JPS5946508B2 - Method for producing 2-mercaptobenzimidazole compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a 2-mercaptobenzimidazole compound, and more specifically, the present invention relates to a method for producing a 2-mercaptobenzimidazole compound, and more specifically, a method for producing a 2-mercaptobenzimidazole compound. 0.5-2.5 per mole
2-Mercaptobenzimidazole (hereinafter abbreviated as 2-MB) characterized by reacting with carbon disulfide in the presence of a gram equivalent of alkali hydroxide in the presence or absence of a surfactant. It relates to a method for producing a compound.

It is well known that 2-MB can be obtained by reacting OPD with carbon disulfide.

Industrially, 2-MB is obtained by reducing 0-nitroaniline and then reacting the generated OPD with carbon disulfide. However, in this PB method, after reduction to OPD, the reaction with carbon disulfide takes 16 hours. and the theoretical yield based on OPD is as low as 75-80%.

Furthermore, since 0-nitroaniline is reduced with sodium sulfide, the crude product contains impurities such as sodium thiosulfate and sulfur, so this is dissolved in alkali, treated with activated carbon, and reprecipitated with acid. A purification step is required. A method that provides a relatively good yield is to react OPD and carbon disulfide in an ethanol solution in the presence of potassium hydroxide, and after treatment with activated carbon, neutralize with acetic acid (Org, Synth, Coll. , Vol.

(2), 569), but since this method uses ethanol as a solvent, recovery is expensive and it is difficult to adopt it as an industrial method for producing 2-MB. It has been reported that when 2-MB is synthesized by reacting 0PD and carbon disulfide in a solvent, the time required to complete the reaction can be shortened by performing the reaction in the presence of quaternary ammonium hydroxide ( Japanese Patent Publication No. 51-17552), in this case, the example exemplifies the reaction of o-toluene amine containing 4.4% isomer instead of 0PD with carbon disulfide, and the addition time of carbon disulfide is 75 ~135 minutes, total reaction time ~125 minutes
Weight yield based on o-toluenediamine in 340 minutes: 9
Methylbenzimidazole-2-thiol was obtained with a yield of 2.7 to 100% (theoretical yield 69.0 to 74.4% based on 0-toluenediamine). The present inventors also tried this method, but the yield was In terms of yield, the yield was as low as described, and the product was found to be colored brown.Moreover, since the solvent is limited to organic liquids, recovery is still expensive.On the other hand, JP-A-48- According to 78170, o-
A method has been proposed in which 0PD containing 2% impurities obtained by catalytically hydrogenating nitroaniline is used by simple distillation, and 0PD is reacted with carbon disulfide using benzothiazole as a solvent. The solvent used is benzothiazole, which is a special solvent, and is too expensive to be used for industrial purposes.Furthermore, the reaction conditions are harsh, at 130°C and under pressure, and after the reaction, benzothiazole, etc. The tedious method of extracting the organic layer with alkali, washing it with xylene, and neutralizing it to obtain 2-MB is used. 〇2-MB was thought to dissolve in the form of an alkali salt in an alkaline aqueous solution, but this study The inventors previously studied the reaction between 0PD and carbon disulfide in an aqueous medium in the presence of an alkali, and found that 0% alkali hydroxide was added to 1 mole of 0PD.
．． It was found that when 5 to 2.5 gram equivalents were used, 2-MB could be obtained in a free form at an extremely high yield. As a result of further investigation, the present inventors found that 2-MB can be obtained in the form of the general formula (1). Surprisingly, it was discovered that 0PD-based compounds react with carbon disulfide to obtain 2-MB-based compounds in extremely high yields even when using the 0PD-based compounds represented by the formula, and the present invention was completed.〇This invention When using this method, a high-purity product can be obtained by a simple operation of heating the 0PD compound and carbon disulfide in the presence of alkali hydroxide in an aqueous medium, reacting, filtering, and washing with water. No steps are required.

Moreover, the yield is far superior to any conventionally known method. The OPD compound in the method of the present invention is expressed by the general formula (1) [In the general formula (1), Rl, R
2, R3 and R4 are a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 12 carbon atoms, or a nitro group, and may be the same or different from each other.

However, except for the case where Rl, R2, R3 and R4 are hydrogen atoms at the same time, a compound represented by the following is used.

Specifically, examples of OPD-based compounds include those having the following substituents as nuclear substituents of OPD.

3- or 4-chloro, bromo or iodo; 4-fluor; 3,4-, 3,5-, 3,6- or 4,5-
Dichlor or dibrome; 3,5-difluoro- or short: 3,4,6-trichlor: 4-brome-
3,5-dichloro; 3,4,5,6-tetrachlor or tetrafluoro; 3-methyl or ethyl; 4-
Methyl, ethyl, isopropyl, n-butyl, Sec-
Butyl, t-butyl, isobutyl t-amyl or dodecyl: 3,4-, 3,5-, 3,6- or 4,5
-dimethyl; 4,5-diethyl; 4-ethyl-5-propyl; 3,4,5-trimethyl; 4-ethyl-3,5,
6-trimethyl; 4-methoxy or ethoxy; 3,
6-dimethoxy, diethoxy, dipropoxy or dibutoxy; 4,5-dimethoxy, diisopropoxy or dibutoxy: 3,4,5-trimethoxy; 3,4
,6-trimethoxy:4-nitro;3,5- or 4,
5-dinitro: 5-bromo-3,4-dimethyl; 3,4
-dichloro-5,6-dimethyl; 3,5-dichloro-4
,6-dimethyl;4-chloro-3-methoxy;5-bromo-3-methoxy:4-chloro-5-methoxy;4-chloro-5-nitro;5-isopropyl-3,4-dimethoxy;3,6 -dimethyl-4-nitro; 3-methoxy-
5-nitro; 4-methoxy-6-nitro; 5-methoxy-3-nitro: 5-ethoxy-3-nitro The alkali hydrosulfides used in the method of the present invention are specifically sodium hydroxide and potassium hydroxide. , lithium hydroxide and ammonium hydroxide, preferably 0.5 to 2.5 gram equivalent per mole of the 0PD compound, preferably 0.6 to
Use 1.8 gram equivalents.

If the amount of alkali hydroxide used is less than this, the reaction rate will be very slow and the yield will be low.If more than this is used, the generated 2-MB compound will be in the form of an alkali salt in the aqueous medium. In order to extract it, it is necessary to neutralize it with an inorganic acid such as sulfuric acid or hydrochloric acid, or an organic acid such as acetic acid. In the method of the present invention, the amount of carbon disulfide used is 1. If carbon disulfide is used in excess of 0 to 2.0 molar ratio, preferably 1.1 to 1.5 molar ratio, recovery becomes a problem.Water is generally used as the aqueous medium, but In some cases, it is also possible to contain a water-miscible solvent such as alcohol in an amount equivalent to that derived from the raw material OPD-based compound.

The amount of the aqueous medium to be used is 2 to 10 times, preferably 3 to 6 times, the amount of the 0PD compound.If it is less than this, stirring will be difficult due to a heterogeneous reaction, and if it is more than this, the reaction will occur. The process of the present invention generally does not require additives, but in some cases cationic surfactants such as lauryltrimethylammonium chloride, anionic surfactants, etc. may be used as additives. An ionic surfactant, such as sodium dialkyl sulfosuccinate, or a nonionic surfactant, such as sorbitan monooleate, is added to the O-PD compound at a concentration of 0.
When about 1 to 20 (f) is added and reacted, about 40 to 45
Since the reflux time of carbon disulfide at °C can be shortened, foaming can be suppressed, or the crystal form can become dense, the reaction can be carried out at a higher concentration in some cases.General Embodiments of the Invention For example, an 0PD compound, an alkali hydroxide (or its aqueous solution), and water are placed in a reaction vessel equipped with a stirrer, a cooler, and a thermometer, and carbon disulfide is added dropwise while stirring.

When heated gradually, carbon disulfide refluxes at 40 to 50°C, but the reflux stops in about 30 minutes to 1 hour, and the temperature starts to rise again.Then, the temperature is gradually heated to 90°C. Generally, the temperature is raised to 90°C after sufficient reaction at 60 to 70°C.Of course, at this time, 90°C
It is also possible to raise the temperature to 0C. Therefore, the reaction is completed in a short time of 1 to 3 hours from the start of heating until the temperature reaches 90°C. Even if the reaction is stopped at 70℃ midway, 2
-MB derivatives can be obtained in a considerable yield, but at this time there is still some unreacted 0PD derivatives, so it is better to raise the temperature to 90°C to obtain more favorable results.
A very high purity 2-MB compound can be obtained by filtering the reaction product at room temperature to 90°C, washing and drying it. Note that the furnace solution is alkaline, so neutralize it with sulfuric acid, hydrochloric acid, etc. However, since hydrogen sulfide is generated at this time, after the reaction, the reaction can be neutralized with an acid such as sulfuric acid or hydrochloric acid to drive out the hydrogen sulfide, and then filtered at room temperature to 90°C. During this neutralization, the precipitated crystals are accompanied by the generated hydrogen sulfide, resulting in intense foaming, but foaming can be suppressed by adding a surfactant such as sodium dialkyl sulfosuccinate. be able to. Of course, it is also effective to add a surfactant to the reaction system from the beginning. Hydrogen sulfide generated during the reaction and neutralization can be absorbed into an aqueous sodium hydroxide solution and used as sodium bisulfide or sodium sulfide. In the method of the present invention, it is colored black and brown without being purified as an 0PD compound. When using a crude 0PD compound, a highly pure 2-MB compound can be obtained, but in some cases it may be colored light brown, so in this case an alkali should be added. Alternatively, a colorless 2-MB compound can be easily produced by dissolving the crude product taken out again in alkali and treating it with activated carbon, and then acidifying the solution with an inorganic acid such as sulfuric acid or hydrochloric acid, or an organic acid such as acetic acid. 0 obtained by also 0P obtained by sodium sulfide reduction
The D-based compound contains water-soluble impurities, but since it reacts in an aqueous medium in the method of the present invention, it has no effect and can be used as a raw material 0PD-based compound. In addition, in the method of the present invention, The 2-MB compound produced is important as an anti-aging agent for rubber or a stabilizer for polymer compounds. Next, the present invention will be specifically explained with reference to Examples.

Example 1: By-produced during the production of m-tolylenediamine.

-Tolylene diamine mixture (this one contains 53.801% of 3,4-tolylene diamine), 45.4% of 2,3-tolylene diamine, 0.6% of m-tolylene diamine, and other impurities (contains 0.2%) 61.19, 95
A mixture of 21.1% sodium hydroxide 21.1f11 sodium dialkyl sulfosuccinate and 4001LI of water was placed in a flask with an internal volume of 11, and carbon disulfide 5
0.09 was added dropwise for about 1 hour.After heating to 60℃, stirred at 60-70℃ for 2 hours.Finally, 9
After raising the temperature to 0℃, add 24.5% sulfuric acid 100% at the same temperature.
9 was added dropwise to neutralize it. The precipitate that had separated out was heated and washed with 500 d of water. The weight of the wet abyss mass is 147.9
f10 Drying at 90°C gives a mixture of 4-methyl-2-mercaptobenzimidazole and 5-methyl-2-mercaptobenzimidazole 80.7f! Obtained o yield 9
8.30t). Mp295-310°C. Example 2 4-Chlor-0PD 71.89, 49.6% sodium hydroxide 40.4f11 sodium dialkyl sulfosuccinate 0.0759 and water 3001 LI were mixed and heated to 35°C.

At the same temperature, 50.09% of carbon disulfide was dropped.As the carbon disulfide was dropped, the color of the liquid changed from brown to light brown to blackish brown, and the temperature rose to 43.
After about 30 minutes of dropping the carbon disulfide, which started to generate a lot of gas and bubbled a little at around ~46°C, it was gradually heated to 60°C and heated to 200M of warm water. After adding 1, the mixture was stirred at 60 to 70°C for 2 hours, and finally the temperature was raised to 90°C. The precipitated crystals were filtered at 80°C, and 10
00! The weight of the zero-wet abyss mass pre-cleaned with ILe is 118.1
Dry at 9090°C for 20 hours to obtain 5-chloro-2-MB9.
l. The theoretical yield based on 04-chloro-0PD obtained with 39 was 98.9% 0mp295-7°C. Example 3 The reaction and post-treatment were carried out in exactly the same manner as in Example 1, except that 29.59 95% potassium hydroxide was used instead of 21.19 95% sodium hydroxide in Example 1, and 4-
Methyl-2-mercaptobenzimidazole and 5-
Mixture of methyl-2-mercaptobenzimidazole 8
0.39 was obtained.

Yield 97.8%. Mp275-285℃0 Example 4 Concentrated ammonia water with a concentration of 25 (Ft) 34.19 instead of 95% sodium hydroxide 21.19 in Example 1
The reaction and post-treatment were carried out in exactly the same manner as in Example 1, except that 78.89% of a mixture of 4-methyl-2-mercaptobenzimidazole and 5-methyl-2-mercaptobenzimidazole was obtained.

Claims (1)

[Claims] 1 General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) [General formula (
In I), R_1, R_2, R_3, and R_4 are the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group, or a nitro group, provided that R_1, R_2, R_3, R_
4 is a hydrogen atom at the same time]
- Phenylenediamine compound in an aqueous medium, 0.5 to 2.0% per mole of O-phenylenediamine compound.
A method for producing a 2-mercaptobenzimidazole compound, which comprises reacting it with carbon disulfide in the presence of 5 gram equivalents of an alkali metal hydroxide or ammonia, in the presence or absence of a surfactant.