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As a reliable redox mediator, potassium nitrate was employed in homogeneous electrolysis with CH3CN at room temperature to electrochemically oxidize aryl compounds. The oxidation reactions carried out in an undivided cell that was provided with a carbon anode and a stainless steel cathode, along with the minimum amount of H2SO4 at a current density of 50 mA/cm2. A variety of substituted toluenes and aromatic alcohols were effectively oxidized to the corresponding aldehydes with the maximum degree of selectivity. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae can undergo filamentous growth in response to specific environmental stressors, particularly nitrogenlimitation, whereby cells undergo pseudohyphal differentiation, a process where cells transition from a singular ellipsoidal appearance to multicellular filamentous chains from the incomplete scission of the mother-daughter cells. Previously, it was demonstrated that filamentous growth in S. cerevisiae is co-regulated by multiple signaling networks, including the glucose-sensing RAS/cAMP-PKA and SNF pathways, the nutrient-sensing TOR pathway, the filamentous growth MAPK pathway, and the Rim101 pathway, and can be induced by quorum-sensing aromatic alcohols, such as 2-phenylethanol. However, the prevalent research on the yeast-pseudohyphal transition and its induction by aromatic alcohols in S. cerevisiae has been primarily limited to the strain -1278b. Due to the prospective influence of quorum sensing on commercial fermentation, the native variation of yeast-to-filamentous phenotypic transition and its induction by 2-phenylethanol in commercial brewing strains was investigated. Image analysis software was exploited to enumerate the magnitude of whole colony filamentation in 16 commercial strains cultured on nitrogen-limiting SLAD medium; some supplemented with exogenous 2-phenylethanol. The results demonstrate that phenotypic switching is a generalized, highly varied response occurring only in select brewing strains. Nevertheless, strains exhibiting switching behavior altered their filamentation response to exogenous concentrations of 2-phenylethanol. [ABSTRACT FROM AUTHOR]

The HPLC chiral resolution of ten chiral aromatic alcohols were screened using six different polysaccharides-based chiral stationary phases (CSP) and under four normal phase conditions, using UV absorbance as detection. The screening showed that all compounds can be baseline resolved in at least one of the tested conditions, being the cellulose-methylbenzoate CSP the one with the best performance by resolving the full set. Furthermore, the use of two chiroptical detectors, based in optical rotation and electronic circular dichroism, permitted the ascertain of the elution order for each of the baseline separations. Finally, several options for a single-column batch analysis, in which samples of all compounds are tested for enantiomeric excess and absolute configuration, are proposed to analyze samples from the asymmetric reduction of the corresponding ketones. These options vary in the number of injections, analysis time and reliability, and their choice will mostly depend on the hardware and standards availability. [ABSTRACT FROM AUTHOR]

The mechanism for aerobic oxidation of methylaromatic compounds using Co(CH 3 COO) 2 –Mn(CH 3 COO) 2 –KBr was further studied. The experimental results suggested that the intermediates (aromatic alcohols) are unexpectedly inert to direct oxidation via Co–Mn–Br catalysts under moderate conditions. In addition, it is found that both aromatic and aliphatic alcohols can inhibit the oxidation of the substrates and other intermediates (aromatic esters, aromatic aldehydes). UV–vis spectra indicated that oxidation from Co(II) to Co(III) would be interrupted in the presence of a given amount of alcohol. A plausible mechanism was also proposed. The intermediates analyzed by LC–MS and control experiments showed that aromatic alcohols prefer to undergo esterification rather than being directly oxidized as described in previous studies, and aromatic acetates are subsequently oxidized to corresponding aldehydes. According to the new mechanism, a strategy of highly selectively synthesizing aromatic alcohols and aldehydes from corresponding methylaromatic compounds was designed. The selectivities of aromatic alcohols and aldehydes could also be tuned by the added amount of CH 3 COOK. [ABSTRACT FROM AUTHOR]

The hydrogenolysis reaction of aromatic alcohols (benzyl alcohol, 1-phenylethanol and diphenylmethanol), promoted by supported palladium catalysts, such as Pd/TiO, Pd/SiO and Pd/CoO, has been investigated at 0.1 MPa H and 323 K. The catalysts have been characterized by BET, TPR, XRD, TEM and XPS. A different kinetic behaviour was observed: in presence of Pd/TiO and Pd/SiO catalysts, prepared by impregnation, the hydrogenolysis activity follows the order benzyl alcohol > 1-phenylethanol ≥ diphenylmethanol, whereas it is totally reversed on Pd/CoO, prepared by co-precipitation. All results indicate that the reactivity of supported Pd catalysts, in the hydrogenolysis reaction, depends on the support nature, the preparation method of catalysts and the aromatic alcohols structure. Kinetic experiments carried out at different partial hydrogen pressure allow to elucidate the pathway of the C-OH bond scission, involving a radical substitution of the carbon bonded OH group by a hydrogen atom coming from the metal surface 'via' associative and dissociative paths. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new transition metal-free catalyst system for aerobic oxidation is developed. [•] The efficient oxidation of alcohols with molecular oxygen is achieved. [•] The catalytic system is composed of DDQ, NaNO2 and NBS. [•] 76–99% yields of aldehydes are obtained from oxidation of aromatic alcohols. [Copyright &y& Elsevier]

Abstract: Mo2N nanobelts about 60nm wide and 0.5–7.2μm long have been synthesized by reacting a belt-shaped α-MoO3 precursor with ammonia at 850°C. The Mo2N nanobelts effectively and selectively catalyzed dehydrogenation of a variety of aromatic alcohols. The coordinatively unsaturated Mo sites on the surface of the Mo2N nanobelts might be the active species. [Copyright &y& Elsevier]

In the present study, heterogeneous copper(II)-cysteine/SiO-AlO catalyst was successfully prepared by a simple adsorption method. The physical and chemical properties of Cu(II)-cysteine/SiO-AlO were investigated by X-ray diffraction, thermal gravimetric analyzer, FT-IR spectroscopy, Brunauer-Emmett-Teller, UV-Vis spectroscopy, scanning electron microscopy and atomic absorption spectrometer. The obtained composite was effectively employed as catalyst for selective oxidation of various aromatic alcohols to corresponding aldehydes in high yields using hydrogen peroxide as an oxidant under mild condition. The catalyst can be recycled over five times without significant loss of activity. [ABSTRACT FROM AUTHOR]

Abstract: Solvent intensification for aromatic alcohol oxidation was performed by experimentally extensive screening. A co-solvent mixture of [Omim]Cl and toluene was found to significantly intensify this class of reactions with high conversion of alcohols (>90%) and high selectivity to their aldehydes (>90%). The intensification effect can be jointly attributed to the interaction of [Omim]Cl with the catalyst WO3 surface, which enhances its catalytic reactivity, and to the aqueous–organic biphasic formation by toluene, which inhibits the over-oxidation of aromatic alcohols. [Copyright &y& Elsevier]

Abstract: The oxidation of benzyl alcohol (BnOH) and a few para-substituted benzyl alcohols by tripropylammonium fluorochromate (TriPAFC) in dimethylsulphoxide (DMSO) leads to the formation of corresponding aldehydes. The reaction is first order each in TriPAFC and the alcohols. The reaction is catalysed by hydrogen ions. The hydrogen ion dependence has the form: k obs = a + b[H+]. The oxidation of α α′-dideuterio benzyl alcohol exhibited a substantial primary kinetic isotope effect (k H/k D =5.45 at 303K). Oxidation of benzyl alcohol was studied in 19 different organic solvents. The solvent effect has been analysed using Kamlet''s and Swain''s multiparametric equation. A mechanism involving a hydride ion transfer via chromate ester is proposed. [Copyright &y& Elsevier]

Abstract: The removals of single aromatic alcohols, including para nitro phenol (PNP), meta nitro phenol (MNP), phenol (P), catechol (CC), beta napthol (BN) and ortho chloro phenol (OCP) from aqueous solution have been studied using micellar-enhanced ultrafiltration (MEUF). Cetyl (hexadecyl) pyridinium chloride (CPC) has been taken as the cationic surfactant. An organic polyamide membrane of molecular weight cut-off 1000 is used in the MEUF experiments. Experiments are conducted using unstirred batch cell and a continuous cross flow cell. The effects of surfactant-to-solute concentration ratio in the feed, transmembrane pressure drop and cross flow rate on the permeate flux and observed retention of each solute have been studied in detail. The retention of solutes without using surfactant varies from 3 to 15% only at a typical feed solute concentration of 0.09kg/m3. However, under the same operating pressure (345kPa), retention increases to about 66–98% depending on the nature of solute at the end of 30min of experiment in the batch cell using surfactant micelles (10kg/m3). The maximum retention of solute is obtained at surfactant-to-solute concentration ratio of 110. Free surfactant molecules present in the permeate and retentate are then recovered by a two-step chemical treatment process. In the first step, the surfactant is precipitated by potassium iodide and in the second step, the surfactant is recovered from the precipitate by the addition of cupric chloride. Optimum consumptions of potassium iodide and cupric chloride are also obtained experimentally. [Copyright &y& Elsevier]

• Kraft lignin depolymerization was performed over 5Ni-5Re/Nb 2 O 5 catalyst. • Liquid product was rich in low-molecular-weight aromatic alcohol compounds. • The oxophilicity of Nb 2 O 5 was beneficial for promoting cleavage of C-O bonds. • Ethanol was more favorable for the hydrogenolysis of Kraft lignin. Direct hydrogenolysis of Kraft lignin was catalyzed over a series of supported Ni or Re catalysts in ethanol solvent. The best results showed that the oil yield of 96.70 wt% was obtained with less char formation at 330 °C for 3 h over 5Ni-5Re/Nb 2 O 5 catalyst. Product analysis demonstrated that the monomer yield of 35.41 wt% was given under mild condition, and low-molecular-weight aromatic alcohols were the main component in the liquid products. Ethanol was found to be more effective in H 2 production and facilitated the transformation of phenolic monomers to aromatic chemicals. The results confirmed that the optimal 5Ni-5Re/Nb 2 O 5 catalyst had superior oxophilicity and appropriate acid sites, which improved the ability to directly remove the methoxyl and hydroxyl groups of lignin-derived phenolic compounds without aromatic ring hydrogenation. In addition, the temperature, time and solvent effects on the lignin depolymerization were also investigated. [ABSTRACT FROM AUTHOR]