Disperse red CNB synthesis method

Abstract

The invention discloses a method for synthesizing disperse red CNB. The steps are: (1) using chloroform as a reaction solvent, TBAB as a phase transfer catalyst, and p-propoxybenzaldehyde Ia as a reaction raw material, in alkaline Addition under conditions, hydrolysis under acidic conditions to obtain the intermediate p-propoxymandelic acid Ib step; (2) using nitrobenzene as the reaction solvent and oxidant, using concentrated sulfuric acid as the catalyst, and using the condensate 5‑hydroxy‑2 -Oxo-3-phenyl-2,3-dihydrobenzofuran Ic and p-propoxymandelic acid Ib are the reaction raw materials, and the step of obtaining the target product through cyclization-oxidation reaction. In the present invention, nitrobenzene is used as the reaction solvent and oxidant, and the two sections of cyclization and oxidation are carried out almost simultaneously. In the later stage of this section, the temperature is raised to ensure that the oxidation reaction is carried out thoroughly. Therefore, the entire cyclization and oxidation section reacts relatively thoroughly. resulting in a higher yield.

Description

technical field [0001] The invention relates to a synthesis method of disperse red, in particular to a synthesis method of disperse red CNB, which belongs to the technical field of chemical dye manufacture. Background technique [0002] Disperse Red CNB is also called Disperse Red 356, CAS: 159968-00-0, the chemical name is 3-phenyl-7(4-propoxyphenyl)-benzodifuran-2,6-dione, which is benzene The largest variety of difuranone disperse dyes, Disperse Red CNB has been widely valued for its bright color, high color strength and good dyeing performance, especially for its excellent performance in the application of polyester microfibers. The structural formula of disperse red CNB is: [0003] [0004] The production method of domestic existing disperse red CNB is mainly accomplished through the following synthetic routes: [0005] [0006] [0007] The above-mentioned synthesis reaction involves the highly toxic sodium cyanide, and the highly toxic gas hydrocyanic acid...

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Problems solved by technology

[0007] The above synthesis reaction involves the highly toxic sodium cyanide, and the highly toxic gas hydrocyanic acid is produced in the cyanation reaction section, which is a high-risk reaction, so the safety and environmental protection measures in this section are particularly strict

In addition, the yield of the above-mentioned synthetic route is low, only about 50%, and the production cost is also relatively high

Although many improvements have been made around the above synthetic routes at home and abroad, such as process optimization of condensates, selection of oxidants, addition of catalysts, selection of reaction solvents, etc., although the yield has been improved to a certain extent, the effect is not significant. Production costs remain high, and product quality does not meet expectations

Tracing it to its cause, mainly comes from two aspects, one, the excess of condensate leads to too much tar produced in the epoxidation process, thereby causes product quality to decline, produces too much solid waste; Second, the choice of oxidant, such as Chloranil, chloranil, etc. are relatively expensive, resulting in high costs

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