JPS5946507B2 - 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, to a method for producing a 2-mercaptobenzimidazole compound, and more specifically to a method for producing a 2-mercaptobenzimidazole compound, and more specifically, a method for producing a surface-activated 0-phenylenediamine (hereinafter abbreviated as OPD) compound in the presence of a base in an aqueous medium. In the presence or absence of an agent,
When producing a 2-mercaptobenzimidazole (hereinafter abbreviated as 2-MB) type compound by reacting carbon disulfide, the 0PD type compound is added in a liquid state to an aqueous medium, dispersed, and then reacted. , or a method for producing a 2-MB compound, characterized in that the reaction is carried out while being dispersed.

2-MB has traditionally been well known as an anti-aging agent for rubber, but in recent years 2-MB has been added to polymer compounds, especially polyamides.
It has been found that the stability against heat etc. can be improved by adding substances such as
.

However, when 2-MB is added to polyamide, etc., the quality of 2-MB, which has been conventionally used as a rubber chemical, is insufficient in terms of quality. Uncolored quality is required. 2-MB has conventionally been synthesized industrially by reducing O-nitroaniline and then reacting the generated 0PD with carbon disulfide (PB-4'7735). However,
In this PB method, O-nitroaniline is reduced with sodium sulfide, so the crude product contains impurities such as sodium thiosulfate and sulfur, which are then dissolved in alkali, treated with activated carbon, and reprecipitated with acid. Even after purification, the quality is insufficient for use as an additive for polyamide.

Furthermore, in this PB method, the reaction with carbon disulfide after reduction to 0PD is as long as 16 hours, and the theoretical yield for 0PD is as low as 75 to 80(f). A method that can obtain a relatively good yield is to react 0PD and carbon disulfide in an ethanol solution in the presence of potassium hydroxide, and after treatment with activated carbon, neutralize with acetic acid (0rg.Synth.C01
1. V01. ．． 569). According to this method, the raw material is 0PD
Commercial quality 2-MB can be obtained by using substantially uncolored 2-MB, but since ethanol is used as a solvent, recovery is expensive, and 2-MB is expensive.
It is difficult to adopt this method as an industrial manufacturing method for MB. 0PD
It has been reported that when synthesizing 2-MB by reacting carbon disulfide 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 (Tokuko Sho 51-17552), in this case containing isomer 4.4(f) instead of OPD in the example.

The reaction of mono-toluenediamine with carbon disulfide is exemplified, with a carbon disulfide addition time of 75-135 minutes, a total reaction time of 125-340 minutes, and a weight yield of 92.7-100% based on o-toluenediamine. (Methylbenzimidazole-2-thiol was obtained with a theoretical yield of 69.0 to 74.4% based on 0-toluenediamine. The present inventors also tried this method, but the yield was as described. It was found that the yield was low and the product was colored brown.Moreover, since the solvent was limited to organic liquids, recovery was also expensive. Catalytic hydrogenation of o-nitroaniline with 2% impurities
A method has been proposed in which the contained 0PD is used by simple distillation and the 0PD and carbon disulfide are reacted using benzothiazole as a solvent, but in this case, the solvent is a special one called benzothiazole, Too expensive to use for industrial purposes. Furthermore, the reaction conditions were 130°C.
After the reaction, the organic layer such as benzothiazo-thiazole is extracted with an alkali, washed with xylene, and neutralized to obtain 2-MB. It was thought that 2-MB dissolves in the form of an alkali salt in an alkaline aqueous solution, but the present inventors previously investigated the reaction between 0PD and carbon disulfide in an aqueous medium in the presence of an alkali. Either 0.5 to 2.5 gram equivalent of alkali oxide is used per 0 PDI mole, or one or more selected from the group consisting of carbonates, phosphates, and borates of alkali metals such as sodium and potassium. (0.5 to 5.0) × - mole equivalent amount of salt per 0PD1 mole Z (where n is the number of alkali metal atoms contained in one molecule of the salt used, and two or more types are used) It has now been found that, surprisingly, 2-MB can be obtained in free form in very high yields.

In this method, if a substantially uncolored 0PD compound is used as a raw material, extremely pure and virtually uncolored 0PD compound can be used as a raw material.
-MB-based compound is obtained. However, generally 0PD
These compounds are easily colored by oxidation, and are virtually uncolored.
In order to use a PD-based compound as a raw material, it must be distilled immediately before use, cooled and crushed while blocking air and light, and then charged into a reactor as a raw material, or the distilled product must be recrystallized. As a result of further investigation, the present inventors discovered that it was necessary to use a purified product obtained by distillation, and as a result, the 0PD compound obtained by distillation was added directly to an aqueous medium in a liquid state and dispersed. The present invention has been completed based on the discovery that a substantially uncolored 2-MB compound with extremely high purity can be obtained by reacting it with carbon disulfide or by reacting it while being dispersed.

To explain an embodiment of the method of the present invention, an 0PD compound obtained by distillation is directly added in a liquid state to an aqueous medium and dispersed, and then heated and reacted with carbon dioxide in the presence of a base. Alternatively, it can be reacted while being added and dispersed in an aqueous medium containing a base and carbon disulfide, or it can be reacted by adding each in proportion to an aqueous medium, and the precipitate can be filtered out and washed with water. A substantially uncolored 2-MB compound with extremely high purity is obtained.

When the OPD compound has a high melting point, it is possible to add a small amount of a suitable inert solvent to lower the melting point before use.

The OPD compound used in the method of the present invention has the general formula (1
) [In general formula (1), R,, R2, R3 and R
4 is a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 12 carbon atoms, or a nitro group, which may be the same or different from each other.

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

3- or 4-chlor, prom or iodo: 4-fluor; 3,4-, 3,5-, 3,6- or 4,5-
Dichlor or diprom: 3,5-difluor or short 3,4,6-tritalol: 4-prom-3,
5-dichloro: 3,4,5,6-tetrachlor or tetrafluoro: 3-methyl or ethyl: 4-methyl, ethyl, isopropyl, n-butyl, See-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 diptoxy: 4,5-dimethoxy, diisopropoxy or diptoxy-3,4,5-trimethoxy: 3,4,
6-trimethoxy: 4-nitro: 3,5- or 4,5
-Dinitro:5-prom-3,4-dimethyl:3,4-
dichloro-5,6-dimethyl, 3,5-dichloro-4,
6-dimethyl: 4-chloro-3-methoxy: 5-prom-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-ethoxy-
3-nitro; 5-ethoxy-3-nitro.

Examples of alkali hydroxides and alkali metal carbonates, phosphates, and borates used in the method of the present invention include sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, sodium carbonate, and carbonate. potassium, sodium bicarbonate, potassium bicarbonate,
Tertiary sodium phosphate, dibasic potassium phosphate, dibasic potassium phosphate, sodium pyrophosphate, sodium metaphosphate, sodium tripolyphosphate, sodium metaborate, potassium metaborate, sodium tetraborate, tetraborate Examples include potassium borate, sodium pentaborate, potassium pentaborate, and the like, and these can be used alone or in combination of two or more.

In the method of the present invention, the alkali hydroxide is 0PD compound 1
0.5 to 2.5 gram equivalents, preferably 0.6 to 1.8 gram equivalents per mole, and sodium, potassium carbonate, phosphate or borate per mol of 0PD compound (0.5-5.0)X-mol equivalent amount (
However, n is the number of sodium and potassium atoms contained in the salt 1n molecule used, or the total amount of each if two or more types are used), preferably (0.6. to 3.0.) x - molar equivalent. use.

n If the amount of these bases used is less than this, the reaction rate will be slow and the yield will be low.

If the amount of alkali hydroxide used is larger than this, the generated 21MB-based compound will dissolve in the aqueous medium in the form of an alkali salt. Needs to be neutralized with acid. Furthermore, it is uneconomical to use more carbonates, phosphates, or borates of alkali metals, and stirring may become difficult in some cases. In the method of the present invention, the amount of carbon disulfide used is 1.0 to 1.0 per CPD compound.
3.

0 molar ratio, preferably 1.1 to 1.5 molar ratio.

If carbon disulfide is used in excess, recovery becomes a problem. Water is generally used as the aqueous medium, but in some cases a water-miscible solvent such as alcohol may be added to the raw material.
It is also possible to contain the amount derived from a PD-based compound or the like.

The amount of the aqueous medium to be used is 2 to 20 times, preferably 3 to 8 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. Slower speed and lower productivity. In the process of the present invention, additives are generally unnecessary, but in some cases additives may include cationic surfactants, such as lauryltrimethylammonium chloride, anionic surfactants, such as sodium dialkyl sulfonate. Succinate or a nonionic surfactant such as sorbitan monooleate at 0.1 to 0.1 to 0 PD type compound.
By adding about 20% to the reaction, the reflux time of carbon disulfide at about 40 to 45°C can be shortened, foaming can be suppressed, or the crystal form can become denser, so the reaction temperature should be increased. I can do it.

A single embodiment of the present invention includes a water stirrer,
A reaction vessel equipped with a cooler and a thermometer is placed, and the OPD compound obtained by distillation in advance is added dropwise while stirring in a liquid state.

After adding the base, carbon disulfide is added dropwise. In this case, it is of course possible to place the base and/or carbon disulfide in water and then dropwise add the OPD compound. 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, it is gradually heated to 90°C. Generally, the reaction is carried out sufficiently at 60 to 70°C, and then the temperature is raised to 90°C. Of course, at this time, 9
It is also possible to raise the temperature to 0°C. 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 type compounds can be obtained in a considerable yield, but at this time, some 0PD type compounds still remain unreacted, so it is better to increase the temperature to 90°C to obtain preferable results. The reaction product is filtered at room temperature to 90°C, washed and dried to obtain a very highly pure 2-MB compound. Note that if the deep water is strongly alkaline, it must be neutralized with sulfuric acid, hydrochloric acid, etc., but hydrogen sulfide is generated at this time, so after the reaction, neutralize it with an acid such as stirred acid or hydrochloric acid. After expelling hydrogen sulfide, it is also possible to carry out filtration 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. According to the method of the present invention, 2-MB due to time-dependent changes in 0PD-based compounds
In addition to being able to prevent coloring of system compounds, in the case of conventional solid charging, the work time required for the crushing process or flaking process can be shortened, and the work environment pollution caused by scattering of powder and steam can be reduced. There is.

The 2-MB compound produced by the method of the present invention 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 A crude o-toluenediamine mixture produced as a by-product during the production of m-toluenediamine was subjected to simple distillation under reduced pressure, and the obtained o-toluenediamine mixture (this one was
, 53.8% of 4-toluenediamine, 45.4% of 2,3-toluenediamine, and 0.4% of m-toluenediamine.
6% and other impurities 0.2%) 61.1
9 was added dropwise in a molten state to 200 mf of water while stirring to disperse it.

Then 40.4 g of 49.6% aqueous sodium hydroxide solution and 0.0759 g of sodium dialkyl sulfocinate
was added and heated to 35°C. Carbon disulfide 5 at the same temperature
00f1 was added dropwise for 30 minutes or so. Crystals began to precipitate during the dropping. 200 me of water was added and heated to 60°C. After stirring at 60-70℃ for 2 hours, 90℃
The temperature was raised to ℃.

After the reaction, it was filtered under heat at 80°C and washed with water. The weight of the wet abyss mass is 8
2,29. Drying overnight at 90°C yielded 80.39 g of a mixture of 4-methyl-2-mercaptobenzimidazole and 5-methyl-2-mercaptopenzimidazole. Yield 97.8%. Colorless powdery crystals. Mp27O~28
5℃. In this example, when the o-toluenediamine mixture was added in liquid form and the distilled product was cooled and pulverized for about 40 hours, the resulting methyl-2-MB mixture had a white appearance. It was clearly inferior in terms of performance.

Example 2 Melted 0PD54.19 obtained by distillation was added to 200% water.
After adding 40.49% of a 496% aqueous sodium hydroxide solution and 0.19% of sodium dialkyl sulfosuccinate, 5% of carbon disulfide was added.
0.09 was added dropwise.

After the reflux is finished, the temperature is raised to 60℃, and the temperature is increased to 60-70℃ for 2 hours.
I stirred the time. Finally, the temperature was raised to 90℃ and 2
4.5% sulfuric acid 107f! 1 was added dropwise over a period of approximately 30 minutes. The precipitated crystals were filtered, washed with water, and dried at 90°C.
MB74. Obtained O9. Mp297-298°C. 0PD
The theoretical yield is 98.5%.

Example 3 o-Toluenediamine mixture 61.1 in Example 1
4-thalol-0PD7 in the molten state instead of using 9
The reaction and post-treatment were carried out in the same manner using 1.89.

5-chloro-2-MB9l. I got 39.

Mp295-7°C. Example 4 0PD54.1f instead of o-toluenediamine 61.19 in Example 1! The reaction and post-treatment were carried out in the same manner using 49.6% sodium hydroxide aqueous solution (40.49 g) and 26.59 g (26.59 g) of sodium carbonate.

2-MB74. Obtained O9.

Mp293-5°C. Example 5 The same reaction and post-treatment as in Example 4 were carried out using 63.39 g of trisodium phosphate (decahydrate) instead of 26.59 g of sodium carbonate.

2-MB74. Obtained O9.

Mp293-5°C. Example 6 In Example 4, dibasic sodium phosphate (26.59% of sodium carbonate was replaced with
The reaction and post-treatment were carried out in the same manner using 179.19 (12 hydrate salt).

2-MB74.29 was obtained.

Mp293-5°C. Example 7 In Example 4, sodium tetraborate (N
The reaction and post-treatment were carried out in the same manner using a2B4O7.10H20)95.49.

2-MB72.29 was obtained.

Mp29l~3°C. Example 8 In Example 4, 53.0 y of sodium carbonate was used instead of 26.5 y of sodium carbonate.
The reaction and post-treatment were the same as in Example 4, except that 9 was used.

21MB74. I got 19.

Mp292-4°C. Example 9 In Example 4, 26.59% of sodium carbonate was replaced with trisodium phosphate (
The reaction and post-treatment were carried out in the same manner as in Example 4, except that 190.09 (12-hydrate) was used.

2-MB73.99 was obtained.

Mp294-6°C0 Example 10 The same reaction and post-treatment as in Example 4 were carried out except that 12.6 g of sodium hydroxide with a purity of 95% was used instead of 26.59 g of sodium carbonate.

2-MB7O. lf! I got it.

Mp3OO~2°C. Example 11 49.6% sodium hydroxide in Example 1 40.4
The reaction and post-treatment were carried out in the same manner as in Example 1, except that 34.19 of concentrated ammonia water with a concentration of 25% was used instead of 9.

Mixture of 4-methyl-2-mercaptobenzimidazole and 5-methyl-2-mercaptobenzimidazole 78.

I got 8f1.

Claims (1)

[Claims] 1 General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) [However, in formula (I), R_1, R_2, R_3 and R_
4 are the same or different, hydrogen atom, halogen atom,
In producing a 2-mercaptobenzimidazole compound by reacting an O-phenylene diamine compound represented by an alkyl group having 1 to 12 carbon atoms, an alkoxy group, or a nitro group with carbon disulfide, O-phenylene 0.5 to 2.0% per mole of diamine compound.
An O-phenylenediamine compound is added and dispersed in a liquid state in an aqueous medium in the presence or absence of a surfactant in the presence of 5 gram equivalents of alkali metal hydroxide or ammonia, and then reacted. A method for producing a 2-mercaptobenzimidazole compound, which comprises reacting while dispersing or dispersing the compound. 2 General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) [However, in formula (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. ]. In producing a 2-mercaptobenzimidazole compound by reacting an O-phenylenediamine compound with carbon disulfide, sodium or potassium carbonate, phosphate,
and one or more salts selected from borates (0.5 to
5.0) x 1/n mole equivalent (where n is the number of sodium or potassium atoms contained in one molecule of the salt used, and if two or more types are used, the total amount of each) 2-, characterized in that the O-phenylenediamine compound is added in a liquid state to an aqueous medium in the presence or absence of a surfactant, dispersed, and then reacted, or reacted while being dispersed. A method for producing a mercaptobenzimidazole compound.