NaNO2-activated, iron–TEMPO catalyst system for aerobic alcohol oxidation under mild conditions

Abstract

FeCl3-TEMPO-NaNO2 catalyses the selective and mild aerobic oxidation of a broad range of alcohols to the corresponding aldehydes and ketones.

Iron‐Catalyzed Oppenauer‐Type Oxidation of Alcohols

“…[4] The development of new catalysts containing abundant and inexpensive metals, particularly those derived from iron, for the oxidation of alcohols is highly desirable. It has been reported that aerobic alcohol oxidation is catalyzed by FeA C H T U N G T R E N N U N G (NO 3 ) 3 / FeBr 3 [5] or FeCl 3 ·6 H 2 O/NaNO 2 /TEMPO, [6] and the catalytic oxidation of secondary alcohols with tBuO 2 H is affected by FeA C H T U N G T R E N N U N G (NO 3 ) 3 ·9 H 2 O/picolinic acid. [7] These catalytic reactions may be easy to operate, but the structures of the actual catalysts are ill-defined, providing little mechanistic information for further catalyst improvement.…”

Recyclable Carbon Supported Copper‐Manganese Oxide for Selective Aerobic Oxidation of Alcohols in Combination with 2,2,6,6‐Tetramethylpiperidyl‐1‐oxyl under Neutral Condition

“…Upon catalysis with the Cu-Mn oxide/C (10 wt%) and TEMPO (0.5-5 mol%), various alcohols were oxidized selectively to the corresponding aldehydes or ketones with molecular oxygen at 80 8C. Such a stable, recyclable heterogeneous cocatalyst permits alcohols to be oxidized under neutral and mild conditions.Keywords: aerobic oxidation; alcohols; carbon; catalysis; copper-manganese mixed oxide; 2,2,6,6-tetramethylpiperidyl-1-oxyl (TEMPO)The transformation of alcohols to the corresponding aldehydes or ketones is of importance in fundamental research and industrial manufacturing.[1] Many catalytic systems have been discovered for using molecular oxygen as environmentally friendly oxidant for the selective oxidation of alcohols.[2] Of particular interest are the catalytic systems using 2,2,6,6-tetramethylpiperidyl-1-oxyl (TEMPO) as a key catalyst [3] in combination with various homogeneous multicomponent cocatalytic systems, such as, tert-butyl nitrite/HBr, [4] NaNO 2 /FeCl 3 , [5] NaNO 2 /Br 2 , [6] NaNO 2 /1,3-dibromo-5,5-dimethylhydantoin, [7] [bisA C H T U N G T R E N N U N G (acetoxy)iodo]benzene/ KNO 2 , [8] MnAin acetic acid, [9] CuBr 2 (2,2'-bipyridine)/t-BuOK, [10] RuCl 2 A C H T U N G T R E N N U N G (PPh 3 ) 3 , [11] CuBr·Me 2 S, [12] CH 3 ReO 3 /HBr in acetic acid, [13] Cu(II)-diimine complexes, [14] etc. These multicomponent cocatalytic systems build one (or more) redox bridge(s) between molecular oxygen activation and in situ oxidation of TEMPO to its oxammonium cation, which is the real oxidant for the selective oxidation of alcohols.…”

Room temperature aerobic oxidation of alcohols using CuBr2 with TEMPO and a tetradentate polymer based pyridyl-imine ligand

“…In the interest of sustainability, there has been significant development in the use of more abundant and cheaper transition metals such as iron [18][19] and copper as active catalysts. Following the first reported aerobic oxidation of activated primary alcohols by Semmelhack [20] et al in 1984, inexpensive and abundant copper has attracted much attention in the field of alcohol oxidations.…”