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A kind of preparation method of 2-chloroisonicotinic acid

A technology of chloroisonicotinic acid and dichloroisonicotinic acid, applied in the direction of organic chemistry, can solve the problems of harsh diazotization reaction conditions, reduced yield, long reaction cycle, etc., to avoid corrosion and environmental pollution, dechlorination The effect of mild conditions and short reaction time

Active Publication Date: 2015-08-19
SINO HIGH CHINA
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AI Technical Summary

Problems solved by technology

[0008] Among the above three methods for preparing 2-chloroisonicotinic acid, the disadvantage of method (1) is that the steps are relatively cumbersome, the diazotization reaction conditions are harsh, difficult to operate and have certain dangers; It is carried out under acidic conditions, which requires high production equipment
The shortcoming of method (2) is that the preparation of nitrogen oxides requires high-concentration hydrogen peroxide or the use of catalysts. These methods either have a long reaction cycle, or complex reaction components, and high cost; rate is also lower
Method (3) except having the shortcoming of method (2), also has one more step hydrolysis reaction, causes yield to further reduce

Method used

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Embodiment 1

[0033] Embodiment 1: Preparation of 2,6-dichloroisonicotinic acid

[0034] Citric acid (77.6g, 0.5mol), (CH 3 ) 4 NCl (57.5g, 0.525mol) and triphosgene (137mL, 1.5mol) were sequentially added into a 1L four-neck flask; stirred, heated in an oil bath, and reacted at 130°C for 12 hours; after the reaction solution was cooled to room temperature, it was slowly added dropwise to About 1Kg on ice, stirred for 2 hours, then filtered; the resulting filtrate was added with NaHCO 3 Adjust the pH to weak acidity, let stand, separate out unreacted citrazinic acid, suction filter, reclaim to obtain 7.8g citric acid; the solid obtained by filtering in the previous step is dissolved with ethyl acetate after drying, and then filtered to remove insoluble matter, the filtrate After removal of ethyl acetate in vacuo, 78.3 g of 2,6-dichloroisonicotinic acid was obtained as a light yellow solid with a yield of 90.6% (based on the actual consumption of citrazine). m.p.: 209.1~210.7℃.

[0035] ...

Embodiment 2

[0037] Embodiment 2: Preparation of 2-chloroisonicotinic acid

[0038] Put 2,6-dichloroisonicotinic acid (38.4g, 0.2mol) and 80wt% hydrazine hydrate (240g, 3.8mol) into a 2L four-neck flask, stir, heat to 45°C in a water bath, and react for 3 hours; In addition to residual hydrazine hydrate, the resulting brown solid was dissolved with a small amount of water; the resulting solution was heated to boil, and 640 mL of 10 wt% CuSO 4 Solution; continue to boil for 15 minutes, adjust it to strong alkalinity with NaOH solution, and boil for 15 minutes; suction filter while hot, acidify the filtrate with hydrochloric acid to precipitate solids, and obtain 16.3g of 2-chloroisonicotinic acid by suction filtration, which is a white solid. The yield was 51.8%. m.p.: 231.8-233.3°C.

[0039] Spectral data of 2-chloroisonicotinic acid

[0040] IR(KBr,cm -1 ):3106,2917,2904,2784,2706,2617,2662,2494,2484,1884,1800,1716,1603,1566,1548,1459,1266,1234,1161,1160,1077,1008,997,903,868,766,729,...

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Abstract

The invention discloses a preparation method of 2-chloroisonicotinate. The preparation method comprises the following steps of: getting citrazinic acid as the raw material; performing chlorination reaction to obtain 2, 6-dichloroisonicotinic acid; and then performing directional dechlorination reaction to obtain 2-chloroisonicotinate. The method is simple, easy to carry out, safe, practical, relatively high in yield, and suitable for batch production.

Description

technical field [0001] The invention belongs to the field of fine chemical industry, and in particular relates to a preparation method of halogenated pyridine compounds, in particular to a selective dechlorination method using hydrazine hydrate as a dechlorination agent. Background technique [0002] In the development of pesticides in recent years, many heterocyclic compound pesticides are an important development trend, and they occupy an important position in biologically active compounds. Pyridine is a common and very important heterocycle in organic synthesis. Its application in pesticides can be traced back to Europe from the end of the 17th century to the beginning of the 18th century; and the real organic synthesis of pyridine pesticides began in the mid-1950s Herbicides Diquat and Paraquat (Qin Zhaohai. Modern Agriculture, 2003, 2, 1~6.). [0003] Through systematic research on pyridine derivatives, we found that they have good herbicide, bactericide, insect repell...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D213/803C07D213/79
CPCC07D213/79C07D213/803
Inventor 汤浩严留新张海娟王大胜陈年海
Owner SINO HIGH CHINA
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