关键词:

3,6-二氯吡啶甲酸, 3,4,5,6-四氯吡啶甲酸, 电化学合成, 工业化

Abstract:

The industrialization of electrochemical synthesis of 3,6-dichloropicolinic acid(3,6-DCP) from 3,4,5,6-tetrachloropicolinic acid(3,4,5,6-TCP) in a tank-type undivided electrolytic cell with silver cathode was investigated. The experimental results showed that the electrolytic performance greatly depended on the operation parameters, such as flow rate of electrolyte, temperature, and concentration of NaOH. The reduction of 3,4,5,6-TCP to 3,6-DCP was favored by increasing temperature and flow rate of electrolyte. Industrialization tests of electrochemical synthesis of 3,6-DCP were conducted under the following conditions: silver cathode, temperature 313 K, flow rate 6 cm·s^-1, concentration of NaOH 8%(mass), concentration of 3,4,5,6-TCP 5%（mass）, cathode current density 600 A·m^-2. The current efficiency and conversion ratio of 3,4,5,6-TCP were more than 76% and 99%, respectively. The yield of 3,6-DCP was up to 90% and DC power consumption was 2. 939 kW·h·(kg 3,6-DCP)^-1. The purity of the product was higher than 95%, and its melting point was 151—153℃.

Key words:

3,6-二氯吡啶甲酸, 3,4,5,6-四氯吡啶甲酸, 电化学合成, 工业化