3

6-Dichloropicolinic acid(3

6-DCP)as a highly active and low-toxicity compound is mainly used as herbicide

pesticide and plant growth regulator.Synthesis methods of 3

6-DCP are summarized as follows:(1)Due to high cost

hydrolysis of 3

6-dichloro-2-(trichloromethyl)pyridine or 2-cyano-3

6-dichloropyridine to prepare 3

6-DCP(in spite of the method is good in reaction selectivity)is not suitable for commercial production.(2)The synthesis method of 3

6-DCP by hydrolysis-reduction dechlorination of 2-cyano-3

4

5

6-tetrachloropyridine or reduction dechlorination of 3

4

5

6-tetrachloropicolinic acid is replaced by electrochemical methods because hydrazine and cyanide must be used in this method

though the method could provide many advantages

such as low price of raw materials and reaction equipment

high yield(70%—80%).(3)Electrochemical synthesis is gradually becoming the main method to prepare 3

6-DCP in commercial production

and very high yield(>90%)and product purity(95%)can achieved by using this method.In addition

two separation methods of 3

6-DCP are compared: extraction-stripping and neutralization-crystallization-extraction

the former is a more effective method for separation because of its better performance.Based on the statements above

some suggestions for the synthesis of 3

6-DCP are presented.