Ruthenium-modified solid catalyst Ru-Co(OH)₂-CeO₂ was applied to the lactonization of diols in the presence of molecular oxygen and achieved highly efficient catalytic performance. Hydroxyl group on the primary carbon could be preferentially oxidized to the corresponding carbonyl group. The research towards reaction mechanism presented that Ru-alkoxide intermediate could be formed from active ruthenium center and reactants, followed by oxidative β-hydride elimination, isomeric cyclization, and further oxidative dehydrogenation, and the product lactone could be obtained.

Key words: diol, lactonization, solid catalyst