JPH0374470A - Production of indigo compound - Google Patents

Abstract

PURPOSE:To obtain in a single step both in high yield and efficiency the title compound useful as a dye by reaction between a specific indole compound and hydrogen peroxide in the presence of a specified amount of a ketone compound. CONSTITUTION:The objective compound can be obtained by reaction between (A) an indole compound free from substituents both at 2- and 3-sites (e.g. indole, 1-methylindole) and (B) hydrogen peroxide in the presence of a ketone compound (e.g. acetone, acetophenone, methyl cyclohexyl ketone, isophorone) at such an amount as to be 0.001-5 (pref. 0.01-1)mol per mol of the component A. The amount of the component B to be used is pref. 0.1-20mol per mol of the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing an indigo compound. More specifically, the present invention relates to a method for producing an indigo compound by reacting an indole compound having no substituents at the 2- and 3-positions with hydrogen peroxide in the presence of a specific amount of a specific compound. Indigo compounds are important compounds as dyes.

(Prior technology) Currently, the industrial method for producing indigo is to produce N-phenylglycine salt using aniline and chloroacetic acid or aniline, hydrocyanic acid, and hydraldehyde as raw materials, and then melt this in an alkali at high temperature to produce indigo. A method has been adopted in which the xyl compound is converted into a xyl compound and then further air oxidized. However, these methods not only have a multi-step reaction process and are extremely complex, but also require the use of large amounts of potassium hydroxide and sodium hydroxide. There is a problem in that it consumes a lot of energy and requires special equipment for that purpose. Therefore, it is desired to convert these methods into simpler processes.

Meanwhile, Indore and i! ! There are examples of reactions with hydrogen tetroxide (Khi+*, Geterotsikl, 5oe
din, +11t! +1490-1496 pages, 197
8), here the indole skeleton trimer 2,2
-diindyl-φ-indoxyl was produced in high yield, and it was reported that indigo could be detected by chromatography. However, this method oxidizes indole to obtain 2,2-diindyl-1φ-indoxyl, and the indigo that the present inventors are aiming at is only one of the by-products produced in a very small amount. This cannot be said to be a satisfactory manufacturing method.

(Issues to be Solved by the Invention!) The problem of the present invention is to fundamentally improve the current multi-step and complicated manufacturing method for indigo, and to provide a simpler method for manufacturing indigo compounds compared to this. Another object of the present invention is to provide a method for producing an indigo compound using an indole compound and hydrogen peroxide as raw materials with higher reaction performance than the above-mentioned conventional techniques.

(Means for Solving !II!) The present inventors have intensively studied a method for efficiently producing an indigo compound by reacting an indole compound with hydrogen peroxide, and surprisingly found that an indigo compound The inventors have discovered that when a specific amount of a ketone compound is present during the reaction with hydrogen peroxide, the production of indigo compounds is significantly increased, leading to the development of the present invention.

That is, in the present invention, an indole compound having no substituents at the 2- and 3-positions and hydrogen peroxide are mixed in an amount of 0.0% per mole of the indole compound.
This is a method for producing an indigo compound, characterized in that the reaction is carried out in the presence of a ketone compound in a range of 0.001 to 5 moles.

Indole compounds having no substituents at the 2- and 3-positions, which are raw materials in the method of the present invention, include, for example, indole; l-methylindole, 4-ethylindole, 5-methylindole, 6-methylindole, 6-methylindole,
-isopropylindole, 7-methylindole, 4
．． Alkylindoles having 1 to 4 alkyl groups having 1 to 10 carbon atoms such as 5-dimethylindole; having 1 to 4 cycloalkyl groups having 3 to 12 carbon atoms such as 4-cyclohexylindole and 5-cyclopentylindole Cycloalkylindoles; 6 or more carbon atoms such as 5-phenylindole and 6-β-naphthylindole
1 to 30 alkyl groups or alkyl-substituted aryl groups
Arylindole W having 4: 4-chloroindole, 5-chloroindole, S, 7-dichloroindole, 5-bromoindole, 6-bromoindole, 5
．． Halogenated indoles having 1 to 4 halogen atoms such as 7-dibromoindole and 4-chloro-5-bromoindole: 1 to 4 halogenated indoles such as 4-hydroxyindole, 5-hydroxyindole, and 4.5-dihydroxyindole Hydroxyindole containing 1 to 10 alkoxy groups; 4-methoxyindole, 5-benzyloxyindole, etc.
Alkoxy indoles having ~4; phenoxy groups having 6 to 30 carbon atoms such as 5-phenoxy indole;
Fuunoxiindoles having 4; 4-chloro-5-
Ethylindole, 6-chloro-4-methylindole, 4-bromo-5-ethylindole, 5-bromo-4
- Halogenated alkylindole having 1 to 3 halogen atoms and 1 to 3 alkyl groups having 1 to 10 carbon atoms such as methyl indole; 4-nitroindole, 5
-1 to nitroindole, 7-nitroindole, etc.
Nitroindoles having 4 nitros; acylindoles having 1 to 4 acyl groups having 2 to 20 carbon atoms such as 1-benzoylindole and 4-acetylindole; 1-acetoxyindole and 4-benzoyloxindole Acyloxyindole having 1 to 4 acyloxy groups having 2 to 20 carbon atoms; such as indole carboxylic acids or esters thereof such as indole-5-carboxylic acid; alkyl moieties such as 5-N,N-dimethylaznoindole has a carbon number of 1 to 10,
These include N,N-dialkylamino groups having 1 to 4 N-dialkylamino groups, and sulfonated indoles, and are compounds that do not have these substituents at the 2- and 3-positions. In addition, two different substituents
It is an indole compound that has a combination of more than one species. In addition, substituents may be present at positions other than the 2- and 3-positions as long as they do not inhibit the reaction.

Hydrogen peroxide, which is the other raw material in the method of the present invention, may be used as it is, or may be an aqueous solution or a solution of another solvent.Usually, an aqueous solution of hydrogen peroxide is used. The amount of hydrogen peroxide used is not particularly limited, but is usually in the range of 0.01 to 100 mol per mol of the indole compound, preferably 0.
．． It ranges from 1 to 20 moles.

The ketone compound in the method of the present invention is defined by the general formula (where R and R' have the same or different number of carbon atoms
20 saturated or unsaturated aliphatic hydrocarbon groups,
Ketone compounds represented by the general formula (where X and Y are the same or different atomic groups); cyclic ketone compounds represented by the above-mentioned R# and R', in which at least one hydrogen atom bonded to a carbon atom in the hydrocarbon group is removed from the hydrocarbon group defined by R - A halogenated ketone compound in which some or all of the hydrogen atoms of the compound represented by the general formula are replaced with halogen atoms. Furthermore, these ketone compounds may be di-substituted as long as they are substituents that do not inhibit the reaction. Examples of these ketone compounds include aliphatic compounds such as acetone, methyl ethyl ketone, ethyl isopropyl ketone, and benzyl methyl ketone. Ketone compound! 5; Aromatic ketone compounds such as acetophenone and benzophenone; Alicyclic ketone compounds such as methylcyclohexylketone, phenylcyclohexylketone, and dicyclohexylketone; cyclic ketone compounds such as cyclohexanone and isophorone; hexafluoroacetone, trichloroacetone, hexachloroacetone, Examples include halogenated ketone compounds such as 4-bromocyclohexanone.

The amount of these ketone compounds used in the method of the present invention is 0.001 per mole of the indole compound used.
The amount ranges from 5 to 5 moles. If the amount is less than this, no effect will be produced, and if it is more than this, the performance will deteriorate. Preferably, the amount of the ketone compound used is in the range of 0.01 to 1 mol per 1 mol of the indole compound used.

The reaction method of the present invention is not particularly limited, and may be a batch method, a semi-batch method, or a continuous flow method.

The temperature during the reaction is usually in the range of -10 to 120°C. If the temperature is lowered too much, the reaction will slow down, and if the temperature is raised too much, there is a risk of an explosion of hydrogen peroxide. Preferably it is in the range of 10 to 100°C. The reaction time is usually within 50 hours, preferably in the range of 0.1 to 24 hours. The reaction can be carried out under reduced pressure, normal pressure or increased pressure.

Further, in the method of the present invention, the reaction may be carried out under an inert gas atmosphere, but may also be carried out in the presence of molecular oxygen such as air.

In the method of the present invention, additives, catalysts, and the like may be used to further improve the yield, selectivity, or production rate of the indigo compound.

In the method of the present invention, an indigo compound is obtained by treating the reaction product after the completion of the reaction according to a conventional method.Normally, most of the indigo compounds produced after the completion of the reaction are precipitated, and are separated by filtration or centrifugation. Alternatively, it can be easily taken out as a solid by ordinary solid-liquid separation operations such as decanethisilane. If the amount of indigo compound precipitated is insufficient, the reaction solution can be taken out after being subjected to WA condensation in order to precipitate more.

(Examples) Next, the present invention will be explained in more detail with reference to Examples, but these should be understood as merely illustrative rather than limiting.

Example 1 Equipped with a stirrer, thermometer, dropping funnel and cooling tube,
Into a 4-/Low flask with an internal volume of 200ξL, 10.0 grams (85,459 mol) of indole and 1.88 grams (8,54:
This solution was heated to 80°C in an oil bath, and 29.0 g of a 30% by weight hydrogen peroxide aqueous solution (in terms of hydrogen peroxide) was added through the dropping funnel while stirring in an air atmosphere. So 256
: mmol) was added dropwise over 30 minutes, and then
As the reaction proceeded for 9 hours, a blue solid was gradually precipitated. After the reaction was completed, the reaction solution was filtered, and the solid was thoroughly washed with methanol (indigo is almost insoluble in methanol). Drying under reduced pressure at 50°C yielded 6.02 grams of blue solid.0 Elemental analysis and IR
As a result of analysis, it was confirmed that this solid was indigo. The molar yield of isolated indigo to the charged indole (hereinafter simply referred to as indigo isolated yield) was 53.
It was 8%.

Example 2 The reaction and post-treatment were carried out in exactly the same manner as in Example 1, except that the amount of hexafluoroacetone trihydrate was changed to 0.19 g (0.86 mmol). 3.51 grams of indigo were obtained. The indigo isolation yield was 31.4%.

Comparative Example 1 The reaction and post-treatment were carried out in exactly the same manner as in Example 1, except that the hexafluoroacetone trihydrate in Example 1 was not used, and 1.86 grams of indigo was obtained. The indigo isolation yield was 16.6%.

Example 3 Equipped with a stirrer, thermometer, dropping funnel and cooling tube,
5.0 g (42.7 mmol) of indole, 0.42 g (4.28 mmol) of cyclohexanone, and 30 ml of toluene were placed in a 4-neck flask with an internal volume of 100ξ liters, and this liquid was heated at 80°C in an oil bath. 9.67 g of a 30% by weight hydrogen peroxide aqueous solution (85.3 mmol in terms of hydrogen peroxide) was added dropwise from the dropping funnel over 15 minutes while stirring in an air atmosphere, and the mixture was left to react for 5 hours. After the completion of the three reactions, post-treatment was carried out in the same manner as in Example 1, and 76 grams of indigo was obtained. Indigo isolated yield is 13.6
%Met.

Comparative Example 2 The reaction and post-treatment were carried out in exactly the same manner as in Example 3, except that cyclohexanone in Example 3 was not used, and 0.40 g of indigo was obtained. The isolated indigo yield was 7.1%.

Comparative Example 3 The reaction and post-treatment were carried out in exactly the same manner as in Example 3, except that 30 G liters of cyclohexanone was used in place of toluene in Example 3, and 0.29 g of indigo was obtained. Indigo isolation yield is 5.2%
Met.

Example 4 The reaction and post-treatment were carried out in exactly the same manner as in Example 3, except that 1.13 grams (4.27 mmol) of hexachloroacetone was used instead of cyclohexanone in Example 3, and 1.67 grams of Indigo was obtained. The indigo isolation yield was 29.8%.

Example 5 The reaction and post-treatment were carried out in exactly the same manner as in Example 3, except that 2.48 g (42.7 mmol) of acetone was used instead of cyclohexanone in Example 3, and 0.79 g of indigo was obtained. was gotten. The indigo isolation yield was 1461%.

Example 6 The reaction and post-treatment were carried out in exactly the same manner as in Example 3, except that 0.51 g (4,24Q 9 mol) of acetophenone was used instead of cyclohexanone in Example 3, and 0.58 g of indigo was obtained. was gotten. The isolated indigo yield was 10.4%.

Example 7 Internal volume 100 equipped with stirrer, thermometer and cooling tube
In a 3 liter flask, 5.0 g (42.7 mmol) of indole, hexafluoroacetone,
0.94 grams (4,2719 moles) of trihydrate, 14.5 grams of 30% by weight aqueous hydrogen peroxide solution (128 mmoles of hydrogen peroxide), and 35 grams of monochlorobenzene.
ξ liter was charged at once, and this liquid was heated to 80°C in an oil bath while stirring, and reacted for 5 hours. As the reaction progressed, a blue solid was gradually precipitated.

After the reaction was completed, post-treatment was carried out in the same manner as in Example 1.
．． 43 grams of indigo was obtained. The indigo isolation yield was 43.4%.

Comparative Example 4 The reaction and post-treatment were carried out in exactly the same manner as in Example 7, except that hexafluoroacetone trihydrate in Example 7 was not used, and 0.99 g of indigo was obtained. The isolated indigo yield was 17.6%.

Example 8 The reaction and post-treatment were carried out in exactly the same manner as in Example 7, except that 35 ξ liters of diphenyl ether was used instead of monochlorobenzene in Example 7.
2.55 grams of indigo was obtained. The indigo isolation yield was 45.6%.

Comparative Example 5 The reaction and post-treatment were carried out in exactly the same manner as in Example 8, except that hexafluoroacetone trihydrate in Example 8 was not used, and 1.00 g of indigo was obtained. The isolated indigo yield was 17.8%.

Example 9 The reaction and post-treatment were carried out in exactly the same manner as in Example 7, except that nitrobenzene 35''S liter was used instead of monochlorobenzene in Example 7.
．． 11 grams of indigo were obtained. The indigo isolation yield was 37.7%.

Comparative Example 6 The reaction and post-treatment were carried out in exactly the same manner as in Example 9, except that hexafluoroacetone trihydrate in Example 9 was not used, and 0.50 g of indigo was obtained. The isolated indigo yield was 9.0%.

(Effects of the Invention) According to the method of the present invention, an indole compound having no substituents at the 2- and 3-positions and hydrogen peroxide are mixed into a ketone in a range of 0.001 to 5 moles per mole of the indole compound. An extremely efficient method for producing an indigo compound, in which the indigo compound can be produced in one step and in a higher yield than the method described in the above-mentioned literature by an extremely simple method of reacting in the presence of the compound. Become.

Claims (1)

[Claims] 1. It is characterized by reacting an indole compound having no substituents at the 2- and 3-positions with hydrogen peroxide in the presence of a ketone compound in an amount of 0.001 to 5 moles per mole of the indole compound. A method for producing an indigo compound.