A Homogeneous Mixture Composed of Vanadate, Acid, and TEMPO Functionalized Ionic Liquids for Alcohol Oxidation by H₂O₂

Abstract

The functionalized ionic liquids (ILs) of N‐n‐dodecyl pyridinium vanadate (1), N‐(propyl‐1‐sulfonic acid) pyridinium tetrafluoroborate (2), and 4‐(propanoate‐2,2,6,6,‐tetramethylpiperidine‐1‐oxyl) pyridinium tetrafluoroborate (5) were synthesized. The mixture of 1, 2, and 5 in [Bpy]BF4 yielded the compatible IL compositions (ILCs) as a homogenous mixture, which proved to be an efficient catalytic system for oxidation of a wide range of alcohols using H2O2. With the aid of 2 and 5, 1 in [Bpy]BF4 could easily be recovered and reused for at least six runs without a loss in activity. UV/Vis spectroscopic analysis indicated that the role of 2 was to promote the formation of the active peroxo VV species, which is responsible for substrate activation, and the role of 5 was to oxidize the low‐valent vanadium(II–IV) species to regenerate 1.

Oxidovanadium complexes with tridentate aroylhydrazone as catalyst precursors for solvent-free microwave-assisted oxidation of alcohols

“…Addition of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) radical, an efficient mediator for the aerobic oxidation of alcohols [23,24,[61][62][63][64][65], although scarcely used for the peroxidative oxidation [35,43,66,67] of those substrates, provided almost quantitative formation of acetophenone (Fig. 3) and a significant increase in cyclohexanone yield (from 38 to 58% (2), Fig.…”

“…The use of polyoxidovanadates has also been reported for the efficient oxidation of benzylic alcohols to the corresponding carbonyl compounds with p-toluenesulfonic acid [40]. However, the vanadium catalyzed peroxidative oxidation of secondary alcohols is comparatively scarce [35][36][37][38][39][41][42][43]. Some efficient systems concern the use of tert-butylhydroperoxide (TBHP) in the presence of silica [41] or graphene [42] supported oxidovanadium Schiff bases, or of hydrogen peroxide in a homogeneous mixture composed of vanadate, acid and TEMPO functionalized ionic liquids [43].…”

Direct Oxidation of Primary Alcohols to Carboxylic Acids

“…14 A vanadate-TEMPO catalytic system was used for benzyl alcohol oxidation to benzaldehyde with hydrogen peroxide. 15 In this case, peroxovanadates, but not oxovanadate, VO 4 3-, could be responsible for the oxidation.…”

“…For example, in dehydrogenation of 4-chlorobenzyl alcohol catalyzed by 15, 4-chlorobenzoic and benzoic acids were isolated in 70% and 10% yields, respectively. 15 Hydrogenation of unsaturated functional groups is another common side reaction for ruthenium catalytic systems and was detected in the case of 14, 18, and 19. It is remarkable that alkenes are tolerated by 15, as well as primary, secondary, and tertiary amines.…”

Applications of inorganic‐organic hybrid architectures based on polyoxometalates in catalyzed and photocatalyzed chemical transformations

“…In recent years, there has been an overgrowing demand for the preparation of efficient catalysts for the selective oxidation of alcohols to the corresponding carbonyl compounds as appropriate precursors in multistep reactions, the production of new materials and energy sources . The Pd (II)‐catalyzed oxidation of alcohols in the presence of a base is a well‐known transformation .…”