Iodoarene-directed photoredox ß-C(sp3)-H arylation of 1-(o-iodoaryl)alkan-1-ones with cyanoarenes via halogen atom transfer and hydrogen atom transfer.

Site selective functionalization of inert remote C(sp3)-H bonds to increase molecular complexity offers vital potential for chemical synthesis and new drug development, thus it has been attracting ongoing research interest. In particular, typical ß-C(sp3)-H arylation methods using chelation-assisted metal catalysis or metal-catalyzed oxidative/photochemical in situ generated allyl C(sp3)-H bond processes have been well developed. However, radical-mediated direct ß-C(sp3)-H arylation of carbonyls remains elusive. Herein, we describe an iodoarene-directed photoredox ß-C(sp3)-H arylation of 1-(o-iodoaryl)alkan-1-ones with cyanoarenes via halogen atom transfer (XAT) and hydrogen atom transfer (HAT). The method involves diethylaminoethyl radical-mediated generation of an aryl radical intermediate via XAT, then directed 1,5-HAT to form the remote alkyl radical intermediate and radical-radical coupling with cyanoarenes, and is applicable to a broad scope of unactivated remote C(sp3)-H bonds like ß-C(sp3)-H bonds of o-iodoaryl-substituted alkanones and α-C(sp3)-H bonds of o-iodoarylamides. Experimental findings are supported by computational studies (DFT calculations), revealing that this method operates via a radical-relay stepwise mechanism involving multiple SET, XAT, 1,5-HAT and radical-radical coupling processes.

Electroreductive Remote Benzylic C(sp3)-H Arylation of Aliphatic Ethers Using Cyanoarenes for the Synthesis of α-(Hetero)aryl Ethers.

An iodoarene-driven electroreductive remote C(sp3)-H arylation of unsymmetrical 1-(o-iodoaryl)alkyl ethers with cyanoarenes for the site selective synthesis of α-(hetero)aryl ethers is developed. With the introduction of cyanoarenes as both aryl sources and electron transfer mediators, this method includes an iodoarene-driven strategy to enable the regiocontrollable formation of two new bonds, one C(sp2)-H bond, and one C(sp2)-C(sp3) bond, in a single reaction step through the sequence of halogen atom transfer (XAT), hydrogen atom transfer (HAT), radical-radical coupling, and decyanation.

Preparation of a novel poly-(di-ionic liquid)/BDD-modified electrode for the detection of tetrachloro-p-benzoquinone.

During the COVID-19 pandemic, the release of toxic disinfection by-products (DBPs) has increased due to the intensive, large-scale use of disinfectants. Halogenated benzoquinones (HBQs) are among the most toxic DBPs, but there is no rapid, convenient, and economical detection method. In this study, a novel PDIL/BDD-modified electrode was prepared in a mixed solvent of dimethyl sulfoxide (DMSO) and acetonitrile (ACN) by electrochemical polymerization with a di-ionic ionic liquid containing alkenyl groups as the monomer. The electrochemical behavior of tetra-chloro-p-benzoquinone (TCBQ) on the modified electrode was studied. By studying the cyclic voltammetry behavior of TCBQ on the PDIL/BDD electrode, it was concluded that the electrode reactions of TCBQ included the reduction of TCBQ to TCBQH2 (C1) and the reduction of bis-quinhydrone imidazole π-π type charge transfer complex to TCBQH2 (C2). By studying the SWV responses of TCBQ in the concentration range of 1-100 ng/L on the PDIL/BDD electrode, it was found that the reduction peak current (Ipa) had a linear relationship with the concentration. The electrochemical SWV technique was used to detect the concentration of trace TCBQ in water and is expected to be used for the detection of other HBQs in drinking water and swimming pool water.

PbO2 modified BDD electrode by dicationic ionic liquids assisted electrodeposition for efficient electrocatalytic degradation of pesticide wastewater.

Pesticide wastewater is difficult to treat, and it is necessary to develop a new anode material electrochemical oxidation to efficiently degrade pesticide wastewater. DIL-PbO2-Ti/BDD electrodes with better electrocatalytic oxidation performance were obtained by using dicationic ionic liquid (DIL) for assisted electrodeposition of PbO2 modified boron-doped diamond (BDD) electrodes. At a current density of 100 mA cm-2 and a temperature of 25 °C, the DIL-PbO2-Ti/BDD electrode was used as anode and titanium plate as cathode. The electrochemical window and oxygen evolution potential (OEP) of the DIL-PbO2-Ti/BDD electrode obtained by CV testing at a scan rate of 50 mV s-1 in 1 M H2SO4 were 4.12 and 3.29 V, respectively. Under the conditions of current density of 100 mA cm-2, 25 °C, pH 12, salt content of 8%, chemical oxygen demand (COD) of 24,280.98 mg L-1, and total nitrogen (TN) content of 5268 mg L-1, after electrification for 12 h, the removal efficiency of COD and TN reached 64.88 and 67.77%, respectively, indicating that the DIL-PbO2-Ti/BDD electrode has excellent electrocatalytic performance. In order to further understand the mechanism of electrochemical degradation of pesticide wastewater, HPLC-MS was used to detect the intermediates in the degradation process, and the possible degradation pathways were proposed in turn.

Efficient electrochemical degradation of X-GN dye wastewater using porous boron-doped diamond electrode.

Surface porous Ti substrates were obtained by electrodeposition-hot melt-alkali etching. Porous-Ti/BDD and flat-Ti/BDD electrodes were prepared for comparative study. The results of SEM, Raman, and XRD analyses show that the BDD films of these two electrodes had good uniformity and stable quality. The electrochemical window (EW) and electrochemical-active surface area (EASA) of the porous-Ti/BDD electrode is as high as 4.21 V and 22.78 cm2 (11.39 cm2/cm2), respectively. Furthermore, the electrochemical catalytic performance and degradation mechanism of porous-Ti/BDD electrode as the anode were studied by the electrolysis of Active Orange dye X-GN (X-GN), and the optimal electrochemical degradation operating parameters were obtained. The results show that when the degradation time was 50 min, the X-GN was completely decolorized. The TOC removal rate reached 69.24%, and the energy consumption was 5.62 kWh m-3. The contribution rate of •OH and SO4•- was calculated to be 91.40% and 1.26% by radical quenching experiments, respectively, indicating that the active substances in the degradation system were mainly •OH and SO4•-. The high specific surface characteristics of porous-Ti/BDD electrode enhanced its electrochemical oxidation advantages, and it showed a high degradation efficiency and low energy consumption for the treatment of X-GN simulated wastewater.

Nickel-Catalyzed C-S Reductive Cross-Coupling of Alkyl Halides with Arylthiosilanes toward Alkyl Aryl Thioethers.

A nickel-catalyzed C-S reductive cross-coupling of alkyl halides with arylthiosilanes for producing alkyl aryl thioethers is developed. This reaction is initiated by umpolung transformations of arylthiosilanes followed by C-S reductive cross-coupling with alkyl halides to manage an electrophilic alkyl group onto the electrophilic sulfur atom and then construct a C(sp3)-S bond, and features exquisite chemoselectivity, excellent tolerance of diverse functional groups, and wide applications for late-stage modification of biologically relevant molecules.

The adsorption mechanism of CF4 on the surface of activated carbon made from peat and modified by Cu.

In order to find a way to deal with CF4 with good removal effect and easy to promote. In this study, peat was used as raw material, and copper-loaded activated carbon (Cu/AC) was successfully prepared through nitric acid oxidation and copper chloride impregnation. Compared with commercial activated carbon and widely used metal organic frameworks (MOFs), it shows a fast adsorption rate and larger adsorption capacity for CF4. The static experiment was used to study the influence of Cu/AC on the adsorption of CF4 in the adsorbent dosage, reaction time, temperature, and initial concentration. SEM, FTIR, XPS, XRF, and BET were used to study the changes of physical and chemical properties before and after the adsorption. It was found that the oxygen-containing group was consumed during this process. Unsaturated sites on Cu can accelerate the adsorption of CF4, and the adsorption process is reversible. For the first time, the kinetic model, adsorption isotherm, and thermodynamic model are used to analyze the adsorption mechanism of CF4 on the Cu/AC surface from different angles. The results show that the adsorption of CF4 on the Cu/AC surface is a process of exothermic entropy reduction. The static adsorption process conforms to the pseudo-first-order, the pseudo-second-order, and the Freundlish adsorption model. Through 5 adsorption and desorption processes, it is found that Cu/AC has excellent recycling and recyclability performance.

Rhodium-Catalyzed Reductive trans-Alkylacylation of Internal Alkynes via a Formal Carborhodation/C-H Carbonylation Cascade.

A rhodium-catalyzed reductive annulation cascade reaction that consists of a formal anti-carborhodation of a C≡C bond and an aromatic C-H carbonylation cascade for producing cyclopenta[de]quinoline-2,5(1H,3H)-diones is described. This method uses the Mn reductant to reductively regenerate the active rhodium species, hence obviating the need for prefunctionalization, and represents a new route to the carbonylation of aromatic C-H bonds with alkynes leading to aryl vinyl ketone frameworks.

A novel graphene oxide-dicationic ionic liquid composite for Cr(VI) adsorption from aqueous solutions.

A novel graphene oxide-dicationic ionic liquid composite (GO-DIL) was prepared by modifying graphene oxide (GO) with a dicationic ionic liquid (DIL), 3,3'-(butane-1,4-diyl) bis (1-methyl-1H-imidazol-3-ium) chloride ([C4(MIM)2]Cl2). GO and GO-DIL were characterized by SEM, BET, FTIR, and XPS, and the materials were used for Cr(VI) adsorption. Batch adsorption studies showed that adsorption reached equilibrium within 40 min, and the optimal pH was 3, where the electrostatic attraction between GO-DIL and Cr(VI) was maximized. The maximum theoretical Cr(VI) adsorption capacity (qm) was 271.08 mg g-1, and qm remained above 228.00 mg g-1 after five cycles. The adsorption data were fitted well by both the pseudo-first-order kinetic model and the Langmuir model. Furthermore, thermodynamics calculations revealed that adsorption was a spontaneous endothermic process. Importantly, electrostatic attraction between Cr(VI) and the protonated imidazole N+ of GO-DIL played a critical role in Cr(VI) adsorption, and Cr(VI) was reduced to Cr(III). Thus, GO-DIL is predicted to be an effective adsorbent for Cr(VI) and other heavy metal ions in wastewater.

Electrochemical oxidative degradation of X-6G dye by boron-doped diamond anodes: Effect of operating parameters.

Boron-doped diamond (BDD) is an excellent electrode material. As the anode in an electrochemical degradation tank, BDD has been receiving widespread attention for the treatment of azo dye wastewater. In this study, electrochemical oxidation (EO) was applied to electrolyze reactive brilliant yellow X-6G (X-6G) using BDD as the anode and Pt as the cathode. To balance the degradative effects and power consumption in the electrolysis process, the effects of a series of operating parameters, including current density, supporting electrolyte, initial pH, reaction temperature and initial dye concentration, were systematically studied. The oxidative process was analyzed by color removal rate, and the degree of mineralization was evaluated by TOC. The optimal experimental parameters were finally determined: 100 mA cm-2, 0.05 M Na2SO4 electrolyte, pH 3.03, 60 °C, and an initial X-6G concentration of 100 mg L-1. As a result, color completely disappeared after 0.75 h of electrolysis, and TOC was removed by 72.8% after 2 h of electrolysis. In conclusion, the EO of a BDD electrode as an anode can be a potent treatment method for X-6G synthetic wastewater.

Electrochemical dehydrogenative cross-coupling of two anilines: facile synthesis of unsymmetrical biaryls.

A new, general ortho/para-selective anodic dehydrogenative cross-coupling of two aryl amines, naphthalen-2-amine derivatives and anilines, is described. This electrochemical protocol assembles a wide range of unsymmetrical biaryls in good to excellent yields under mild, additional-metal-catalyst-free, oxidant-free conditions with excellent selectivity, broad substrate scope, and wide functional group tolerance. This electrochemical technology is highlighted with facile incorporation of important pharmacophores into the resulting biaryls, and is applicable to the homocoupling of anilines for producing symmetrical biaryls.

Osteological characteristics of Chinese foot-binding in archaeological remains.

Foot-binding was a widespread custom in China for hundreds of years, though the severity and type of binding varied considerably over time and space. To examine the morphological consequences of extremely severe foot-binding, this paper uses 35 sets of bound and 33 sets of unbound foot bones, from the remains of women excavated from the Xinzhi cemetery in northern Shandong Province. Based on macroscopic observation, CT slices, and measurements of bound foot bones, multiple distinctive consequences of foot-binding were identified. Compared with normal bones, bound foot bones have severely reduced overall size and weight. The density of trabecular mesh was reduced and its structure was altered in all tarsal bones. While the talus and navicular bones of bound feet retained all major groups of trabeculae, the calcaneus experienced massive trabecular loss, suggesting that in a bound foot the calcaneus lost its weight bearing function and its role in plantarflexion. The severity of changes was greater in the laterally positioned foot bones, i.e. the lateral cuneiform, the cuboid, and 4th and 5th metatarsals, than in the medial ones, showing that most of the body weight in the bound foot was transmitted along the first ray. Degenerative osteoarthritic changes affected articular surfaces of the foot bones, even in young individuals. These changes suggest that the biomechanics of bipedal locomotion were considerably affected in all females with severely bound feet.

The Electrochemical Oxidation of Hydroquinone and Catechol through a Novel Poly-geminal Dicationic Ionic Liquid (PGDIL)-TiO2 Composite Film Electrode.

A novel poly-geminal dicationic ionic liquid (PGDIL)-TiO2/Au composite film electrode was successfully prepared by electrochemical polymerization of 1,4-bis(3-(m-aminobenzyl)imidazol-1-yl)butane bis(hexafluorinephosphate) containing polymerizable anilino groups in the electrolyte containing nano-TiO2. The basic properties of PGDIL-TiO2/Au composite films were studied by SEM, cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. The SEM results revealed that the PGDIL-TiO2 powder has a more uniform and smaller particle size than the PGDIL. The cyclic voltammetry results showed that the catalytic effect on electrochemical oxidation of hydroquinone and catechol of the PGDIL-TiO2 electrode is the best, yet the Rct of PGDIL-TiO2 electrode is higher than that of PGDIL and TiO2 electrode, which is caused by the synergistic effect between TiO2 and PGDIL. The PGDIL-TiO2/Au composite electrode presents a good enhancement effect on the reversible electrochemical oxidation of hydroquinone and catechol, and differential pulse voltammetry tests of the hydroquinone and catechol in a certain concentration range revealed that the PGDIL-TiO2/Au electrode enables a high sensitivity to the differentiation and detection of hydroquinone and catechol. Furthermore, the electrochemical catalytic mechanism of the PGDIL-TiO2/Au electrode was studied. It was found that the recombination of TiO2 improved the reversibility and activity of the PGDIL-TiO2/Au electrode for the electrocatalytic reaction of HQ and CC. The PGDIL-TiO2/Au electrode is also expected to be used for catalytic oxidation and detection of other organic pollutants containing -OH groups.

Adsorption of Ni2+ and Pb2+ from water using diethylenetriamine-grafted Spirodela polyrhiza: behavior and mechanism studies.

Novel adsorbent, diethylenetriamine-grafted Spirodela polyrhiza (DSP), was synthesized via modifying natural S. polyrhiza (SP) with diethylenetriamine by cross-linking with epichlorohydrin and applied to adsorb Ni2+ and Pb2+ from water. The effecting parameters on adsorption of Ni2+ and Pb2+ such as adsorbent dosage, pH, contact time, temperature, and initial concentration were studied through equilibrium experiments. The adsorption of Ni2+ and Pb2+ followed the pseudo-second-order model and the Langmuir isotherm adsorption model. The study discusses thermodynamic parameters, including changes in Gibbs free energy, entropy, and enthalpy, for the adsorption of Ni2+ and Pb2+ on DSP, and revealed that the adsorption process was spontaneous and exothermic under natural conditions. The maximum Ni2+ and Pb2+ adsorption capacities of DSP were 33.02 and 36.50 mg/g, respectively. The newly prepared materials were characterized through scanning electron microscopy (SEM), mapping analysis, and zeta potential analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that functional groups (-OH and N-H) were involved in Ni2+ and Pb2+ adsorption. Notably, DSP can be easily regenerated and reused for multiple cycles. Therefore, DSP is a promising adsorbent for effective Ni2+ and Pb2+ removal.

Decarboxylative [4+2] annulation of arylglyoxylic acids with internal alkynes using the anodic ruthenium catalysis.

A new electrochemical decarboxylative [4+2] annulation of arylglyoxylic acids with internal alkynes involving C-H functionalization by means of a cooperative anode and ruthenium catalysis is presented. This reaction represents a mechanistically novel strategy as an ideal supplement to the decarboxylative [4+2] annulation methodology by employing an electrooxidative process to avoid the use of an additional external oxidizing reagent and utilizing H2O as the carboxyl oxygen atom source to be engaged in the synthesis of 1H-isochromen-1-ones.

Characterization of modified Alternanthera philoxeroides by diethylenetriamine and its application in the adsorption of copper(II) ions in aqueous solution.

By a simple and convenient method of using epichlorohydrin as linkages, a novel Alternanthera philoxeroides (AP) derivative modified with diethylenetriamine (DAP) was synthesized, which can remove copper(II) ions (Cu(II)) in the water environment efficiently. The adsorption capacity of DAP for Cu(II) under various factors was measured using ultraviolet spectrophotometer. The adsorption capacity and removal ratio were 19.33 mg/g and 95.57% at pH 5.5 and 298 K. The kinetic and equilibrium study shows that pseudo-second-order kinetic (R2 = 0.9964) and Langmuir isotherm models (R2 > 0.982) could properly describe DAP adsorption behaviors, and thermodynamic parameters indicate a spontaneous endothermic process (ΔG = - 3.6636 kJ/mol). The combined results of SEM, XRD, FTIR, and XPS analyses reveal that the dominant contribution for enhancement in Cu(II) adsorption is made by the formation of an amino group. And the adsorption mechanism is mainly the complexation reaction. The adsorption efficiency of DAP remained above 72.06% after 6 cycles of adsorption-desorption, which indicated that DAP has good regenerability and stability. All the results suggest that DAP could serve as promising adsorbents for Cu(II) pollution minimization.

Ruthenium(ii)-catalyzed electrooxidative [4+2] annulation of benzylic alcohols with internal alkynes: entry to isocoumarins.

A new ruthenium(ii)-catalyzed electrooxidative [4+2] annulation of primary benzylic alcohols with internal alkynes is described, which enables benzylic alcohols as weakly directing group precursors to access isocoumarins via multiple C-H functionalization. The reaction works well with a broad substrate scope, tolerates a wide range of functional groups, and incorporates practically the isocoumarin unit into diverse bioactive molecules. Mechanistic studies indicate that activation of aryl C(sp2)-H bonds is achieved through the generation of the active benzoyloxy-Ru(ii) intermediates via oxidation of benzylic alcohols using an electrooxidative Ru(ii) catalyst.

Adsorption of Cu (II) and Ni (II) from aqueous solutions by taro stalks chemically modified with diethylenetriamine.

Taro stalks (TS) were modified by diethylenetriamine (DETA) to obtain the modified taro stalks adsorbents (recorded as MTSA). This kind of raw material is unprecedented and the method of modification is relatively simple. The physicochemical properties of MTSA were characterized by scanning electron microscope (SEM), FTIR, and zeta potential analyzer. The capacity of MTSA for adsorbing heavy metals under different influencing factors was tested by UV-visible spectrophotometer. The results indicated that the gaps between the microspheres of MTSA are more, which are conducive to adsorption. The MTSA might have increased the amino-functional groups which are beneficial for adsorption, resulting in an increase in the adsorption capacity of copper and nickel ions (35.71 and 31.06 mg/g) of about 5-7 times compared to bare taro stalks (5.27 mg/g and 6.08 mg/g). High Cu2+ uptake on MTSA was observed over the pH range of 5.5-7.0, while for Ni2+ the range was 7.0-8.5, and the optimum dosage of adsorbent were both about 0.80 g for Cu2+ and Ni2+. The adsorption kinetics of Cu2+ and Ni2+ on MTSA could be interpreted with a pseudo-second order and the equilibrium data were best described by the Langmuir isotherm model. Graphical abstract ᅟ.

Copper-Catalyzed Annulation Cascades of Alkyne-Tethered α-Bromocarbonyls with Alkynes: An Access to Heteropolycycles.

We here describe a new Cu-catalyzed annulation cascade of alkyne-tethered α-bromocarbonyls with common alkynes for the synthesis of various heteropolycycle frameworks, including 1 H-benzo[ de]quinolin-2(3 H)-ones, 4 H-dibenzo[ de,g]quinolin-5(6 H)-one, and benzo[ de]chromen-2(3 H)-one, which were constructed with high selectivity. This was achieved by two-component annulation cascades, rather than atom-transfer radical cyclization (ATRC), with alkyne-tethered α-bromocarbonyls for one-step accessing heteropolycycles via C-Br bond split, intramolecular cyclization, intermolecular [4 + 2] annulation, and aryl C(sp2)-H functionalization cascades.

An access to 1,3-azasiline-fused quinolinones via oxidative heteroannulation involving silyl C(sp3)-H functionalization.

A Mn-promoted intermolecular oxidative radical heteroannulation of N-(2-cyanoaryl)-acrylamides and tertiary silanes has been described, which provides an efficient route to produce silicon/nitrogen heterocycles, sila-analogues of the known carbon-based structural motifs prevalent in bioactive natural products, pharmaceuticals and materials. The reaction enables Si-incorporation by controlling accurately several chemical bond cleavage and formation processes. Moreover, this reaction represents a new one-step construction of 1,3-azasiline-fused quinolinones that was achieved via silyl C(sp3)-H functionalization using an oxidative radical strategy.