KR100208158B1 - Process for preparing of 2,6-dicyano-4'-dialkylaminoazobenzene derivatives, and method for purification of the same - Google Patents

Abstract

The present invention relates to a method for preparing a 2,6-dicyano-4'-dialkylaminoazo benzene derivative to be used as a sublimation dye, and to the following (II-1) to (II-4) reaction steps. It provides a method for producing a 2,6-dicyano-4'-dialkylaminoazobenzene derivative, which is made.

(Wherein R ¹ is a hydrogen atom, carbon number 1 6 alkyl groups, alkoxy groups, 2 carbon atoms An alkoxyalkyl group of 6 or a halogen atom, X represents a hydrogen atom, carbon number 1 4 represents an alkoxy group, a methyl group, or a halogen atom, and Y represents a methyl group, a methoxy group, formylamino group, or 1 carbon atom. An alkylcarbonylamino group, an alkylsulfonylamino group, or an alkoxycarbonylamino group of 6 is represented, and R ² and R ³ each have 1 carbon atom. 6 alkyl group, 2 carbon atoms 6 represents an alkoxyalkyl group, an aralkyl group, a phenyl derivative or a hydroxy alkyl group.)

Description

Preparation of 2,6-dicyano-4'-dialkylaminoazobenzene derivative and its purification method

The present invention relates to the preparation of a dye for thermal transfer recording and a purification method thereof, and more particularly to a new 2,6-dicyano-4'-dialkylaminoazobenzene derivative used as a dye for sublimation thermal transfer recording. A manufacturing method and its purification method are related.

The sublimation thermal transfer recording method is a suitable recording method for reproducing a natural color image on a computer monitor or a video through a video color printer. The principle of the sublimation thermal transfer recording is a yellow, magenta, cyan color filter. And then transfer it to the thermal element in the form of an electrical signal, and the applied energy is controlled by the thermal element by this signal to control the sublimation transfer amount of the dye to be transferred to the receiving layer of the recording material, and this process is carried out in yellow, magenta and cyan. By repeating sequentially, a combination of three corresponding dyes is induced to form a desired color image.

The following properties are required for dyes used as dyes for sublimation thermal transfer recording.

1) Easily sublimated and does not thermally decompose under the operating conditions of the thermal recording head,

2) Color should be good when reproduced.

3) the molecular extinction coefficient must be large,

4) It should be stable against light, moisture and chemicals.

5) It should be easy to synthesize.

The 2,6-dicyano-4'-dialkylaminoazobenzene derivative is a compound represented by the following general formula (I), and has the required properties of the dye used as the dye for sublimation thermal transfer recording described above. It is widely used and satisfied, and an easier synthesis method for this is being actively studied.

(Wherein R ¹ is a hydrogen atom, carbon number 1 6 alkyl groups, alkoxy groups, 2 carbon atoms An alkoxyalkyl group of 6 or a halogen atom, X represents a hydrogen atom, carbon number 1 4 represents an alkoxy group, a methyl group, or a halogen atom, and Y represents a methyl group, a methoxy group, formylamino group, or 1 carbon atom. An alkylcarbonylamino group, an alkylsulfonylamino group, or an alkoxycarbonylamino group of 6 is represented, and R ² and R ³ each have 1 carbon atom. 6 alkyl group, 2 carbon atoms 6 represents an alkoxyalkyl group, an aralkyl group, a phenyl derivative or a hydroxy alkyl group.)

As a conventional method for producing a 2,6-dicyano-4'-dialkylaminoazobenzene derivative represented by the above structural formula (I), the following reaction steps (I-1) to (I-3), namely , Diazo reaction (I-1) of 4-substituted 2,6-dibromoaniline (II) to obtain 4-substituted 2,6-dibromodiazo compound (III), and (III) a compound A method of producing a dibromodiazoaminobenzene compound (V) with an alkyl-substituted aniline compound (IV) and a coupling reaction (I-2) and then carrying out a cyanoation reaction (I-3) is, for example, Japanese Japanese Patent Laid-Open No. 2-175295 and Japanese Patent Laid-Open No. 61-227092.

According to the conventional preparation method, Compound V, which is produced through routes I-1 and I-2, is crystallized by adding and neutralizing an aqueous sodium hydroxide solution to an acid solution after completion of the reaction according to a conventional method. It is known that the by-products are also crystallized at the same time, the recrystallization process is essential for its purification. However, purification through recrystallization leads to an increase in purity but with a decrease in yield.

In addition, the reaction in the route I-3 may not be 100%, and the mono substituent in which only one bromine is substituted with a cyano group remains. In this case, the structure of the desired compound I and the mono substituent and Similarity of molecular weight makes it difficult to obtain pure Compound I through recrystallization.

Thus, following the conventional synthetic route, satisfactory results are obtained due to the overall yield from the starting materials and the problems listed above in the final purification step in obtaining pure 2,6-dicyano-4'-dialkylaminoazobenzene derivatives. Hard to get.

The present invention has been made to solve the problems of the prior art, it is possible to obtain a 2,6-dicyano-4'-dialkylaminoazobenzene derivative more easily and with high purity and to increase the production yield It is an object of the present invention to provide a method for preparing a new 2,6-dicyano-4'-dialkylaminoazobenzene derivative and a method for purifying the same.

In order to achieve the above object, the present invention is a method for producing a 2,6-dicyano-4'-dialkylaminoazobenzene derivative characterized by the following (II-1) to (II-4) reaction step To provide.

(Wherein R ¹ is a hydrogen atom, carbon number 1 6 alkyl groups, alkoxy groups, 2 carbon atoms An alkoxyalkyl group of 6 or a halogen atom, X represents a hydrogen atom, carbon number 1 4 represents an alkoxy group, a methyl group, or a halogen atom, and Y represents a methyl group, a methoxy group, formylamino group, or 1 carbon atom. An alkylcarbonylamino group, an alkylsulfonylamino group, or an alkoxycarbonylamino group of 6 is represented, and R ² and R ³ each have 1 carbon atom. 6 alkyl group, 2 carbon atoms 6 represents an alkoxyalkyl group, an aralkyl group, a phenyl derivative or a hydroxy alkyl group.)

By using the above-described preparation route according to the present invention, after completion of the reaction in route (II-2), the amount of the remaining mono-cyano group substituents is significantly reduced, and the separation and purification thereof can be facilitated by using benzene. This effect also affects the reaction of route (II-4), which can inherently inhibit the generation of azo products of mono substituents.

In addition, starting materials II and IV, which may remain in the reaction of route (II-4), can be easily removed by controlling p H of the reaction solution to 4 after the completion of the final reaction, and the desired compound I is determined in the p H 4 state. Neutralizing reaction (p H 6) In addition to reducing the input amount of the aqueous sodium hydroxide solution according to 7), it is also possible to reduce the difficulty due to the exothermic reaction during the neutralization reaction, and to obtain Compound I of high purity more easily.

In conclusion, by improving the preparation route of the present invention, according to the conventional method, it is possible to suppress the generation of azo products of mono substituents that may be produced as by-products in the final reaction, and the purification method in the final step is not neutral but acidic. The compound I of high yield and high purity is obtained by performing on (pH4) conditions.

At this time, the synthesis of starting material IV is, for example, X = H, If R ₂ = R ₃ = -C ₂ H ₅ , it is carried out by the following path.

In order to examine the effects of the present invention, the following compounds were used to prepare the final compound (I), which is an azo magenta pigment, starting from the same starting material (II) and using the preparation routes (I) and (II), respectively. Compare the overall manufacturing yield.

However, the following examples are provided only for better understanding of the present invention, and the present invention is not limited to these examples.

Example 1

Synthesis of Compound C-1

(A) Synthesis of Starting Material A (2,6-dibromotoluidine)

A dropping funnel was placed in a 2 L flask, and 107.15 g (1 mol) of P-toluidine was dissolved in 500 ml of glacial acetic acid. 336 g (2.1 mol) of bromine was dissolved in 500 ml of glacial acetic acid, and then slowly added for 1 hour while stirring under a water bath through a dropping funnel. After the addition was completed, the temperature was raised to room temperature and stirred for 3 hours.

After the reaction is completed, to remove the remaining bromine, an aqueous solution of sodium bisulfite is added, and when the reaction product turns white, excess water is added to the cold water, and the resulting white precipitate is filtered with suction and washed several times with water. After drying under vacuum with sodium hydroxide to completely remove water, 260 g (98 mol%) of 2,6-dibromotoluidine was obtained.

(B) Synthesis of Intermediate D (2,6-dicyanotoluidine)

In a 2 L flask equipped with a reflux condenser, 217 g (2.2 mol) of copper cyanide was dissolved in 500 ml of dimethylformamide (DMF). 265 g (1 mol) of 2,6-dibromotoluidine was dissolved in 500 ml of dimethylformamide, added to the solution, and refluxed for 4 hours. When the reaction was completed, 400 g of sodium cyanide was dissolved in 1 L of water, and then the reaction mixture was slowly added with stirring the solution at 40 ° C. After the product was extracted with ether, the solvent was dried in vacuo and the solid obtained was dissolved in benzene at 60 ° C. and immediately filtered. The resulting solution was cooled to room temperature and crystallized to give 126 g (80 mol%) of pure 2,6-dicyanotoludine. .

(C) Synthesis of Intermediate B (3-acetamido-N, N-diethylaniline)

① Synthesis of N, N-diethyl-3-nitroaniline

In a 2-liter flask equipped with a reflux condenser, 138 g (1 mol) of 3-nitroaniline and 304 g (2.2 mol) of potassium carbonate were dissolved in toluene, and then 339 g (2.2 mol) of diethyl sulfate was added. It was refluxed for 24 hours.

After the reaction was completed, the mixture was extracted with ethyl acetate, washed several times with water and brine, dried over magnesium sulfate, filtered, and the solvent was vacuum dried to obtain 190 g (98 mol%) of pure NN-diethyl-3-nitroaniline. Got it.

② Synthesis of 3- (N, N-diethylamino) aniline

590 ml of concentrated hydrochloric acid was added to a 3 L flask equipped with a reflux condenser, and 119 g (1 mol) of tin powder and 41.3 g (0.2 mol) of N, N-diethyl-3-nitroaniline were slowly added at 0 ° C. After stirring for 30 minutes to mix the reactants uniformly, 1 liter of ethanol was added and refluxed for 2 hours. Upon completion of the reaction, the reaction mixture was poured into excess water and extracted with ethyl acetate. The extracted solution was dried over magnesium sulfate, and then the solvent was vacuum dried to obtain 131 g (80 mol%) of 3- (N, N-diethylamino) aniline.

② Synthesis of 3-acetamido-N, N-diethylaniline

1 L of ethanol was added to a 2 L flask, and 164 g (1 mol) of 3-acetamido-N, N-diethylaniline was dissolved, and 103 ml (1.1 mol) of acetic anhydride was slowly added at room temperature under stirring.

After stirring for about 2 hours, the reaction was poured into water, extracted with ethyl acetate, washed with water several times, dried over magnesium sulfate, filtered and the solvent removed to remove pure 3-acetamido-N, N-diethylaniline 205 g (100 mol%) were obtained.

(D) Synthesis of Azo Compound P

In a 100 ml flask containing 5 ml of concentrated sulfuric acid, 690 mg (10 mmol) of sodium nitrite was slowly dissolved at 25 캜 or lower.

To a 50 ml flask containing 10 ml of concentrated sulfuric acid and 5 ml of glacial acetic acid, 1.57 g (10 mmol) of 2,6-dicyanotoluidine was slowly added at 5 ° C or less, stirred for 30 minutes, and the solution was added to the flask via a dropping funnel. Stir for 1 hour with slow addition at ° C.

In a 500 ml flask containing 50 g of water and 3 g of concentrated hydrochloric acid, 2.05 g (10 mmol) of 3-acetamido-N, N-diethylaniline was added to dissolve the solution. Stir vigorously with addition for 1 hour. After the addition was complete, the mixture was stirred at room temperature for 3 hours, and when the reaction was completed, the pH of the reaction mixture was adjusted to 4, filtered, washed several times with water, and dried in vacuo to give 2,6-dicyano-4-methyl. 3.4 g (90 mol%) of -2'-acetamido-4 '-(N, N-diethylamino) azobenzene were obtained purely.

Thus, the total production yield of Compound I prepared using Preparation Routes II-2, II-3, II-4 from Starting Material P was 72%.

Example 2 7]

Compounds of C-2 to C-7 were synthesized in the same preparation route as in Example 1.

Comparative Example 1 7]

Compounds C-1 to C-7 were synthesized according to the above production routes (I-1), (I-2) and (I-II) disclosed in Japanese Patent Laid-Open No. 02-175295A, respectively.

The results shown above are shown in the following table.

As shown in the results table above, the case of using the preparation route II presented in the present invention was higher depending on the compound in terms of overall yield than the case of using the preparation route I of the related art. The yield increased by 11%.

In addition, as described above in the above example, the final compound I was easily obtained in the manufacturing process without the neutralization reaction in the case of route II.

Claims (3)

A method for producing a 2,6-dicyano-4'-dialkylaminoazobenzene derivative comprising the following reaction steps of (II-1) to (II-4). (Wherein R ¹ is a hydrogen atom, carbon number 1 6 alkyl groups, alkoxy groups, 2 carbon atoms An alkoxyalkyl group of 6 or a halogen atom, X represents a hydrogen atom, carbon number 1 4 represents an alkoxy group, a methyl group, or a halogen atom, and Y represents a methyl group, a methoxy group, formylamino group, or 1 carbon atom. An alkylcarbonylamino group, an alkylsulfonylamino group, or an alkoxycarbonylamino group of 6 is represented, and R ² and R ³ each have 1 carbon atom. 6 alkyl group, 2 carbon atoms 6 represents an alkoxyalkyl group, an aralkyl group, a phenyl derivative or a hydroxy alkyl group.) The method of claim 1, wherein the compound (VI) is separated and purified using benzene after completion of the reaction (II-2). The method of claim 1, wherein the compound (I) is a p H 4 in the reaction step (II-4) Obtained in the acidic solution state of 5.