JPH04189871A - Production of indigos - Google Patents

Abstract

PURPOSE:To efficiently obtain an indigo important as dye by reacting an indole with an organic hydroperoxide in the presence of a specific catalyst while controlling water content brought to the reaction system in <=a fixed amount. CONSTITUTION:(A) An indole not containing a substituent group at the 2 and the 3-positions such as 1-methylindole is reacted with (B) an organic hydroperoxide such as tertiary-butyl hydroperoxide in the presence of a catalyst composed of a compound of a metal such as titanium or zirconium, etc., of the group 4, group 5 and/or group 6 of the periodic table and water content brought to the reaction system is controlled in <=1mol based on the component A to give the objective indigo.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing indigo compounds.

More specifically, indoles having no substituents at the 2- and 3-positions are reacted with an organic hydroperoxide in the presence of a specific catalyst, while controlling the amount of water brought into the reaction system to a specific amount or less. In particular, the present invention relates to a novel method for producing indigo compounds corresponding to the indoles.

Indigo compounds are important compounds as dyes.

[Prior Art] Currently, as an industrial method for producing indigo, N-phenylglycine salt is produced using aniline and chloroacetic acid or aniline, hydrocyanic acid and formaldehyde as raw materials,
A method is adopted in which this is melted with an alkali at high temperature to form an indoxyl compound, and then further oxidized in air.

However, these methods not only involve extremely complex reaction steps with multiple steps, but also require the use of large amounts of potassium hydroxide and sodium hydroxide, which consumes a large amount of energy when recovered and reused. There is a problem in that special equipment is required for this purpose. Therefore, a shift to a simpler process is desired.

On the other hand, there is a report that a trace amount of indigo is produced in the organic synthetic chemical oxidation reaction of indole. For example, Kobaba et al. generated peracetic acid, which is a percarboxylic acid, in a reaction system using hydrogen peroxide and acetic acid, and reacted it with indole as an oxidizing agent. -ψ-indoxyl was obtained as the main product, and a small amount of indigo was also produced as a by-product (Bull, Agr, Chem, So
c, Japan, vol. 20, pp. 80-83, 1956
Year).

Furthermore, Bernat Vintconobu et al. used perbenzoic acid, a percarboxylic acid, as an oxidizing agent and reacted it with indole in a chloroform solvent overnight in a refrigerator, producing many components in addition to orthoformaminobenzaldehyde. , Uustus Liebigs Annalen d reported that a very small amount of indigo was also produced at this time.
er Chemie, Vol. 558, pp. 91-98.

(1947). Furthermore, when hydrogen peroxide, which is an inorganic peroxide, is used as an oxidizing agent and indole is reacted with indole in a methanol solvent, a trimer of 2, 2-diindyl-ψ-
reported that indigo was obtained in high yield and that indigo could be detected by chromatography (Khim
, Geterotsikl, 5oedin.

, Vol. 11, pp. 1490-1496, 1978). However, these are all reports that examine the reactivity of indole using an oxidizing agent different from that of the organic hydroperoxide of the present invention, and the indigo targeted by the present inventors is only available in a very small amount. This is just one of the by-products produced, and it cannot be said to be a satisfactory method for producing indigo compounds.

Also, although the reaction itself is different from the method of the present invention,
Using 3-formylindoles as raw materials in an organic solvent,
After reacting with peroxide, it is further oxidized.
There is an example of obtaining indigo compounds by step reaction (Japanese Patent Application Laid-open No. 1983-12)
4027).

However, 3-formylindoles, which are the starting materials, are not easily available compounds, and must be synthesized from indoles through complicated reactions. Furthermore, since the 3-position carbon of indoles combines with oxygen to form indigo compounds, this method requires elimination of the 3-formyl group, which leads to the formation of by-products that disrupt the reaction system. It cannot be said to be a simple method for producing indigo compounds, as it is complicated.

Recently, a method for producing indigo compounds in a simple step by reacting indoles having no substituents at the 2- and 3-positions with an organic hydroperoxide has been proposed (JP-A-1-215
859) However, even with this method, the yield and reaction rate of indigo compounds are still not sufficient.

[Problem to be solved by the invention]

An object of the present invention is to provide an improved and simple method for producing indigo compounds.Another object of the present invention is to provide an improved and simple method for producing indigo compounds. An object of the present invention is to provide a manufacturing method.

[Means and effects for solving the problem] The present inventors use industrially easily available indoles as raw materials and organic hydroperoxides as oxidizing agents to efficiently and easily produce indigo compounds in one step. We have continued to study intensively with the aim of developing a reaction system, and have found that when a reaction is carried out in the presence of a specific catalyst and by controlling the amount of water brought into the reaction system to a specific amount or less, -
The present inventors have discovered that indigo compounds corresponding to the raw material indoles can be obtained easily and at high yields and production rates, and have completed the present invention.

That is, the present invention uses indoles having no substituents at the 2- and 3-positions and an organic hydroperoxide as a catalyst, and a compound of a metal selected from the group consisting of Groups 4, 5 and 6 of the periodic table. This is a method for producing indigo compounds corresponding to indoles, which is characterized in that the reaction is carried out in the presence of indoles, with the amount of water brought into the reaction system being reduced to 1 mole or less relative to the indoles.

In the method of the present invention, the carbons at the 2-position of indoles trimerize with a double bond, and the carbon at the 3-position forms a bond with oxygen to produce indigo compounds.
The presence of a substituent at the position hinders the production of indigo compounds. Therefore, the indoles used as raw materials in the method of the present invention must not have substituents at the 2- and 3-positions. Such indoles having no substituents at the 2- and 3-positions include, for example, indole; 1-methylindole, 4-ethylindole, 5-methylindole, 6-methylindole;
Methylindole, 6-ituprobylindole, 7-
Alkylindoles having 1 to 4 alkyl groups having 1 to 10 carbon atoms such as methylindole and 4.5-dimethylindole; cycloalkyl groups having 3 to 12 carbon atoms such as 4-cyclohexylindole and 5-cyclopentylindole; Cycloalkylindoles having 1 to 4 arylindoles; arylindoles having 1 to 4 aryl groups or alkyl-substituted aryl groups having 6 to 30 carbon atoms such as 5-phenylindole and 6-β-naphthylindole; 4-chloroindole , 5-chloroindole, 5.
7-dichloroindole, 5-bromoindole, 6-
Bromoindole, 5.7-dibromoindole, 4-
Halogenated indoles having 1 to 4 halogen atoms such as chloro-5-bromoindole; hydroxy having 1 to 4 hydroxy groups such as 4-hydroxyindole, 5-hydroxyindole, 4,5-dihydroxyindole Indole g: 1-1 carbon atoms such as 4-/toxiindole, 5-hensyloxindole, etc.
Alkoxyindoles having 1 to 4 alkoxy groups; 6 to 30 carbon atoms such as 5-phenoxyindole
Phenoxyindole W4 having 1 to 4 phenoxy groups: 1 such as 4-chloro-5-ethylindole, 6-chloro-4-methylindole, 4-bromo-5-ethylindole, 5-bromo-4-methylindole, etc. ~
Halogenated alkylindoles having 3 halogen atoms and 1 to 3 alkyl groups having 1 to 1° of carbon atoms; 4
-Nitroindole having 1 to 4 nitro groups such as nitroindole, 5-nitroindole, 7-nitroindole; C2-20 acyl group such as l-hendiylindole and 4-acetylindole 1 to 4
Acylindoles with 2 or more carbon atoms, such as l-acetoquinindole and 4-hendiyloxindole
Acyloxyindoles having 1 to 4 acyloxy groups; indole carboxylates such as indole-5-carboxylic acid or esters thereof; 5-N, N-
N,N-dialkylaminoindoles having 1 to 4 N,N-dialkylamino groups in which the alkyl moiety has 1 to 10 carbon atoms, such as dimethylaminoindole; and sulfonated indoles.

Furthermore, indoles having two or more of the above substituents are also included. In addition, substituents may be present at positions other than the 2- and 3-positions as long as they do not inhibit the reaction. Among these indoles, indole, alkylindoles and halogenated indoles are preferred, and among these, indole is particularly preferred.

The organic hydroperoxide, which is the other raw material in the method of the present invention, is an organic compound having a hydroperoxy group C-00H.
7 (D, Swern) “Organic Peroxides” Vol.
, TI'', Willy, Interscience (kiley
-rnterscience) (1971);
In the table on pages 107-127, or in "Organic Peroxides" by A. G. Davies, published by Butterworths (19
1961); 9-33 Fit as listed in the table.

Among these, for example, tert-butyl hydroperoxide, ■-phenylethyl hydroperoxide,
-Methyl-1-phenylethyl hydroperoxide (common name cumene hydroperoxide), bis(1-methylethyl)phenyl hydroperoxide, 1-methyl-1-
(4-Methylcyclohexyl)ethyl hydroperoxide, 2.5-dimethylhexane-2,5-dihydroperoxide, 1,1,3.3-tetramethylbutylhydroperoxide, etc., where the number of carbon atoms in the alkyl moiety is 3
-30 secondary or tertiary alkyl hydroperoxides are preferred.

These organic hydroperoxides may be used alone, two or more types may be mixed and used simultaneously, or two or more types may be used sequentially.

Furthermore, these organic hydroperoxides may be a combination of components that can generate these organic hydroperoxides within the reaction system, such as a combination of isopropylbenzene and an oxygen-containing gas. .

The amount of these organic hydroperoxides to be used is not particularly limited, but is usually in the range of 0.01 to 100 mol, preferably 0.01 to 100 mol per mol of the indole.
．． It is in the range of 1 to 20 mol, more preferably 0.
It ranges from 2 to 10 moles.

The metal compound selected from the group consisting of Groups 4, 5 and 6 of the periodic table, which is the catalyst in the method of the present invention, is:
Specifically, compounds of the metals titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum or tungsten, and more specifically, for example, halides, oxohalides and oxides of these metals. , complex oxides, sulfides, borides, phosphides, hydroxides, oxyhydroxides, noano complexes, salts of inorganic acids such as sulfuric acid, nitric acid and phosphoric acid, such as titanic acid, molybdic acid and tungstic acid. of these metals; acetic acid, oxalic acid, benzoic acid,
Salts of organic acids such as naphthenic acid, alkokids such as ethyl alcohol and isopropyl alcohol, phenoxides such as phenol and metachlorophenol, halides with alkoxy or phenoxy groups, etc. or carbonyl complexes of these metals, amine complexes, pyridine complexes such as pyridine and bipyridyl, oxo complexes, thiolate ti forms such as cysteine and dithiocatechol,
Sulfide complexes, 18 dithiocarbamates, thionate complexes, isocyanate complexes, nitrile complexes, phosphine complexes such as triphenylphosphine and 1,2-diphenylphosphinoethane, phosphoryl complexes, phthalocyanine complexes, porphyrin complexes, nitrile complexes, ethers Complex compounds such as complexes, ketone complexes, β-ketocarbonyl complexes such as acetylacetone, alkyl or arene complexes, olefin complexes, cyclopentagenyl complexes; Examples include compounds such as These compounds can be used alone or in combination of two or more. It may also be a combination of components that can generate these compounds within the reaction system. It is preferable that these compounds be dissolved in the reaction mixture, but some or all of them may be insoluble. Among these compounds, titanium or molybdenum metal compounds are preferred. The amount of these compounds used is usually 0.5 mol or less per 11 mol of indole, preferably 0.00001 to 0.1 mol, more preferably 0.0001 to 0.1 mol. range.

The method of the present invention is usually carried out in the presence of a solvent, although in some cases the reaction can be carried out without using a solvent. Any solvent may be used as long as it does not inhibit the reaction. Such solvents include, for example, n
-Aliphatic or alicyclic hydrocarbons such as hexane, n-pentane, n-hebutane, and cyclohexane; Aromatic hydrocarbons such as henzene, toluene, xylene, ethylbenzene, and cumene; dichloromethane, chloroform,
Aliphatic or aromatic halogen compounds such as chlorohenzene and dichlorobenzene; ethers such as diethyl ether, di-n-butyl ether, diphenyl ether, tetrahydrofuran, and ethylene glycol diethyl ether; methanol, ethanol, hensyl alcohol, isopropyl alcohol, cyclohexanol, tertiary butanol, tertiary amyl alcohol,
Alcohols such as propylene glycol; acetone,
Ketones such as ethyl methyl ketone and acetophenone;
Examples include esters such as ethyl acetate and ethyl propionate; carboxylates such as dimethyl carbonate; and aromatic nitro compounds such as nitrohenzene. These may be used alone or in combination of two or more. Furthermore, by using these solvents, it does not matter whether the reaction mixture becomes a homogeneous phase or a plurality of heterogeneous phases.
Among these solvents, secondary alcohols such as isopropyl alcohol or cyclohexanol, or tertiary alcohols such as tertiary-butanol or tertiary-amyl alcohol are preferred.

In the method of the present invention, it is extremely important to control the amount of water brought into the reaction system. The organic hydroperoxides and indoles that are the raw materials of the present invention, and the solvents used may contain water due to manufacturing reasons, as listed below, for example.

■Organic hydroperoxide can be mixed with water using emulsification method! When produced in a two-phase system with a solvent, the organic hydroperoxide is obtained by separation from the aqueous phase as a solution of the organic solvent, but water cannot be mixed in at this time.

■ Available mechanical hydroperoxides (e.g. tertiary
butyl hydroperoxide) are often in aqueous solutions.

■ Solvents that are azeotropic with water are difficult to dehydrate if water is mixed in.

If raw materials, solvents, etc. containing moisture are used as they are, moisture will be brought into the reaction system. If the amount of water is large, the reaction will be inhibited, and both the yield of indigo compounds and the reaction rate will decrease. Therefore, it is necessary to reduce the amount of water brought into the reaction system as much as possible. Therefore, in the reaction, the water brought into the reaction system is reduced to a predetermined amount by using raw materials and solvents that have been subjected to commonly used dehydration operations, such as using a dehydrating agent, distilling off water, azeotropic dehydration, or membrane separation. Perform the reaction after controlling it. The dehydration operation may be carried out independently for each raw material, solvent, etc., or may be carried out for a mixture of them under conditions that do not initiate the reaction. The allowable amount of water brought into the reaction system is 1 mole or less, preferably 0.5 mole or less, and more preferably 0.1 mole or less relative to the indoles.

In the method of the present invention, it is preferable to use organic carboxylic acids as additives because it further improves the yield and production rate of indigo compounds. Examples of such organic carboxylic acids include acetic acid, propionic acid, and stearic acid. , aliphatic carboxylic acids such as phenylacetic acid, oleic acid or cinnamic acid, or aromatic carboxylic acids such as benzoic acid, paramethylbenzoic acid, metachlorobenzoic acid or parahydroxybenzoic acid, among which acetic acid, propionic acid Or benzoic acid is preferred.

Also, organic silanols such as trimethylsilanol, triethylsilanol, or triphenylsilanol are also effective as additives. Furthermore, in order to improve the yield or production rate of indigo compounds, additives other than these may be used, or a plurality of types of additives may be used in combination.

The method of conducting the reaction in the method of the present invention is not particularly limited, and may be any method in which the indoles, organic hydroperoxide, catalyst, and solvents and additives when used are effectively mixed and brought into contact with each other. Any method may be used, including a batch method, a semi-batch method, or a continuous flow method.

The temperature and reaction time during the reaction are as follows:
It varies depending on the type and amount of the organic hydroperoxide, catalyst, solvent and additives used, and is not uniform.

However, the reaction temperature is usually between -10 and 200°C.
The reaction time is usually within 50 hours, preferably 0.01 to 20 hours. It is. 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 under an inert gas atmosphere or in the presence of molecular oxygen such as air.

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

The indigo compounds obtained by the method of the present invention correspond to the raw material indoles, and have the same substituents on the aromatic ring and nitrogen atom of the indigo compounds in the same positions as the indoles of the seeds. It is.

〔Example〕

The present invention will now be described in more detail with reference to Examples, which should be understood as merely illustrative rather than limiting.

First, this preparation method was carried out based on the emulsification method and purification method described in ``Organic Compound Synthesis Methods, Volume 11'' (edited by the Organic Synthetic Chemistry Society, published by Gihodo), 35-36.

4 with internal volume 5'J 7 torr, equipped with stirrer, gas inlet, gas outlet with reflux condenser and thermometer
4.0 g of caustic soda, 2 borax in a turok flask
Add 2.5 liters of a 9g aqueous solution and 2.5 grams of sodium stearate as an emulsifier, heat in a water bath, and after the emulsifier has completely dissolved, add 1.25 liters of a cumene solution of % cumene hydroperoxide. I put it in.

When the internal temperature reached 85°C, oxygen was started to be blown in at a rate of 50 liters per hour while stirring vigorously. After reacting as it is for 9 hours, cool to room temperature, blow carbon dioxide gas until the aqueous layer no longer becomes cloudy, remove the lower aqueous layer by liquid separation, and wash once with 250 ml of water. % cumene hydroperoxide (hereinafter abbreviated as CHP solution (a)) 1260 ml was obtained. The water content of this solution was analyzed by Karl Fischer method and was found to be 0.92% by weight.

This CHP solution (a) 1050 ml of anhydrous PL
Add 400 grams of sodium acid and rinse with water. 34.
A cumene solution of 25% by weight cumene hydroperoxide (hereinafter referred to as CHP solution Q)) was obtained in an amount of 1030 liters. The water content of this solution was 0.13Ii% by weight.

820 milliliter of this CHP solution (b) was placed in a 2-liter glass distiller with 3 grams of anhydrous sodium carbonate fine particles, and while air was passed through a boiling water bath, low-boiling components were evaporated under reduced pressure to leave a residue of 82. 290 ml of a cumene solution (hereinafter abbreviated as CHP solution (C)) of 01% by weight cumene hydroperoxide was obtained. The water content of this solution was 0.044 kg.

Example 1 Internal volume 5 equipped with stirrer, thermometer and reflux condenser
Indole 1O in a 00ml 3-NO flask
10 g (85.4 mmol), 22.5 mg (0.085 mmol) of molybdenum hexacarbonyl as catalyst, 300 g of cumene as solvent and 79.2 g of CHP solution (C) as organic hydroperoxide (
426.8 mmol (calculated as cumene hydroperoxide) was charged in bulk. No water was detected in indole and molybdenum hexacarbonyl, but cumene contained 0.026% water by weight. Therefore, the amount of water brought into the reaction system, including the water contained in the CHP solution (C), was 0.11 grams (6.1 mmol), which was 0,607 times the molar amount of indole. This liquid was heated to 100"C in an oil bath and reacted for 5 hours with stirring in an air atmosphere. At the beginning of the reaction, the liquid was homogeneous, but as the reaction progressed, a blue solid gradually precipitated. After the reaction was completed, the reaction mixture was filtered, and the product was washed with a small amount of cumene and methanol, and then dried under reduced pressure at 50°C to obtain 6.29 g of a blue solid. The analysis and IR analysis revealed that it was indigo.The molar yield of isolated indigo to the charged indole (hereinafter simply referred to as indigo yield) was 56.2%, which is used as a guideline for the production rate. The indigo yield per hour was 11.2%.

Example 2 In Example 1, CHP solution (instead of ClO, CH
The reaction was carried out in the same manner as in Example 1 except that 189.7 grams of PR solution (b) (426.9 mmol in terms of cumene hydroperoxide) was used and the amount of cumene was changed to 189.5 grams to match that of Example 1. I did this. The amount of water brought into the reaction system was 0.30 g (16,
7 mmol), which was 0.20 times the molar amount of indole. When the obtained reaction mixture was post-treated in the same manner as in Example 1, 6.08 g of indigo was obtained. The indigo yield was 54.3%, and the indigo yield per hour was 1089%.

Comparative Example I In Example 1, CH
P melt! (a) The reaction was carried out in the same manner as in Example 1, except that 6 grams of cumene (426.9 mol in terms of cumene hydroperoxide) was used and the amount of cumene was changed to 188.6 grams to match that of Example 1. Ta.

The amount of water brought into the reaction system was 1.80 grams (100.2 mmol) including the water contained in CHP solution (a) and cumene, which was 1.80 grams (100.2 mmol) relative to indole.
It was 17 times the molar amount. The resulting reaction mixture was used in Example 1.
After post-processing in the same way as above, indigo was 5.35.
Grams obtained. The indigo yield was 47.8%, and the indigo yield per hour was 9.6%, and the yield was low and the production rate was slow as too much water was brought into the reaction system.

Example 3 Analysis of Perbutyl H-697 (a toluene solution of tertiary-butyl hydroperoxide) manufactured by NOF Corporation revealed that the content of tertiary-butyl hydroperoxide was 68.71% by weight, and the water content was 2. It was .8% by weight. After diluting 100 grams of this solution with 200 grams of toluene, 100 grams of sodium sulfate was added to dehydrate it overnight, and 100 grams of Molecular Labs 4A was added and further dehydrated overnight, resulting in a yield of 21.6% by weight.
291.4 grams of a toluene solution of tert-butyl hydroperoxide was obtained. The water content of this solution is 0.01
% by weight.

Into a 500 milliliter four-tube flask equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, 10.0 grams (85.4 mmol) of indole and 225.4 milligrams (0.85 millimoles) of molybdenum hexacarbonyl as a catalyst were added. mmol), and toluene 1 as solvent
53.3 grams of this solution was heated to 80°C in an oil bath, and while stirring in an air atmosphere, the liquid was added to the dropping funnel to produce the above-prepared 21.6 hydroperoxide.
A toluene solution of 1% tertiary-butyl hydroperoxide (213.9 grams) (5127 mmol in terms of tertiary-butyl hydroperoxide) was added dropwise over 1 hour, and the mixture was allowed to react for 5 hours. Toluene contains 0.016% water by weight, so the water brought into the reaction system is the toluene of tert-butylhydroberoxide? 8 Including the water contained in the liquid, the amount was 46 grams (2.6 mmol) of O and O', which was 0.03 times the mole of indole. After the reaction was completed, the reaction mixture was filtered, and the solid was washed with a small amount of toluene and methanol and dried under reduced pressure at 50°C to obtain 5.69 g of indigo. Indigo yield is 50.8
%, the indigo yield per hour was 10.2%.

Comparative Example 2 In Example 3, 21,6 M! Instead of a toluene solution of % tert-butyl hydroperoxide, 67.2 grams of a toluene solution of 68.71E lid % tert-butyl hydroperoxide (calculated as tert-butyl hydroperoxide) without dehydration was used.
12.3 mmol) and the amount of toluene in Example 3.
The reaction was carried out in the same PJ as in Example 3 except that the amount was changed to 300 grams to match the above.

The amount of water brought into the reaction system was 1.93 grams (107.2 mmol), including the 68.7% by weight toluene solution of butyl hydroperoxide and the water contained in the toluene. 1.
It was 26 times the molar amount. The resulting reaction mixture was used in Example 3.
After post-processing in the same way as above, indigo was 4.93
Grams obtained. The indigo yield was 44.0%, and the indigo yield per hour was 8.8%, similar to Comparative Example 1.
When the amount of water brought into the reaction system was large, the yield was low and the production rate was also slow.

Comparative Example 3 In Example 3, Perbutyl H-68 (68,2111% by weight aqueous solution of tert-butyl hydroperoxide) manufactured by NOF Corporation was used instead of the toluene solution of 21.6% by weight tert-butyl hydroperoxide 67. 7
The reaction was carried out in the same manner as in Example 3, except that the amount of toluene was changed to 315.7 grams to match that of Example 3. Perbutyl H-68 manufactured by NOF Co., Ltd. contains 279% by weight of water, so the amount of water brought into the reaction system was 18.94 grams (105% by weight), including the water contained in toluene.
2 mmol), which was 12.3 times the molar amount of indole. The resulting reaction mixture was post-treated in the same manner as in Example 3, and 2.68 g of indigo was obtained.

The indigo yield was 23.9%, and the indigo yield per hour was 4.8%.Since the amount of water brought into the reaction system was larger than in Comparative Example 2, the yield was lower, and the production rate was also lower. it was late.

Example 4 Internal volume 3 equipped with stirrer, thermometer and reflux condenser
Indole 10 in a 00ml 3-nozzle flask
．． 0 g (85,4 mmol), toluene solution of molybdenum naphthenate as catalyst (6 as molybdenum metal)
136.5 milligrams (0.085 milligram atoms in terms of molybdenum metal), 0.51 grams (8.5 mmol) of acetic acid as an additive, 150 grams of tertiary-butanol as a solvent and Japan as an organic hydroperoxide. Percmill H-80 (82, manufactured by Yushisha)
Cumene solution of 0 weight 1% cumene hydroperoxide (hereinafter abbreviated as CHP solution M (d)) 34.86 grams (
187.8 mmol (calculated as cumene hydroperoxide) was charged in bulk. No water was detected in the toluene solution of molybdenum naphthenate, but 0.05% by weight in tertiary-butanol and CI (P solution (d
) contained 0.04% water. Therefore, the total amount of water brought into the reaction system was 0.089 g (4.9 mmol), which was 0.0 g relative to indole.
It was 6 times the molar amount. This liquid was heated in an oil bath to reflux, and reacted for 7 hours with stirring under an air atmosphere. The liquid temperature at the beginning of the reaction was 86.5°C, but after 5 hours it was 84.8°C. After the reaction was completed, the reaction liquid was filtered, and the solid was washed with a small amount of tert-butanol. , when dried under reduced pressure at 50°C, the indigo was 8.
90 grams were obtained. The indigo yield was 79.5%, and the indigo yield per hour was 11.4%.

Comparative Example 4 In Example 4, an azeotropic mixture of Tarnary-butanol and water was used instead of Tarnary-butanol [Ternary-butanol content: 88.24% by weight and water content: 11.76% by weight! % mixture] The reaction was carried out in the same manner as in Example 4 except that 150 grams was used. The amount of water brought into the reaction system was 17.65 grams (980 grams), including the water contained in the CHP melt (d) and the azeotropic mixture of ternary butanol and water.
, 6 mmol), which was 11.5 times the molar amount of indole.

When the obtained reaction mixture was post-treated in the same manner as in Example 4, 4.39 grams of indigo was obtained.

The indigo yield was 39.2%, and the indigo yield per hour was 5.6%.As with other comparative examples, the yield is low when the amount of water brought into the reaction system is large, and the production rate is also low. it was late.

Examples 5 to 7 and Comparative Example 5 From Example 4 and Comparative Example 4, it is clear that the indigo yield and reaction rate are significantly affected by the amount of water brought into the reaction system. The reaction and post-treatment were carried out in the same manner as in Example 4, except that the amount of water shown in the table was further added, and the allowable amount of water brought into the reaction system was investigated.

The results are shown in Table 1 together with the results of Example 4 and Comparative Example 4. As is clear from the results, when the water brought into the reaction system was reduced to 1 mole or less relative to the total amount of indoles used, indigo was obtained in a high yield and production rate.

Example Day In Example 1, 1.04% of benzoic acid was added as an additive.
The reaction and post-treatment were carried out in the same manner as in Example 1, except that gram (8.5 mmol) was used. The indigo yield was 66.1%, and the indigo yield per hour was 13.
．． It was 2%.

Example 9 The reaction and post-treatment were carried out in the same manner as in Example 1 except that 2.36 g (8.5 mmol) of triphenylfuranol was further used as an additive, and the indigo yield was as follows. The indigo yield per hour was 12.7%.

Example 10 In Example 1, 1.04% of benzoic acid was added as an additive.
The reaction and post-treatment were carried out in the same manner as in Example 1 except that 2.36 g (8.5 mmol) of triphenylsilanol and 2.36 g (8.5 mmol) of triphenylsilanol were used, and the indigo yield was 72.8%. , the indigo yield per hour was 14.6%.

Example 11 In Example 4, 27.7 milligrams (0,085 mmol) of molybdenum dioxoacetylacetonate was used instead of the toluene solution of molybdenum naphthenate, 150 grams of isopropyl alcohol was used instead of tertiary-butanol, and acetic acid was The reaction was carried out in the same manner as in Example 4, except that the reaction time was changed to 5 hours.

No moisture was detected in molybdenum dioquine acetylacetate, but 0.0 in isopropyl alcohol.
It contained 3% by weight of water.

Therefore, the amount of water brought into the reaction system: yo, CHP (volume M
Combined with the water contained in (d), it is 0.059 g (33 mmol), which is 0.04 g relative to indole.
It was twice the molar amount. After the reaction is completed, the reaction solution is filtered,
After washing the solid with a small amount of isopropyl alcohol,
When dried under reduced pressure at C, the indigo yield was 72.2%.
, the indigo yield per hour was 14.4%.

Comparative Example 6 In Example 11, instead of isopropyl alcohol, 150 grams of an azeotropic mixture of isopropyl alcohol and water (a mixture with an isopropyl alcohol content of 87.4% by weight and a water content of 12.6% by weight) was used. The reaction was carried out in the same manner as in Example 11 except for using the following. The amount of water brought into the reaction system was 18.91 grams (105
1 mmol), which was 12.3 times the molar amount of indole.

When the obtained reaction mixture was post-treated in the same manner as in Example 11, the indigo yield was 26.6%, and the indigo yield per hour was 5.3%, which was similar to other comparative examples. However, when the amount of water introduced into the reaction system was large, the yield was low and the production rate was also slow.

Example 12 In Example 4, isopropyl orthotitanate 241.6 was used instead of the toluene solution of molybdenum naphthenate.
Using milligrams (0.85 mmol), tertiary
Tertiary-amyl alcohol instead of butanol7
The reaction was carried out in the same manner as in Example 4, except that 5 grams were used, the reaction temperature was changed to 100°C, and the reaction time was changed to 5 hours. No moisture was detected in isopropyl orthotitanate, but tertiary amyl alcohol contained 0.05% by weight of moisture.

Therefore, the amount of water brought into the reaction system is the amount of water brought into the reaction system.
) including the water contained in 0.052g (2
, 9 mmol), which was 0.03 times the molar amount of indole. After the reaction was completed, the reaction solution was filtered, and the product was washed with a small amount of turn-amyl alcohol and methanol, and then dried under reduced pressure at 50°C. The indigo yield was 10.6%, and the indigo yield per hour was The yield is 2.
It was 1%.

Comparative Example 7 In Example 12, an azeotropic composition mixture of tertiary-amyl alcohol and water (tertiary-amyl alcohol content: 72.0%) was used instead of tertiary-amyl alcohol.
The reaction was carried out in the same manner as in Example 12, except that 75 grams of the mixture having a water content of 5% by weight and a water content of 27.5% by weight were used. The amount of water brought into the reaction system is CH
The total amount of water contained in the P solution (al and the azeotropic composition mixture of tertiary amyl alcohol and water was 20
．． The amount was 64 grams (1147 mmol), which was 13.4 times the molar amount of indole. When the obtained reaction mixture was post-treated in the same manner as in Example 12, the indigo yield was 0.6%, and the indigo yield per hour was 0.1.
%, and as with other comparative examples, when the amount of water brought into the reaction system was large, the yield was low and the production rate was also slow.

Example 13 In Example 4, 6.48 grams (42.7 mmol) of 5-chloroindole was used instead of indole,
The reaction was carried out in the same manner as in Example 4 except that the amount of CHP solution (d3 was changed to 23.78 g (128.1 mmol in terms of cumene hydroperoxide). No water was detected in 5-chloroindole. Therefore, the amount of water brought into the reaction system was 0.085 g (4.7 mmol) including the water contained in the CHP solution (d) and tert-butyl alcohol, and 5
- 0.11 times the molar amount relative to chloroindole
After the reaction, the reaction solution was filtered, washed with a small amount of methanol, and dried under reduced pressure at 50°C to obtain 5,5', an indigo compound corresponding to 5-chloroindole.
-5.40 grams of dichloroindigo were obtained. Prepared 5
- The molar yield of 5,5'-dichloroindigo relative to chloroindole is 76.3%, which is 5.5% per hour.
The yield of '-dichloroindigo was 10.9%.

Example 14 In Example 4, 22.41 grams (170.8 mmol) of 6-methylindole was used instead of indole, and the amount of CHP solution (d) was 95.11 grams (512.4 grams in terms of cumene hydroperoxide). The reaction was carried out in the same manner as in Example 4 except that the amount was changed to (mmol). 6
- No moisture was detected in methylindole. Therefore, the amount of water brought into the reaction system was 0.113 grams (6.3 mmol), including the water contained in the CHP solution (d) and tert-butyl alcohol, and was 0.113 grams (6.3 mmol) relative to 6-methylindole. It was .04 times the molar amount. After the reaction, the reaction solution was filtered, washed with a small amount of methanol, and dried under reduced pressure at 50°C to convert 6°6'-dimethylindigo, an indigo compound corresponding to 6-methylindole, into 16 .77 grams were obtained. The molar yield of 6,6'-dimethylindigo based on the charged 6-methylindole was 68.1%, and the yield of 6,6'-dimethylindigo per hour was 9.7%.

(Effects of the Invention) According to the method of the present invention, indoles having no substituents at the 2- and 3-positions and an organic hydroperoxide are used as catalysts for groups 4, 5 and 6 of the periodic table. In the presence of a metal compound selected from the group consisting of This is an extremely effective method that can produce indigo compounds corresponding to the raw material indoles at a higher yield and reaction rate than the conventional techniques used or when the moisture introduced into the reaction system is not controlled. This is a method for producing indigo.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1) Indoles having no substituents at the 2- and 3-positions and an organic hydroperoxide are used as catalysts for group 4 of the periodic table.
The indoles are reacted in the presence of a metal compound selected from the group consisting of Groups 5 and 6, with the amount of water brought into the reaction system being reduced to 1 mole or less relative to the indoles. Corresponding method for producing indigo species. 2) The method according to claim 1, wherein the reaction is carried out in the presence of a solvent. 3) The method according to claim 2, wherein the solvent is a secondary or tertiary alcohol. 4) The method according to claims 1 to 3, wherein the reaction is carried out in the presence of an additive. 5) The method according to claim 4, wherein the additive is an organic carboxylic acid.