Combination of CuBr2 and multi-functional ligand bearing a bidentate nitrogen unit,a phenol group and a TEMPO moiety as catalyst for the aerobic oxidation of primary alcohols

A novel ligand (L) bearing a bidentate nitrogen ligand unit, a phenol group and a TEMPO moiety has been synthesized. The ligand has been used as a catalyst precursor for the copper-catalyzed aerobic oxidation of alcohols to aldehydes, in the presence of K₂CO₃. The complex obtained in-situ from the ligand with copper(II) bromide (CuBr₂) in a 2:1 acetonitrile/water mixture, selectively catalyzes the aerobic oxidation of primary benzylic and allylic alcohols to their corresponding aldehydes, and no over-oxidation products are detected.     

Single-Pot Synthesis of Alkyl-Substituted Quinolines and Indoles via Photoinduced Oxidation of Primary Alcohols

Single-pot synthesis of alkyl-substituted quinolines and indoles has been performed via photoinduced oxidation of primary aliphatic alcohols (C₂–C₅) and condensation of the aldehydes (products of the alcohols oxidation) with aniline under the action of iron-containing catalysts and inorganic oxidants. The synthesis was the most efficient in the presence of FeCl₃·6H₂O as catalyst and 10% aqueous solution of NaOCl as oxidant with irradiation by Hg lamp. The synthesis mechanism through photoinduced oxidation of primary aliphatic alcohol has been suggested.     

tert-Butylnitrite as a convenient and easy-removable oxidant for the conversion of benzylic alcohols to ketones and aldehydes

The oxidation of primary and secondary benzylic alcohols was achieved by using tert-butyl nitrite (t-BuONO) as a stoichiometric oxidant. Various substrates were effectively converted into the corresponding ketones or aldehydes in good to excellent yields. The reaction presumably proceeded by a nitrosyl exchange and a subsequent thermal decomposition of benzylic nitrites. This process would realize an oxidation of alcohols with oxygen in theory by combining with a reproduction of alkyl nitrites from NO and alcohols under an O₂ atmosphere. In addition, almost pure oxidized products were readily obtained by simple evaporation of the reaction mixtures since t-BuONO produced only volatile side products.     

Nanoparticles TiO2-photocatalyzed oxidation of selected cyclohexyl alcohols

The present article embraces the photocatalytic oxidation (PCO) of three selected cyclohexyl alcohols namely cyclohexylmethanol (1), 2-cyclohexylethanol (2) and 1-cyclohexylethanol (3) using nanoparticles titanium dioxide (TiO₂-P25) as a semiconductor photocatalyst in acetonitrile under aerated conditions. The photocatalytic experiments showed moderate conversion ratios (55.2%, 51.8% and 60.3%, respectively). The primary photocatalytic oxidation products are the corresponding aldehydes or ketones and acids. The photocatalytic oxidation products were identified mainly by GC and GC/MS techniques using authentic samples. Formation of electron–hole pair at the surface of the semiconductor nanoparticles followed by oxidation reaction was the suggested mechanism. A first-order kinetic model was observed for the photocatalytic oxidation of the investigated alcohols and the rate constants were calculated.     

Reactions of palladium(I) carbonylacetate cluster with alcohols

Reactions of a tetranuclear palladium cluster [Pd(CO)(OAc)[4 with C₁-C₃ alcohols have been found to proceed simultaneously via several routes to form CO, and dialkyl carbonates, the products of oxidation of coordinated CO ligands, along with carbonyl compounds which form due to oxidation of the corresponding alcohols. Alkoxy, alkoxycarbonyl, and acyl palladium derivatives are shown to be the intermediates of the reactions studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2456–2459, October, 1996.     

C–C Bond Rupture in the Oxidation of Lower (C2–C6) Alcohols with Hydrogen Peroxide Mediated by Iron-Containing Compounds

C–C bond rupture upon the oxidation of alcohols in the Fe(ClO₄)₃+ H₂O₂system in aqueous acetonitrile at room temperature is found. The relative yield of the products of C–C bond rupture is 20–30% under standard conditions for C₂and C₃alcohols and decreases in the series C₂> C₃> C₄> C₆. The alkyl radical and carboxylic acid are the products of C–C bond rupture in alcohol oxidation. Cyclohexane is a competitive inhibiting agent for C–H bond oxidation in 1-propanol, and it does not affect the yield of the products of C–C bond rupture. When H₂O₂is replaced by tert-BuOOH, the fraction of the products of C–C bond rupture decreases by an order of magnitude. Our data suggest that a non-radical intermediate, likely Fe(III) hydroperoxo complex, is responsible for C–C bond rupture in alcohol under the reaction conditions.     

Oxidation of cyclohexene and α-pinene with O2—H2 mixture in the presence of supported platinum or palladium catalysts

Oxidation of cyclohexene and -pinene with an O₂—H₂ mixture in the catalytic systems containing Pt or Pd and heteropoly compounds (HPC) was studied. The main oxidation products are epoxides, allyl alcohols, and ketones. The highest yield of the oxidation products was obtained in the presence of the platinum catalyst in combination with HPC PW₁₁ or PW₁₁Fe. The reaction mechanism was proposed. A relationship between the HPC composition and the nature of intermediates involved in oxidation was examined.     

Efficient and convenient oxidation of alcohols to aldehydes and ketones with molecular oxygen mediated by In(NO3)3 in ionic liquid [C12mim][FeBr4]

A simple, efficient, and ecofriendly procedure for the aerobic oxidation of alcohols to aldehydes and ketones in the presence of In(NO₃)₃/[C₁₂mim][FeBr₄] in aqueous media has been developed. The oxidation reactions afford the target products in good to high yields and no over-oxidation was observed. The products can be separated by a simple extraction with dichloromethane, and the system can be recycled and reused without loss of activity.     

Fast selective oxidation of alcohols under solvent-free conditions

A combination of acetic anhydride, H₂SO₄-nano silica, wet-SiO₂ (60 %), and K₂Cr₂O₇ as a new oxidizing system for the selective oxidation of different types of alcohols to the corresponding aldehydes and ketones at room temperature under solvent-free conditions is introduced. Mild reaction conditions, high yields of the products, short reaction time, no further oxidation to the corresponding carboxylic acid, and easy work-up make this new system a useful method for oxidizing alcohols.     

tBu4NCl/K2S2O8 System Induced C-2 Functionalization of 8-Aminoquinoline Amides with Primary Alcohols

A metal and light-free Minisci-type acylation approach of 8-aminoquinoline amides with general primary alcohols was demonstrated under ^tBu₄NCl/K₂S₂O₈ system. Simultaneously, the C2−H alkylation can be realized by accident for special benzyl alcohols bearing strong electron-donating groups. Most N-heterocycles were also compatible to afford corresponding acylated products. Furthermore, the mechanism investigation reveals that chlorine radical induced the original ketyl radical generation through abstracting the α-C−H from the alcohols, then underwent nucleophilic carbon-centered radicals addition, deprotonation, and oxidation to provide the target acylation products.     

A Practical Catalytic Procedure for Oxidation of Alcohols Into Aldehydes or Ketones with RuCl3/Water and Ca(OCl)2 or NaIO4

Ruthenium complexes catalyze the oxidation of alcohols to the corresponding ketones or aldehydes when Ca(OCl)₂ or NaIO₄ are used as oxygen donors in the presence of water (5–10 equiv.). The reactions take place at room temperature affording products in yields of 45–80%.     

Transformations of C<Subscript>2</Subscript>-C<Subscript>4</Subscript> alcohols on the surface of a copper catalyst

The interaction of monoatomic alcohols C₂-C₄ with the surface of a copper catalyst preliminarily oxidized under various conditions was studied by the temperature-programmed reaction method to determine the detailed mechanism of partial oxidation. The conditions of oxygen preadsorption on the surface of copper for the preparation of the desired products were determined. The selective formation of carbonyl compounds was shown to occur at the boundary between reduced and oxidized copper surface regions. The role played by Cu₂O was the deep oxidation of alcohols to CO₂. Alcohols with branched hydrocarbon structures experienced parallel partial oxidation and dehydrogenation, which was related to the high stability of intermediate keto-type compounds.     

Bimetallic Co–Pd alloy nanoparticles as magnetically recoverable catalysts for the aerobic oxidation of alcohols in water

Co–Pd bimetallic alloy nanoparticle catalysts were prepared from CoCl₂, Pd(OAc)₂ and several capping agents with Li(C₂H₅)₃BH. The nanoparticle catalysts were applied to the aerobic oxidation of a variety of alcohols in water to give the corresponding carbonyl products. The catalyst was magnetically recovered and reused for further oxidation. The nanoparticle catalysts were characterized with TEM, ICP, and XPS analyses.     

A Highly Efficient Bismuth Nitrate/Keto-ABNO Catalyst System for Aerobic Oxidation of Alcohols to Carbonyl Compounds under Mild Conditions

An efficient and practical catalytic system for the oxidation of alcohols to aldehydes/ketones using catalytic amounts of Bi(NO₃)₃ and Keto-ABNO (9-azabicyclo [3.3.1]nonan-3-one N-oxyl) with air as the environmentally benign oxidant was developed. Various primary and secondary alcohols were smoothly oxidized to the corresponding products under mild conditions, and satisfactory yields were achieved. Moreover, this methodology avoids the use of a ligand and base. The gram-scale reaction was demonstrated for the oxidation of 1-phenyl ethanol, and the product of acetophenone was obtained at an isolated yield of about 94%.     

Catalytic Properties of Heteropolyacid-Modified ZrO2 in the Partial Oxidation of Lower Alkanes by Nitric Oxide

The partial oxidation of C₃ and C₄ hydrocarbons by nitric oxide, in particular, their oxidation to alcohols, occurs on zirconium dioxide modified by various heteropolyacids (HPA). The catalyst activity depends on the amount of deposited HPA, while the reaction selectivity relative to the partial oxidation products correlates with the acid properties of the surface, in particular, with the concentration of weak acid sites.     

Gold-Catalyzed Oxidative Aminocyclizations of Propargyl Alcohols and Propargyl Amines to Form Two Distinct Azacyclic Products: Carbene Formation versus a 3,3-Sigmatropic Shift of an Initial Intermediate

Gold-catalyzed oxidations of propargyl alcohols with nitrones by using a P(tBu)₂(o-biphenyl)Au⁺ catalyst, afforded bicyclic annulation products from the Mannich reactions of gold enolates. The same reactions of propargyl amines with nitrones by using the same gold catalyst gave distinct oxoarylation products. Our DFT calculations indicate that oxidation of propargyl alcohols with nitrones by using electron-rich gold catalysts lead only to gold carbenes, which can generate gold enolates or oxoarylation intermediates with enolate species having a barrier smaller than that of oxoarylation species.     

Na4H3[SiW9Al3(H2O)3O37]·12H2O/H2O: a new system for selective oxidation of alcohols with H2O2 as oxidant

This work describes a catalytic system consisting of both Na₄H₃[SiW₉Al₃(H₂O)₃O₃₇]·12H₂O(SiW₉Al₃) and water as solvents (a small quantity of organic solvents were used as co-solvent for a few substrates) that can be good for selective oxidation of alcohols to ketones (aldehydes) using 30% H₂O₂ without any phase-transfer catalyst under mild reaction conditions. The catalyst system allows easy product/catalyst separation. Under the given conditions, the secondary hydroxyl group was highly chemoselectively oxidized to the corresponding ketones in good yields in the presence of primary hydroxyl group within the same molecule, and hydroxides are selectively oxidized even in the presence of alkene. Benzylic alcohols were selectively oxidized to the corresponding benzaldehydes in good yields without over oxidation products in solvent-free conditions. Nitrogen, oxygen, sulfur-based moieties, at least for the cases where these atoms are not susceptible to oxidation, do not interfere with the catalytic alcohol oxidation.     

Heterogeneous Catalytic Partial Oxidation of C3-C4 Alkanes with Nitrogen Monoxide

The possibility of making products of partial oxidation, alcohols and acids in particular, by the reaction of C₃-C₄ alkanes with nitrogen monoxide over oxide and zeolite catalysts is demonstrated. The most effective catalysts are CeO₂ and Fe-TsVK. The dependence of the rate and selectivity of the process on the reaction conditions has been established.     

Pb(OAc)4 mediated transannular oxidative ring cleavage

Pb(OAc)₄ oxidation of homoallylic alcohols at room temperature leads to the formation of a variety of fragmentation products, whose formation requires spatial proximity of the alcohol and the olefin moieties.     

Nano–silica functionalized with thiol–based dendrimer as a host for gold nanoparticles: An efficient and reusable catalyst for chemoselective oxidation of alcohols

In this paper, we present the synthesis of Au nanoparticles supported on nanosilica thiol based dendrimer, nSTDP. The catalyst was prepared by reduction of HAuCl₄ with NaBH₄ in the presence of nSTDP. The resulting Au_np–nSTDP materials were characterized by FT–IR and UV–vis spectroscopic methods, SEM, TEM, TGA, XPS and ICP analyses. The characterization of the catalyst showed that Au nanoparticles with the size of 2–6 nm are homogeneously distributed on the nSTDP dendrimer with a catalyst loading of about 0.19 mmol/g of catalyst. The Au_np–nSTDP catalyst was used in the oxidation of alcohols with tert–butyl hydroperoxide (TBHP) as oxidant. The influence of vital reaction parameters such as solvent, oxidant and amount of catalyst on the oxidation of alcohols was investigated. These reactions were best performed in an acetonitrile/water mixture (3:2) in the presence of 0.76 mol% of the catalyst on the basis of the Au content at 80 °C under atmospheric pressure of air to afford the desired products in high yields (80–93% for benzyl alcohols). The Au_np–nSTDP catalyst exhibited a high selectivity toward the corresponding aldehyde and ketone (up to 100%). Reusabiliy and stability tests demonstrated that the Au_np–nSTDP catalyst can be recycled with a negligible loss of its activity. Also this catalytic exhibited a good chemoselectivity in the oxidation of alcohols.