JPS5940389B2 - Method for producing benzimidazolone - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing benzimidazolones.

As is well known, benzimidazolone is widely used as an intermediate for dyes, pigments, etc., and as a raw material for resins. Conventionally, the method of reacting 0-phenylenediamine hydrochloride with excess phosgene in toluene, It is produced by a method in which 0-phenylenediamine and urea are reacted in an organic solvent or an aqueous solvent at a temperature of around 150°C.

However, the production of 0-phenylenediamine, the starting material in these methods, requires a number of steps such as nitration of chlorobenzene, ammonorinsing, and reduction, resulting in high production costs of benzimidazolones and ,
The yield is also low. To solve the above problem, we have already used 0−
A method for producing benzimidazolones by reacting dichlorobenzene, aqueous ammonia, and alkaline earth metal carbonate or bicarbonate in the presence of a monovalent copper salt catalyst containing metallic copper has also been proposed. (・Ruga (Unexamined Japanese Patent Publication No. 50-1123)
No. 67), continuous use is difficult due to the combined use of metallic copper, and a portion of the catalyst changes to divalent copper salt after the reaction is completed, so there is a problem in circulating and reusing the catalyst. .

Therefore, this method was improved by reacting 0-dichlorobenzene, ammonia aqueous solution, and urea or ethylene carbonate in the presence of a monovalent or divalent copper salt catalyst, thereby making it possible to recycle and reuse the catalyst. (Japanese Unexamined Patent Publication No. 54-24873) has also been proposed, but it requires a long time for the reaction and
Post-treatment after the completion of the reaction is complicated, and the yield is still unsatisfactory. The present invention was made in order to solve the various problems described above, and it is possible to produce highly pure benzimidazolone from 0=nitroaniline, and the catalyst can be easily recovered and reused, and furthermore, The purpose of the present invention is to provide a method for producing benzimidazolone that takes a short time and allows easy post-treatment after the reaction. The method for producing benzimidazolone according to the invention is characterized in that 0-nitroaniline is reacted with carbon monoxide in water or an organic solvent containing water in the presence of a base and selenium. The selenium used in the present invention is preferably powdered selenium, and general commercially available products can be used as they are.

The reaction rate increases as the amount of selenium used increases, but it is usually 0.1 to 2 mol, preferably 0.5 to 1 mol, per 1 mol of 0-nitroaniline, and especially beyond this range. There is no need to use large amounts. Although the present invention is not limited to any theory, selenium reacts with carbon monoxide in the presence of a base to form carbonyl selenide (SeC0), which further reacts with water to form hydrogen selenide, and this selenium It is thought that hydrogen chloride is dissolved in water as a base salt.

Note that this hydrogen selenide appears to produce metallic selenium when 0-nitroaniline is reduced, but as mentioned above, it is thought that it quickly returns to hydrogen selenide again, and the reaction system is substantially homogeneous. As the base, inorganic bases such as carbonates, bicarbonates, hydroxides, and oxides of alkali metals and alkaline earth metals, and organic bases such as amines are used.

Specific examples include potassium carbonate, potassium hydroxide, sodium hydroxide, triethylamine, pyridine, dimethylformamide, N-methylpyrrolidine, etc., but preferably an organic base is used. The amount of the base to be used is not particularly limited, but is usually about 1 to 3 mol, preferably about 2 to 2.5 mol, per 1 mol of o-nitroaniline. In the present invention, water participates in the reaction with selenium as described above, and is usually used in excess of selenium. Therefore, in the present invention, water can be used both as a reaction reagent and as a solvent. However, in order to obtain benzimidazolones in high yields, it is desirable to carry out the reaction in an organic solvent containing water.

Any organic solvent can be used as long as it does not adversely affect the reaction, especially one that is not reduced by hydrogen selenide, including ethers, amides, amines, and aromatic hydrocarbons. One or a mixture of two or more of hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, etc. may be optionally used.Specifically, tetrahydrofuran, dioxane, diethyl ether, dimethylformamide, dimethylacetamide, triethylamine, pyridine, N-methylpyrrolidine, benzene, hexane, etc. are used, but among these, polar organic solvents are preferably used.As is clear from the above, in the present invention, the above-mentioned organic bases are also used as solvents.Organic The water content in the solvent is usually 1 to 100 times mole relative to selenium, preferably 2 to 30 times mole.

However, this water content is not necessarily critical. The reaction of the present invention is carried out in a carbon monoxide atmosphere, and the pressure is usually 1 to 50 k9/Cd, preferably 3 to 30 kg/Cd.
d, particularly preferably 5 to 10 kg/Cd.

In addition, the reaction temperature is not particularly limited, but is usually room temperature to
The temperature is 100°C, preferably 50 to 80°C, and the time required for the reaction is usually within 10 hours, and is completed in about 3 hours in many cases. In the method of the present invention, as described above, the reaction thread is substantially in a solution state, but when air is passed through the reaction mixture after the reaction is completed to decompose the dissolved selenium compound, red amorphous selenium is produced. After that, black metallic selenium is precipitated. Separate this metallic selenium,
After washing, the washing solution and the sap after separating the metal selenium are combined, and the solvent is distilled off to obtain benzimidazolone. The benzimidazolones thus obtained are usually of such high purity that recrystallization is not required. If recrystallization is required, it may be recrystallized from water, for example. Method of the Invention As described above, o-nitroaniline is reacted with carbon monoxide in water or a water-containing organic solvent in the presence of a base and metallic selenium, and has the following advantages.

(a) All necessary raw materials, including o-nitroaniline, can be obtained easily and inexpensively.

(b) In preferred cases, highly pure benzimidazolone can be obtained almost quantitatively, and undesirable side reactions do not substantially occur.

(c) After completion of the reaction, metallic selenium can be quantitatively and easily recovered and can be recycled and reused as is.

(d) The reaction system is substantially homogeneous, and the reaction operation and post-treatment after the reaction is simple. (e) The reaction conditions are mild and the time required for the reaction is short.

Examples of the present invention are listed below.

Example 1 0-nitroaniline 0.697 (5mm01), metal selenium powder 0.207 (2.5mm01), water 0.66y
(36.6 mm01), triethylamine 5 m1 (36
mm01) and 20ml of tetrahydrofuran were charged into an autoclave with a capacity of 100WLI under a nitrogen stream, and after sufficient replacement with carbon monoxide, the carbon monoxide pressure was reduced to 5k9/Cd.
And so.

After heating the inside of the autoclave to 80°C and stirring for 3 hours, the autoclave was cooled to room temperature and carbon monoxide was removed.

The reaction mixture was then stirred in air for about 20 minutes,
Metallic selenium was precipitated, separated ▲, and washed with methanol. This washing solution was combined with the washing solution, and the solvent was distilled off to obtain 0.637 g of benzimidazolone in the form of silvery white flakes (94.4% theoretical yield based on 0-nitroaniline). The purity of this benzimidasolone was 97.6% as a result of high performance liquid chromatography. Example 2 Except for using metallic selenium 0.407 (5mm01),
Benzimidazolone 0.66 was prepared in exactly the same manner as in Example 1.
7 (theoretical yield 99.0%) was obtained.

Example 30-nitroaniline 0.69y (5mm01
), metallic selenium powder 0.40y (5mm01), triethylamine 5ml (36.6mm01) and water 40ml
was placed in a 100ml autoclave under a nitrogen stream, and after sufficiently replacing it with carbon monoxide, the carbon monoxide pressure was reduced to 10
k9/Cd.

After heating the inside of the autoclave to 80°C and stirring for 4 hours, the same treatment as in Example 1 was carried out to obtain 0.3% of benzimidazolone.
9y (theoretical yield 67.3%) was obtained.

In addition, in the above method, the carbon monoxide pressure is set to 30k9/C.
It was found that the yield of benzimidazolone was improved by increasing the reaction time and increasing the reaction time. Example 4 Benzimidazolone 0
．． 50f7 (theoretical yield 75.0%) was obtained.

Claims (1)

[Claims] 1. A method for producing benzimidazolone, which comprises reacting o-nitroaniline with carbon monoxide in water or an organic solvent containing water in the presence of a base and selenium.