Production method for preparing chlorinated aniline via chlorination of nitrobenzene hydrogenation by utilizing solvent-free process

Abstract

The invention belongs to the production field of catalytic hydrogenation, and particularly discloses a production method for preparing chlorinated aniline via the chlorination of nitrobenzene hydrogenation by utilizing a solvent-free process. Chlorinated nitrobenzene is used as a raw material. The method is characterized in that under the existence of a catalyst and an aiding agent, the chlorinated nitrobenzene reacts with hydrogen at the temperature of 80 to 100 DEG C and under the pressure of 0.3 to 2.5 MPa, wherein a solvent is not added; and after the reaction is finished, the water diversion treatment is carried out, thereby obtaining the chlorinated aniline. The catalyst containing 1% of Pt / C precious metal is developed independently, wherein the adding amount of the catalyst accounts for 0.05% to 20% of that of the chlorinated nitrobenzene as the raw material. The aiding agent is a mixture of ethanol amine and pyridine, wherein the adding amount of the aiding agent accounts for 0.01% to 10% of that of the chlorinated nitrobenzene as the raw material. For the obtained o-chloroaniline, the chromatographic purity is above 99.5%, and the dechlorination quantity can be controlled within 0.1%. For the obtained 2,5-dichloroaniline, the chromatographic purity is above 99%, and the dechlorination quantity can be controlled within 0.1%. For the obtained 3,4-dichloroaniline, the chromatographic purity is above 99%, and the dechlorination quantity can be controlled within 0.1%.

Description

technical field [0001] The invention belongs to the field of catalytic hydrogenation production, and particularly discloses a production method for preparing chloroaniline by hydrogenation of chlorinated nitrobenzene in a solventless method. Background technique [0002] Chloroaniline is an important class of fine chemical intermediates, and has a wide range of uses in the fields of medicine, pesticides, dyes and daily chemicals. O-chloroaniline is the color base of ice dyes, and can also be used as the diazo component of azo dyes to produce acid black, acid blue and organic lakes such as permanent yellow R, permanent red FR, Hansa yellow HR, etc. It can also be used to prepare medicines, pesticides, and cross-linking agent methyl dichloroaniline of polyurethane resin; 2, 5-dichloroaniline is an important intermediate of medicines and pesticides, mainly used to synthesize the pesticide dicamba, and can also be used to make ice Dye dye bright red base and nitrogen fertilizer...

AI Technical Summary

Problems solved by technology

However, the catalytic hydrogenation process of chloroaniline has the problem of hydrogenolysis and dechlorination, which causes equipment corrosion and product purity decline. Choosing the right additive can effectively reduce dechlorination and increase the content of the main product. Key points and difficulties of research in this field

Most of the traditional processes use Raney nickel catalyst, low molecular weight methyl ethanol as the solvent, and add an appropriate amount of anti-dechlorination additives. This process is difficult to control dechlorination. Raney-Ni is not safe to use and needs to be removed in industrial production. Solvent, there are many processes, the product solvent is lost, and the energy consumption is high, which affects the overall cost