Method for synthesizing permanent violet

Abstract

The invention discloses a method for synthesizing permanent violet. The method comprises the following steps of: 1) alkylating, namely, in a closed reaction kettle, putting carbazole into solution consisting of an inert halogenated aryl hydrocarbon solvent and an alkali metal hydroxide; and performing a reaction with bromoethane in the presence of a quaternary ammonium salt catalyst; 2) nitrifying, namely, treating an obtained N-ethyl carbazole-contianing organic phase by using dilute nitric acid; and after cooling, crystallizing and separating, obtaining a midbody 3-nitryl-N-ethyl carbazole by washing paste; 3) reducing, namely, after dissolving a 3-nitryl-N-ethyl carbazole material in inert halogenated aryl hydrocarbon, performing hydrogenated reduction by using fermium-containing Raney's nickel as a catalyst; and 4) performing a condensation reaction and a ring closing reaction. The method has the advantages that: 1) in the alkylation of the invention, the inert halogenated aryl hydrocarbon is taken as a solvent, so that pollution and cost are reduced and production devices are simplified at the same time; 2) in the method, the temperature for the nitration is improved, so that raw material consumption and the discharge of waste water are reduced; and 3) the process of industrial hydrogenated reduction is perfected, so that the problem of waste water reduction treatment is solved basically, and energy consumption is reduced obviously.

Description

Technical field [0001] The invention relates to a method for synthesizing permanent violet, in particular to a method for synthesizing permanent violet with high raw material utilization rate, low pollution and stable product quality. Background technique [0002] Water solid violet is a high-grade purple organic pigment, which belongs to dioxazine pigments. Its pigment index number is C.I.Pigment violet23, No.51319, and its structural formula is: [0003] [0004] Due to its excellent weather resistance, light resistance, good oil resistance, migration resistance, thermal stability, pure color, and good gloss, it is currently widely used as a colorant for plastics, coatings, paints, and inks. Since the invention of this structure, great progress has been made through unremitting innovations. The current industrialized methods are almost all using carbazole as the starting material, through alkylation, nitration, reduction, condensation, ring closure and other processes. The detai...

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Problems solved by technology

The above method has the disadvantages of difficult control of the reaction temperature, more by-products in the product and large energy consumption through actual verification.

Reported in Chinese patent 200610088488.3, ​​in the chlorobenzene organic medium, use dilute nitric acid (concentration 37-38%) to carry out nitration under the condition of 28~30 ℃, and then use dilute alkali to neutralize the corresponding nitro Carbazole, wherein chlorobenzene: N-ethylcarbazole: the weight ratio of nitric acid=5: 4.6: 6.7, although this method partly avoided the shortcoming of aforementioned bibliographical information, still there are raw material utilization rate low, the shortcoming such as loaded down with trivial details operation

Among them, the sodium sulfide reduction method is the main production process in China at present. This process has the advantages of simple operation, easy control, good quality, and high yield, but there are problems such as serious pollution. For example, it is disclosed in the Chinese patent 200610088488. The concrete process of wherein ethanol: sodium sulfide (52%): the weight ratio of nitrate=2: 5.6: 4.3

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