Electrochemical Reduction of Pyridinic Herbicides Picloram and Clopyralid on a Mercury Pool Electrode

This paper presents the identification by GC/MS of the products obtained after the total reduction of picloram and clopyralid on a mercury pool electrode. The products found in the strongly acidic media reduction of picloram are 4‐amino‐3,5,6‐trichloro‐2‐pyridinecarboxaldehyde, 4‐amino‐3,5,6‐trichloro‐2‐pyridinecarbinol and 4‐amino‐3,5‐dichloro‐2‐pyridinecarboxylic acid; at pH 3–4 the first compound is substituted by 4‐amino‐3,5‐dichloro‐2‐pyridinecarboxaldehyde. For clopyralid 3,6‐dichloro‐2‐pyridinecarbinol was detected. Under the light of such products the overall reduction processes are discussed showing the partial reductive cleavage of chlorine atoms in both cases.