Alcohol oxidation

A facile and quantitative preparation of carboxylic acids by a pyridinium chlorochromate (PCC) catalyzed (2 mol%) oxidation of primary alcohols and aldehydes using 2.2 equivalents and 1.1 equivalents of H 5 IO 6 , respectively, in acetonitrile is described here.

Substituted benzoic acids are very important materials in chemical and pharmaceutical industries and can be prepared by the oxidation of corresponding substituted toluenes 1 . The tranformation of substituted toluenes to substituted benzoic acids have been less reported 2 . This conversion has been accomplished using a variety of reagents such as nickel-catalyzed benzylic oxidation 3 , ceric ammonium nitrate in aqueus acetic acid 4 , potassium bromate 5 , selenium dioxide 6 , chromyl chloride 7 , silver(II)oxide in phosporic acid 8 , potassium permanganate adsorbed on alumina 9 . Since oxygen is highly soluble in subcritical water, it is one of the most atractive oxidants. The increasing environmental concern surrounding the use of toxic and dangerous oxidants has impelled organic chemists to develope oxidation methodologies using molecular oxygen . The oxidation of toulenes to benzoic acids by molecular oxygen was reported to use several organic solvents 11 , which is not desired environmentally friendly. Thus, there is a need to develop precedures for benzylic oxidation, which use inexpensive oxidizing agent and minimize the use of chromium complex. Although pyridinium chlorochromate (PCC) oxitadions are routinely performed in organic transformations the requirement of at least a stoichiometric amount of pyridinium chlorochromate to complete the oxidation is disadvantage due to the high toxicity of chromium reagents 12 . Therfore, new methods for oxidations of toluenes to corrosponding benzoic acids and that generate less chromium waste are stil needed. In our previous study 13 , we have reported the oxidation of toluenes to aromatic aldehydes with molecular in subcritical water. In continuation of our work oxidation reactions NOTE

Summary The total cuticular alcohols in larvae, male, and female of M. domestica were detected in comparable amounts (4.59, 3.95 and 4.03 µg/g of the insect body, respectively). The total cuticular alcohols in pupae occurred in smaller quantities (2.16 µg/g of the insect body). The major free alcohol in M. domestica larvae was C12:0 (70.4%). Internal alcohols of M. domestica larvae were not found. Among cuticular pupae alcohols, C12:0 (31.0%) was the most abundant compound. Other alcohols were detected in smaller amounts from 3.7% (C14:0) to 14.4% (C16:0). In the internal lipids of pupae, only 5 alcohols were identified in traces. Most abundant alcohol in male was C24:0 (57.5%). The percentage content of cuticular C24:0 in male and female were significantly higher than those of cuticular lipids in larvae and pupae and compromised 57.5%, 36.5%, 0.9% and 5.6%, respectively. Only two alcohols were present in internal lipids of male in traces (C18:0 and C20:0). Most abundant cuticular a...

The catalytic oxidation of alcohols with molecular oxygen on supported nanometallic catalysts represents one of the green methods in a crucial process for the synthesis of fine chemicals. We have designed an experiment using physically mixed Au/AC and Pd/AC (AC=activated carbon) as the catalyst in the liquid‐phase oxidation of benzyl alcohol by aerobic oxygen. The evolution of the physically mixed catalyst structures at different stages in the catalytic reaction was investigated by aberration‐corrected high‐resolution transmission electron microscopy and spatially resolved element mapping techniques at the nanometre scale, and they were also compared with the structure of the bimetallic alloy. For the first time we show the formation of surface Au–Pd bimetallic sites by reprecipitation of Pd onto Au nanoparticles. Negligible Au leaching was observed. The in situ structural evolution can be directly correlated to the great enhancement of the catalyst activity. Moreover, we distinguis...

A straightforward, efficient and sustainable copper catalyzed method was developed for oxidation of benzylic alcohols with 30% H 2 O 2 in water. The reaction proceeded with CuSO 4 catalyst (1 mol%) at 100 • C without additional base or ligand. Primary benzylic alcohols were converted almost quantitatively to aldehydes with 70-90% selectivity, corresponding acids being the major side products. Also secondary benzylic alcohols afforded the corresponding ketones in high conversion with selectivities greater than 90%. It was demonstrated that the CuSO 4 catalyst can be recycled and reused at least for three runs, even though with some loss of catalytic activity. Selectivity of the CuSO 4 based catalyst system could be further increased by using 2-N-(p-fluorophenyl)-pyrrolecarbaldimine (1) as a ligand in combination with TEMPO in K 2 CO 3 solution. The catalyst system was individually optimized (1 mol% CuSO 4 , 2 mol% 1, 0.1 M K 2 CO 3 and 5 mol% TEMPO) for a wide range of benzylic and allylic alcohols, which were quantitatively and selectively converted into the corresponding aldehydes with 3 eq. of H 2 O 2 in 1 h.

G imine-based catalysts for the aerobic oxidation of benzylic alcohols mediated by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical are reported. The catalytic activity for both synthesized and in situ made complexes in alkaline water solutions was studied revealing high efficiency and selectivity (according to GC selectivity always > 99%) for both of these catalytic systems. For example, quantitative conversion of benzyl alcohol to benzaldehyde can be achieved with the in situ prepared bisA -pyrrolylcarbaldimide]copper(II) catalysts in 2 h with atmospheric pressure of O 2 at 80 8C. Interestingly, these catalysts can utilize dioxygen as well as air or hydrogen peroxide as the end oxidants, producing water as the only by-product.

To improve the performance of direct ethanol fuel cells (DEFCs), which are hindered by traditional catalysts, having matters pertaining to stability, activity, and selectivity in reaction environments, various electrocatalysts such as Pd/Ni 2 P, Pd/MoS 2 , and Pd/Ni 2 P-MoS 2 were synthesized using the microwaveassisted NaBH 4-ethylene glycol reduction method. The research findings suggest that the Pd/Ni 2 P-MoS 2 catalyst we developed had the highest activity (1579 mA mg Pd-1), approximately 21 times greater than that of commercial Pd/C. The stability of the electrocatalysts were examined using chronoamperometry (CA) and cyclic voltammetry (CV) measurements, which indicated that the Pd/ Ni 2 P-MoS 2 electrocatalyst had good stability towards the ethanol oxidation reaction (EOR) in alkaline electrolyte. Electrochemical impedance spectroscopy (EIS) analysis showed that the Pd/Ni 2 P-MoS 2 electrocatalyst had lower charge transfer resistance, indicating better electrochemical kinetics. According to XRD, HR-TEM, XPS, and electrochemical analysis, the enhanced electrocatalytic activity, long-term stability of the Pd/Ni 2 P-MoS 2 electrocatalyst were attributable to the interface synergism as well as electronic and strain effects between the Pd, Ni 2 P, and MoS 2 interactions. This resulted in a downshift in the d-band center of the Pd/Ni 2 P-MoS 2 electrocatalyst, weakening intermediate adsorption and the adsorbate metal interaction.

Immobilized Metalloporphyrins on 3-Aminopropyl-Functionalized Silica Support as Heterogeneous Catalysts for Selective Oxidation of Primary and Secondary Alcohols. -Fe(III), Mn(III) and Co(II) metalloporphyrins immobilized onto 3-aminopropyl-functionalized silica are synthesized and evaluated for their catalytic activity in the biomimetic oxidation of primary and secondary benzylic alcohols to corresponding carbonyl compounds (II). The immobilized Fe(III) porphyrin demonstrates the highest activity. This heterogeneous catalyst can be reused at least four times without any significant loss of activity. -(RAHIMI*, R.; GHOREISHI, S. Z.;

The effect of slow ON-OFF liquid flow modulation on the oxidation of aqueous solutions of ethanol using a 0.5% Pd/Al 2 O 3 commercial egg-shell catalyst was investigated in a laboratory trickle bed reactor (TBR). In this mode of operation, the catalyst was cyclically exposed to oxidative and reductive environments. The study was carried out under different gas and liquid flow rates, cycle periods and splits. Cycling results have been compared with the steady-state experiments performed at the corresponding average liquid flow rate. Significant improvements over the continuous operation were obtained when the catalyst was exposed to a short surplus of oxygen (to minimize deactivation by overoxidation in the kinetic regime) after a longer time of working in the mass transfer limited regime. According to the results presented here, it is recommended to work with high liquid flow rates and moderate gas flow rates to ensure complete wetting of the catalyst during the ON cycle and to minimize the overoxidation process during the OFF cycle.

Progress in the use of ATR-IR spectroscopy to improve the understanding of liquid-phase heterogeneous catalytic reactions is illustrated using the example of the oxidation of benzyl alcohol over Pd/Al 2 O 3 and Bi-Pd/ Al 2 O 3 . The in situ studies performed in both batch and continuous reactor cells provide rich information on the reaction pathway and important facets of the mechanism, such as the nature of active Pd sites and the effect of the Bi-promoter. The combination of CO site blocking prior to reaction and isotopic labeling suggests that alcohol dehydrogenation occurs uniformly over Pd nanoparticles, but only selected sites may allow desorption of the product benzaldehyde thus providing the required selectivity. Promotion of Pd/Al 2 O 3 using bismuth produces infrared spectra free of adsorbed CO. This information demonstrates that Bi is deposited on selected adsorption sites (terraces rather than defects) and simultaneously confirms that open terraces favor product decomposition. Experiments performed in the continuous reactor cell using different catalyst film thickness show that reactions can be studied under kinetic or mass transfer limited conditions depending on catalyst film thickness. This allowed to study the alcohol oxidation under conditions of oxygen diffusion limitation, which are preferably applied in praxis in order to prevent catalyst deactivation by over-oxidation.

Progress in the use of ATR-IR spectroscopy to improve the understanding of liquid-phase heterogeneous catalytic reactions is illustrated using the example of the oxidation of benzyl alcohol over Pd/Al 2 O 3 and Bi-Pd/ Al 2 O 3 . The in situ studies performed in both batch and continuous reactor cells provide rich information on the reaction pathway and important facets of the mechanism, such as the nature of active Pd sites and the effect of the Bi-promoter. The combination of CO site blocking prior to reaction and isotopic labeling suggests that alcohol dehydrogenation occurs uniformly over Pd nanoparticles, but only selected sites may allow desorption of the product benzaldehyde thus providing the required selectivity. Promotion of Pd/Al 2 O 3 using bismuth produces infrared spectra free of adsorbed CO. This information demonstrates that Bi is deposited on selected adsorption sites (terraces rather than defects) and simultaneously confirms that open terraces favor product decomposition. Experiments performed in the continuous reactor cell using different catalyst film thickness show that reactions can be studied under kinetic or mass transfer limited conditions depending on catalyst film thickness. This allowed to study the alcohol oxidation under conditions of oxygen diffusion limitation, which are preferably applied in praxis in order to prevent catalyst deactivation by over-oxidation.

The structure of Ru in Ru-substituted hydroxyapatite (RuHAp) has been investigated using infrared spectroscopy in the attenuated total reflection mode (ATR-IR). Oxidation-reduction cycles, 12 CO and 13 CO adsorption have been used to determine the state of Ru in the presence of cyclohexane solvent. The spectroscopic data support the existence of a hydrated RuO x -like phase, which is identified by overtone signals of Ru-O bonds at ca. 1850 cm -1 and is likely organized as a two-dimensional phase on the apatite. This phase coexists with isolated Ru 3+ cations likely located in the hardly accessible channels of the apatite structure. The RuO x -like phase is shown to be highly reactive at the solid-liquid interface and exhibits a number of carbonyl species upon CO adsorption. The relevance of the RuO x -like phase for the liquid-phase aerobic oxidation of benzyl alcohol has been investigated under close to reaction conditions. Although weak signals of benzaldehyde indicate that conversion is likely low under flow conditions, their presence makes the results relevant to draw structure-activity relationships. Blocking of accessible Ru sites using CO prior to reaction reveals that only selected CO species on the hydrated RuO x -like phase are depleted when reaction occurs. The likely formation of HCO - 3 in the absence of the alcohol indicates that benzyl alcohol oxidation and HCO - 3 formation may occur on similar Ru sites providing evidence that these sites are located on the RuO x phase.

A highly active kenaf cellulose supported poly(amidoxime) palladium catalyst was synthesized and characterized with FTIR, UV-Vis, FESEM, XPS and TEM analyses. The catalyst (65 mol ppm to 6.5 mol ppm) was found to promote efficiently the allylic arylation of allylic ester with sodium tetraarylborates in ethanol at 60 °C temperature. Outstanding yields of the corresponding products as well as significant reusability of the catalyst were obtained. The total turnover number (TON) and frequency (TOF) were 144615 and 9641 h–1 respectively.

Bis [S-allyl-β-N-(benzylidene)dithiocarbazato]copper(II) complex was grafted into SiO2 matrix. Heterogenized catalyst was characterized by FT-IR, SEM, EDX TEM, N2 absorption and atomic absorption spectroscopy (AAS) and its catalytic performance in the oxidation of alcohols was investigated. The experimental results showed that the prepared heterogeneous nanocatalyst is an efficient and selective catalyst for examined oxidation reaction. Thus, secondary alcohols were oxidized to ketones and primery alcohols converted to aldehydes by hydrogen peroxide in the presence of newly nanocatalyst in mild conditions.

Bis [S-allyl-β-N-(benzylidene)dithiocarbazato]copper(II) complex was grafted into SiO2 matrix. Heterogenized catalyst was characterized by FT-IR, SEM, EDX TEM, N2 absorption and atomic absorption spectroscopy (AAS) and its catalytic performance in the oxidation of alcohols was investigated. The experimental results showed that the prepared heterogeneous nanocatalyst is an efficient and selective catalyst for examined oxidation reaction. Thus, secondary alcohols were oxidized to ketones and primery alcohols converted to aldehydes by hydrogen peroxide in the presence of newly nanocatalyst in mild conditions.

Al 2 O 3 was purchased from Japan Aerosil. Other chemicals were purchased from Sigma-Aldrich Co., Acros Organics or Wako Pure Chemical Industries, Ltd. and were used without further purification. Au nanoparticles were synthesized by the reduction of HAuCl 4 (99.9%) in a P123 (EO 20 PO 70 EO 20 , MW = 5800) aqueous solution using NaBH 4 as a reducing agent. In a typical synthesis, 190 ml of P123 aqueous solution was stirred at 35 o C for 30 min. Then 4 ml of 0.05 M HAuCl 4 aqueous solution was introduced to the solution and immediately, 6 ml of 0.1% NaBH 4 aqueous solution was added very slowly under vigrous stirring within 15 min and further stirred at 35 o C for 5 min. The final gold concentration was 1.0 × 10 -3 M and the molar ratio of Au to P123 was varied in the range from 0 to 7. Upon the addition of NaBH 4 aqueous solution to the system, the light yellowish solution was immediately changed to wine red color by visual observation. The UV-Vis absorption band from the surface plasmon of the Au nanoparticles were obtained at 520 nm by a Jasco V-570 UV/Vis spectrophotometer. To compare the oxidation reactivity, 2.5wt%Au/Al 2 O 3 , 2.5wt%Pd/Al 2 O 3 and 2.5wt%Au/2.5wt%Pd/Al 2 O 3 catalysts were prepared by impregnation of Al 2 O 3 using aqueous solutions of PdCl 2 and/or HAuCl 4 ・3H 2 O and calcined at 400 o C for 3 h according to the literature. 1 To evaluate the size of Au nanoparticles in Fig to c, we counted 225 particles for all samples from TEM images at each conditions. In Figure of this paper, we used the relative percentage to express the particle size distribution.

Supporting gold nanoparticles have shown to be extremely active for many industrially important reactions, including oxidations. Two representative examples are the oxidation of alcohols and alkanes, that are substrates of industrial interest, but whose oxidation is still challenging. This review deals with these reactions, giving an insight of the first studies performed by gold based catalysts in these reactions and the most recent developments in the field.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

A chemoselective and efficient procedure for the oxidation of alcohols to the corresponding carbonyl compounds is reported using ceric ammonium nitrate in the presence of 3-methylimidazolium hydrogensulfate as Brönsted acidic ionic liquid ([Hmim]HSO 4) as the solvent under mild conditions. The use of non-toxic and inexpensive materials, straightforward procedure, short reaction times and good yields of the products are the major advantages of this method.

ChemInform Abstract Zahlreiche Halogenide (I) werden unter Verwendung vonÜbergangsmetall-Komplexen zu den entsprechenden Kohlenwasserstoffen (II) reduziert. Es wird anhand der Reduktion von Benzylchlorid in Alkoholen wie Methanol, Ethanol oder Isopropanol die Effizienz zahlreicher Komplexe von Rhodium-, Ruthenium-, Iridium-und Palladium-chlorid mit Triphenylphosphin, Triphenylphosphit etc. untersucht.

Both RhH(CO)PPh3)3 and a catalyst made in situ from RhCk3H20, PPh3 and NaKO, catalyse the reaction of a range of aldehydes with simple primary alcohols to give esters together with alcohols formed by reduction of the aldehydes. The proportion of ester can be increased by adding an efficient hydrogen acceptor. The reaction can also be used to produce 5-and 'I-membered lactones from aromatic dialdehydes. Propan-2-01 and the in situ catalyst reduce some aromatic aldehydes to the corresponding alcohols without concomitant ester formation.

Highlights  Synergistic effect of Cu (II) and Fe(III) Salen catalysts supported on SBA-15 and H 2 O 2 in HMF oxidation  Cu Salen/SBA-15 catalyst active in HMF oxidation under mild conditions  Mechanism of HMF catalytic oxidation step by step  Higher selectivity to oxidation of alcohol group compared with the aldehyde group of HMF molecule

AuPd nanoparticles have gained substantial attention due to their application in selective oxidation of alcohols. However, due to the radical nature of the oxidation of benzyl alcohol, under specific conditions, even without a catalyst, the reaction occurs and affects the selectivity of the system. Therefore, we aimed to develop a catalyst that enables the control of the oxidation leading to higher reaction selectivity. To accomplish this, we have prepared a catalytic support comprised of CoFe 2 O 4 nanoparticles impregnated with Sr(OH) 2 that presented a significant control of the reaction selectivity without any metal or external base addition. After the impregnation of AuPd nanoparticles in a specific ratio, the reaction reached a selectivity of > 99% for benzaldehyde, in 3.5 h, with a recycle regime of five runs without loss of activity and selectivity. Our results show that the judicious choice of the ratio of the metals prevents the necessity of manipulating the reaction conditions to improve the performance of the system. Additionally, studies under N 2 and O 2 environments, with or without water, confirmed the role of the O 2 in the system. Holding all this information, we propose a possible mechanism for the prepared system.

We have prepared a series of mesoporous silica nanoparticle (MSN) supported Pd-Au bimetallic catalysts using a newly developed sequential impregnation method. These catalysts were fully characterized by various techniques including nitrogen sorption, powder X-ray diffraction, inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and high angle annular darkfield scanning transmission electron microscopy (HADDF-STEM). By using this synthetic approach, we observed metal nanoparticles (NP) with diameters of 1-2 nm homogeneously supported on the MSN. The catalytic performance of these MSN supported metal NPs was tested by aerobic oxidative esterification in a tandem reaction where primary alcohols are oxidized to their corresponding aldehydes and to esters in a subsequent reaction. We determined that Pd NPs are very efficient in the first step of oxidation; however, stagnant in the subsequent oxidation. On the contrary, Au NPs show slow reactivity in converting alcohols to aldehydes, but extraordinarily efficient in the oxidation of aldehydes to esters. By fine tuning the metal ratio, the bimetallic catalyst exhibits better reactivity and selectivity toward a variety of primary alcohols than the corresponding monometallic catalysts. In addition, we also found that the bimetallic Pd-Au@MSN catalysts can be recycled three times without a significant loss in activity.

We have prepared a series of mesoporous silica nanoparticle (MSN) supported Pd-Au bimetallic catalysts using a newly developed sequential impregnation method. These catalysts were fully characterized by various techniques including nitrogen sorption, powder X-ray diffraction, inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and high angle annular darkfield scanning transmission electron microscopy (HADDF-STEM). By using this synthetic approach, we observed metal nanoparticles (NP) with diameters of 1-2 nm homogeneously supported on the MSN. The catalytic performance of these MSN supported metal NPs was tested by aerobic oxidative esterification in a tandem reaction where primary alcohols are oxidized to their corresponding aldehydes and to esters in a subsequent reaction. We determined that Pd NPs are very efficient in the first step of oxidation; however, stagnant in the subsequent oxidation. On the contrary, Au NPs show slow reactivity in converting alcohols to aldehydes, but extraordinarily efficient in the oxidation of aldehydes to esters. By fine tuning the metal ratio, the bimetallic catalyst exhibits better reactivity and selectivity toward a variety of primary alcohols than the corresponding monometallic catalysts. In addition, we also found that the bimetallic Pd-Au@MSN catalysts can be recycled three times without a significant loss in activity.

The square-planar cobalt(III) complexes of o-phenylenebis(N′-methyloxamidate) (Me 2 opba) and related oxamate (Meopba) and bis(oxamate) (opba) ligands catalyse the selective oxidation, by dioxygen and pivalaldehyde, of a wide range of secondary alcohols to the ...

The iron(II) complexes [Fe(N-N) 3 ](OTf) 2 (N-N = 2,2-bipyridine, 1,10-phenanthroline and substituted derivatives) were employed as catalyst precursors for the oxidation of primary and secondary alcohols, including glycerol. The single-crystal structure of [Fe(bipy) 3 ](OTf) 2 was determined by X-ray crystallography.The catalytic reactions were performed using either H 2 O 2 or tert-butilhydroperoxide (TBHP) as oxidating agent, in mild experimental conditions: with all catalysts employed, secondary alcohols were oxidized to the corresponding ketones with up to 100% yields, whereas other substrates gave lower conversions. Indications on the nature of the catalytically active species, which is probably formed via dissociation of a nitrogen ligand from the iron center, were obtained from NMR and ESI-MS spectra.

The study involved the conversion of Palladium (Pd) and Ruthenium (Ru) metal-supported carbon black (CB) into a hybrid nano electrocatalyst using the microwave synthesis method. Among the four tested catalysts (Pd/CB, Pd1Ru1, Pd1Ru2, and Pd2Ru1), Pd2Ru1 electrocatalyst demonstrated the most effective performance for ethylene glycol electrooxidation (−0.51 V onset potential, 0.13 mA/cm2 current density and −0.21 V anodic peak potential). The physical and chemical properties of the hybrid electrocatalysts were characterized using optical and electrochemical techniques. Additionally, the electrochemical test indicated that Pd2Ru1 exhibited superior poisoning resistance and improved electrochemical stability compared to other tested materials. Also, the catalyst generated close to 0.055 A hydrogen production current while the presence of ethanol enhanced the oxidative current. The performance of the cell at two different temperatures (22 and 56 °C) was also elucidated with up to 0.87 and 0.57 V voltage outputs respectively. The study revealed the potential of Pd2Ru1 as an efficient anodic electrocatalyst in the ethylene glycol direct fuel cell assemblies.

Partial oxidation of alcohols is a topic of great interest in the field of gold catalysis. In this work, we provide evidence that the partial oxidation of allyl alcohol to its corresponding aldehyde, acrolein, over oxygen-precovered gold surfaces occurs via multiple reaction pathways. Utilizing temperature-programmed desorption (TPD) with isotopically labeled water and oxygen species, reactive molecular beam scattering, and density functional theory (DFT) calculations, we demonstrate that the reaction mechanism for allyl alcohol oxidation is influenced by the relative proportions of atomic oxygen and hydroxyl species on the gold surface. Both atomic oxygen and hydroxyl species are shown to be active for allyl alcohol oxidation, but each displays a different pathway of oxidation, as indicated by TPD measurements and DFT calculations. The hydroxyl hydrogen of allyl alcohol is readily abstracted by either oxygen adatoms or adsorbed hydroxyl species on the gold surface to generate a surface-bound allyloxide intermediate, which then undergoes α-dehydrogenation via interaction with an oxygen adatom or surface hydroxyl species to generate acrolein. Mediation of a second allyloxide with the hydroxyl species lowers the activation barrier for the α-dehydrogenation process. A third pathway exists in which two hydroxyl species recombine to generate water and an oxygen adatom, which subsequently dehydrogenates allyloxide. This work may aid in the understanding of oxidative catalysis over gold and the effect of water therein.

Selective direct synthesis of symmetric acetals through a tandem aerobic oxidation-acetalization of primary alcohols, using a chloride-free Pd(OAc) 2 /Cu(OAc) 2 /p-TsOH system as an efficient bifunctional catalyst, has been developed. The reactions occur in neat alcohols with no use of other solvent under mild conditions (50-80 8C, 1-10 atm). p-Toluenesulfonic acid exerts a great accelerative and catalyst stabilizing effect, showing a synergism with Cu(OAc) 2. Bimetallic Pd-Cu catalysis is suggested in these reactions. Under similar conditions, a secondary alcohol, propanol-2, reacts more slowly giving mainly acetone. Conventional palladium catalytic systems, such as PdCl 2 /CuCl 2 , Pd(OAc) 2 /LiNO 3 , and Pd(OAc) 2 /pyridine, showed no or very low activity in the oxidation of neat n-butanol.

Kraft lignin derivatives having cationic poly 2-(trimethylamino)ethyl methacrylate side chains were synthesized and their property as dye-flocculant was investigated. Lignin-based flocculants having three types of side chain densities and three types of side chain lengths were synthesized by esterification of the lignin hydroxyl groups with bromoisobutyryl groups, atom transfer radical polymerization using 2-(dimethylamino)ethyl methacrylate, and quaternization of the amino groups. Dye removal test was performed using three organic dyes and the obtained lignin-based flocculants. The results indicated that the density and the length of the side chains obviously affected the flocculation behavior. When the flocculants containing the same nitrogen amount were compared, the flocculation performance was improved with the increase of the side chain length within the samples having low and middle side chain densities. In the case of the samples having high side chain density, the most efficient sample was not the sample having the longest side chain. Most of the lignin-based flocculants removed dyes more efficiently than the poly 2-(trimethylamino)ethyl methacrylate homopolymer. From these results, it was suggested that lignin has a potential character as the core molecule to design the high-efficient dye-flocculant.

OsH(CO)(PPh 3) 2 (SRaaiNR /)] + (2) (SRaaiNR / (1) = 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole) act as catalyst to the oxidation of primary/secondary alcohols to aldehyde/ketone by N-methylmorpholine N-oxide (NMO). The catalysts have been characte riz ed by the sp ectr osc opic d ata an d t wo of the co mple xes [O sH(CO) (PPh 3) 2 (SMea aiNMe)]PF 6 (2a) an d [OsH(CO)(PPh 3) 2 (SMeaaiNEt)]PF 6 (2b) have been structurally characterized by single crystal X-ray diffraction measurements. The complexes are redox active and show Os III /Os II (~0.8 V) and Os IV /Os III (~1.5 V) couples. The catalytic activity of the complexes may be due to oxidation to Os IV =O species by NMO (supported by (Os=O), 857 cm-1) which could oxidize alcohols to aldehydes or ketones.

In situ prepared sodium ferrate was used for the oxidation of structurally different hydrocarbons, cyclic alcohols and aldehydes thus eliminating the tedious process of separating potassium ferrate in the solid form before its use as an oxidant. Montmorillonite KlO under microwave irradiations catalyzed the oxidations resulting in the excellent yields. Maximum yields of the products under controlled conditions were obtained by changing the reaction conditions one by one keeping other factors constant which may affect the yield. The system is simple, proceeds without over-oxidation under reported conditions and in some cases gives even better results compared to potassium ferrate oxidations. Phenanthrene was oxidized to 9-fluorenone (86.1%) instead of phenanthraquinone. Ferrate oxidations are environmentally benign and being very fast under microwave irradiations, become economical also.

Nitrous oxide (N2O), an important greenhouse gas usually decomposed under harsh thermal conditions, was completely reduced into climate neutral N2 and H2O under mild photocatalytic conditions, in the presence of alcohols as reducing agents. This reaction, which combines the synergistic removal of N2O and alcohols oxidation, was extended to the selective production of valuable ketones and aldehydes, using Ag/TiO2 as dual-reaction site.

A nanocrystalline magnesium oxide‐stabilized molybdenum(VI) complex catalyzed the oxidation of primary and secondary alcohols to carbonyl compounds in excellent yields using molecular oxygen as stoichiometric oxidant. The nanomaterials with their three‐dimensional structure and defined size and shape act as suitable supports for metal complexes. The catalyst can be reused for four runs without any significant loss of activity.

Boron doped (BDD) diamond electrodes have a wide potential window and thus allow the formation of radicals and the investigation of their reactions. Hexafluoroisopropanol is able to extend greatly the lifetime of radical cations. Here, we investigated the oxidation of a series of the hydroxyl containing species at a BDD electrode in that solvent: water and the simplest primary, secondary, and tertiary alcohols, i.e. methanol, i-propanol, and t-butanol. The ease of their oxidation does not follow the hydrogen basicity but rather the bond dissociation energy. The radicals formed from water, methanol, and i-propanol are very short-lived and we can detect electrochemically only the second reaction product, i.e. the hydrogen ions. In contrast, t-butanol is oxidised to an intermediate, which is transformed much more slowly within some seconds to another species. This species can be further oxidised more easily than the first intermediate or the initial reactant. There is some evidence, that the reactant molecules play a dual role: on the one hand they undergo oxidative hydrogen abstraction. On the other hand, they stabilise the produced hydrogen ions.

Benzyl alcohols and benzyl TBDMS ethers were efficiently oxidized to the corresponding carbonyl compounds in high yield with periodic acid catalyzed by CrO 3 at low temperature (-78°C). The oxidation procedure was highly functional group tolerant and very selective for the TBDMS group over the TBDPS group.

An efficient, copper-based catalyst has been discovered that oxidizes a wide range of alcohols into aldehydes and ketones under mild conditions. This catalytic system utilizes oxygen or air as the ultimate, stoichiometric oxidant, producing water as the only by-product.