A three-component umpolung cascade coupling reaction of phenols, C
, and different nucleophiles which includes H
O, alcohols, triphenylamines and carbazoles was developed. Furthermore, one-pot ...1,4-bisphenol coupling on C
has been realized by this method. This practical protocol features high chemo- and regioselectivity, wide substrate range, easy operation and low cost, thus providing a robust method for the one-pot synthesis of various unsymmetrical 1,4-60fullerephenols.
Patients with eating disorders exhibit problems with appetitive impulse control. Interactions between dopamine and serotonin (5-HT) neuron in this setting are poorly characterized. Here we examined ...5-HT receptor-mediated changes in extracellular dopamine during impulsive appetitive behavior in rats. Rats were trained to perform a cued lever-press (LP) task for a food reward such that they stopped experiencing associated dopamine increases. Trained rats were administered the mixed 5-HT.sub.1B/2C-receptor antagonist metergoline, the 5-HT.sub.2A/2C-receptor antagonist ketanserin, and p-chlorophenylalanine (PCPA). We measured dopamine changes in the ventral striatum using voltammetry and examined the number of premature LPs, reaction time (RT), and reward acquisition rate (RAR). Compared with controls, metergoline increased premature LPs and shortened RT significantly; ketanserin decreased premature LPs and lengthened RT significantly; and PCPA decreased premature LPs, lengthened RT, and decreased RAR significantly. Following metergoline administration, rats exhibited a fast phasic dopamine increase for 0.25-0.75 s after a correct LP, but only during LP for an incorrect LP. No dopamine increases were detected with ketanserin or PCPA, or in controls. After LP task completion, metergoline also caused dopamine to increase slowly and remain elevated; in contrast, ketanserin caused dopamine to increase slowly and decrease rapidly. No slow dopamine increase occurred with PCPA. Inhibition of 5-HT.sub.1B- and 5-HT.sub.2C-receptors apparently induced dual modes of extracellular dopamine increase: fast phasic, and slow long-lasting. These increases may be associated with the suppression of acquired prediction learning and retention of high motivation for reward, leading to impulsive excessive premature LPs.
Fe-BiOCl-Vsub.o nanosheets with electron-capture centers of doped Fe and surface oxygen vacancies (Vsub.o) for enhanced photocatalytic-Fenton performances were conducted. Compared with pristine BiOCl ...nanosheets, the band gap of the resulting Fe-BiOCl-Vsub.o nanosheets was narrowed, and defective bands were introduced due to the Fe doping and Vsub.o. Furthermore, the integrated electron trapping effect of Vsub.o and doped Fe can efficiently drive charge transfer and separation. As a result, the photocatalytic-Fenton performances of phenol over Fe-BiOCl-Vsub.o nanosheets were enhanced. The photocatalytic-Fenton performances of Fe-BiOCl-Vsub.o nanosheets were enhanced two-fold and four-fold, respectively, as compared with the photocatalytic performances of Fe-BiOCl-Vsub.o and pristine BiOCl nanosheets. During the photocatalytic-Fenton process, the multiple reactive species referring holes (hsup.+), superoxide radicals (●Osub.2 sup.−), and hydroxyl radicals (●OH) induced by the efficiently separated charge carriers and Fenton reaction played synergetic roles in phenol degradation and mineralization. This work provides a sophisticated structure design of catalysts for efficient charge transfer and separation, promoting photocatalytic-Fenton performance.
TiOsub.2-supported catalysts have been widely used for a range of both liquid-phase and gas-phase hydrogenation reactions. However, little is known about the effect of their different crystalline ...surfaces on their activity during the hydrodeoxygenation process. In this work, Au supported on anatase TiOsub.2, mainly exposing 101 or 001 facets, was investigated for the hydrodeoxygenation (HDO) of guaiacol. At 300 °C, the strong interaction between the Au and TiOsub.2-101 surface resulted in the facile reduction of the TiOsub.2-101 surface with concomitant formation of oxygen vacancies, as shown by the Hsub.2-TPR and Hsub.2-TPD profiles. Meanwhile, the formation of Ausup.δ−, as determined by CO-DRIFT spectra and in situ XPS, was found to promote the demethylation of guaiacol producing methane. However, this strong interaction was absent on the Au/TiOsub.2-001 catalyst since TiOsub.2-001 was relatively difficult to be reduced compared with TiOsub.2-101. The Au on TiOsub.2-001 just served as the active site for the dissociation of hydrogen without the formation of Ausup.δ−. The hydrogen atoms spilled over to the surface of TiOsub.2-001 to form a small amount of oxygen vacancies, which resulted in lower activity than that over Au/TiOsub.2-101. The catalytic activity of the Au/TiOsub.2 catalyst for hydrodeoxygenation will be controlled by tuning the crystal plane of the TiOsub.2 support.
MoSsub.2/TiOsub.2-based nanostructures have attracted extensive attention due to their high performance in many fields, including photocatalysis. In this contribution, MoSsub.2 nanostructures were ...prepared via an in situ bottom-up approach at the surface of shape-controlled TiOsub.2 nanoparticles (TiOsub.2 nanosheets and bipyramids). Furthermore, a multi-technique approach by combining electron microscopy and spectroscopic methods was employed. More in detail, the morphology/structure and vibrational/optical properties of MoSsub.2 slabs on TiOsub.2 anatase bipyramidal nanoparticles, mainly exposing {101} facets, and on TiOsub.2 anatase nanosheets exposing both {001} and {101} facets, still covered by MoSsub.2, were compared. It was shown that unlike other widely used methods, the bottom-up approach enabled the atomic-level growth of well-defined MoSsub.2 slabs on TiOsub.2 nanostructures, thus aiming to achieve the most effective chemical interactions. In this regard, two kinds of synergistic heterojunctions, namely, crystal face heterojunctions between anatase TiOsub.2 coexposed {101} and {001} facets and semiconductor heterojunctions between MoSsub.2 and anatase TiOsub.2 nanostructures, were considered to play a role in enhancing the photocatalytic activity, together with a proper ratio of (101), (001) coexposed surfaces.
We report a heterojunction photocatalyst by coupling CdS with Bisub.12Osub.17Clsub.2 via a facile thermal annealing process. Such heterostructure can promote the charge separation between CdS and ...Bisub.12Osub.17Clsub.2, thereby leading to a considerable improvement on the performance for COsub.2 reduction into valuable CHsub.4 and phenol conversion under visible light exposure. The CdS/Bisub.12Osub.17Clsub.2 heterojunction with mass ratio of 1:1 (50% CdS/Bisub.12Osub.17Clsub.2) shows the highest CHsub.4 production rate (1.28μ mol·hsup.-1·gsup.-1), which is as 9.8 and 5.8 times as the CHsub.4 generation rate of pure Bisub.12Osub.17Clsub.2 and CdS (0.13 and 0.22μ mol·hsup.-1·gsup.-1), respectively. Also, the 50% CdS/Bisub.12Osub.17Clsub.2 sample shows the highest activity of phenol conversion with a conversion ratio of 92%, which is as 2.2 times and 1.9 times as the conversion ratio of pristine Bisub.12Osub.17Clsub.2 (41%) and CdS (48%), respectively. The present study demonstrates the great potential of the CdS/Bisub.12Osub.17Clsub.2 heterojunction for efficient charge separation towards increased photocatalytic CHsub.4 production and phenol conversion.
The available technologies for the abatement of phenol from water and gaseous streams are briefly reviewed, and the recent advancements summarized. Separation technologies such as distillation, ...liquid–liquid extraction with different solvents, adsorption over activated carbons and polymeric and inorganic adsorbents, membrane pervaporation and membrane–solvent extraction, have been discussed. Destruction technologies such as non-catalytic, supercritical and catalytic wet air oxidation, ozonation, non-catalytic, catalytic and enzymatic peroxide wet oxidation, electrochemical and photocatalytic oxidation, supercritical wet gasification, destruction with electron discharges as well as biochemical treatments have been considered. As for the abatement of phenol from gases, condensation, absorption in liquids, adsorption on solids, membrane separation, thermal, catalytic, photocatalytic and biological oxidation have also been considered. The experimental conditions and the performances of the different techniques have been compared.
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