Photochemical Alkylation, Hydroxyalkylation, and Alkoxylation of Pyridinecarboxamides in Alcohol

The UV-irradiation of 2- and 4-pyridinecarboxamides in alcohol brings about alkylation and/or hydroxyalkylation in the pyridine ring. In the irradiation of 3-pyridinecarboxamide in the presence of sulfuric acid, ionic reaction (alkoxylation at the 2- and 6-position) and radical reaction (alkylation at the 4- and 6-position) occur in parallel. The effects of quenchers indicate that two alkylation products originate from one excited triplet state which is quenched by energy-transfer mechanism and that two alkoxylation products originate from the excited singlet state.