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Method for preparing 2-chloro-5-trichloromethylpyridine

A technology for trichloromethylpyridine and methylpyridine, which is applied in the field of preparation of pharmaceutical and pesticide intermediates, can solve the problems of high reaction temperature requirements, difficulty in separation and purification, low yield of target products, etc., and reduces the generation of by-products. , the ratio is easier to control, and the reaction conditions are easier to control.

Inactive Publication Date: 2012-05-16
NINGBO UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most of the synthesis processes are based on the gas phase method, and the reaction temperature is relatively high, generally around 300-400 °C, and the reaction process and the ratio of the reactants and the reaction process are not easy to control, so that a large number of by-products are produced during the reaction process, resulting in Low yield of target product
On the other hand, due to the similar properties of the various products generated by the reaction, many difficulties are brought to the separation and purification. The total yield of the step-by-step chlorination method is generally about 40%, which is obviously lower. The Bottleneck of Industrial Production of -5-Trichloromethylpyridine

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] 18.8 g of 3-picoline and 100 mL of o-dichlorobenzene were added to a four-necked flask, and 0.1 g of a mixed initiator composed of 0.8 g of phosphorus trichloride and 0.1 g of azobisisobutyronitrile was added at the same time. Introduce nitrogen, electromagnetically stir, heat up to 80°C, stop nitrogen flow and switch to chlorine gas, continue to heat up to 140°C, at constant temperature, chlorine gas bubbles for reaction. During the reaction, 0.1 g of the remaining mixed initiator was added every 1.5 h, and the addition was completed in 8 times to reach 0.9 gram of the mixed initiator. The reaction time is 16 hours, stop heating, close the chlorine gas injection valve, feed nitrogen gas, and chase chlorine by bubbling for 1 hour. After the reaction solution was distilled off under reduced pressure, a brown-red oily liquid was obtained. The product was purified by high vacuum fractional distillation, and the distillate above 200°C was collected. After extraction with ...

Embodiment 2

[0020] 18.8 g of 3-picoline and 100 mL of o-dichlorobenzene were added to a four-neck flask, and 0.1 g of a mixed initiator composed of 0.5 g of phosphorus trichloride and 0.1 g of azobisisobutyronitrile was added at the same time. Introduce nitrogen, electromagnetically stir, heat up to 80°C, stop nitrogen flow and switch to chlorine gas, continue to heat up to 140°C, at constant temperature, chlorine gas bubbles for reaction. During the reaction, 0.1 g of the remaining mixed initiator was added every 1.5 h, and the addition was completed in 8 times to reach 0.9 gram of the mixed initiator. The reaction time is 16 hours, stop heating, close the chlorine gas injection valve, feed nitrogen gas, and chase chlorine by bubbling for 1 hour. After the reaction solution was distilled off under reduced pressure, a brown-red oily liquid was obtained. The product was purified by high vacuum fractional distillation, and the distillate above 200°C was collected. After extraction with ch...

Embodiment 3

[0022] 18.8 g of 3-picoline and 100 mL of o-dichlorobenzene were added to a four-necked flask, and 0.1 g of a mixed initiator composed of 0.8 g of phosphorus trichloride and 0.1 g of azobisisobutyronitrile was added simultaneously. Nitrogen gas was introduced, electromagnetic stirring was carried out, and the temperature was raised to 80°C. The nitrogen gas flow was stopped and chlorine gas was switched, and the temperature was continued to rise to 120°C. At a constant temperature, chlorine gas bubbled and reacted. During the reaction, 0.1 g of the remaining mixed initiator was added every 1.5 h, and the addition was completed in 8 times to reach 0.9 gram of the mixed initiator. The reaction time is 16 hours, stop heating, close the chlorine gas injection valve, feed nitrogen gas, and chase chlorine by bubbling for 1 hour. After the reaction solution was distilled off under reduced pressure, a brown-red oily liquid was obtained. The product was purified by high vacuum fractio...

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Abstract

The invention relates to a method for preparing 2-chloro-5-trichloromethylpyridine, which is characterized by comprising the following steps of: initiating reaction of 3-methylpyridine serving as a raw material in the presence of an organic solvent and chlorine gas by a one-step liquid-phase chlorination method by using an initiator to synthesize the 2-chloro-5-trichloromethylpyridine, and purifying to obtain a finished product, wherein the reaction temperature is 100 to 160 DEG C, reaction time is 15 to 17 hours, and the initiator is formed by combining an organic compound initiator with an inorganic compound initiator and is added in an amount which is 3 to 6 percent based on the weight of the 3-methylpyridine serving as the raw material. The liquid-phase chlorination method is adopted, so that the raw material reacts in a liquid state, the ratio of reactants and reaction conditions are easy to control, and byproducts are reduced; and the inorganic initiator and the organic initiator are used simultaneously, so that the yield of the target product reaches 84 percent, and the method is an ideal method for synthesizing the 2-chloro-5-trichloromethylpyridine.

Description

technical field [0001] The invention relates to a preparation method of a medicine and pesticide intermediate, in particular to a preparation method of 2-chloro-5-trichloromethylpyridine. Background technique [0002] 2-Chloro-5-trichloromethylpyridine is a very important pharmaceutical and pesticide intermediate, which can be used to prepare pharmaceuticals, agricultural chemicals and biological agents, especially for the synthesis of high-efficiency new pesticides such as haloxyfop and imidacloprid As well as the crucial intermediates of new chloropyridine-containing pesticides in the future, new chloropyridine-containing pesticides synthesized from 2-chloro-5-trichloromethylpyridine are currently being researched and developed vigorously at home and abroad. [0003] The synthesis of 2-chloro-5-trichloromethylpyridine began in the 1970s, and its synthetic routes mainly include 3-methylpyridine, nicotinic acid chlorination and direct cyclization. The synthesis process is m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
Inventor 张剑锋王爽米罗毅王明升许自扬
Owner NINGBO UNIV
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