CN-121990987-A - Fluroxypyr-meptyl purification method of isooctyl ester

Abstract

The invention relates to the field of organic synthesis, in particular to a method for purifying isooctyl fluroxypyr, which comprises the step of adjusting the pH value of a solution to 3-5 in the crystallization process. The method can effectively remove impurities in the product, and the purity of the product can reach more than 99 percent. The method provided by the invention is environment-friendly, simple and convenient to operate, easy to control, low in cost and good in economic benefit, and is suitable for industrial production.

Inventors

• WANG YUCHI
• ZHANG SHENG
• CAO KOUSEN

Assignees

• 淮安国瑞化工有限公司

Dates

Publication Date

20260508

Application Date

20260316

Claims (10)

1. 1. A process for purifying isooctyl fluroxypyr ester, the process comprising the steps of: S1, dissolving a crude product of fluroxypyr-meptyl in an organic solvent 1, and heating to dissolve the fluroxypyr-meptyl; s2, adding a pH value regulator, and regulating the pH value of the solution to 3-5; s3, adding activated carbon for decoloring and filtering; and S4, cooling the filtrate obtained in the step S3, crystallizing, filtering, washing and drying to obtain the fluroxypyr isooctyl ester.
2. 2. The method according to claim 1, wherein the organic solvent 1 is selected from one or more of methanol, ethanol and isopropanol, preferably from ethanol.
3. 3. The process according to claim 1 or 2, characterized in that the mass to volume ratio of crude product of fluroxypyr-meptyl ester to organic solvent 1 is 1:2-1:5, preferably 1:2-1:3, g/mL.
4. 4. A method according to claim 1 or 2, characterized in that the heating in step S1 is at a temperature of 40-80 ℃, preferably 50-70 ℃.
5. 5. The method according to claim 1 or 2, wherein the pH adjustor is one or more selected from the group consisting of dilute hydrochloric acid, acetic acid, benzoic acid and oxalic acid, preferably acetic acid.
6. 6. The method according to claim 1 or 2, wherein the pH is adjusted to 3.5-4.5 in step S2.
7. 7. The method according to claim 1 or 2, wherein the preparation method of the crude product of fluroxypyr comprises the following steps: , Step Sa, carrying out substitution reaction on the compound 1 and the compound 2 to obtain the fluroxypyr-meptyl.
8. 8. The method according to claim 1 or 2, characterized in that step Sa is carried out in an organic solvent 2; Preferably, the organic solvent 2 is selected from one or more of DMF, pyridine, NMP, ethanolamine and HMDS, preferably from one or more of DMF and NMP.
9. 9. The method according to claim 8, wherein the reaction temperature of step Sa is 50-80 ℃.
10. 10. The method according to claim 1 or 2, wherein in step S4, the filtrate obtained in step S3 is cooled to 0-10 ℃ for crystallization; Preferably, the filtrate obtained in the step S3 is cooled to 0-5 ℃ for crystallization.

Description

Fluroxypyr-meptyl purification method of isooctyl ester Technical Field The invention relates to the field of organic synthesis, in particular to a method for purifying isooctyl fluroxypyr. Background The fluroxypyr isooctyl ester, also called fluroxypyr ester, is a high-efficiency, systemic-conduction post-emergence stem and leaf treatment herbicide, which is developed by Tao Shiyi agricultural company in the United states in 1985 and is first registered in China in 1991. The herbicide belongs to pyridyloxyacetic acid herbicides from the chemical structure division, is a typical hormone herbicide from the action mechanism, can be quickly absorbed by leaves and roots of weeds and is transmitted to the whole plant, so that symptoms such as malformation, distortion and the like of sensitive weeds are caused, and finally the weeds die. The fluroxypyr is mainly suitable for crops such as wheat, barley, corn, orchards and the like, is used for preventing various malignant broadleaf weeds such as water-removed peanuts, field inula flowers and the like, and has no residual influence on the safety of aftercrop crops. Because of the characteristics of strong selectivity, broad weed killing spectrum, safety to gramineous crops and the like, the product is widely applied in the global scope, 31 enterprises in China register the production of raw medicines at present, and the product becomes an important variety in the field of broad-leaved weed control. Regarding a preparation method of fluroxypyr isooctyl ester, US3761486A discloses that pyridine is taken as a starting material, pentachloropyridine is generated through chlorination reaction, and then key intermediate 4-amino-3, 5-dichloro-2, 6-difluoropyridine is prepared through two procedures of fluorination and ammoniation. The intermediate is subjected to condensation reaction with the isooctyl glycolate to finally synthesize the target product, namely the fluroxypyr isooctyl chlorofluoroacetate. The synthetic steps of the route are relatively less, the process flow is simple, and the operation is convenient. However, this process also has the obvious disadvantage that the core condensation reaction step yields are low, resulting in a low purity of the final product, which affects to some extent the economics of its commercial production and the quality of the product. In addition, the prior art also discloses that 4-amino-3, 5-dichloro-6-fluoropyridine-2-phenolic potassium and isooctyl chloroacetate are directly etherified to obtain isooctyl fluroxypyr, the route is simple to operate, the yield is not high, and the product purity is low. The product mainly comprises the following two byproducts, wherein the byproduct (1) is obtained by reacting amino in 4-amino-3, 5-dichloro-6-fluoropyridine-2-phenolic potassium with chloracetic acid Zhong Xin ester, and the byproduct (2) is generated by hydrolysis reaction of isooctyl fluroxypyr. Disclosure of Invention In order to solve the above problems, the present invention provides a method for purifying isooctyl fluroxypyr, the method comprising the steps of: S1, dissolving a crude product of fluroxypyr-meptyl in an organic solvent 1, and heating to dissolve the fluroxypyr-meptyl; s2, adding a pH value regulator, and regulating the pH value of the solution to 3-5; s3, adding activated carbon for decoloring and filtering; and S4, cooling the filtrate obtained in the step S3, crystallizing, filtering, washing and drying to obtain the fluroxypyr isooctyl ester. Preferably, the organic solvent 1 is selected from one or more of methanol, ethanol and isopropanol, preferably from ethanol. Preferably, the mass volume ratio of the crude product of the fluroxypyr to the organic solvent 1 is 1:2-1:5, and preferably 1:2-1:3, g/mL. Preferably, the temperature of heating in step S1 is 40-80 ℃, preferably 50-70 ℃. Preferably, the pH regulator is selected from one or more of dilute hydrochloric acid, acetic acid, benzoic acid and oxalic acid, preferably from acetic acid. Preferably, the pH is adjusted to 3.5-4.5 in step S2. Preferably, the preparation method of the crude product of the fluroxypyr-meptyl comprises the following steps: , Step Sa, carrying out substitution reaction on the compound 1 and the compound 2 to obtain the fluroxypyr-meptyl. Preferably, step Sa is carried out in an organic solvent 2. Preferably, the organic solvent 2 is selected from one or more of DMF, pyridine, NMP, ethanolamine and HMDS, preferably from one or more of DMF and NMP. Preferably, the reaction temperature of step Sa is 50-80 ℃. Preferably, in the step S4, the filtrate obtained in the step S3 is cooled to 0-10 ℃ for crystallization. ADVANTAGEOUS EFFECTS OF INVENTION In the recrystallization process, the purification method provided by the invention adjusts the pH value of the solution to be 3-5, so that impurities in the product can be effectively removed, and the purity of the product is improved. The purity of the fluroxypyr isooctyl ester prepared