Uses
2-Chloro-5-trichloromethylpyridine serves as a precursor for synthesizing high-value chlorinated aromatics, including 2-chloro-5-dichloromethylpyridine, 2-chloro-5-chloromethylpyridine, and 2-chloro-5-methylpyridine, via selective dechlorination[1]. Electrochemical reduction of this compound over an activated silver electrode in oxygen-saturated methanol yields methyl 6-chloronicotinate and 6-chloronicotinic acid through a dechlorination-oxygenation pathway[1-2]
Synthesis
A synthetic method of 2-chloro-5-trichloromethyl pyridine comprises the following steps of (1) synthesis of N-oxygen-3-methylpyridine: reacting by taking 3-methylpyridine as a raw material, glacial acetic acid as a solvent and 60% hydrogen peroxide as an oxidizing agent to obtain N-oxygen-3-methylpyridine; (2) synthesis of 2-chloro-5-methylpyridine: carrying out oriented chlorination on N-oxygen-3-methylpyridine by taking benzoyl chloride as a chlorinating agent to obtain 2-chloro-5-methylpyridine; (3) synthesis of 2-chloro-5-trichloromethyl pyridine: reacting by taking methyl ethyl ketone peroxide as an initiating agent to obtain a crude 2-chloro-5-trichloromethyl pyridine product; (4) refining of 2-chloro-5-trifluoromethyl pyridine: carrying out halogen exchange fluoridation reaction by taking excessive potassium fluoride as a fluorizating agent, dimethyl sulfoxide as a solvent and hexadecyl trimethyl ammonium bromide as a phase transfer catalyst, and rectifying and purifying to obtain a fine 2-chloro-5-trichloromethyl pyridine product.
References
[1]
Zhao, Z., Zhang, L., Chen, M., Yu, R., Yao, X., Xu, Y., Chu, Y., Mao, X., Zheng, H. (2024). Oxygen-Controlled Electrocatalysis for Selective Dechlorination of 2-Chloro-5-Trichloromethyl Pyridine on Activated Ag Electrode. Journal of The Electrochemical Society, 171(9), 096505.
https://doi.org/10.1149/1945-7111/ad7534 [2]
Zhao, Z., Zhang, L., Chen, M., Yu, R., Jin, R., Jian, F., Shui, S., Yan, W., Xu, Y., Mao, X., Chu, Y., Zheng, H. (2025). Electrochemical Oxygen Reduction Reaction-Coupled Dechlorination Promoting Acylation Reaction for Aromatic Ester Synthesis. Journal of the American Chemical Society, 147(32), 29109–29118.
https://doi.org/10.1021/jacs.5c07666
