. . "A precursor solution of the pyridone having the desired substituents thereon is prepared in an appropriate solvent, such as a mixture of water, organic solvents, including lower alcohols such as ethanol, ethanol, isopropanol, and the like, water-miscible nonbasic organic solvents such as tetrahydrofuran, acetone, dimethoxyethane, N,N-dimethylformamide, N,N-dimethylacetamide, and the like, as well" . . . .