Aerobic Oxidation Of Secondary Alcohols Research Articles

Aerobic Oxidation of Secondary Alcohols with Nitric Acid and Iron(III) Chloride as Catalysts in Fluorinated Alcohol.

Fluorinated alcohols as solvents strongly influence and direct chemical reaction through donation of strong hydrogen bonds while being weak acceptors. We used 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the activating solvent for a nitric acid and FeCl3-catalyzed aerobic oxidation of secondary alcohols to ketones. Reaction proceeded selectively with excellent yields with no reaction on the primary alcohol group. Oxidation of benzyl alcohols proceeds selectively to aldehydes with only HNO3 as the catalyst, while reaction on tertiary alcohols proceeds through dehydration and dimerization. A mechanistic study showed in situ formation of NOCl that converts alcohol into alkyl nitrite, which in the presence of Fe3+ ions and fluorinated alcohol decomposes into ketone. The study indicates that iron(III) acts also as the single-electron transfer catalyst in regeneration of NOCl reactive species.

Asymmetric aerobic oxidation of secondary alcohols catalyzed by poly(N-vinyl-2-pyrrolidone)-stabilized gold clusters modified with cyclodextrin derivatives.

Surface modification of poly(N-vinyl-2-pyrrolidone)-stabilized gold clusters (1.8 ± 0.6 nm) with aminated cyclodextrins induced aerobic oxidative kinetic resolution of racemic secondary alcohols (krel = 1.2).

Synthesis, characterization and catalytic activities of rhenium carbonyl complexes bearing pyridine-alkoxide ligands

Thermal treatment of Re2(CO)10 with pyridine-alkoxide ligands PyC(CH2)4OH (LaH) and PyCR1R2OH (R1 = CH3, R2 = C6H5 (LbH); R1 = H, R2 = C6H5 (LcH); R1 = H, R2 = 4-CH3C6H4 (LdH); R1 = H, R2 = 4-OMeC6H4 (LeH); R1 = H, R2 = 4-ClC6H4 (LfH); R1 = H, R2 = 4-CF3C6H4 (LgH)) respectively in refluxing xylene generated a series of dirhenium carbonyl complexes [PyC(CH2)4O]2 [Re(CO)3]2 (1a) and (PyCR1R2O)2 [Re(CO)3]2 (R1 = CH3, R2 = C6H5 (1b); R1 = H, R2 = C6H5 (1c); R1 = H, R2 = 4-CH3C6H4 (1d); R1 = H, R2 = 4-OMeC6H4 (1e); R1 = H, R2 = 4-ClC6H4 (1f); R1 = H, R2 = 4-CF3C6H4 (1g)). Complexes 1a−1g were characterized by NMR spectroscopy, elemental analyses and FT-IR spectroscopy. Furthermore, the molecular structures of complexes 1a, 1d and 1g were determined by single crystal X-ray diffraction analysis. In the presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxyl) as co-oxidant and molecular oxygen (ambient air) as terminal oxidant, these dirhenium carbonyl complexes showed moderate catalytic activity for aerobic oxidation of secondary alcohols.

Ruthenium carbonyl complexes with pyridylalkanol ligands: synthesis, characterization and catalytic properties for aerobic oxidation of secondary alcohols

Several new trinuclear ruthenium carbonyl complexes were synthesized and their application in aerobic oxidation of secondary alcohols was also established.

Aerobic oxidation of secondary alcohols in water with ABNO/tert-butyl nitrite/KPF6 catalytic system

A green and efficient transition-metal free ABNO/tert-butyl nitrite/KPF6-catalyzed aerobic oxidation of secondary alcohols in water has been achieved. Under the optimal reaction conditions, a number of secondary aliphatic alcohols and secondary benzylic alcohols can be converted to their corresponding ketones in excellent yields (up to 99%).

Comparative Catalytic Evaluation of Nano-ZrOx Promoted Manganese Catalysts: Kinetic Study and the Effect of Dopant on the Aerobic Oxidation of Secondary Alcohols

This work reports the zirconia (ZrOx) nanoparticles doped MnCO3 catalysts prepared by facile and simple coprecipitation technique and the synthesis of zirconia-manganese carbonate [X% ZrOx–MnCO3] (where X% = 0–7%) catalyst which upon calcination at 400°C is converted to zirconia-manganese dioxide [1% ZrOx–MnO2] and when calcined at 500°C is converted to zirconia-manganic trioxide [1% ZrOx–Mn2O3]. A comparative catalytic study was performed to investigate the catalytic efficiency between carbonate and oxides for the selective oxidation of 1-phenylethanol by using molecular O2 as a clean oxidant. The influence of several parameters such as w/w% of ZrOx, reaction time, calcination temperature, catalyst amount, and reaction temperature has been thoroughly examined using oxidation of 1-phenylethanol as a model substrate. The 1% ZrOx–MnCO3 precalcined at 300°C exhibited the best catalytic efficiency. It was found that ZrOx nanoparticles also play an essential role in enhancing the effectiveness of the catalytic system for the aerobic oxidation of alcohols. Furthermore, the physical and chemical properties of synthesized catalysts were evaluated by microscopic and spectroscopic techniques. An extremely high specific activity of 40 mmol·g−1·h−1 with a 100% conversion of oxidation product and selectivity of >99% was achieved within extremely short reaction time (6 min).

Aerobic Oxidation of Secondary Alcohols to Ketones Catalyzed by Ionic Liquid Functionalized TEMPO

Protocols of aerobic oxidation of secondary alcohols to ketones by using TEMPO modified by bifunctionalized imidazolium-based ionic liquids have been developed. [Imim-TEMPO][X] (X= FeCl4, CuCl2) has been proved to be efficient and recyclable catalysts with modest or excellent yields and selectivity. Therefore, relevant literatures are summarized herein.

Aerobic oxidation of secondary alcohols using NHPI and iron salt as catalysts at room temperature

Aerobic oxidation of various alcohols has been accomplished by using a novel catalytic system, N-hydroxyphthalimide (NHPI) combined with Fe(NO3)3·9H2O. Secondary alcohols, especially benzylic and aliphatic alcohols, were smoothly transformed into corresponding ketones with up to 92% yields at room temperature under one atmosphere pressure of oxygen. The influences of reaction conditions such as solvent, different metal catalyst, catalyst loading and the structure of alcohols on the promotion effect were studied. And a possible radical mechanism for the oxidation of secondary alcohols in Fe(NO3)3·9H2O/NHPI/O2 system was proposed.

Efficient Aerobic Oxidation of Secondary Alcohols at Ambient Temperature with an ABNO/NOx Catalyst System

New highly practical methods are presented for aerobic oxidation of secondary alcohols with a nitroxyl radical in combination with HNO3, NaNO2, or both as cocatalysts. Diverse nitroxyls are compared, including several novel bicyclic derivatives. Catalyst systems with the readily available nitroxyls, 9-azabicyclo[3.3.1]nonane-N-oxyl (ABNO) and 9-azabicyclo[3.3.1]nonan-3-one-N-oxyl (keto-ABNO), are optimized in acetic acid or acetonitrile as the solvent. The reactions are compatible with substrates bearing diverse functional groups and proceed efficiently under mild conditions at ambient pressure and temperature.

Efficient Aerobic Ruthenium‐Catalyzed Oxidation of Secondary Alcohols by the Use of a Hybrid Electron Transfer Catalyst

AbstractBiomimetic aerobic oxidation of secondary alcohols has been performed using hybrid catalyst 1 and Shvo's catalyst 2. This combination allows mild reaction conditions and low catalytic loading, due to the efficiency of intramolecular electron transfer. By this method a wide range of different alcohols have been converted into their corresponding ketones. Oxidation of benzylic as well as aliphatic, electron‐rich, electron‐deficient and sterically hindered alcohols could be oxidized in excellent yield and selectivity. Oxidation of (S)‐1‐phenylethanol showed that no racemization occurred during the course of the reaction, indicating that the hydride 2b adds to the quinone much faster than it re‐adds to the ketone product. The kinetic deuterium isotope effect of the oxidation was determined by the use of 1‐phenylethanol (3a) and 1‐deuterio‐1‐phenylethanol (3a‐d1) in parallel and competitive manner, which gave the same isotope effect within experimental error (kH/kD ≈ 2.8). This indicates that there is no strong coordination of the substrate to the catalyst.

Pd-catalyzed enantioselective aerobic oxidation of secondary alcohols: applications to the total synthesis of alkaloids.

Enantioselective syntheses of the alkaloids (-)-aurantioclavine, (+)-amurensinine, (-)-lobeline, and (-)- and (+)-sedamine are described. The syntheses demonstrate the effectiveness of the Pd-catalyzed asymmetric oxidation of secondary alcohols in diverse contexts and the ability of this methodology to set the absolute configuration of multiple stereocenters in a single operation. The utility of an aryne C-C insertion reaction in accessing complex polycyclic frameworks is also described.

Aerobic oxidation of secondary alcohols to ketones catalyzed by cobalt(II)/ZnO in poly(ethylene glycol)/CO2 system

The aerobic oxidation of benzhydrol, 1-phenylethanol and cyclohexanol to corresponding ketones was carried out in poly(ethylene glycol) (PEG-600)/supercritical CO 2 (SCCO 2 ) biphasic system using unsupported and supported CoCl 2 ·6H 2 O as the catalysts. It was demonstrated that CoCl 2 ·6H 2 O, Co(II)/Al 2 O 3 , and Co(II)/ZnO were all active and selective for the reactions. The reactivity of the substrates followed the order benzhydrol > 1-phenylethanol > cyclohexanol. Co(II)/ZnO was most stable and could be reused four times without considerable reduction of activity. The effect of CO 2 pressure, reaction time and solvent was further investigated. The Co(II)/ZnO/PEG-600 system is active, selective, cheap, clean, and recyclable for the aerobic oxidation of secondary alcohols.

Direct Aerobic Oxidation of Secondary Alcohols Catalysed by Pt(0) Nanoparticles Stabilized by PV2Mo10O40 5− Polyoxmetalate

Pt(0) nanoparticles stabilized by the H5PV2 Mo10O40 polyoxometalate were prepared in water by a sequence of redox reactions and supported on a-alumina. Characterization by TEM showed an average particle size of 2.6 nm with an approximate size dispersion of about ±25%. EDS analysis confirmed the amounts of metal and polyoxometalate as indicated from the reaction stoichi- ometry. These nanoparticles were further used as catalysts for the oxidation of secondary alcohols with molecular oxygen to the corresponding carbonyl products. The oxi- dation of secondary alcohols was further improved by the use of Pt nanoparticles stabilized by Rh1.7PV2Mo10O40.

The Resolution of Important Pharmaceutical Building Blocks by Palladium‐Catalyzed Aerobic Oxidation of Secondary Alcohols.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Resolution of Important Pharmaceutical Building Blocks by Palladium‐Catalyzed Aerobic Oxidation of Secondary Alcohols

AbstractThe palladium‐catalyzed aerobic oxidative kinetic resolution of key pharmaceutical building blocks is described. Substrates investigated are relevant to the enantioselective preparation of Prozac®, Singulair®, and the promising hNK‐1 receptor antagonist from Merck. The latter provides the most selective aerobic oxidative kinetic resolution yet described.

Cobalt Phthalocyanine Catalyzed Aerobic Oxidation of Secondary Alcohols: An Efficient and Simple Synthesis of Ketones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Cobalt phthalocyanine catalyzed aerobic oxidation of secondary alcohols: an efficient and simple synthesis of ketones

A variety of activated and non-activated secondary alcohols have been efficiently oxidized to their corresponding ketones in excellent yields with molecular oxygen using cobalt phthalocyanine as catalyst in the presence of powdered potassium hydroxide.

Manganese(IV) oxamato-catalyzed oxidation of secondary alcohols to ketones by dioxygen and pivalaldehyde

A new manganese(IV) oxamato complex possessing a bis(µ-oxo)dimanganese core has been synthesized, magnetically and structurally characterized, and found to catalyze the aerobic oxidation of secondary alcohols to ketones with co-oxidation of pivalaldehyde to pivalic acid with good yields and high selectivities.

ChemInform Abstract: Aerobic Oxidation of Secondary Alcohols via Ruthenium‐Catalyzed Hydrogen Transfer Involving a New Triple Catalytic System.

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Aerobic oxidation of secondary alcohols via ruthenium-catalysed hydrogen transfer involving a new triple catalytic system

Aerobic oxidation of secondary alcohols was performed employing a new triple catalytic system (Ru-catalyst 1, 2,6-di-tert-butylbenzoquinone 2, and Co-macrocycle 3) under a low concentration of molecular oxygen (air : nitrogen is between 1 : 3 and 1 : 20) at ambient pressure.