Method for preparing iron oxide red pigment and synchronously producing aromatic amine

Abstract

The invention relates to the technical field of fine chemicals, in particular to a method for preparing iron oxide red pigment and synchronously producing aromatic amine. The method comprises the following steps: preparing an iron oxide red seed crystal from an oxidant nitro aromatic compound and ferrous iron under the action of a catalyst, reducing the nitro aromatic compound by using iron powder, synchronously generating iron oxide in situ, and growing iron oxide red with pigment performance on the seed crystal. The method particularly provides a clean and economic way for preparing aromaticamine by reducing aromatic rings containing other easy-to-reduce substituent groups.

Description

technical field [0001] The invention relates to the technical field of fine chemicals, in particular to a method for preparing iron oxide red pigment and synchronously producing aromatic amines. Background technique [0002] Aromatic amines are important chemical intermediates, which can be used to synthesize fine chemicals such as dyes, medicines, and pesticides. Aromatic amines are mainly prepared by reducing aromatic nitro compounds. The main preparation methods are catalytic hydrogenation, iron powder / acid, alkali sulfide and hydrogen transfer reduction. These methods have their own advantages and disadvantages: catalytic hydrogenation is the cleanest and easiest reduction method, but when there are functional groups sensitive to hydrogenation in the molecule, such as halogens, double bonds and triple bonds, the reduction selectivity is poor; The reduction method has a certain selectivity for the reduction of polynitro groups, but the waste water produced will pollute t...

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Problems solved by technology

These methods have their own advantages and disadvantages: catalytic hydrogenation is the cleanest and easiest reduction method, but when there are functional groups sensitive to hydrogenation in the molecule, such as halogens, double bonds and triple bonds, the reduction selectivity is poor; The reduction method has a certain selectivity for the reduction of polynitro groups, but the waste water produced will pollute the environment; the hydrogen transfer reagents commonly used in the hydrogen transfer reduction method include hydrazine hydrate, sodium borohydride, formic acid and its salts, hypophosphorous acid and isopropanol etc., it is characterized in that reaction conditions are gentle and selectivity is high, but the price of hydrogen transfer reagent is generally higher, does not have cost advantage in industrial production; Iron powder reduction method is basically applicable to the reduction process of all nitro compounds, CN101037393A has reported Preparation of Aromatic Diamines by Reduction of Aromatic Nitro Compounds by Coupling Process of Iron Powder Reduction and Hydrazine Hydrate Reduction

CN101376634A has reported the method for iron powder reduction to produce o-chloroaniline, which is characterized in that o-nitrochlorobenzene, water, hydrochloric acid and iron powder are added to the reactor, and after the reduction reaction at 90-100 ° C, the iron is separated by rake vacuum drying Mud, but neither described the whereabouts of solid waste

However, this method consumes a lot of alkali, and the saline mother liquor needs to be desalted, so there is no cost advantage

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