WANG Yixiang, CHEN Zewei, ZHANG Wen, et al. Electrochemical hydrodechlorination of 2-chloro-5-trichloromethylpyridine to 2-chloro-5-methylpyridine[J]. CIESC Journal, 2017, (5): 1882-1891.
DOI:
WANG Yixiang, CHEN Zewei, ZHANG Wen, et al. Electrochemical hydrodechlorination of 2-chloro-5-trichloromethylpyridine to 2-chloro-5-methylpyridine[J]. CIESC Journal, 2017, (5): 1882-1891.DOI: 10.11949/j.issn.0438-1157.20161591.
Electrochemical hydrodechlorination of 2-chloro-5-trichloromethylpyridine to 2-chloro-5-methylpyridine
Electrochemical hydrodechlorination of 2-chloro-5-trichloromethylpyridine (TCMP) for the synthesis of 2-chloro-5-chloromethylpyridine (CCMP) or 2-chloro-5-methylpyridine (CMP) has important application in preparation of imidacloprid. Feasibility of electrochemical hydrodechlorination of TCMP to CCMP or CMP was first investigated in a weak acidic solvent mixture of methanol
acetic acid and water. Then
influence of cathode material and catholyte composition on electrochemical hydrodechlorination was studied. Finally
influence of supporting catholyte and anolyte on cell voltage and influence of current density and TCMP concentration on efficiency of electrochemical hydrodechlorination were investigated in a plate and frame cell. The experimental results show that: TCMP can be selectively hydrodechlorinated to CMP on a silver mesh cathode in the weak acidic solvent mixture
which cathode material with CMP production rate from high to low is silver
copper
zinc
lead
titanium
graphite
and nickel. Cell voltage is decreased substantially when lithium acetate (CH3COOLi) and sulfuric acid are used to replace tetrabutylammonium perchlorate (TBAP) as supporting cantholyte and anolyte. Efficiency of electrochemical hydrodechlorination is increased by reducing current density and raising initial concentration of TCMP. Under optimized condition (catholyte: 0.2 mol·L-1 CH3COOLi in 10%(vol) CH3COOH and 5%(vol) methanol aqueous solution. Cathode silver mesh
current density 333 A·m-2
temperature 30℃). 0.2 mol·L-1 TCMP is hydrodechlorinated to CMP with yield of 91% at current efficiency of 54% and cell voltage of 3.0 V.