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Preparation method of 2,5-dimethylphenylacetic acid

A technology of dimethylphenylacetic acid and dimethylphenyl, applied in the field of preparing spirotetramat key intermediate 2, can solve the problems of inability to carry out industrialized production, no industrialization significance, a large amount of sulfur-containing wastewater, waste residue and the like

Inactive Publication Date: 2015-05-20
CHINA PHARM UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] The second disclosed method is to use 2,5-dimethylacetophenone as the starting material and prepare it through the Willgerodt-Kindler rearrangement reaction, but this method will produce a large amount of sulfur-containing waste water and waste residue. , will also produce a large amount of hydrogen sulfide gas with a foul smell
[0008] There are also many public patents on 2,5-dimethylphenylacetic acid in China, such as CN 102140062A, which uses p-xylene as a raw material to generate the target product through chloromethylation and CO addition, but the reaction requires the use of tetraphenyl Precious reagents such as phosphine palladium cannot carry out industrialized production; Such as CN 103804176A, take p-xylene as raw material, through bromomethylation, CO addition, etc., also need to use bistriphenylphosphine palladium dichloride, [RhCl Precious reagents such as (COD)2]2 have no industrial significance; such as WO2012122747A1, it is also necessary to use precious metals such as palladium

Method used

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  • Preparation method of 2,5-dimethylphenylacetic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] Synthesis of compound (V)

[0047]

[0048] In a 250ml reaction flask, add 120ml of dichloroethane, cool to -5~0°C, add 21.23g (0.20mol) of p-xylene, 34.67g (0.26mol) of anhydrous aluminum trichloride, stir, and dropwise add bromine 48.44 g (0.24 mol) of acetyl bromide, after the dropwise addition, it was raised to room temperature for reaction until the reaction was completed. The product was poured into 100ml of 5% ice-hydrochloric acid solution, stirred for 30min, separated, the aqueous layer was extracted with dichloroethane, the organic phases were combined, washed with water, and the solvent was removed to obtain 41.97g of a yellow liquid product with a yield of 92.41%.

[0049] 1 H NMR (CDCl 3 , 300Hz) δ: 2.35 (s, 3H, CH 3 ), 2.50(s, 3H, CH3), 4.43(s, 2H, CH2), 7.14~7.24(m, 2H, Ar-H), 7.45(s, 1H, Ar-H); ESI-MS: 251.0[ M+Na] + .

Embodiment 2

[0051] Synthesis of compound (IV)

[0052]

[0053] In a 500ml reaction flask, add 34.06g (0.15mol) of 2,5-dimethylbromoacetophenone, 15.62g (0.15mol) of neopentyl glycol, a catalytic amount of p-toluenesulfonic acid, 200ml of toluene, and heat to 110-115°C Reflux with water until the raw materials react completely to obtain yellow 2-bromomethyl-2-(2,5-dimethylphenyl)-5,5-dimethyl-[1,3]dioxane The toluene solution of alkane, wherein the product is 42.32g (GC analysis), the yield is 90.09%.

[0054] 1 H NMR (CDCl3 , 300Hz) δ: 0.62 (s, 3H, CH 3 ), 1.39(s, 3H, CH3), 2.35(m, 6H, CH3), 3.47(m, 6H, CH3), 7.07(s, 2H, Ar-H), 7.30(s, 1H, Ar-H) ;ESI-MS: 335.1[M+Na] + .

Embodiment 3

[0056] Synthesis of compound (III)

[0057]

[0058] The toluene solution of 2-bromomethyl-2-(2,5-dimethylphenyl)-5,5-dimethyl-[1,3]dioxane obtained in the previous step was cooled to room temperature, Add ZnCl 2 4.09g (0.03mol), warming up to reflux, monitoring the reaction process to the end, to obtain 3-bromo-2,2-dimethylpropyl-2-(2,5 dimethylphenyl) acetate (III) Toluene solution, wherein product 36.44g (GC analysis), yield 86.10%.

[0059] 1 H NMR (CDCl 3 , 300Hz) δ: 0.83~1.25(m, 6H, CH 3 ), 2.27(m, 3H, CH3), 2.47(m, 3H, CH3), 3.20(s, 2H, CH2), 3.61(s, 2H, CH2), 3.94(s, 2H, CH2), 7.04(m , 3H, Ar-H); ESI-MS: 335.0[M+Na] + .

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Abstract

The invention relates to the field of organic synthesis and aims at providing a synthesis preparation method of 2,5-dimethylphenylacetic acid. According to the method, paraxylene is taken as a raw material, and five steps of reactions, namely friedel-crafts acylation, ketalation, zinc salt catalytic rearrangement, alkaline hydrolysis and acidification, are performed to obtain the target product 2,5-dimethylphenylacetic acid; under optimized conditions, the total yield is 63.4%; the preparation method is simple to operate, free from the use of noble metals, relatively high in total yield, and capable of providing important reference for industrial production.

Description

technical field [0001] The invention relates to a method for preparing 2,5-dimethylphenylacetic acid, a key intermediate of spirotetramat, by using p-xylene as a raw material. Background technique [0002] 2,5-Dimethylphenylacetic acid (CAS 13612-34-5) is one of the key intermediates for the preparation of the pesticide spirotetramat, and its chemical structure is as follows: [0003] [0004] Spirotetramat, developed by Bayer CropScience, is a lipid synthesis inhibitor that can cause larval death or reduce the reproductive ability of adults by interfering with lipid synthesis in insects. Spirotetramat has good systemic properties, can be conducted to the top (upper) through the xylem and phloem of the plant, and can be conducted from top to bottom in the plant. Its advantages are wide insecticidal spectrum, high efficiency and long-lasting effect The period is longer. The synthesis method of spirotetramat is obtained through related reaction of key intermediate 2,5-dim...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C57/30C07C51/02
Inventor 张大永彭道文汤维维吴晓明
Owner CHINA PHARM UNIV
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