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Sugars are natural and environmentally benign substances, which can offer various hydroxyl groups. The understanding of details of the hydroxyl interactions in the hydrophilic groups of sugar-based surfactants, as well as the related properties, is still indistinct. Here, novel d-gluconic acetal surfactants with bicyclic and monocyclic structures in the head group were designed and synthesized. The obtained surfactant with a bicyclic architecture exhibited excellent foamability and a multistimulus-responsive behavior toward foam stabilization. In addition, the control of foamability from defoaming and foaming could be achieved by changing pH values or bubbling gas of CO2/N2. To explore the structural effects such as hydroxyl groups and rigidity of the head group on the properties of sugar-based surfactants, another kind of amphiphilic molecule with various OH– groups and a monocycle in the head group was designed for comparison. These two series of amphiphilic molecules both exhibited good surface activity. However, only the d-gluconic acetal surfactant with a bicyclic structure and a smaller number of OH– groups exhibited excellent foamability. Further studies showed that the foam behaviors were attributed to the conformation and arrangement of the surfactant molecule at the surface layer with the assistance of hydrogen bonds formed by hydroxyl groups and H2O molecules. In addition, the surfactant could provide an environmentally friendly foamer in many potential applications.

Synthesis of value-added chemicals from biomass-derived polyols and CO2is of great importance. Herein we report a strategy to produce higher carboxylic acids by the reaction of polyol, CO2, and H2. The reaction can be efficiently accelerated by Rh catalyst in a binary solvent of ionic liquid (1-butyl-3-methylimidazolium iodide) and water, where cheap and nontoxic I2was used as a promoter. The reaction can occur at above 100°C. At optimal conditions, the yield of the carboxylic acids was as high as 86.4%. The catalytic mechanism is proposed based on a series of control experiments. Interestingly, the polyol could be effectively transformed into olefin intermediate at metal-free and mild conditions, which was the key to the success of this strategy. The peculiar solvent effect was also favorable to the reaction. In addition, the catalytic system was adaptable to various polyol substrates.

•This review focuses on recent advances of graphene-based catalysts in ECR.•We provide the fundamentals of CO2catalysis and possible key reaction intermediates.•We highlight strategies available for optimizing ECR performance.

Selective oxidation of benzylic C–H to benzylic alcohols is a well-known challenge in the chemical community since benzylic C–H is more prone to be overoxidized to benzylic ketones. In this work, we report the highly selective electro-oxidation of benzylic C–H to benzylic alcohols in an undivided cell in ionic liquid-based solution. As an example, the selectivity toward xanthydrol could be as high as 95.7% at complete conversion of xanthene, a typical benzylic C–H compound, on gram-scale in imidazolium bromide/H2O/DMF. Mechanism investigation reveals that the imidazolium radical generated in situ participants in a proton-coupled electron transfer process and low-barrier hydrogen bonds stabilize the reaction intermediates, together steering the redox equilibrium, favoring benzylic alcohols over benzylic ketones.

Highly efficient and greener hydrogenation of benzene to cyclohexene is of great importance but is challenging. In this work, Ru/TiO2catalyst was prepared by a simple chemical-reduction method. The catalyst was characterized by transmission electron spectroscopy (TEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption techniques. It was shown that the Ru nanoparticles with average size of about 2.2 nm were dispersed uniformly on the surface of the TiO2support. The effect of a very small amount of ZnO in NaOH solution on the selectivity to cyclohexene was investigated under different conditions by using Ru/TiO2catalyst. It was found that the addition of a small amount of ZnO to the NaOH solution could effectively enhance the selectivity to cyclohexene and that the yield of cyclohexene could reach 41.5%. Control experiments revealed that the main reason for the enhancement of the selectivity to cyclohexene was the presence of ZnO in the form of Na2Zn(OH)4in the alkaline solution, which effectively retarded the further hydrogenation of cyclohexene. A recycling experiment showed that the yield of cyclohexene was not obviously decreased after four reuses.

Efficient and greener oxidation of cyclohexene to 2-cyclohexene-1-one is an interesting topic. In this work, we prepared a series of Fe–Co doped graphitic carbon nitride (Fe–Co–g-C3N4) catalysts through simple impregnation and calcination methods. The catalysts were characterized by different techniques, such as transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), nitrogen adsorption–desorption measurement, powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The selective oxidation of cyclohexene to 2-cyclohexene-1-one was carried out in different solvents over the catalysts using molecular oxygen as an oxidant. The influence of supports, solvents, Fe/Co molar ratio in the catalysts, pressure of oxygen, reaction temperature and time of the reaction was investigated. It was revealed that the bimetallic Fe–Co–g-C3N4catalysts were very efficient for the reaction. More interestingly, the selectivity of the reaction in water was much higher than that in other solvents. Under optimized conditions, the selectivity to 2-cyclohexene-1-one could reach 95% at a cyclohexene conversion of 36%. The Fe–Co–g-C3N4catalyst could be reused at least four times without obvious loss of efficiency.

Abstract: Bimetallic Au/Pd nanoparticles were prepared and used to catalyze oxidation of alcohols in the poly(ethylene glycol) (PEG)/CO2 biphasic system using O2 as the oxidant without adding any base. The catalytic activity of Au/Pd bimetal with different mole ratios was studied using benzyl alcohol as the substrate. It was found that bimetallic Au/Pd nanoparticles with Au:Pd=1:3.5 had higher catalytic activity than monometallic Au, Pd and the bimetallic Au/Pd nanoparticles with other molar ratios. The effect of CO2 pressure on the oxidation of benzyl alcohol and 1-phenylethanol in PEG/CO2 was investigated. It was demonstrated that CO2 pressure could be used to tune the conversion and selectivity of the reactions effectively. α,β,-Unsaturated alcohols were also studied and found to be more reactive than benzyl alcohol and 1-phenylethanol. Recycling experiments showed that the Au/Pd/PEG/CO2 catalytic system could be recycled at least four times without reducing the activity. In addition, the catalytic system is clean and the products can be separated easily.

We developed a method to immobilize Pd/Au bimetallic nanoparticles (NPs) on highly cross-linked polymer microspheres. In this route, the cross-linker divinylbenzene and ionic liquid (IL) 1-vinyl-3-butyl imidazolium chloride ([VBIM]Cl) were first copolymerized in ethanol to prepare the cross-linked polymer microspheres with the IL. The PdCl42−ions were immobilized on the polymer support, and the Pd NPs immobilized on the support were formed after the PdCl42−ions were reduced. The supported bimetallic Pd/Au NPs were obtained after seeding growth process. The polymer support and metallic NPs/support composites were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, inductively coupled plasma analysis, X-ray photoelectron spectroscopy, and elemental analysis. It was demonstrated that the immobilized metallic NPs were nearly monodispersed and the Pd and Au in the composites showed excellent synergy to catalyze the hydrogenation of cyclohexene.

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The catalytic activity of polyaniline‐HX (X=I, Br, Cl) (PANI‐HI, PANI‐HBr, PANI‐HCl) for the cycloaddition of CO2to propylene oxide (PO) to produce propylene carbonate (PC) was studied for the first time. It was shown that all the PANI salts were active for the reaction, and PANI‐HI was most active and selective. On the basis of the preliminary results, the effect of the reaction conditions on the cycloadditions of CO2to propylene oxide and epichlorohydrin was further investigated by using PANI‐HI as the catalyst. The results indicated that the optimized temperature was around 115 °C. The maxima occurred in yield versus pressure curves at about 5 MPa for both substrates. Complete conversion was achieved in 3 h for epichlorohydrin and 6 h for propylene oxide at 115 °C and 5 MPa. With propylene oxide as the substrate, the reusability of PANI‐HI was evaluated and no loss of catalytic activity was detectable after the catalyst had been reused five times. The catalyst was characterized by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), which provided further evidence for the high stability of the catalyst. We believe that the catalyst has great potential for industrial applications because it has some unusual advantages, such as its easy preparation, high activity, selectivity, stability, low cost, and simple separation from products.

Phenol in waste water threatens human health and is difficultly to be decomposed by nature. Efficient degradation of high-loaded phenol in water under mild condition is still a great challenge. Herein, ionic liquids with tungstate anion were designed and prepared. It was found that dodecyltrimethylammonium tungstate could catalyzed degradation of phenol into gases and water thoroughly at 323 k in 8 h. Tungstate anion revealed good catalytic oxidative activity and long carbon chain group connecting with cation of ionic liquids enriched phenol around catalysts, which induced the complete degradation of phenol at mild conditions. Increasing the amounts of hydrogen peroxide benefited to the total degradation of phenol. In addition, the ionic liquid could be reused for its excellent thermal stability. Our work provided a different strategy to treat waste water containing phenol efficiently.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.