JPH0753828B2 - Process for producing 3,3-bis- (4-dimethylaminophenyl) -6-dimethylaminophthalide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] 3,3-Bis- (4-dimethylaminophenyl) -6-dimethylaminophthalide is known as crystal violet lactone (hereinafter abbreviated as CVL). . Although it is colorless or close to itself in color, it rapidly develops blue-violet color by intimate contact with an electron-accepting substance such as organic acid acid clay, phenol formalin resin, metal salt of aromatic carboxylic acid, and bisphenol A. It has characteristics and is most widely used as a dye for recording materials such as pressure-sensitive copying paper and heat-sensitive recording paper.

The present invention relates to an improved manufacturing method thereof.

[Problems to be solved by conventional technology and invention]

Although there are many known methods for synthesizing CVL by oxidizing 2- [4,4′-bis- (dimethylamino) -benzohydryl] -5-dimethylaminobenzoic acid (hereinafter abbreviated as LC), It is difficult to obtain a high-quality CVL with a high yield because the manufacturing process is complicated and there are many split by-products due to oxidation.

For example, a method of oxidizing with lead peroxide or potassium permanganate in an aqueous solution of mineral acid (U.S. Pat. No. 2417897), a method of oxidizing with oxygen in the presence of chloranil and a metal complex in an organic solvent such as glacial acetic acid and chloroform (Japanese Patent Laid-Open No. 2004-187242). 48-25730) and a method of oxidizing with hydrogen peroxide in a mixed solution of a water-insoluble hydrocarbon solvent and water in the presence of an acid catalyst (JP-A-52-78867), etc. A large amount of by-products are produced, the yield and quality of CVL are very poor, and a complicated process such as recovery of an organic solvent is required. Further, a method of oxidizing with hydrogen peroxide in an aqueous solution or a water-soluble organic solvent in the presence of an alkali (JP-A-52-31384) and with hydrogen peroxide, oxygen or air in the presence of a catalyst of a cobalt or copper compound in an alkaline aqueous solution In any of the oxidation methods (Japanese Examined Patent Publication No. 59-19548) and the like, the reaction product is difficult to proceed such that a large amount of unreacted material is included in the reaction product to form a lump, and the yield and quality of CVL are poor. In addition,
A method of oxidizing in a carboxylic acid aqueous solution or a mineral acid aqueous solution using air or oxygen at a pH value of 1.5 to 5.5 (JP-A-52-
77131), and according to the publication, the yield of the example using glacial acetic acid is 92.6% of the theoretical value, but the yield of the example using sulfuric acid is 62.1% of the theoretical value, The yield of the examples with hydrochloric acid is only 34.3% of theory.

The present invention, as described above, provides a novel production method in which the conventional drawbacks in the synthesis of CVL are improved.

[Means for solving problems]

The present inventors have conducted intensive studies to improve the drawbacks of the conventional oxidation method, and as a result, found that the improved production method of the present invention can easily obtain high yield and high quality CVL in a short time. . That is, LC with a particle size of 20 microns or less is 2.0
Air, oxygen, in the presence of at least one catalyst selected from copper compounds and cobalt compounds in an aqueous solution of a mineral acid having a PH value of −4.0.
Alternatively, it is a method for producing CVL, which is characterized in that it is oxidized using an oxygen-air mixture.

Specific examples of the metal compound used as a catalyst in the present invention include ferric chloride, ferrous sulfate, cupric chloride, copper sulfate, copper acetate, cobalt chloride, cobalt sulfate, cobalt acetate, manganese chloride, manganese sulfate. And the like, and copper compounds and cobalt compounds are particularly preferable. Mineral acids include hydrochloric acid and sulfuric acid. The LC used in the present invention is effective in the finest possible state, preferably 10-20 microns or less, and it is advantageous to carry out the oxidation at a temperature of 40-100 ° C, and the air, oxygen or oxygen-air mixture is finely divided. It is desirable to introduce them into the reaction mixture as bubbles. In order to uniformly disperse the reaction mixture, it is effective to add a surface active agent such as polyoxyethylene alkyl ether.

(Effects and Actions of the Invention) The improved CVL production method of the present invention eliminates the drawbacks of the conventional oxidation method, and is extremely excellent in synthesizing high yield, high quality CVL in a short time as follows. Explained.

That is, in the present invention, the mineral acid aqueous solution, preferably the sulfuric acid aqueous solution, has a CV at a PH value of 2.0-4.0, preferably 2.0-3.0.
It hardly dissolves L, and well dissolves LC and impurities or reaction by-products contained in LC. As a result, CVL generated by oxidation immediately precipitates outside the reaction system, CVL is smoothly generated, and a high yield can be obtained.

Further, the catalyst composed of the metal compound of the present invention, preferably a copper and cobalt compound, exhibits a high catalytic effect and greatly accelerates the reaction as compared with the case where these metal compounds are not used.
All of these metal compounds are water-soluble and can be removed almost completely together with the impurities and reaction by-products in the LC just by removing the precipitated CVL after the reaction and washing it with water. Is very convenient for manufacturing.

[Examples, etc.]

Next, the present invention will be described more specifically with reference to comparative examples.

Example 1. Industrial LC 46.3g (pure L with particle size below 10-20 microns)
C41.7g) containing 1% sulfuric acid aqueous solution 250g, copper sulfate 0.05
g, score roll ^# 100 (manufactured by Kao Atlas) was added, and air was introduced at 60 ° C. with stirring at a rate of 100 ml per minute for 10 hours. After the reaction was completed, the reaction product was filtered, and the excess residue was washed with water to neutrality to give 41.1 g of a crude dry product having a melting point of 172-175 ° C.
(Containing 97% of theoretical CVL) was obtained.

Comparative Example The same operation as in Example 1 was carried out except that copper sulfate was not added, to obtain 37.5 g of a dry crude product (containing 12% of theoretical CVL).

Example 2. 0.1 g of cobalt chloride was added in place of copper sulfate in Example 1 and the same operation as in Example 1 was carried out to give a melting point of 171-175 ° C.
40.5 g of dried crude product (containing 95.6% of theoretical CVL)
Got

Example 3 Instead of air in Example 1, oxygen was absorbed at normal pressure for 5 hours until it was saturated, and the same operation as in Example 1 was carried out to obtain 40.8 g of a dry crude product having a melting point of 172-175 ° C. (Theoretical amount of 9
Containing 7% CVL).

Claims (1)

[Claims] 1. A copper compound containing 2- [4,4'-bis- (dimethylamino) -benzohydryl] -5-dimethylaminobenzoic acid having a particle size of 20 microns or less in an aqueous mineral acid solution having a PH value of 2.0-4.0. And 3,3-bis- (4-dimethylaminophenyl) -6-dimethyl, which is oxidized with air, oxygen, or an oxygen / air mixture in the presence of at least one catalyst selected from cobalt compounds. Aminophthalide manufacturing method.