CN109761928B

CN109761928B - Preparation method of 2, 6-dichlorobenzoxazole

Info

Publication number: CN109761928B
Application number: CN201910117937.XA
Authority: CN
Inventors: 周康伦; 苏朝辉; 施亦敏
Original assignee: Anhui Fengle Agrochemical Co Ltd
Current assignee: Anhui Fengle Agrochemical Co Ltd
Priority date: 2019-02-15
Filing date: 2019-02-15
Publication date: 2023-06-23
Anticipated expiration: 2039-02-15
Also published as: CN109761928A

Abstract

The invention provides a preparation method of high-yield 2, 6-dichlorobenzoxazole, which comprises the steps of directly carrying out chlorination reaction on 6-chlorobenzooxazolone and phosphorus pentachloride in a solvent in the presence of a catalyst to obtain a 2, 6-dichlorobenzoxazole product. The preparation method has the advantages of increased operation elasticity, one-time feeding, obviously improved yield, single component of the reaction byproduct, only phosphoric acid and hydrochloric acid, easy treatment of waste water, capability of preparing phosphate fertilizer for sale and reduction of production cost. The preparation method is carried out at normal pressure and low temperature of 60-70 ℃, and the reaction condition is mild and the production is easy.

Description

Preparation method of 2, 6-dichlorobenzoxazole

Technical Field

The invention belongs to the technical field of pesticides, and particularly relates to a preparation method of high-yield 2, 6-dichlorobenzoxazole.

Background

Fenoxaprop-p-ethyl is a novel phenoxy carboxylic acid heterocyclic herbicide, and has the characteristics of high efficiency, low toxicity, small environmental pollution and the like. The fenoxaprop-p-ethyl has good control effect on controlling gramineous weeds such as wheat, rye and other crops, such as wheat-grass, wild oat, green bristlegrass and other weeds. 2, 6-dichlorobenzoxazole is a key intermediate for synthesizing herbicide fenoxaprop-p-ethyl, and is also an important pesticide and medical intermediate, and the English name is 2, 6-Dichrobenzoxazo 1e. The structural formula is as follows:

2, 6-dichlorobenzoxazole is generally obtained by the pressurized reaction of 6-chlorobenzoxazolone in a mixture of chlorine, phosphorus trichloride and phosphorus oxychloride or in a mixture of phosphorus pentachloride and phosphorus oxychloride at a temperature of 150-170 ℃, but the yield is lower; the process also comprises the steps of carrying out sulfhydrylation on 6-chlorobenzoxazolone and then reacting with thionyl chloride, wherein the process generates a large amount of mixed tail gas of sulfur dioxide and hydrogen chloride, so that the tail gas treatment capacity is large.

Disclosure of Invention

The invention aims to provide a preparation method of high-yield 2, 6-dichlorobenzoxazole.

The technical scheme of the invention is as follows:

a process for preparing high-yield 2, 6-dichlorobenzoxazole includes such steps as adding 6-chlorobenzooxazolone and phosphorus pentachloride to solvent, and direct chlorination reaction in the presence of catalyst to obtain 2, 6-dichlorobenzoxazole.

The specific reaction formula is as follows:

further, the solvent is toluene.

Further, the catalyst is polyphosphoric acid and ferric trichloride, and the mass ratio is 1:5-5:2, mixing.

Further, the chlorination reaction is carried out under stirring, the temperature is 60-70 ℃, and the stirring time is 0.5-1.5h.

Further, the mass ratio of the 6-chlorobenzoxazolone to the phosphorus pentachloride to the catalyst is 17:21-25:0.6-1.

Further, the content of the 2, 6-dichlorobenzoxazole product is 96.5-98.5%, and the yield is 90.7-95.2%.

The preparation method has the advantages of increased operation elasticity, one-time feeding, obviously improved yield, single component of the reaction byproduct, only phosphoric acid and hydrochloric acid, easy treatment of waste water, capability of preparing phosphate fertilizer for sale and reduction of production cost. The preparation method is carried out at normal pressure and low temperature of 60-70 ℃, and the reaction condition is mild and the production is easy.

Detailed Description

Example 1: a preparation method of high-yield 2, 6-dichlorobenzoxazole comprises the following steps:

into a 500ml three-neck flask, 250ml of toluene, 0.1mol of 6-chlorobenzoxazolone, 25 g of phosphorus pentachloride, 0.5 g of polyphosphoric acid and 0.5 g of ferric trichloride are added, the mixture is stirred and heated to 60 ℃, the temperature is controlled and stirred for 0.5h, and then the post-treatment is carried out, so that the product, the content of 2, 6-dichlorobenzoxazole in the product is 98.5%, and the yield is 95.2%.

Example 2:

into a 500ml three-neck flask, 250ml of toluene, 0.1mol of 6-chlorobenzoxazolone, 21 g of phosphorus pentachloride, 0.5 g of polyphosphoric acid and 0.5 g of ferric trichloride are added, the mixture is stirred and heated to 70 ℃, the temperature is controlled and stirred for 1h, and then the post-treatment is carried out, so that the product with the content of 98.1% and the yield of 92.3% is obtained.

Example 3:

into a 500ml three-neck flask, 250ml of toluene, 0.1mol of 6-chlorobenzoxazolone, 25 g of phosphorus pentachloride, 0.1 g of polyphosphoric acid and 0.5 g of ferric trichloride are added, the mixture is stirred and heated to 70 ℃, the temperature is controlled and stirred for 1.5 hours, and then the mixture is subjected to post-treatment, so that the product with 96.5 percent of content and 90.7 percent of yield is obtained.

Example 4:

into a 500ml three-neck flask, 250ml of toluene, 0.1mol of 6-chlorobenzoxazolone, 25 g of phosphorus pentachloride, 0.5 g of polyphosphoric acid and 0.2 g of ferric trichloride are added, the mixture is stirred and heated to 70 ℃, the temperature is controlled and stirred for 1.5 hours, and then the mixture is subjected to post-treatment, so that the product with the content of 97.0% and the yield of 94.3% is obtained.

While the present invention has been shown and described with respect to the above embodiments, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims

1. A preparation method of 2, 6-dichlorobenzoxazole is characterized by comprising the following steps: adding 6-chlorobenzoxazolone and phosphorus pentachloride into a solvent, and directly carrying out chlorination reaction in the presence of a catalyst to obtain a 2, 6-dichlorobenzoxazole product; the catalyst is polyphosphoric acid and ferric trichloride according to the mass ratio of 1:5-5:2, mixing; the temperature of the chlorination reaction is 60-70 ℃.

2. The method of manufacturing according to claim 1, characterized in that: the chlorination reaction is carried out under stirring, and the stirring time is 0.5-1.5h.

3. The method of manufacturing according to claim 1, characterized in that: the mass ratio of the 6-chlorobenzoxazolone to the phosphorus pentachloride to the catalyst is 17:21-25:0.6-1.

4. The method of manufacturing according to claim 1, characterized in that: the content of the 2, 6-dichlorobenzoxazole product is 96.5-98.5%, and the yield is 90.7-95.2%.