Catalytic hydrogenation method for preparing 3,4-dichloroaniline

Abstract

The invention discloses a preparing method of 3, 4-dichloroaniline, which is characterized by the following: adopting 3, 4-dichloronitrobenzene as raw material and alcohol solution as solvent system; aerating H2 under 0.5-1.5Mpa at 80-120 Deg C in the condition of Raney-Ni catalyst and dechlorination inhibitor; proceeding catalytic hydrogenating reducing reaction to produce the product. The selectivity of 3, 4-dichloroaniline is more than 99%, whose dechlorination quantity is less than 2%.

Description

technical field

[0001] The present invention relates to a preparation method of 3,4-dichloroaniline, in particular to a method for preparing 3,4-dichloroaniline by catalytic hydrogenation reduction method using 3,4-dichloronitrobenzene as raw material . Background technique

[0002] 3,4-Dichloroaniline is an important chemical intermediate for medicines, pesticides, dyes, spices, etc., and has a wide range of uses. The synthesis methods of 3,4-dichloroaniline usually include iron powder reduction method, alkali sulfide reduction method and catalytic hydrogenation reduction method, and 3,4-dichloroaniline is prepared by reduction of 3,4-dichloronitrobenzene.

[0003] The chemical reduction methods such as the iron powder reduction method under acidic conditions or the alkali sulfide reduction method under alkaline conditions are used to prepare 3,4-dichloroaniline although the cost is low, but a large amount of amine-containing toxic metal residues or hydrochloric acid-conta...

Examples

Embodiment 1

[0020] Add 5 g of 3,4-dichloronitrobenzene and 25 mL of methanol into a 75 mL autoclave, add 0.5 g of W-4 ​​type Raney-Ni catalyst, and 0.1 g of dechlorination inhibitor ethanolamine at the same time, close the autoclave, and open the H 2 Valve to feed H into the autoclave 2 , adjust the kettle pressure to 0.9MPa, stir and heat up to 80°C, react for 50min, close the H 2 Valve, open the autoclave after cooling, discharge, add in the distillation bottle after filtering, add 50mL water and a small amount of gac, in N 2 The solvent methanol was recovered by atmospheric distillation under protection, and the remaining liquid was hot-filtered to remove activated carbon, then cooled to precipitate crystals, and vacuum-dried to obtain 3.50 g of 3,4-dichloroaniline, which was 99.93% by mass according to gas chromatography analysis.

Embodiment 2

[0022] Add 5 g of 3,4-dichloronitrobenzene and 30 mL of methanol into a 75 mL autoclave, add 0.6 g of W-4 ​​type Raney-Ni catalyst, and 0.1 g of dechlorination inhibitor ethanolamine at the same time, close the autoclave, and open the H 2 Valve to feed H into the autoclave 2 , adjust the kettle pressure to 1.0MPa, stir and heat up to 90°C, react for 60min, close the H 2 Valve, open the autoclave after cooling, discharge, add in the distillation bottle after filtering, add 50mL water and a small amount of gac, in N 2 The solvent methanol was recovered by atmospheric pressure distillation under protection, and the remaining liquid was hot filtered to remove activated carbon, then cooled to precipitate crystals, and dried in vacuum to obtain 3.47 g of 3,4-dichloroaniline, which was 99.36% by mass according to gas chromatography analysis.

Embodiment 3

[0024] Add 5 g of 3,4-dichloronitrobenzene and 30 mL of methanol into a 75 mL autoclave, add 0.8 g of W-4 ​​type Raney-Ni catalyst, and 0.2 g of dechlorination inhibitor ethanolamine at the same time, close the autoclave, and open the H 2 Valve to feed H into the autoclave 2 , adjust the kettle pressure to 1.3MPa, stir and heat up to 80°C, react for 70min, close the H 2 Valve, open the autoclave after cooling, discharge, add in the distillation bottle after filtering, add 50mL water and a small amount of gac, in N 2 The solvent methanol was recovered by atmospheric pressure distillation under protection, and the remaining liquid was hot-filtered to remove activated carbon, cooled to precipitate crystals, and vacuum-dried to obtain 3.51 g of 3,4-dichloroaniline, which was 99.36% by mass according to gas chromatography analysis.

technical field

[0001] The present invention relates to a preparation method of 3,4-dichloroaniline, in particular to a method for preparing 3,4-dichloroaniline by catalytic hydrogenation reduction method using 3,4-dichloronitrobenzene as raw material . Background technique

[0002] 3,4-Dichloroaniline is an important chemical intermediate for medicines, pesticides, dyes, spices, etc., and has a wide range of uses. The synthesis methods of 3,4-dichloroaniline usually include iron powder reduction method, alkali sulfide reduction method and catalytic hydrogenation reduction method, and 3,4-dichloroaniline is prepared by reduction of 3,4-dichloronitrobenzene.

[0003] The chemical reduction methods such as the iron powder reduction method under acidic conditions or the alkali sulfide reduction method under alkaline conditions are used to prepare 3,4-dichloroaniline although the cost is low, but a large amount of amine-containing toxic metal residues or hydrochloric acid-conta...

Examples

Embodiment 1

[0020] Add 5 g of 3,4-dichloronitrobenzene and 25 mL of methanol into a 75 mL autoclave, add 0.5 g of W-4 ​​type Raney-Ni catalyst, and 0.1 g of dechlorination inhibitor ethanolamine at the same time, close the autoclave, and open the H 2 Valve to feed H into the autoclave 2 , adjust the kettle pressure to 0.9MPa, stir and heat up to 80°C, react for 50min, close the H 2 Valve, open the autoclave after cooling, discharge, add in the distillation bottle after filtering, add 50mL water and a small amount of gac, in N 2 The solvent methanol was recovered by atmospheric distillation under protection, and the remaining liquid was hot-filtered to remove activated carbon, then cooled to precipitate crystals, and vacuum-dried to obtain 3.50 g of 3,4-dichloroaniline, which was 99.93% by mass according to gas chromatography analysis.

Embodiment 2

[0022] Add 5 g of 3,4-dichloronitrobenzene and 30 mL of methanol into a 75 mL autoclave, add 0.6 g of W-4 ​​type Raney-Ni catalyst, and 0.1 g of dechlorination inhibitor ethanolamine at the same time, close the autoclave, and open the H 2 Valve to feed H into the autoclave 2 , adjust the kettle pressure to 1.0MPa, stir and heat up to 90°C, react for 60min, close the H 2 Valve, open the autoclave after cooling, discharge, add in the distillation bottle after filtering, add 50mL water and a small amount of gac, in N 2 The solvent methanol was recovered by atmospheric pressure distillation under protection, and the remaining liquid was hot filtered to remove activated carbon, then cooled to precipitate crystals, and dried in vacuum to obtain 3.47 g of 3,4-dichloroaniline, which was 99.36% by mass according to gas chromatography analysis.

Embodiment 3

[0024] Add 5 g of 3,4-dichloronitrobenzene and 30 mL of methanol into a 75 mL autoclave, add 0.8 g of W-4 ​​type Raney-Ni catalyst, and 0.2 g of dechlorination inhibitor ethanolamine at the same time, close the autoclave, and open the H 2 Valve to feed H into the autoclave 2 , adjust the kettle pressure to 1.3MPa, stir and heat up to 80°C, react for 70min, close the H 2 Valve, open the autoclave after cooling, discharge, add in the distillation bottle after filtering, add 50mL water and a small amount of gac, in N 2 The solvent methanol was recovered by atmospheric pressure distillation under protection, and the remaining liquid was hot-filtered to remove activated carbon, cooled to precipitate crystals, and vacuum-dried to obtain 3.51 g of 3,4-dichloroaniline, which was 99.36% by mass according to gas chromatography analysis.