阅读说明：本技术 一种制备2-苯基苯并咪唑的方法 (Method for preparing 2-phenylbenzimidazole ) 是由 黄雄 袁明翔 廖凯 张志红 于 2021-09-16 设计创作，主要内容包括：本发明公开了一种制备2-苯基苯并咪唑的方法,所述制备方法包括如下步骤：在水中加入邻苯二胺和亚硫酸氢钠,搅拌升温至80～90℃,然后加入苯甲醛并保温进行反应,反应结束后的产物经降温、离心、水洗后烘干即可。本发明采用水替代现有技术中的有机溶剂作为溶剂介质制备得到了2-苯基苯并咪唑,通过控制反应原料和反应温度获得了高达96.3％的收率,符合当今阶段绿色环保的理念。(The invention discloses a method for preparing 2-phenylbenzimidazole, which comprises the following steps: adding o-phenylenediamine and sodium bisulfite into water, stirring and heating to 80-90 ℃, then adding benzaldehyde and preserving heat for reaction, and drying a product after the reaction is finished after cooling, centrifuging, washing with water. According to the invention, water is adopted to replace an organic solvent in the prior art as a solvent medium to prepare the 2-phenylbenzimidazole, the yield of 96.3% is obtained by controlling reaction raw materials and reaction temperature, and the method conforms to the concept of green environmental protection at the present stage.)

1. A method for preparing 2-phenylbenzimidazole, which is characterized by comprising the following steps: adding o-phenylenediamine and sodium bisulfite into water, stirring and heating to 80-90 ℃, then adding benzaldehyde and preserving heat for reaction, and drying a product after the reaction is finished after cooling, centrifuging, washing with water.

2. The process for preparing 2-phenylbenzimidazole according to claim 1, wherein the stirring is carried out at an elevated temperature of 85 ℃.

3. The method for preparing 2-phenylbenzimidazole according to claim 1, wherein the molar ratio of o-phenylenediamine to benzaldehyde to sodium bisulfite is 1: 1: 2 to 2.4.

4. The method for preparing 2-phenylbenzimidazole according to any one of claims 1 to 3, wherein the o-phenylenediamine and the water are used in a ratio of 1 mol: 1100-1300 g.

5. The method for preparing 2-phenylbenzimidazole according to claim 4, wherein the o-phenylenediamine and the water are used in a ratio of 1 mol: 1200 g.

6. The method for preparing 2-phenylbenzimidazole according to claim 1, wherein the benzaldehyde is added within 0.5-1.5 hours.

7. The process for preparing 2-phenylbenzimidazole according to claim 6, wherein the benzaldehyde is added over 1 hour.

8. The method for preparing 2-phenylbenzimidazole according to any one of claims 1 to 3, wherein the reaction is carried out for 1.5 to 2.5 hours under heat preservation.

9. The method for preparing 2-phenylbenzimidazole according to claim 8, wherein the incubation is carried out for a period of 2 hours.

10. The method for preparing 2-phenylbenzimidazole according to any one of claims 1 to 3, wherein the drying step further comprises a purification step, and the purification step comprises the following steps: dissolving the dried product with alcohol, adding active carbon, filtering to remove impurities, cooling, crystallizing, and centrifuging to obtain crystal, and drying again.

Technical Field

The invention belongs to the field of organic synthesis, and particularly relates to a method for preparing 2-phenylbenzimidazole.

Background

In the prior art, the preparation method of 2-phenylbenzimidazole and the corresponding advantages and disadvantages are as follows: 1. in the presence of strong acid such as catalysts p-toluenesulfonic acid, polyphosphoric acid and the like, o-phenylenediamine and benzaldehyde are subjected to heating reaction in an organic solvent, and recrystallization is carried out to obtain 2-phenylbenzimidazole, wherein the method usually needs higher reaction temperature or longer reaction time and is not favorable for large-scale production; 2. benzaldehyde reacts with thionyl chloride to prepare dichloromethylbenzene, and the dichloromethylbenzene and o-phenylenediamine generate 2-phenylbenzimidazole in a reaction system under the condition of an oxidant, so that raw materials are easy to oxidize, the yield is low, environmental pollution is caused, and the cost is high; 3. the method has the advantages of high yield and short reaction time, but the catalyst has poor stability in the process of repeated use.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for preparing 2-phenylbenzimidazole, which selects sodium bisulfite as a catalyst, can complete the preparation of a target product in water, does not use an organic solvent, and solves the technical problem of high cost of the organic solvent used in the prior art.

The purpose of the invention is realized by the following technical scheme:

a process for preparing 2-phenylbenzimidazole comprising the steps of: adding o-phenylenediamine and sodium bisulfite into water, stirring and heating to 80-90 ℃, then adding benzaldehyde and preserving heat for reaction, and drying a product after the reaction is finished after cooling, centrifuging, washing with water.

Preferably, the molar ratio of the o-phenylenediamine to the benzaldehyde to the sodium bisulfite is 1: 1: 2 to 2.4.

Preferably, the dosage ratio of the o-phenylenediamine to the water is 1 mol: 1100-1300 g, more preferably 1 mol: 1200 g.

Preferably, the benzaldehyde is added within 0.5-1.5 h, and more preferably, the benzaldehyde is added within 1 h.

Preferably, the reaction time is 1.5-2.5 h, and more preferably, the reaction time is 2 h.

Preferably, the method further comprises a purification step after drying, wherein the purification step comprises the following steps:

dissolving the dried product with alcohol, adding active carbon, filtering to remove impurities, cooling, crystallizing, and centrifuging to obtain crystal, and drying again.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, water is adopted to replace an organic solvent in the prior art as a solvent medium to prepare the 2-phenylbenzimidazole, the yield of 96.3% is obtained by controlling reaction raw materials and reaction temperature, the yield performance is better, and the yield is higher if subsequent purification is carried out. The invention does not use organic solvent, saves cost and is more in line with the concept of green and environmental protection at the present stage. The invention has simple process and easy operation.

Drawings

FIG. 1 is a graph showing an infrared absorption spectrum of a product prepared in example 2 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Effect of reaction temperature on product yield

Example 1

A method for preparing 2-phenylbenzimidazole comprises the following steps:

1200g of water, 1mol of o-phenylenediamine and 2mol of sodium bisulfite are added into a reaction kettle, the mixture is stirred and heated to 80 ℃, 1mol of benzaldehyde is added (the benzaldehyde is added within 1 hour), the mixture is kept warm and reacts for 2 hours, the product after the reaction is cooled, centrifuged, washed by water and dried, and the product obtained in the step 1 is recorded as sample 1.

Example 2

A method for preparing 2-phenylbenzimidazole comprises the following steps:

the "80 ℃ C" in example 1 was replaced with "85 ℃ C", and the other steps were the same as in example 1. The product of example 2 was designated sample 2.

Example 3

A method for preparing 2-phenylbenzimidazole comprises the following steps:

the "80 ℃ C" in example 1 was replaced with "90 ℃ C", and the other steps were the same as in example 1. The product of example 3 was designated sample 3.

Comparative example 1

The reaction temperature of "80 ℃ C" in example 1 was sequentially replaced with T, and the procedure of example 1 was followed. T is selected from one of the following: the corresponding products at 50 ℃, 60 ℃, 70 ℃, 75 ℃ and 100 ℃ are in turn noted as: sample 4 to sample 8.

The product yields of examples 1-3 and comparative example 1 are shown in Table 1.

TABLE 1 COUPLING METER

As can be seen from table 1: the reaction is better at 80-90 ℃, and the yield is higher; when the temperature is kept between 50 ℃ and 70 ℃ for reaction, the reaction rate is slow, and the yield is not high; and when the temperature is higher than 90 ℃, impurities are increased and the yield is lower.

Effect of sodium bisulfite dosage on product yield

Example 4

A method for preparing 2-phenylbenzimidazole comprises the following steps:

the procedure of example 2 was otherwise the same as that of example 2 except that "2 mol of sodium hydrogen sulfite" was replaced with "2.2 mol of sodium hydrogen sulfite". The product of example 4 was designated sample A.

EXAMPLE 5

A method for preparing 2-phenylbenzimidazole comprises the following steps:

the procedure of example 2 was otherwise the same as that of example 2 except that "2 mol of sodium hydrogen sulfite" was replaced with "2.4 mol of sodium hydrogen sulfite". The product of example 5 was designated sample B.

Comparative example 2

"2 mol of sodium hydrogen sulfite" in example 2 was replaced with "N sodium hydrogen sulfite" in order, and the procedure of example 2 was followed. N is selected from one of the following: 0.8mol, 1.0mol, 1.2mol, 1.5mol and 1.8mol, the corresponding products being in turn noted: sample C to sample G.

The product yields of examples 2, 4-5 and comparative example 2 are shown in Table 2.

TABLE 2 yield table 2

From table 2 it can be found that: when the using amount of the sodium bisulfite is small, the yield is low; when the amount of the sodium bisulfite is 2mol, the yield is highest, the repeatability is better, the amount is increased finally, and the product yield is basically unchanged, so that the amount of the sodium bisulfite is most suitable for 2 mol.

Influence of pure water dosage on product yield

Example 6

A method for preparing 2-phenylbenzimidazole comprises the following steps:

adding 1200g of water, 1mol of o-phenylenediamine and 2mol of sodium bisulfite into a reaction kettle, stirring and heating to 80 ℃, then adding 1mol of benzaldehyde (the benzaldehyde is added within 1 hour), keeping the temperature and reacting for 1.5 hours, and cooling, centrifuging, washing and drying the product after the reaction is finished. The product of example 6 was designated sample a.

Example 7

A method for preparing 2-phenylbenzimidazole comprises the following steps:

the procedure of example 6 was otherwise the same as that of example 6 except that "1200 g of water" was replaced with "1100 g of water". The product of example 7 was designated sample b.

Example 8

A method for preparing 2-phenylbenzimidazole comprises the following steps:

the procedure of example 6 was otherwise the same as that of example 6 except that "1200 g of water" was replaced with "1300 g of water". The product of example 8 was designated sample c.

Comparative example 3

"1200 g of water" in example 6 was sequentially replaced with "M water", and the procedure of example 6 was followed. M is selected from one of the following: 600g, 700g, 800g, 900g and 1000g, the corresponding products being in turn noted: sample d to sample h.

The product yields of examples 6-8 and comparative example 3 are shown in Table 3.

TABLE 3 Rate table (III)

From table 3 it can be found that: when the pure water is used in a small amount, the system is easy to solidify, the stirring effect is poor, the reaction is slow, and the yield is low; with the use amount of the pure water of 1100 g-1200 g, the stirring effect is good, the yield is higher, and finally, the use amount is improved, and the product yield is basically unchanged, so that the use amount of the pure water of 1200g is most suitable.

FIG. 1 is a chart of an infrared absorption spectrum of a product prepared in example 2, which can be derived from FIG. 1: example 2 the desired product, 2-phenylbenzimidazole, was prepared.

The infrared absorption spectra of the products obtained in examples 1, 3, 4 to 5, and 6 to 8 are similar to those of example 2, which all indicate that the target product is obtained, and are not described herein.

The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.