, with a yield of 70...

technical field

[0001] The present invention relates to the preparation of 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl which can be used as liquid crystal and other raw materials through reduction reaction The preparation method of base)-4,4'-diaminobiphenyl. Background technique

[0002] The preparation method of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl currently has the rearrangement reaction of 3,3'-bis(trifluoromethyl)diphenylhydrazine, and 3, 3'-bis(trifluoromethyl)diphenylhydrazine is prepared by m-nitrobenzotrifluoride in an alkaline solution of Zn powder (Journal of polymer Science Part A: Polymer Chemistry 1999, volume 37, pages 937-957; and See the Chinese invention application whose patent application number is 200480044354.0 and publication number is CN101102992A). However, the process disclosed in this patent application has a large amount of solvent used—for example, the mass ratio of m-nitrobenzotrifluoride to solvent is 1:7.6, and the use of Zn and...

Examples

Embodiment 1

[0020] Under nitrogen atmosphere, 270g (1mol) of 2-bromo-5-nitrobenzotrifluoride, 254g (4mol) of Cu powder and 1L of N,N-dimethylformamide after anhydrous treatment were heated to 155°C for 10 hours , lower the temperature to 120°C and filter, and wash the filter cake with 200ml of N,N-dimethylformamide at a temperature of 100°C. N,N-dimethylformamide was recovered under reduced pressure (110° C. / 3 mmHg), with a recovery rate of 92%, and 300 ml of methanol was added for recrystallization to obtain 123.5 g of yellow crystals, with a yield of 65%. (Melting point: 143-145°C).

[0021] Take 760g (2mol) of 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl, 100g of 10% Pd / C (water content 30%), 2L of methanol, under 1MP hydrogen pressure in React at room temperature for 10 hours. After the reaction, the clear liquid was poured out, and 1.5 L of solvent was recovered by concentration. The crude product obtained by filtration at room temperature was recrystallized from 700 ml of methan...

Embodiment 2

[0023] Under nitrogen atmosphere, 270g (1mol) of 2-bromo-5-nitrobenzotrifluoride, 127g (2mol) of Cu powder and 1L of N,N-dimethylformamide after anhydrous treatment were heated at 155°C for 10 hours. Cool down to 120°C and filter, and wash the filter cake with 200ml of N,N-dimethylformamide at a temperature of 100°C. N,N-dimethylformamide was recovered under reduced pressure (110°C / 3mmHg), with a recovery rate of 92%, and 300ml of methanol was added for recrystallization to obtain 102.6 g of yellow crystals, with a yield of 54% (melting point: 143-145°C).

[0024] Take 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl 760g (2mol), 5%Pd / C (water content 30%) 200g, methanol 2L, under 1MP hydrogen pressure in React at room temperature for 10 hours. After the reaction, the clear liquid was poured out, and 1.5 L of solvent was recovered by concentration. The crude product obtained by filtration at room temperature was recrystallized from 700 ml of methanol to obtain 375 g of white so...

Embodiment 3

[0026] Under nitrogen atmosphere, 270g (1mol) of 2-bromo-5-nitrobenzotrifluoride, 318g (5mol) of Cu powder and 1L of N,N-dimethylformamide after anhydrous treatment were heated at 155°C for 10 hours. Cool down to 120°C and filter, and wash the filter cake with 200ml of N,N-dimethylformamide at a temperature of 100°C. N,N-dimethylformamide was recovered under reduced pressure (110°C / 3mmHg), the recovery rate was 91%, and 300 ml of methanol was added for recrystallization to obtain 125.4 g of yellow crystals, with a yield of 66% (mp 143-145°C).

[0027] Take 760g (2mol) of 2,2'-bis(trifluoromethyl)-4,4'-dinitrobiphenyl, 240g of copper oxide, and 2L of methanol, and react at 100°C for 15 hours under 7MP hydrogen pressure. After the reaction, the clear liquid was poured out, and 1.5 L of solvent was recovered by concentration. The crude product obtained by filtration at room temperature was recrystallized from 700 ml of methanol to obtain 450 g of a white solid, with a yield of 70...