JPH029827A - Preparation of anilines substituted with cyano group and/or halogen atom and compound used for preparing the same compound - Google Patents

Abstract

PURPOSE:To provide an aniline compound useful as an important raw material for photosensitive materials, etc., by catalytically hydrogenating the corresponding aromatic nitro compound substituted with a cyano group and/or a halogen atom in the presence of a metal catalyst and melamine, etc. CONSTITUTION:A compound of formula I (R<1>-R<3> are H, halogen, CN, OH, NH2, alkyl, aryl, alkylcarbonyl, carbonyl, etc., but at least one of them is halogen, cyano or organic group containing the groups) is catalytically hydrogenated in the presence of a metal catalyst (preferably Raney Ni) and a compound of formula II (R<11>-R<16> are H, halogen, alkyl, aryl, alkylcarbonyl, etc.), under a hydrogen pressure of 1-30kg/cm<2> at 10-90 deg.C to provide the corresponding aniline compound. The presence of the compound of formula II prevents the side reactions such as the reduction of the CN group, the reactive elimination of the halogen atom, etc. A compound of formula III (J is -NHCONH-, etc.), is preferable as a raw material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing anilines substituted with -cyano groups and/or halogen atoms. The following relates to a method for producing the above-mentioned anilines by catalytic hydrogen reduction of an aromatic nitro compound.

[Prior art and problems to be solved by the invention] As is well known, anilines substituted with cyano groups and/or halogen atoms are important raw materials for producing photographic materials, dyes and pigments, pharmaceuticals, etc. It is. A common method for producing anilines substituted with cyano groups and/or halogen atoms is to reduce the corresponding nitro compounds, and the reduction method is as follows:
■Chemical reduction method using a metal such as iron or its salt and an acid such as hydrochloric acid, ■Chemical reduction method using hydrosulfide, ■Catalytic hydrogen reduction method in which it reacts with hydrogen gas in the presence of a metal catalyst, etc. It has been known.

However, when method (1) above is used, a large amount of sludge is generated, causing a pollution problem.In method (2), the reaction proceeds under alkaline conditions in the presence of NaOH, etc. Undesirable side reactions such as hydrolysis occur, and NaH5O produced as a result of the reaction
z may cause sulfonation of the amino group or aromatic ring of the product (Piria reaction), and
In this method, when attempting to selectively reduce only the nitro group using a raw material that has a substituent that is easily reduced, such as a cyano group or a halogen atom in addition to a nitro group, reduction of the cyano group and reductive elimination of the halogen atom occur. Because side reactions such as separation occur,
The desired anilines substituted with a cyano group and/or a halogen atom cannot be obtained in high yield.

Furthermore, JP-A-62-123162 discloses a technique for improving the selectivity to anilines by using cyanamide or dicyandiamide during catalytic hydrogen reduction of aromatic nitro compounds; Therefore, anilines substituted with cyano groups and/or halogen atoms are removed by catalytic hydrogen reduction from aromatic nitro compounds containing cyano groups and/or halogen atoms, which are more easily reduced than nitro groups. Currently, no industrially satisfactory process has been established for manufacturing it.

[Findings based on research] In view of the above-mentioned circumstances, the present inventors have conducted various studies, and as a result, the above-mentioned aromatic nitro compounds were subjected to catalytic hydrogen reduction in the presence of a metal catalyst such as Raney nickel or a platinum group metal. When producing anilines substituted with a cyano group and/or a halogen atom, if a compound represented by the following general formula (I [) is present in addition to the above metal catalyst, the general formula ( II) R11RIB (wherein RII, RIt, R13,R'', RI
S and RI& are each independently a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted alkylcarbonyl group, an optionally substituted arylcarbonyl group, optionally substituted alkylsulfonyl group,
or optionally substituted arylsulfonyl group, or R and RII, RII and R14, and RIS and RI6 each jointly represent a substituent consisting of a five-membered ring or a six-membered ring) It has been found that the side reactions of are suppressed, the selectivity to the anilines is significantly improved, and the target product, anilines, can be obtained in high yield.

[Means for solving problems]

The present invention was invented based on the above findings, and is directed to an aromatic nitro compound containing a cyano group and/or a halogen atom, which produces anilines substituted with a cyano group and/or a halogen atom in high yield. For the purpose of providing a catalytic hydrogen reduction method, an aromatic nitro compound represented by the following general formula [I] is prepared as follows: each independently a hydrogen atom, a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), provided that each represents a halogen atom, a cyano group, or an organic group containing a halogen atom and/or a cyano group; , cyano group, hydroxyl group, optionally substituted, i.e. substituted or unsubstituted, amino group (e.g. amino group, methylamino group, (3-cyano-4-chlorophenyl)ureido group), Optionally substituted alkyl groups (e.g. methyl, hydroxymethyl, benzyl), optionally substituted aryl groups (e.g. phenyl, tolyl), optionally substituted alkylcarbonyl groups (e.g. acetyl) a trichloroacetyl group), an optionally substituted arylcarbonyl group (e.g. benzoyl group), a sulfonic acid group, a carboxyl group, an -OR group, or a -5R group, and R is an optionally substituted alkyl group. groups (e.g. methoxycarbonylmethyl), optionally substituted aryl groups (e.g. P-methoxyphenyl), or optionally substituted heterocyclic groups (e.g. benzothiazolyl,
catalytic hydrogen reduction in the presence of a metal catalyst (representing a tetrazolyl group) and a compound represented by the following general formula [II]. "R" and R
I& is each independently a hydrogen atom, a halogen atom (
fluorine atom, chlorine atom, iodine atom), optionally substituted alkyl groups (e.g. methyl group, ethyl group, butyl group, allyl group, methoxymethyl group, cyclohexyl group, ethanesulfonic acid group, benzyl group, p- (aminobenzyl group), optionally substituted aryl groups (e.g. phenyl group, tolyl group, benzenesulfonic acid group), optionally substituted alkylcarbonyl groups (e.g. acetyl group, trichloroacetyl group), optionally substituted an optionally substituted arylcarbonyl group (e.g. benzoyl group), an optionally substituted alkylsulfonyl group (e.g. methanesulfonyl group, aminoethanesulfonyl group), or an optionally substituted arylsulfonyl group (e.g. phenylsulfonyl group) , p-aminophenylsulfonyl group), or RII and Rlz R'3 and R'' and RIS and R'' each jointly represent a five-membered ring or a six-membered ring (e.g. virol ring, pyrrolidine ring). , a piperidine ring, a morpholine ring), which is substituted with a cyano group and/or a halogen atom.

[Detailed description of the invention]

Among the aromatic nitro compounds represented by the general formula [I], the compounds represented by the following general formula [VI] are selected as particularly suitable from the viewpoint of selectivity to the desired product and yield. Ru.

General formula [I'] (wherein R4, R4, R7, R1 and R9 represent a halogen atom, a cyan group, or an organic group containing a halogen atom and/or a cyano group) , all have the same meanings as R', R'' and R3 above, and J is a divalent group (e.g. ethylene group, -NHCONH--NIICO- and -0C1hCH1-1, of which -NICONH- and - NHCO- is preferred, -NlIC0NH- is particularly preferred).

Specific examples of the aromatic nitro compound of the general formula (1) or [VI] used as the starting material of the present invention are shown below.

N r f SO:+H ■-10 H ■-11 ocuzco□C1h ■-15 O1+ H 0011□CO,C)If H H ■-14 H ■-18 r ■-19 H ■-23 ■-27 H ■-28 ■ ■-24 H ■-25 H CI! IhS ■-26 H 3GHzGHzCOJ ■-30 ■-31 ■ next, The general formula (II) Compound represented by A specific example is shown below.

HK ■5 ■-8 Hz NIIGOCF: 1 ■-11 ■-14 ■-12 ■-13 The metal catalysts include Ni, Pd, Pt, Rh.
, Ir+Ru, Os, Co as a simple substance or oxide,
It can be used as a halide, other inorganic salt, or organic salt, or these catalyst components can be supported on a carrier such as carbon or an inorganic salt, but from the viewpoint of reaction selectivity, cost, and ease of handling, , in particular Raney nickel is chosen.

When using the Raney nickel, there are no particular restrictions on its type, activity, and development method, and commercially available developed Raney nickel, which can be easily made and handled by hand, may also be used. There is no particular restriction on the amount used, but it is generally used in the range of 0.1 to 10 parts, usually 0.1 to 3 parts, per 100 parts (parts by weight, the same applies hereinafter) of the aromatic nitro compound as the starting material. The same holds true for other metal catalysts.

The solvent used for the nitro compound may be water, an inert solvent, or a mixture thereof; examples of the inert solvent include aliphatic alcohols such as methanol, ethanol, propatool, dioxane, and tetrahydrofuran. Ethers such as (THF), aprotic polar solvents such as dimethylformamide, dimethylacetamide, and dimethylsulfoxide, and aromatic hydrocarbon solvents such as benzene, toluene, xylene, and chlorobenzene can be used.

The amount of these solvents used is preferably 0.5 to 20 parts per 1 part of the raw material nitro compound. The compound represented by the general formula [II] added to the reaction system together with the metal catalyst may be added as is, or may be added after being dissolved or suspended in the above solvent. The amount used is 0.1 to 10 parts, more preferably 0.1 to 10 parts, per 100 parts of the nitro compound.
．． 1 to 5 parts.

The reaction is usually carried out in a hydrogen atmosphere under a hydrogen pressure of 1 to 30 kg/ci.

The reaction temperature can vary over a wide range, but is usually 10-90°C.
temperature is selected.

The reaction time varies depending on the reaction temperature, solvent, hydrogen pressure, amount of catalyst, and type of raw materials, but usually 8 hours or less is sufficient.

Since there are very few side reactions, the progress of the reaction can be easily checked by measuring the amount of hydrogen absorbed into the reaction system, and there is no need for complicated operations and dangerous sampling.

After the stoichiometric amount of hydrogen has been absorbed, the catalyst can be separated off and the solvent removed to isolate the desired aniline substituted with a cyano group and/or a halogen atom.

The target compound thus obtained generally has sufficient purity, but may be purified by recrystallization, solvent washing, etc., if desired. Further, after the reduction reaction is completed, the aniline can be used in a subsequent predetermined reaction in a solution form without removing the solvent after the catalyst is oxidized.

〔Example〕

Next, the present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 THF240 in a stainless steel autoclave with a capacity of 1β
ml, water 53n/! , Raney nickel 5.0g, melamine 1. Og and 26.6 g of 2-(3-cyano-4-chlorophenyl)ureido-5-nitrophenol were charged and the contents of the autoclave were stirred at 30°C for 7 hours under a hydrogen pressure of 20 kg/c+fi. The catalytic reduction reaction was carried out by After confirming that the theoretical amount of hydrogen was absorbed into the reaction mixture, the autoclave was opened and the catalyst was separated from the reaction mixture.

When the reaction solution separated from the catalyst was analyzed by high performance liquid chromatography, the reaction solution was found to be 2(3-cyano-
4-Chlorphenyl)ureido 5-aminophenol 9
It had a composition of 7.3% (area %, hereinafter the same) and 2.7% of other components (impurities).

After removing the solvent from the above reaction solution, the residue was
! When washed with ethanol and dried, the above 2-
(3-Cyano-4-chlorophenyl)ureido-5-aminophenol was obtained in the form of pale pink crystals with a melting point of 223-226°C (95% yield).

Example 2 The 2-(3-cyano-4-chlorophenyl)ureido-5-ditrophenol used in Example 1 was modified with the exception that 25.2 g of 2-chloro-5-nitropentunitrile was used. , the reaction was carried out according to the same procedure as in Example 1.

When the composition of the reaction solution was examined by gas chromatography, the reaction solution contained 94.5% of 2-chloro-5-aminobenzonitrile and 5.5% of impurities.

After removing the solvent from the reaction solution, the residue was recrystallized from toluene to obtain 2-chloro-5-aminobenzonitrile in the form of a white powder with a yield of 91%.

Example 3 300 mf of water in a stainless steel autoclave with a capacity of 12
, by charging 5.0 g of Raney nickel, 1.0 g of melamine, and 27.3 g of 2-chloro-4-nitroaniline, and stirring the contents of the autoclave at 30'C for 7 hours under a hydrogen pressure of 20 kg/cffl. carried out the reaction. After confirming that the theoretical amount of hydrogen was absorbed into the reaction mixture, the autoclave was opened to separate the catalyst from the reaction solution.

When the composition of the reaction solution was examined by gas chromatography, the reaction solution contained 93.5% of 2-chloro-p-phenylenediamine and 6.5% of impurities. After removing the solvent from the reaction solution, purification results in a melting point of 63-67
The above phenylenediamine was obtained in the form of a brown solid with ゛C (yield 90%).

Comparative Example 1 The reaction was carried out in the same manner as in Example 1, except that melamine was not used and the reaction time was 4 hours. When the composition of the reaction solution was investigated by high performance liquid chromatography, it was found that the reaction solution contained 44.6% of 2-(3-cyano-4-chlorophenyl)ureido-5-aminephenol and 55.4% of other components. there was.

Example 4 5% instead of 5.0g of Raney nickel as a metal catalyst
Except that 2.0 g of Pd/C (water content 50%) was used.
The reaction was carried out according to the same procedure as in Example 1. As a result of examining the composition of the reaction solution by high-performance liquid chromatography, the reaction solution consisted of 90.5% of 2-(3-cyano-4-chlorophenyl)ureido-5-aminophenol and 9.5% of impurities. there were.

After removing the solvent from the reaction solution, the residue was washed with 30 ml of ethanol to obtain the amine phenol in the form of pale pink crystals with a melting point of 222-225°C (
yield 83%).

Example 5 In place of 2-(3-cyano-4-lylorphenyl)ureido-5-nitrophenol used in Example 1, 2-(
The reaction was carried out according to the same procedure as in Example 1, except that 26.6 g of 4-cyanophenyl)ureido-4-chloro-5-nitrophenol was used. When the composition of the reaction solution was investigated by high performance liquid chromatography, it was found that this reaction solution contained 97.8% of 2-(4-cyanophenyl)ureido-4-chloro-5-aminophenol and 2 impurities.
．． It was found that it consisted of 2%. After removing the solvent from the reaction solution, the residue was washed with 30 ml of ethanol and dried to obtain the aminophenol in the form of pale pink crystals with a yield of 94%.

Comparative Example 2 TIIF24 in a stainless steel autoclave with a capacity of 12
0mf, 53m2 of water, 5.0g of Raney nickel.

dicyandiamide 0.67 g, 2-(3-cyano-4
-chlorphenyl)ureido-5-nitrophenol 2
6.6 g was charged and under a hydrogen pressure of 20 kg/cd,
The reaction was carried out by stirring the contents of the autoclave at 30°C for 3 hours. After confirming that the theoretical amount of hydrogen was absorbed into the reaction mixture, the autoclave was opened and the catalyst was removed from the reaction mixture.

When the reaction solution separated from the catalyst is analyzed by high performance liquid chromatography, the composition of the reaction solution is 2-(3
-cyano-4-chlorophenyl)ureido-5-aminophenol 87.6% and impurities 12.4%.

Example 6 62.8 g of 2'-chloro-5'-nitro-1-(4-methoxybenzoyl)acetanilide are dissolved in 1.82 THF in a reactor, and 100 mf of water and 3.27 g of melamine are dissolved therein. After adding 12.4 g of Raney nickel and 12.4 g of Raney nickel, the acetanilide was hydrogenated at room temperature and pressure for 6 hours while stirring the mixture.

After the theoretical amount of hydrogen has been absorbed, the catalyst is separated from the furnace and the separated reaction solution is analyzed by high performance liquid chromatography.The reaction solution is 5'-amino-2'-chloro-1-
It had a composition of 99.2% (4-methoxybenzoyl)acetonilide and 0.8% of other components (impurities).

After concentrating the above reaction solution to remove the solvent, the residue was
When dissolved in 0 ml of acetonitrile and recrystallized,
55.4 g (yield 96.6%) of crystals with a crystal purity of 99.96% (determined by liquid chromatography) were obtained.

Comparative Example 3 2'-Chloro-5 in 360 mff1 THF in a reactor
After dissolving 12.6 g of '-nitro-1-(4-methoxybenzoyl)acetanilide and adding 20 m2 of water and 2.5 g of Raney nickel, the above acetanilide was dissolved at normal temperature and pressure while stirring the mixture. to 4
Hydrogenation was carried out for an hour.

When the reaction solution separated from the catalyst was analyzed by high performance liquid chromatography, the reaction solution was found to be 5'amino-2'
It had a composition consisting of 49.7% -chloro-1-(4-methoxybenzoyl)acetanilide and 50.3% other components, and oxime, which is a raw material and a nitro group reduction intermediate, was not detected.

Comparing the Examples and Comparative Examples shown above, in Examples 1 to 6, in which the compound represented by the general formula (n), which was particularly adopted in the present invention, was present in the reaction system, such Comparative Examples 1 and 3, in which no compound was used, and Comparative Example 2, in which dicyandiamide, which was added for the same purpose, was used instead of the compound of general formula (II), produced a product with significantly less impurities. It can be seen that the selectivity to the target anilines was significantly improved.

〔Effect of the invention〕

As is clear from the above description, according to the present invention,
By catalytic hydrogen reduction using an aromatic nitro compound containing easily reducible substituents such as a cyano group and/or a halogen atom in its molecule as a starting material, the anilines corresponding to the nitro compound are reduced by suppressing the formation of by-products. It can be produced with high yield.

Claims (3)

[Claims] (1) An aromatic nitro compound represented by the general formula [I] below, general formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^1, R^2 and R^3 are , each independently a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, optionally, with the proviso that at least one of them represents a halogen atom, a cyano group, or an organic group containing a halogen atom and/or a cyano group. Substituted amino group, optionally substituted alkyl group, optionally substituted aryl group, optionally substituted alkylcarbonyl group, optionally substituted arylcarbonyl group, sulfonic acid group, carboxyl group group, -OR
or -SR group, and R represents an optionally substituted alkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group) Metal catalyst and the following general formula General formula [II] characterized by catalytic hydrogen reduction in the presence of the compound represented by [II] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^1^1, R^1^ 2, R^1^3, R^1
^4, R^1^5 and R^1^6 each independently represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted aryl group, and an optionally substituted aryl group. represents an alkylcarbonyl group, optionally substituted arylcarbonyl group, optionally substituted alkylsulfonyl group, or optionally substituted arylsulfonyl group, or R^1^1 and R^
1^2, R^1^3 and R^1^4, and R^1^5 and R^1^6 each jointly represent a substituent consisting of a five-membered ring or a six-membered ring) A method for producing an aniline substituted with a cyano group and/or a halogen atom. (2) The aromatic nitro compound has the following general formula [I
′] is a compound represented by the general formula [I ′] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^4, R^5, R^7, R^8 and R^9
is any of the above R^, provided that at least one of them represents a halogen atom, a cyano group, or an organic group containing a halogen atom and/or a cyano group.
1, R^2 and R^3, and J represents a divalent group) The manufacturing method according to claim (1). (3) Catalytic hydrogen production for producing anilines substituted with a cyano group and/or a halogen atom from the aromatic nitro compound represented by the above general formula [I] or [I'] in the presence of a metal catalyst. The general formula [II] as a side reaction inhibitor used together with the metal catalyst in reduction
A compound represented by