JP2557975B2 - Method for producing indigo compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an indigo compound. More specifically, it relates to a novel method for producing an indigo compound by reacting an indole compound having no substituents at the 2- and 3-positions with an organic hydroperoxide in the presence of a specific additive. . The indigo compound is an important compound as a dye.

[Prior Art] Currently, as an industrial method for producing indigo, an N-phenylglycine salt is produced from aniline and chloroacetic acid or aniline, hydrocyanic acid and formaldehyde as raw materials, and this is alkali-melted at a high temperature to produce an indoxyl compound. After that, a method of further air-oxidizing this is adopted. However, these methods are not only complicated in a multi-step reaction process, but also require a large amount of sodium hydroxide of potassium hydroxide, which consumes a lot of energy in recovering and reusing them. There is a problem that a special device for that is required. Therefore, a shift to a simpler process is desired.

On the other hand, it has been reported that a trace amount of indigo was produced in the organic synthetic chemical oxidation reaction of indole. For example, Obata et al. Generate percarboxylic acid, which is a percarboxylic acid, in the reaction system with hydrogen peroxide and acetic acid, and react it with indole as an oxidant, which is a trimer of indole skeleton 2,2-diindyl. -Ψ-Indoxyl was obtained, and it was reported that a small amount of indigo was also generated as a by-product at that time (Bull.Agr.Chem.Soc.Japan, 20: 80-83, 1956).
Year). In addition, Bernard Wittkop et al. Produced a very small amount of indigo together with many products when the percarboxylic acid, perbenzoic acid, was used as an oxidant and reacted with indole in a chloroform solvent in a refrigerator overnight. (Justus Liebigs Annalen der Chemi
e, 558, 91-98, 1947). In addition, Shinekman et al. Use hydrogen peroxide, which is an inorganic peroxide, as an oxidant,
When this is reacted with indole in a methanol solvent, it is a trimer 2,2-as in the case of the reaction with peracetic acid.
It was reported that diindyl-ψ-indoxyl was obtained in high yield, in which indigo could be detected by chromatography (Khim. Geterotsikl. Soedin., Vol. 11, 1490-1496).
P., 1978). However, these are all reports to the extent of examining indole reactivity, and the indigo targeted by the present inventors is only one of the by-products produced in a very small amount, which is satisfactory as a method for producing an indigo compound. It's not the way to do it.

(Problems to be Solved by the Invention) An object of the present invention is to provide an improved and simple method for producing an indigo compound. Another object of the present invention is to provide a method for producing an indigo compound more efficiently than the above-mentioned conventional technique using an indole compound as a raw material.

(Means for Solving the Problems) The present inventors have aimed to develop a reaction system for efficiently and simply producing an indigo compound from an industrially easily available indole compound as a raw material, and have developed various types of oxidizing agents and additions. As a result of intensive studies on the agent, an organic hydroperoxide which has not been known at all as an oxidizing agent is reacted with the indole compound in the presence of a certain specific additive, and the reaction can be further simplified. Moreover, they have found that an indigo compound can be obtained with a higher yield and a higher production rate than the above-mentioned conventional techniques using other kinds of oxidizing agents and the case where no additive is used, and have completed the present invention.

That is, the present invention relates to an indigo compound characterized by reacting an indole compound having no substituents at the 2- and 3-positions with an organic hydroperoxide in the presence of an organic carboxylic acid as an additive. It is a manufacturing method.

Indole compounds having no substituents at the 2- and 3-positions, which are the raw materials in the method of the present invention, include, for example, indole; 1-methylindole, 4-ethylindole, 5-methylindole, 6-methylindole, 6
-Isopurupirindole, 7-methylindole, 4,
Alkylindoles having 1 to 4 alkyl groups having 1 to 10 carbon atoms such as 5-dimethylindole; 1 to 4 cycloalkyl groups having 3 to 12 carbon atoms such as 4-cyclohexylindole and 5-cyclopentylindole Cycloalkylindoles; 5-phenylindole, 6
Arylindoles having 1 to 4 aryl groups having 6 to 30 carbon atoms such as -β-naphthylindole or alkyl-substituted aryl groups; 4-chloroindole, 5-chloroindole, 5,7-dichloroindole, 5-bromo 1-such as indole, 6-bromoindole, 5,7-dibromoindole, 4-chloro-5-bromoindole
Halogenated indoles having 4 halogen atoms; 4
-Hydroxyindole, 5-hydroxyidole, 4,
Hydroxyindoles having 1 to 4 hydroxy groups such as 5-dihydroxyindole; carbon number 1 such as 4-methoxyindole and 5-benzyloxyindole
An alkoxyindole having 1 to 4 alkoxy groups having 1 to 10; a phenoxyindole having 1 to 4 phenoxy groups having 6 to 30 carbon atoms such as 5-phenoxyindole; 4-chloro-5-ethylindole, 6- Chloro-4
1 to 3 halogen atoms such as methyl indole, 4-bromo-5-ethyl indole, and 5-bromo-4-methyl indole and an alkyl group having 1 to 10 carbon atoms
Halogenated alkylindoles having 3; 4-nitroindole, 5-nitroindole, 7-nitroindole and other nitroindoles having 1 to 4 nitro groups; carbon such as 1-benzoylindole and 4-acetylindole Acylindoles having 1 to 4 acyl groups having 2 to 20 carbon atoms; 1-acetoxinindole, 4-benzoyloxyindole, and other acyloxyindoles having 1 to 4 acyloxy groups having 2 to 20 carbon atoms; indole- Indole carboxylic acids such as 5-carboxylic acid or esters thereof; N, N- in which the alkyl moiety such as 5-N, N-dimethylaminoindole has 1 to 10 carbon atoms
N, N-dialkylaminoindoles having 1 to 4 dialkylamino groups; and sulfonated indoles, which are compounds having no substituents at the 2- and 3-positions. Further, it is an indole compound having a combination of two or more kinds having different substituents. Besides this, 2
Substituents other than the 3-position and 3-position may have a substituent as long as they do not inhibit the reaction.

The organic hydroperoxide that is the other raw material in the method of the present invention is an organic compound having a hydroperoxy group (-OOH), for example, De Swarne (D.
Swern) “Organic Peroxide (Organic Peroxide
oxides) Vol.II ", Willie Interscience (Wile
y-Interscience) (1971); in the table on pages 107-127, or by AG Davies, "Organic Peroxides", Butterworths (1961); 9- As listed in the table on page 33. Of these, for example, tertiary butyl hydroperoxide, 1-phenylethyl hydroperoxide, 1-methyl-1-phenylethyl hydroperoxide (conventional name cumene hydroperoxide). Peroxide, bis (1-methylethyl) phenyl hydroperoxide, 1-methyl-1- (4-methylcyclohexyl) ethyl hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3, A secondary or tertiary alkyl group having a carbon number of 3 to 30 such as 3-tetramethylbutyl hydroperoxide. Kill hydroperoxides are preferred, and these organic hydroperoxides may be used alone or in combination of two or more at the same time or sequentially. It may be a combination of components capable of generating these organic hydroperoxides in the reaction system, such as a combination of benzene and an oxygen-containing gas, etc. The amount of these organic hydroperoxides used is not particularly limited. Although not limited, it is usually in the range of 0.01 to 100 mol, preferably 0.1 to 20 mol, per 1 mol of the indole compound.

In the method of the present invention, the organic carboxylic acid as an additive, for example, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, caproic acid,
Saturated aliphatic carboxylic acids such as caprylic acid, lauric acid, stearic acid, phenylacetic acid, diphenylacetic acid, 3-phenylpropionic acid, succinic acid, adipic acid, sebacic acid; oleic acid, linoleic acid, linolenic acid, acrylic acid, meta Unsaturated aliphatic carboxylic acids such as acrylic acid, cinnamic acid, fumaric acid; cyclohexanecarboxylic acid and 1,4-
Alicyclic carboxylic acids such as cyclohexanedicarboxylic acid;
Benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, α-naphthalenecarboxylic acid, aromatic carboxylic acids such as 1,8-naphthalenedicarboxylic acid; paramethylbenzoic acid, metaisopropylbenzoic acid, 3,5-toluenedicarboxylic acid Alkyl-substituted aromatic carboxylic acids such as acids; halogen-substituted aromatic carboxylic acids such as orthochlorobenzoic acid, metachlorobenzoic acid, parachlorobenzoic acid, metabromobenzoic acid, 2,4-dichlorobenzoic acid, 6-bromo-1-naphthalenecarboxylic acid Acid; metahydroxybenzoic acid,
Hydroxy-substituted aromatic carboxylic acids such as para-hydroxybenzoic acid and 6-hydroxy-1-naphthalenecarboxylic acid; orthomethoxybenzoic acid, metatoxybenzoic acid, para-ethoxybenzoic acid, 5-methoxy-2-naphthalenecarboic acid, ethoxyterephthalic acid, etc. An alkoxy-substituted aromatic carboxylic acid of; and nicotinic acid, isonicotinic acid,
Examples thereof include heteroaromatic carboxylic acids such as quinoline-3-carboxylic acid. These organic carboxylic acids may further have any substituent as long as they do not inhibit the reaction. Further, it may be a compound or a combination of compounds capable of generating an organic carboxylic acid in the reaction system, such as an anhydride of these organic carboxylic acids. These organic carboxylic acids may be used alone or in combination of two or more kinds simultaneously or sequentially. The amount of the organic carboxylic acid used as these additives is usually 50 mol or less, preferably 0.001 to 2 mol, per 1 mol of the indole compound.
It is in the range of 0 mol.

In addition, in the method of the present invention, the indole compound 3
The use of a metal compound catalyst that oxidizes the carbon at the position improves the yield or reaction rate of the indigo compound. Therefore, it is extremely preferable to use these. 3 of indole compounds
The metal compound catalyst that oxidizes the carbon at the position is a compound of a metal that oxidizes the carbon at the 3-position of the indole compound with an oxygen atom in the reaction of the indole compound and the organic hydroperoxide. 4A, 5A and
It is a compound of at least one metal selected from the group consisting of 6A group. Specifically, for example, it is a compound of a metal of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten, and more specifically, for example, a halide, an oxyhalide, or an oxide of these metals. Compounds, complex oxides, sulfides, borides, phosphides, hydroxides, oxyhydroxides,
Cyano complex salts, for example, salts of inorganic acids such as sulfuric acid, nitric acid and phosphoric acid, for example metal oxy acids such as titanic acid, molybdic acid and tungstic acid or salts thereof, or heteropoly acids such as phosphomolybdic acid and silicotungstic acid or Inorganic compounds such as salts thereof, etc .; salts of these metals with organic acids such as acetic acid, oxalic acid, benzoic acid, naphthenic acid, alkoxides such as ethyl alcohol and isopropyl alcohol, phenoxides such as phenol and metachlorophenol, A compound having an organic group at least in part such as a halide having an alkoxy or phenoxy group; or a carbonyl complex of these metals, a complex of amines, a pyridine complex such as pyridine or bipyridyl, an oxo complex, cysteine And dithiocatechol DOO complexes, sulfides complexes, dithiocarbamate complexes, thiocyanate complexes, isocyanate complexes, nitrosyl complexes, triphenylphosphine and 1,2
A phosphine complex such as diphenylphosphenoethane,
Complex compounds such as a phosphoryl complex, a phthalocyanine complex, a porphyrin complex, a nitrile complex, an ether complex, a ketone complex, a β-ketocarbonyl complex such as acetylacetone, an alkyl or allene complex, an olefin complex, a cyclopentadienyl complex, and the like. Compounds such as are classified into a plurality of types of compounds. These compounds may be used alone or in combination of two or more. Further, it may be a combination of components capable of generating these compounds in the reaction system. These compounds are preferably dissolved in the reaction mixture, but some or all may be insoluble. The amount of these compounds used is usually 0.5 mol or less, preferably 0.00001 to 0.1 mol, per 1 mol of the indole compound.

The mode of carrying out the reaction in the method of the present invention is not particularly limited, and may be a method in which an indole compound, an organic hydroperoxide, an organic carboxylic acid and a metal compound catalyst when used are effectively mixed and brought into contact with each other. Any method may be used as long as it is a batch system, a semi-batch system or a continuous flow system.

The temperature and time during the reaction vary depending on the type and amount of the raw material indole compound, the organic hydroperoxide, the organic carboxylic acid and the metal compound catalyst used, and are not uniform. However, the reaction temperature is usually -10 to 200 ℃
If the temperature is too low, the reaction becomes slow, and if it is too high, the organic hydroperoxide decomposes violently, which is dangerous. It is preferably in the range of 10 to 150 ° C. The reaction time is usually within 50 hours, preferably 0.01 to 20 hours. The reaction can be carried out under reduced pressure, normal pressure or increased pressure depending on the case.

In the method of the present invention, the reaction can be carried out in an inert gas atmosphere or in the presence of molecular oxygen such as air.

The method of the present invention is usually carried out in the presence of a solvent, although the reaction may be carried out without the use of a solvent. Any solvent may be used as long as it does not inhibit the reaction. As such a solvent, for example,
Water; Aliphatic or alicyclic hydrocarbons such as n-hexane, n-pentane and cyclohexane; Aromatic hydrocarbons such as benzene, toluene, ethylbenzene and cumene;
Aliphatic or aromatic halogen compounds such as dichloroketan, chloroform, chlorobenzene and dichlorobenzene;
Ethers such as diethyl ether, diphenyl ether, tetrahydrofuran, ethylene glycol diethyl ether; alcohols such as methanol, ethanol, tertiary butanol, cyclohexanol, benzine alcohol, propylene glycol; ketones such as acetone, ethyl methyl ketone, acetophenone; acetic acid And carboxylic acids such as propionic acid; esters such as ethyl acetate and ethyl propionate; carbonates such as dimethyl carbonate; and aromatic nitro compounds such as nitrobenzene. You may use these individually or in mixture of 2 or more types. In addition, the use of these solvents may cause the reaction mixture to have a uniform phase or a plurality of non-uniform phases.

In the method of the present invention, the indigo compound is obtained by treating the reaction product after the reaction according to a conventional method. Usually, most of the indigo compound produced after the reaction is precipitated, and can be easily taken out as a solid by an ordinary solid-liquid separation operation such as filtration, centrifugation or decantation. When the amount of the indigo compound deposited is insufficient, the reaction solution can be concentrated and then taken out in order to deposit more.

(Examples) Next, the present invention will be described in more detail by way of examples, but these should not be construed as limiting and should be construed as merely illustrative.

Example 1 Internal volume 100 equipped with a stirrer, thermometer and cooling tube
In a milliliter three-necked flask, 1.0 g (8.5 mmol) of indole, 104.5 mg (0.85 mmol) of benzoic acid as an additive, 30 g of toluene as a solvent and 83% by weight of 1-methyl-organohydroperoxide as an organic hydroperoxide.
A cumene solution of 1-phenylethylhydroperoxide (conventional name cumene hydroperoxide) (hereinafter simply referred to as CHP solution) (7.83 g, 42.7 mmol in terms of cumene hydroperoxide) was charged all at once. This liquid was heated to 80 ° C. in an oil bath and reacted for 10 hours while stirring in an air atmosphere. The liquid was uniform at the start of the reaction, but as the reaction proceeded, a deep blue solid gradually began to precipitate. After completion of the reaction, the reaction mixture is filtered, the solid is washed with a small amount of toluene, and then dried under reduced pressure at 50 ° C. to obtain an indigo solid.
Got 108.6 mg. This was indigo as a result of elemental analysis and 1R analysis. The molar yield of the isolated indigo with respect to the charged indole (hereinafter simply referred to as the indigo yield) is 9.7%, which is used as a guide for the production rate.
The indigo yield per hour was 1.0%.

Comparative Example 1 When the reaction and post-treatment were performed in the same manner as in Example 1 except that benzoic acid was not used, 24.5 mg of indigo was obtained. The indigo yield was 2.2%, and the indigo yield per hour was 0.2%.
The yield was low and the production rate was slow when no additives were used.

Example 2 In Example 1, except that 51.0 mg of acetic acid was used instead of benzoic acid and 20 g of cumene was used instead of toluene, and the reaction temperature was changed to 90 ° C., and the reaction and post-treatment were performed in the same manner as in Example 1. Was done. Indigo yield is 8.
3%, and the indigo yield per hour was 0.8%. The yield and production rate were higher than when acetic acid was not added.

Example 3 Internal volume 500 equipped with a stirrer, thermometer and cooling tube
In a milliliter three-necked flask, 10.0 g (85.4 mmol) of indole, 1.04 g (8.5 mmol) of benzoic acid as an additive, 225 mg (0.85 mmol) of molybdenum hexacarbonyl as a catalyst, 300 g of cumene as a catalyst and organic hydroperoxidation. CHP solution 4
7.0 g (256.3 mmol in terms of cumene hydroperoxide) was charged all at once. Use this liquid in an oil bath
The mixture was heated to 80 ° C. and reacted for 5 hours while stirring in an air atmosphere. After completion of the reaction, the reaction solution was filtered, the solid was washed with a small amount of cumene and methanol, and dried under reduced pressure at 50 ° C. to obtain 7.91 g of indigo. Indigo yield is 70.7
%, The indigo yield per hour was 14.1%.

Comparative Example 2 When the reaction and the post-treatment were carried out in the same manner as in Example 3 except that benzoic acid was not used, 5.91 g of indigo was obtained. Indigo yield is 5
The yield of indigo per hour was 2.8% and 10.6%.
As in Comparative Example 1, when the organic carboxylic acid is not used, the yield is low and the production rate is slow.

Examples 4 to 28 In Example 3, the reaction and post-treatment were carried out in the same manner as in Example 3, except that the kind and amount of the organic carboxylic acid shown in Table 1 were used instead of benzoic acid. The results are shown in Table 1 together with the results of Example 3 and Comparative Example 2.
In each of the examples, the yield and the production rate were improved as compared with the results of Comparative Example 2 in which the organic carboxylic acid was not added.

Examples 29 to 36 The amounts of the indole and CHP solutions, the types and amounts of the organic carboxylic acid and the solvent, the reaction temperature and the reaction time were changed as shown in Table 2, and the types and amounts of the catalysts shown in Table 2 were changed. The reaction and the post-treatment were carried out in the same manner as in Example 1 except that the components were used. The results are shown in Table 2.

Comparative Examples 3 to 10 All of Examples 29 to 36 were the same as the corresponding Examples 29 to 36 except that the organic carboxylic acid used in each Example was not used. The results are shown in Example 29 to
Both of the 36 results are shown in Table 2. In each case, the yield was low and the production rate was slow unless the organic carboxylic acid was added.

Example 37 In a 4-necked flask with an internal volume of 100 ml equipped with a stirrer, a thermometer, a dropping funnel and a cooling tube, 1.0 g (8.5 mmol) of indole and 10 benzoic acid as an additive agent were added.
4.2 mg (0.85 mmol), molybdenum hesacarbonyl 11.3 mg (0.043 mmol) as a catalyst,
And 30 g of toluene was charged as a solvent. This liquid was heated to 80 ° C. in an oil bath, and a 69% by weight aqueous solution of tertiary butyl hydroperoxide as an organic hydroperoxide was added from a dropping funnel while stirring in an air atmosphere.
After 6 g (42.9 mmol in terms of tertiary butyl hydroperoxide) was added dropwise over 1 hour, the reaction was continued for 5 hours. The obtained reaction mixture was post-treated in the same manner as in Example 1, and the indigo yield was 29.3%, 1
The insigo yield per hour was 5.9%.

Examples 38-40 In Example 37, the amounts of indole and benzoic acid were changed as shown in Table 3 and the organic hydroperoxides shown in Table 3 were used instead of the 69% by weight aqueous solution of tert-butyl hydroperoxide. The reaction and post-treatment were carried out in the same manner as in Example 37 except that the type and the amount thereof were used. The results are shown in Table 3 together with the result of Example 37. In each case, the yield and the production rate were improved as compared with the result when the organic carboxylic acid was not used.

Example 41 In Example 1, 3.0 g (19.8 mmol) of 5-chloroindole was used instead of indole, and 1 of CHP solution was used.
8.0 g (98.2 mmol of cumene hydroperoxide) and parachlorobenzoic acid instead of benzoic acid
309.8 mg (1.98 mmol) was used, and molybdenum hexacarbonyl was further used as a catalyst at 22.5 mg (0.08 mmol).
5 mmol), and the reaction was carried out in the same manner as in Example 1 except that the reaction time was changed to 5 hours. The obtained reaction mixture was filtered, and the solid was washed with a small amount of methanol.
It is the corresponding indigo compound after drying under reduced pressure at 50 ℃.
1.64 grams of 5,5'-dichloroindigo were obtained. The molar yield of 5,5'-dichloroindigo based on the charged 5-chloroindole was 50.1%.

Example 42 In Example 1, 1.0 g (7.6 mmol) of 6-methylindole was used instead of indole, and 7.0 of CHP solution was used.
Grams (38.2 mmole in terms of cumene hydroperoxide) and 10% of meth-methylbenzoic acid instead of benzoic acid.
3.8 mg (0.76 mmol) was used, and molybdenum hexacarbonyl was used as a catalyst for 22.5 mg (0.085 mmol).
Mmol) was used and the reaction was carried out in the same manner as in Example 1 except that the reaction time was changed to 5 hours. The obtained reaction mixture was filtered, and the solid was washed with a small amount of methanol and then at 50 ° C.
After drying under reduced pressure, the corresponding indigo compound 6,6
-0.64 grams of dimethyl indigo were obtained. The molar yield of 6,6'-dimethylindigo relative to the charged 6-methylindole was 57.8%.

(Effect of the Invention) According to the method of the present invention, an indole compound having no substituents at the 2- and 3-positions is reacted with an organic hydroperoxide in the presence of an organic carboxylic acid as an additive. According to a simple method, it is possible to produce a corresponding indigo compound with a higher yield and a higher reaction rate than in the prior art using a single step and using another oxidizing agent, and as compared with the case where no organic carboxylic acid is added. This is an extremely effective method for producing an indigo compound.

Claims (3)

(57) [Claims] 1. A process for producing an indigo compound, which comprises reacting an indole compound having no substituents at the 2- and 3-positions with an organic hydroperoxide in the presence of an organic carboxylic acid as an additive. Method. 2. The method according to claim 1, wherein the reaction is carried out in the presence of a metal compound catalyst that oxidizes the carbon at the 3-position of the indole compound. 3. The method according to claim 2, wherein the metal compound catalyst is a compound of a metal selected from the group consisting of groups 4A, 5A and 6A of the periodic table.