Electrochemical reduction of derivatives and isomers of ethylpicolinate

Electrolysis of picolinic acid, 2-formylpyridine, 2-hydroxymethylpyridine, ethylnicotinate and ethylisonicotinate in aqueous sulfuric acid solutions was performed on a lead cathode in galvanostatic mode. Electrolyses of picolinic acid, ethylnicotinate and ethylisonicotinate were performed in aqueous solutions to prepare the different hydroxymethylpyridine isomers. Results were compared with those for ethylpicolinate: the chemical yield in 2-hydroxymethylpyridine is lower than that in 3-hydroxymethylpyridine while that in 4-hydroxymethylpyridine is better. Electrolyses of the intermediates 2-formylpyridine and 2-hydroxymethylpyridine in aqueous solutions were performed with a view to understanding the competition between the reduction of the side chain and that of the pyridine nucleus. Study of medium acidity, current density, concentration and temperature shows that electroreduction occurs on the pyridinic nucleus of the formylpyridine and the picoline principally and less on the other derivatives.