Showing papers on "Oxidation of secondary alcohols to ketones published in 2017"

Dehydrogenative Oxidation of Alcohols in Aqueous Media Catalyzed by a Water-Soluble Dicationic Iridium Complex Bearing a Functional N-Heterocyclic Carbene Ligand without Using Base

Abstract: A dicationic iridium complex bearing a bidentate ligand that comprises N-heterocyclic carbene and α-hydroxypyridine moieties has been designed and synthesized. The complex exhibited high catalytic performance in aqueous media for the dehydrogenative oxidation of secondary alcohols to ketones accompanying the evolution of hydrogen. Furthermore, dehydrogenative transformation of primary alcohols to the carboxylic acids in aqueous media was also catalyzed by the complex without using base.

Practical Aerobic Oxidation of Alcohols: A Ligand-Enhanced 2,2,6,6-Tetramethylpiperidine-1-oxy/Manganese Nitrate Catalyst System

Abstract: A highly efficient, ligand enhanced TEMPO/Mn(NO3)2 catalyst system for the aerobic oxidation of alcohols is described. From the series of coordinating ligands studied herein, 2-picolinic acid (PyCOOH) remarkably improves the catalytic activity of TEMPO/Mn(NO3)2. Under ambient air, at room temperature and in acetic acid, the ligand-enhanced catalyst converts various functional group-bearing aliphatic and benzylic primary alcohols to their respective aldehydes with near quantitative conversions. Applicability of the catalyst for convenient preparative synthesis was demonstrated. by conducting oxidations in a gram scale. A change of TEMPO to sterically less demanding 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO) turns the Mn-catalyst also capable for oxidation of secondary alcohols to ketones. Mechanistic studies showed that alcohols are oxidized by the oxoammonium cation derived from the nitroxyl radical. The active oxidant is re-generated by Mn(NO3)2 and this process is greatly promoted by the coordination of PyCOOH to Mn.