Preparation method of 2,3-dichloro-4-hydroxyaniline

A technology of hydroxyaniline and dichloro, which is applied in the field of preparation of intermediate 2,3-dichloro-4-hydroxyaniline, can solve the problems of high cost, increased risk of large-scale production, unfriendly metal waste residue, etc. Gentle, simple operation, low reaction cost effect

CN105732403AInactive Publication Date: 2016-07-06INST OF CHEM MATERIAL CHINA ACADEMY OF ENG PHYSICS +1
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2016-07-06
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention discloses a preparation method of 2,3-dichloro-4-hydroxyaniline. The preparation method comprises the steps of adding a reaction raw material 2,3-dichloro-4-phenylazo phenol and a reductant sodium borohydride into an ethanol solution, reacting at 0-25 DEG C for 2-6 hours, cooling to the room temperature after the reaction, regulating pH to 7, extracting by virtue of ethyl acetate, drying by virtue of anhydrous sodium sulfate, then carrying out rotary evaporation to remove the solvent, recrystallizing with methylbenzene, and finally drying so as to obtain 2,3-dichloro-4-hydroxyaniline. According to the preparation method of 2,3-dichloro-4-hydroxyaniline, a catalytic reduction method for utilizing hydrogen / metals at a pressurization condition is avoided, expensive and inflammable Raney nickel or other metal catalysts are not used, the operation is simple, conditions are mild, the yield can reach 90% or above, and the reaction cost is low. The preparation method is applicable to large-scale industrial production.
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Description

Technical field

[0001] The invention belongs to the technical field of crop protection agents, and specifically relates to a preparation method of intermediate 2,3-dichloro-4-hydroxyaniline. Background technique

[0002] Amide fungicides have been successfully developed and used since 1966. This type of crop protection agent has been used as a fungicide for nearly 50 years. Cyprofen is a new amide fungicide with systemic and protective properties developed by Bayer and officially launched in 1999. Cyprofen and its derivative fungicides have toxicological data that are safe and beneficial to crops, and have good ecological effects, making them ideal comprehensive pest management drugs.

[0003] 2,3-Dichloro-4-hydroxyaniline is a key intermediate of cyclofenac and its derivatives for crop fungicides. Its synthesis method has been reported and protected by Bayer Company, that is, it is composed of substituted aryl azo compounds. The raw materials are reduced to obtain the tar...

Examples

Embodiment 1

[0035] Preparation of 2,3-dichloro-4-hydroxyaniline by reduction in sodium borohydride / ethanol system

[0036] In a 100 ml two-necked flask equipped with a stirring bar and a reflux condenser, add 8.0 g (0.03 moles) of raw material 2,3-dichloro-4-phenylazophenol, dissolve in 40 ml of ethanol solution, and place in an ice-water bath Add 4.5 g (0.12 mol) of sodium borohydride in small portions. After the dropwise addition was completed, the ice bath was removed under stirring, and the reaction was continued for 4 hours at room temperature. After the reaction, the dilute hydrochloric acid solution was neutralized to pH=7, extracted three times with ethyl acetate, the combined organic phase was dried with anhydrous sodium sulfate, the solvent was evaporated by a rotary evaporator, 20 ml of toluene was recrystallized, and the product was obtained by drying after filtration: 4.95 g of light pink crystals, yield 92%.

[0037] Figure 2-4 shows the 2,3-dichloro-4-hydroxyaniline 1 ...

Embodiment 2

[0039] Preparation of 2,3-dichloro-4-hydroxyaniline by reduction with sodium borohydride and sodium hydroxide / ethanol system

[0040] In a 100 ml two-necked flask equipped with a stirring bar and a reflux condenser, add 8.0 grams (0.03 moles) of raw material 2,3-dichloro-4-phenylazophenol, and dissolve 1 gram of sodium hydroxide in 40 milliliters of ethanol solution 4.5 g (0.12 mol) of sodium borohydride was added in small portions in an ice-water bath. After the dropwise addition was completed, the ice bath was removed under stirring, and the reaction was continued for 4 hours at room temperature. After the reaction, the dilute hydrochloric acid solution was neutralized to pH=7, extracted three times with ethyl acetate, the combined organic phase was dried with anhydrous sodium sulfate, the solvent was evaporated by a rotary evaporator, 20 ml of toluene was recrystallized, and the product was obtained by drying after filtration: 5.08 g of light pink crystals, yield 95%, puri...