Open AccessDirect Electrochemical Reduction of Acetochlor at Carbon and Silver Cathodes in Dimethylformamide
Author(s) -
Ana G. Couto Petro,
Bishnu Thapa,
Jonathan A. Karty,
Krishnan Raghavachari,
Lane A. Baker,
Dennis G. Peters
Publication year - 2020
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/abb8f9
Subject(s) - chemistry , acetochlor , carbanion , electrochemistry , cyclic voltammetry , glassy carbon , deuterium , inorganic chemistry , dimethylformamide , photochemistry , electrolysis , cathode , carbon fibers , electrode , organic chemistry , materials science , electrolyte , solvent , pesticide , composite number , agronomy , biology , composite material , physics , quantum mechanics
Cyclic voltammetry and controlled-potential (bulk) electrolysis have been employed to investigate the direct electrochemical reduction of acetochlor ( 1 ) at carbon and silver cathodes in dimethylformamide. Voltammograms of 1 exhibit a single irreversible cathodic peak at both cathode materials. Catalytic properties of silver towards carbon–halogen bond cleavage are evidenced by a positive shift in the reduction of acetochlor as compared to the more inert glassy carbon electrode. Voltammograms in the presence of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), and comparisons of calculated relative interaction energies between acetochlor, possible intermediates, and deschloroacetochlor in the presence of different proton donors, suggest strong hydrogen-bonding interactions between HFIP and a carbanion intermediate. Addition of HFIP to electrolysis conditions promotes complete reduction at both cathode materials, with formation of deschloroacetochlor in high yields. In deuterium labelling studies, the use of DMF- d 7 led to no evidence for deuterium atom incorporation. However, when HFIP-OD or D 2 O were employed as a proton source, substantial amounts of deuterated deschloroacetochlor were observed. A mechanism for the reduction of acetochlor is proposed, in which radical intermediates do not play a significant role in reduction, rather a carbanion intermediate pathway is followed.