Synthetic method for crystal violet lactone

Abstract

The invention discloses a synthetic method for crystal violet lactone and relates to a synthetic method for a thermal-pressure sensitive dye. The crystal violet lactone is synthesized through a Schiff base stage, a urea intermediate stage, a colorless crystal violet stage and a final oxidation reaction stage by taking substances such as urea, dimethylaniline, dimethylaminobenzoic acid and paradimethylaminobenzaldehyde as raw materials. The synthetic method comprises the following stages: (1) the Schiff base stage: performing a reaction on paradimethylaminobenzaldehyde and urea to generate Schiff base; (2) the urea intermediate stage: performing a reaction on the product generated in the previous stage and dimethylaniline to obtain a urea intermediate; (3) the colorless crystal violet stage: performing a reaction on the product generated in the previous stage and dimethylaminobenzoic acid as the raw materials to generate colorless crystal violet; and (4) the oxidation reaction stage: performing catalytic oxidation on the colorless crystal violet to generate the crystal violet lactone. The method is the synthetic method which avoids generation of impurities, so that the product yield is improved, and meanwhile, discharge of solid wastes is reduced.

Description

technical field

[0001] The invention relates to a method for synthesizing heat and pressure sensitive dyes, in particular to a method for synthesizing crystal violet lactone. Background technique

[0002] Thermal and pressure-sensitive dyes are chromogenic agents for thermal and pressure-sensitive recording paper. It is different from general dyes and organic pigments. The latter is a conjugated system, which develops its own color and has the function of dyeing fibers or coloring plastics. However, the conjugated system of heat and pressure-sensitive dyes is interrupted and becomes a colorless state. When the thermal energy information generated by the small heating element acts on the thermal recording paper, the thermosensitive dye and the color developer in the heated part melt together and react to return to the color-developing state to produce hair. The pressure-sensitive dye exists in the microcapsule, and when subjected to pressure, the microcapsule ruptures, and t...

Examples

Embodiment 1

[0035] Dissolve 2.4g of urea in 10mL of water, slowly add 3mL of concentrated sulfuric acid dropwise to it, then add 3.07g of p-dimethylaminobenzaldehyde, raise the temperature to 50°C, react for 2h, then add 2.5mL of p-dimethylaniline to it, Raise the temperature to 80°C, keep it warm for 2 hours, add 3.33g p-dimethylaminobenzoic acid, raise the temperature to 90°C, keep it warm for 2h, then add 20mL of water, keep it warm for 8h, cool down to room temperature naturally, at 50°C, dropwise add 10g hydrogen Add 0.1g of copper sulfate pentahydrate to a solution composed of potassium oxide, 100mL of water and 6mL of ammonia water, heat up to 70°C, add dropwise a solution of 12mL of 30% hydrogen peroxide and 24mL of water, add dropwise for 2 hours, and cool down , filtered, and dried to obtain 6.8 g of the product.

Embodiment 2

[0037] (replace concentrated sulfuric acid with concentrated hydrochloric acid)

[0038] The experiment was carried out with concentrated hydrochloric acid instead of concentrated sulfuric acid as raw material, and other conditions were the same as in Example 1. 0.5 g of the product was obtained, and in the step of adding dropwise to the potassium hydroxide solution, a large amount of solid insoluble impurities appeared.

Embodiment 3

[0040] (The reaction temperature of the colorless crystal violet lactone stage is heating to reflux)

[0041] The synthesis experiment was carried out with the reaction temperature of the colorless crystal violet lactone stage being heated to reflux, and other conditions were the same as in Example 1. During the step of adding dropwise to the potassium hydroxide solution, a large amount of colloidal impurities appeared. The product 4.8g was obtained.

technical field

[0001] The invention relates to a method for synthesizing heat and pressure sensitive dyes, in particular to a method for synthesizing crystal violet lactone. Background technique

[0002] Thermal and pressure-sensitive dyes are chromogenic agents for thermal and pressure-sensitive recording paper. It is different from general dyes and organic pigments. The latter is a conjugated system, which develops its own color and has the function of dyeing fibers or coloring plastics. However, the conjugated system of heat and pressure-sensitive dyes is interrupted and becomes a colorless state. When the thermal energy information generated by the small heating element acts on the thermal recording paper, the thermosensitive dye and the color developer in the heated part melt together and react to return to the color-developing state to produce hair. The pressure-sensitive dye exists in the microcapsule, and when subjected to pressure, the microcapsule ruptures, and t...

Examples

Embodiment 1

[0035] Dissolve 2.4g of urea in 10mL of water, slowly add 3mL of concentrated sulfuric acid dropwise to it, then add 3.07g of p-dimethylaminobenzaldehyde, raise the temperature to 50°C, react for 2h, then add 2.5mL of p-dimethylaniline to it, Raise the temperature to 80°C, keep it warm for 2 hours, add 3.33g p-dimethylaminobenzoic acid, raise the temperature to 90°C, keep it warm for 2h, then add 20mL of water, keep it warm for 8h, cool down to room temperature naturally, at 50°C, dropwise add 10g hydrogen Add 0.1g of copper sulfate pentahydrate to a solution composed of potassium oxide, 100mL of water and 6mL of ammonia water, heat up to 70°C, add dropwise a solution of 12mL of 30% hydrogen peroxide and 24mL of water, add dropwise for 2 hours, and cool down , filtered, and dried to obtain 6.8 g of the product.

Embodiment 2

[0037] (replace concentrated sulfuric acid with concentrated hydrochloric acid)

[0038] The experiment was carried out with concentrated hydrochloric acid instead of concentrated sulfuric acid as raw material, and other conditions were the same as in Example 1. 0.5 g of the product was obtained, and in the step of adding dropwise to the potassium hydroxide solution, a large amount of solid insoluble impurities appeared.

Embodiment 3

[0040] (The reaction temperature of the colorless crystal violet lactone stage is heating to reflux)

[0041] The synthesis experiment was carried out with the reaction temperature of the colorless crystal violet lactone stage being heated to reflux, and other conditions were the same as in Example 1. During the step of adding dropwise to the potassium hydroxide solution, a large amount of colloidal impurities appeared. The product 4.8g was obtained.

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