Preparation method of thermosensitive dye compound N-acyl phenothiazine

Abstract

The invention discloses a preparation method of a thermosensitive dye compound N-acyl phenothiazine, which is characterized by comprising the following steps: adding aromatic acid, triphenylphosphine, N-chlorophthalimide and a solvent into a reaction container, conducting stirring for 1-10 minutes, then adding phenothiazine or phenothiazine derivatives, conducting stirring and reacting for 4-12 hours at the temperature of 15-35 DEG C, and separating and purifying the obtained reaction product to obtain the N-acyl phenothiazine. The N-acyl phenothiazine derivative is synthesized by adopting triphenylphosphine and N-chlorophthalimide as catalysts, the method has the advantages of small environmental pollution, no generation of a lot of acidic wastewater and waste gas, mild reaction conditions, simple reaction treatment, high yield, stability and the like, and the preparation process of the N-acyl phenothiazine derivative is greatly optimized.

Description

technical field [0001] The invention relates to the technical field of organic chemical synthesis, in particular to a preparation method of a thermosensitive dye compound N-acyl phenothiazine. Background technique [0002] Thermosensitive dyes are a kind of light-colored or colorless organic compounds, belonging to leuco dyes, which react with color-developing agents to display colors when heated. At present, there are more than 3,000 structures of thermosensitive dyes publicly reported in the world, with more than 60 series and more than 20 practical varieties. [0003] According to their performance and composition, reversible thermochromic dyes can be roughly divided into three categories: inorganic, crystalline and organic. The organic category includes electron donors, Schiff bases and other categories, among which electron donors can change the molecular structure and corresponding color according to the acid-base changes of the medium. Electron donor color-changing ...

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Problems solved by technology

In the traditional method, due to the use of acid chloride or phosphorus pentachloride / phosphorus oxychloride as raw materials, a large amount of acid waste water and waste gas will inevitably be produced in the reaction process, the environmental pollution is more serious, and the post-treatment is also more troublesome (follow-up usually needs to use alkaline water treatment)

Now there are also schemes to synthesize N-acyl phenothiazine derivatives by other methods. For example, patent CN20S1366A04109133A discloses a kind of N-acyl phenothiazine and its preparation method, which uses aromatic acid, phenothiazine and phosphorus oxychloride As a raw material, N-acyl phenothiazine is synthesized by solid-phase grinding method, which claims that the process has the advantages of simple operation and little environmental pollution because no solvent is needed; but known, its raw material phosphorus oxychloride (POCl 3 ) is a compound that is volatile and has a strong pungent smell. When it is exposed to humid air, it will be hydrolyzed into phosphoric acid and hydrogen chloride, and white smoke will occur; The introduction of phosphorus oxychloride is still unavoidable and prone to acid waste gas and / or wastewater

Moreover, in this process, how to realize the sealing of the reaction system is not disclosed, and the waste water and waste gas generated by the reaction system will be exposed

In addition, although solid-phase grinding method for organic synthesis has the advantages of high yield and no solvent in theory, as a new process, its mechanism of action is not completely clear, and its defects such as poor repeatability cannot be ignored (Geng Lijun et al. , "Application of Grinding Method in Solid-Phase Organic Synthesis", "Organic Chemistry", No. 5, 2005; Zhang Yingpeng et al., "New Progress of Grinding Method in Solid-Phase Organic Synthesis", "Jiangxi Chemical Industry", 2008- 06-30.)

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