Oxidation of secondary alcohols and ethers by dimethyldioxirane

The oxidation of several series of secondary alcohols 2-9, ethers 10-17, and related derivatives 18 and19, by dimethyldioxirane, 1, in acetone at 25°C produced the corresponding ketones in good to excellent yields for all but two cases. (The exceptions: oxidation of 1-methoxy-2-methyl-1-phenylpropane (48%) and 1-methoxy-2,2-dimethyl-1-phenylpropane (24%).) The oxidation of the secondary alcohols was found to yield k2 values that were roughly 10-fold greater than those of the corresponding methyl ethers. The rate constant for oxidation of a silyl ether was slightly lower than that for the corresponding methyl ether while that for the ester derivative was roughly half the value. For oxidation of alcohols and methyl ethers, the k2 values became smaller as the R " series (Me, Et, nPr, iPr, and tBu) increased in steric bulk (ρ* = 1.7; r = 0.998 and ρ* = 3.2; r = 0.95, respectively). The Hammett study for the oxidation of the methyl ethers of α-methyl-p-benzyl alcohols (10, 20-25) yielded a ρ value of -0.74. The activation parameters for oxidation of the parent compound of the ether series (1-methoxy-1-phenylethane) were ΔH = 14.8 ± 0.5 kcal/mol, ΔS = -21.9 eu, ΔG = 21.3 kcal/mol, k2 (25°C) = 1.6 × 10-3 M-1 s-1. The mechanistic aspects of the oxidation are discussed in relation to two mechanistic extremes: (a) direct insertion of the oxygen atom into the CH bond and (b) direct abstraction of the H by dimethyldioxirane to yield a caged-radical pair, with subsequent coupling to hemi-ketal intermediates that fragment to yield acetone, alcohol or water, and ketone as the final products.Key words: dimethyldioxirane, oxidation.

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Mechanisms for the oxidation of secondary alcohols by dioxoruthenium(VI) complexes

Canadian Journal of Chemistry ◽

10.1139/v98-087 ◽

1998 ◽

Vol 76 (6) ◽

pp. 919-928 ◽

Cited By ~ 11

Author(s):

Zhao Wang ◽

W David Chandler ◽

Donald G Lee

Keyword(s):

Transition State ◽

Isotope Effects ◽

Substituent Effects ◽

Secondary Alcohols ◽

Benzyl Alcohols ◽

Radical Intermediates ◽

Oxidation Of Alcohols ◽

Substituent Constants ◽

Deuterium Isotope Effects ◽

Rate Limiting

Possible mechanisms for the oxidation of alcohols by dioxoruthenium(VI) complexes are critically evaluated. Rate constants for the reduction of trans-[(TMC)RuVI(O)2]++ (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) by substituted benzhydrols are correlated more satisfactorily with Hammett σ substituent constants ( rho = -1.44 ± 0.08, r2 = 0.98) than with σ + substituent constants ( rho = -0.72 ± 0.11, r2 = 0.83). Similar observations for the oxidation of substituted benzyl alcohols have recently been reported, confirming that the transition state for these reactions is not carbocation-like. Primary deuterium isotope effects indicate that cleavage of the α -C-H bond is rate-limiting. The lack of an observable O-D isotope effect and the ease of oxidation of ethers indicates that the presence of a hydroxyl is not essential. The previously reported observation that cyclobutanol is quantitatively converted into cyclobutanone by dioxoruthenium(VI) complexes eliminates free-radical intermediates from consideration as part of the mechanism, and negative entroπes of activation (-Δ Sdouble dagger = 96-137 J mol-1 K-1) suggest a structured transition state. Only two of eight possible reaction mechanisms considered were found to be consistent with the available data. A critical analysis of the available data indicates that a 2 + 2 (C-H + Ru font 35137 roman T O) addition and a reaction initiated by ligand formation through the interaction of the reductant's HOMO with the oxidant's LUMO are the most likely reaction mechanisms.Key words: oxidation, alcohols, ruthenium(VI), mechanism, substituent effects.

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Synthesis of smart bimetallic nano-Cu/Ag@SiO2for clean oxidation of alcohols

New Journal of Chemistry ◽

10.1039/c7nj02062g ◽

2017 ◽

Vol 41 (22) ◽

pp. 13377-13381 ◽

Cited By ~ 5

Author(s):

Arijit Saha ◽

Soumen Payra ◽

Subhash Banerjee

Keyword(s):

Silver Nanoparticles ◽

Catalytic Performance ◽

Benzyl Alcohols ◽

Nano Catalyst ◽

Oxidation Of Alcohols

Silica (SiO2) supported bimetallic copper/silver nanoparticles (Cu/Ag@SiO2NPs) were synthesized for clean oxidation of benzoins/benzyl alcohols. All the reactions were fast, clean and high yielding (95–99%) and the Cu/Ag@SiO2nano-catalyst was reused eight times without loss of its catalytic performance.

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Kinetics and Mechanism of Oxidation of Aliphatic Secondary Alcohols by Benzimidazolium Fluorochromate in Dimethyl Sulphoxide Solvent

Oriental Journal Of Chemistry ◽

10.13005/ojc/370315 ◽

2021 ◽

Vol 37 (3) ◽

pp. 626-633

Author(s):

Bhawana Arora ◽

Jitendra Ojha ◽

Pallavi Mishra

Keyword(s):

Activation Parameters ◽

Sigmatropic Rearrangement ◽

Dimethyl Sulphoxide ◽

Secondary Alcohols ◽

Hydrogen Ions ◽

Reaction Conditions ◽

First Order Kinetics ◽

Aqueous Solvent ◽

Ester Formation ◽

Different Temperatures

Oxidation of secondary alcohols is an important part of synthetic organic chemistry. Various studies are carried out at different reaction conditions to determine the best mechanistic pathways. In our study, oxidation of different secondary alcohols was done by using Benzimidazolium Fluorochromate in Dimethyl Sulphoxide, which is a non-aqueous solvent. Oxidation resulted in the formation of ketonic compounds. The reaction showed first order kinetics both in BIFC and in the alcohols. Hydrogen ions were used to catalyze the reaction. We selected four different temperatures to carry out our study. The correlation within the activation parameters like enthalpies and entropies was in accordance with the Exnerʼs criterion. The deuterated benzhydrol (PhCDOHPh) oxidation exhibited an important primary kinetic isotopic effect (kH / kD = 5.76) at 298 K. The solvent effect was studied using the multiparametric equations of Taft and Swain. There was no effect of addition of acrylonitrile on the oxidation rate. The mechanism involved sigmatropic rearrangement with the transfer of hydrogen ion taking place from alcohol to the oxidant via a cyclic chromate ester formation.

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Revisiting Sodium Hypochlorite Pentahydrate (NaOCl·5H2O) for the Oxidation of Alcohols in Acetonitrile without Nitroxyl Radicals

Synlett ◽

10.1055/s-0037-1609629 ◽

2018 ◽

Vol 29 (18) ◽

pp. 2404-2407 ◽

Cited By ~ 2

Author(s):

Tsunehisa Hirashita ◽

Yuto Sugihara ◽

Shota Ishikawa ◽

Yohei Naito ◽

Yuta Matsukawa ◽

...

Keyword(s):

Sodium Hypochlorite ◽

Nitroxyl Radicals ◽

Secondary Alcohols ◽

Primary Alcohols ◽

Oxidation Of Alcohols

Sodium hypochlorite pentahydrate (NaOCl·5H2O) is capable of oxidizing alcohols in acetonitrile at 20 °C without the use of catalysts. The oxidation is selective to allylic, benzylic, and secondary alcohols. Aliphatic primary alcohols are not oxidized.

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Titelbild: Oxygen Atom Transfer in the Photocatalytic Oxidation of Alcohols by TiO2: Oxygen Isotope Studies (Angew. Chem. 33/2009)

Angewandte Chemie ◽

10.1002/ange.200990172 ◽

2009 ◽

Vol 121 (33) ◽

pp. 6085-6085

Author(s):

Miao Zhang ◽

Qi Wang ◽

Chuncheng Chen ◽

Ling Zang ◽

Wanhong Ma ◽

...

Keyword(s):

Oxygen Atom ◽

Oxygen Isotope ◽

Photocatalytic Oxidation ◽

Atom Transfer ◽

Oxygen Atom Transfer ◽

Oxidation Of Alcohols ◽

Isotope Studies

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Lignans of western red cedar (Thuja plicata Donn). VI. Dihydroxythujaplicatin methyl ether

Canadian Journal of Chemistry ◽

10.1139/v67-054 ◽

1967 ◽

Vol 45 (3) ◽

pp. 305-309 ◽

Cited By ~ 5

Author(s):

Harold MacLean ◽

Koji Murakami

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Methyl Ether ◽

Degradation Products ◽

Parent Compound ◽

Thuja Plicata ◽

Red Cedar ◽

Magnetic Resonance Data ◽

Resonance Data ◽

Thuja Plicata Donn

Proof of structure is presented for another lignan of the thujaplicatin series, 2,3-dihydroxy-2-(4″-hydroxy-3″,5″-dimethoxybenzyl)-3-(4′-hydroxy-3′-methoxybenzyl)-butyrolactone (I) (dihydroxythujaplicatin methyl ether). Analytical and spectral (ultraviolet, infrared, and nuclear magnetic resonance) data on derivatives and degradation products, in addition to the parent compound, are presented.

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Cu(II) and Fe(III) Complexes Derived from N-Acetylpyrazine-2-Carbohydrazide as Efficient Catalysts Towards Neat Microwave Assisted Oxidation of Alcohols

Catalysts ◽

10.3390/catal9121053 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1053 ◽

Cited By ~ 7

Author(s):

Manas Sutradhar ◽

Tannistha Roy Barman ◽

Armando J. L. Pombeiro ◽

Luísa M. D. R. S. Martins

Keyword(s):

Catalytic Activity ◽

Ir Spectroscopy ◽

Maximum Yield ◽

Catalytic Efficiency ◽

Benzyl Alcohols ◽

X Ray ◽

X Ray Crystallography ◽

Microwave Assisted ◽

Tert Butyl Hydroperoxide ◽

Oxidation Of Alcohols

The mononuclear Cu(II) complex [Cu((kNN′O-HL)(H2O)2] (1) was synthesized using N-acetylpyrazine-2-carbohydrazide (H2L) and characterized by elemental analysis, IR spectroscopy, ESI-MS and single crystal X-ray crystallography. Two Fe(III) complexes derived from the same ligand viz, mononuclear [Fe((kNN′O-HL)Cl2] (2) and the binuclear [Fe(kNN′O-HL)Cl(μ-OMe)]2 (3) (synthesized as reported earlier), were also used in this study. The catalytic activity of these three complexes (1–3) was examined towards the oxidation of alcohols using tert-butyl hydroperoxide (TBHP) as oxidising agent under solvent-free microwave irradiation conditions. Primary and secondary benzyl alcohols (benzyl alcohol and 1-phenylethanol), and secondary aliphatic alcohols (cyclohexanol) were used as model substrates for this study. A comparison of their catalytic efficiency was performed. Complex 1 exhibited the highest activity in the presence of TEMPO as promoter for the oxidation of 1-phenylethanol with a maximum yield of 91.3% of acetophenone.

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Aroylhydrazone Schiff Base Derived Cu(II) and V(V) Complexes: Efficient Catalysts towards Neat Microwave-Assisted Oxidation of Alcohols

International Journal of Molecular Sciences ◽

10.3390/ijms21082832 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2832

Author(s):

Manas Sutradhar ◽

Tannistha Roy Barman ◽

Armando J. L. Pombeiro ◽

Luísa M. D. R. S. Martins

Keyword(s):

Schiff Base ◽

Aliphatic Alcohol ◽

Cinnamyl Alcohol ◽

X Ray Diffraction ◽

Reaction Conditions ◽

Benzyl Alcohols ◽

X Ray ◽

Microwave Assisted ◽

Tert Butyl Hydroperoxide ◽

Oxidation Of Alcohols

A new hexa-nuclear Cu(II) complex [Cu3(μ2-1κNO2,2κNO2-L)(μ-Cl)2(Cl)(MeOH)(DMF)2]2 (1), where H4L = N′1,N′2-bis(2-hydroxybenzylidene)oxalohydrazide, was synthesized and fully characterized by IR spectroscopy, ESI-MS, elemental analysis, and single crystal X-ray diffraction. Complex 1 and the dinuclear oxidovanadium(V) one [{VO(OEt)(EtOH)}2(1κNO2,2κNO2-L)]·2H2O (2) were used as catalyst precursors for the neat oxidation of primary (cinnamyl alcohol) and secondary (1-phenyl ethanol, benzhydrol) benzyl alcohols and of the secondary aliphatic alcohol cyclohexanol, under microwave irradiation using tert-butyl hydroperoxide (TBHP) as oxidant. Oxidations proceed via radical mechanisms. The copper(II) compound 1 exhibited higher catalytic activity than the vanadium(V) complex 2 for all the tested alcohol substrates. The highest conversion was found for 1-phenylethanol, yielding 95.3% of acetophenone in the presence of 1 and in solvent and promoter-free conditions. This new Cu(II) complex was found to exhibit higher activity under milder reaction conditions than the reported aroylhydrazone Cu(II) analogues.

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