Synthesis of highly reactive polyisobutylenes with BF<Subscript>3</Subscript>·cyclohexanol initiating system

The selective cationic polymerization of isobutylene（IB）initiated by a BF₃·cyclohexanol（CL）complex was carried out from the mixed C₄ fraction feed containing the 4C saturated and unsaturated hydrocarbons at-20℃.The effects of CL concentration,BF₃ concentration,solvent for preparing BF₃·CL complex and polymerization time on the chemical structure of end groups,number-average molecular weight（M_n）and molecular weight distribution（MWD,M_w/M_n）of the resulting polymers were investigated.The experimental results indicate that the BF₃·CL complex initiating system exhibited an extremely high selectivity toward the cationic polymerization of IB in the mixed C₄ fraction feed and low molecular weight（M_n=900-3600）polyisobutylenes（PIBs）with large proportion of exo-double bond end groups were obtained.The exo-double bond content in PIB chain ends increased by increasing CL concentration or by decreasing solvent polarity in initiating system,BF₃ concentration and polymerization time.The M_n and MWD of the resulting PIBs were dependent on the concentrations of CL and BF₃.Highly reactive PIBs with around 90 mol%of exo-double bonds were successfully synthesized by the selective polymerization of IB from the mixed C₄ fraction feed,providing a potentially practical process for its simplicity and low costs.     

In-situ preparation and the characterization of Pt/SnO2

To enhance the cycling stability of Pt-based catalysts,the anti-corrosion property of support and the attachment of Pt with support should both get improved.For this purpose,a novel method is presented for in situ preparing Pt/SnO₂.The structure of Pt/ SnO₂ is characterized by X-ray diffraction（XRD） and transmission electron microscopy（TEM）,confirming the homogeneous deposition of Pt on SnO₂.The high resolution TEM（HRTEM） shows the large interfaces between Pt and SnO₂.The TEM photos recorded after accelerated durability tests with Pt/SnO₂ show that the agglomeration and size increment of Pt particles is not severe, indicating the good stability of Pt/SnO₂.The electrochemical active surface area（EAS） of Pt/SnO₂ keeps increasing during the 1000 cycles of cyclic voltammetric（CV） sweeping in H₂SO₄,while the EAS decayed by 35%when mixing Pt/SnO₂ with carbon nanotubes（CNTs）,indicating the superior anti-corrosion property of SnO₂ in contrast to CNTs.     

Methane conversion under cold plasma over Pd-containing ionic liquids immobilized on γ-Al2O3

Pd-containing ionic liquid（IL） 1-hexyl-3-methylimidazolium tetrafluoroborate（C₆MIMBF₄） immobilized on 7-Al₂O₃（Pd-IL/γ-Al₂O₃） was prepared and characterized by Fourier transform infrared spectroscopy（FTIR）,scanning electron microscopy（SEM） and Brunauer-Emmett-Teller （BET） analysis.The influences of C₆MIMBF₄ loading and Pd on methane conversion to C₂ hydrocarbons under cold plasma were investigated.FTIR and SEM analyses indicated that C₆MIMBF₄ had been successfully immobilized on 7-Al₂O₃ and the C₆MIMBF₄ showed excellent stability under cold plasma.The results of BET and methane conversion showed that with the increase in immobilization amount of C₆MIMBF₄ ontoγ-Al₂O₃,the specific surface area and pore volume of IL/γ-Al₂O₃ decreased,while the selectivity and yield of C₂ hydrocarbons increased.The selectivity of C₂ hydrocarbons was 94.6%when the loading of C₆MIMBF₄ was 40%,and the percentage of C₂H₄ in C₂ hydrocarbons was as high as 64%when using Pd-IL/γ-Al₂O₃ as a catalyst with no conventional thermal reduction treatment. Optical emission spectra（OES） from the cold plasma reactor during methane conversion were also studied.The results indicated that the intensity of the C₂,CH,H,and C active species from methane and hydrogen decomposition increased when IL/γ-Al₂O₃ or Pd-IL/γ-Al₂O₃ was introduced into the plasma system.Based on the analyses of the gas product and OES spectra,it can be concluded that the surface catalyzed reactions between plasma and ionic liquid were very important for the reduction of Pd²⁺ and the formation of C₂H₄.     

The carbonylation of phenyl bromide and its derivatives under visible light irradiation

The carbonylation of phenyl bromide catalyzed by Co（OAc）₂ has been investigated with PhCOPh as a sensitizer under visible light in the presence of basic additive.With strong base CH₃ONa,PhCOOCH₃ is produced in 70%yield with 100%selectivity,the similar results are also obtained with a stronger base（CH₃）₃CONa.However,with another strong base NaOH,the yield of the ester is only 40%.On the other hand,with weak base NaOAc or（n-C₄H₉）₃N,phenyl bromide cannot be carbonylated.The results of carbonylation of the six substituted phenyl bromides suggest that the activities of o,m,p-BrC₆H₄CH₃ are similar to phenyl bromide, while the activities of o,m,p-BrC₆H₄Cl are higher with the high yields（≥93%） of the corresponding chloro-esters.In addition,the relative position of bromine and chlorine or methyl on phenyl ring has little effect on the activity of the carbonylation.     

Hydrated nickel (II) halides mediated ring opening reaction with N-tosylaziridines

An efficient and water tolerant method for the synthesis ofβ-haloamines is described utilizing hydrated nickel（Ⅱ） halides （NiX₂ⅩnH₂O X = Cl,Br,I） and aziridines as starting materials.N-Tosylaziridines reacted with NiCl₂·6H₂O or NiI₂·6H₂O givingβ-chloro -orβ-iodoamines in high yields（73-99%） within a short time,but 10 mol%of n-Bu₄NBr should be added in the reactions of N-tosylaziridines with NiBr₂·3H₂O in order to obtain the high yields of correspondingβ-bromoamines.Solvent played an important role in the reactions.The proper solvent for the reaction of NiCl₂·6H₂O was DMF,while NiBr₂·3H₂O or NiI₂·6H₂O proceeded well in 1,4-dioxane.     

Influence of ZnSt2 on structure of acrylate-based ionomers with different lanthanide (La(III)) ion and acid contents

A series of acrylate processing aid（ACR）-based ionomers with different lanthanide（La（Ⅲ）） ion and acid contents were synthesized,and the interaction between ionomer and zinc stearate（ZnSt₂） was investigated immediately after thermally annealing the ionomer/ZnSt₂（3/1 in weight） mixtures at 180℃.The results revealed that the ion groups in ionomer have a strong interaction with ZnSt₂.The annealed mixtures contained hot alcohol extractable and unextractable ZnSt₂.The melting of ZnSt₂ and the thermal behavior of the ionomer in the annealed mixtures were seriously influenced by the contents of La（Ⅲ） and acid in the ionomers.The ionomer containing 0.25 mmol/g acid and 0.37 mmol/g La（Ⅲ） has a detectable cluster phase.Annealing its ZnSt₂ mixture could break down the cluster phase and lower glass transition temperature of the ionomer matrix.However,washing away the extractable ZnSt₂ led to the reappearance of the cluster transition temperature and return of the glass transition temperature of matrix to the original position.     

A novel norsesquiterpene alkaloid from the mushroom-forming fungus Flammulina velutipes

A new norsesquiterpe alkaloid（1） was isolated from the solid culture of mushroom-forming fungus Flammulina velutipes fermented on rice.The structure of 1 was elucidated by spectroscopic methods.The absolute configuration of C-1 in 1 was determined using the circular dichroism data of their [Rh₂（OCOCF₃）₄]complex.     

Bi and S Co-doping g-C3N4 to Enhance Internal Electric Field for Robust Photocatalytic Degradation and H2 Production

By adjusting the type and proportion of doping elements in the g-C₃N₄-based photocatalyst, the internal electric field（IEF） strength of the semiconductor can be regulated. This can effectively enhance the driving force of charge separation in the photocatalytic process. It is found that the introduction of appropriate concentration of Bi and S into the skeleton structure of g-C₃N₄ can achieve efficient degradation of tetracycline（TC） and other pollutan...     

Tetrabutylammonium salts of tritransition-metal-substituted A-α-tungstogermanate:Halogen-free and single-component catalysts for the coupling reaction of carbon dioxide and epichlorohydrin

The green synthesis of chloropropylene carbonate via the coupling reaction of carbon dioxide and epichlorohydrin had been achieved using halogen-free and single-component catalysts tetrabutylammonium salts of tritransition-metal-substituted A-α-tungstogermanate [（n-C₄H₉）₄N]₃H₇GeW₉M₃（H₂O）₃O₃₇（M = Cu^Ⅱ,Ni^Ⅱ,Co^Ⅱand Mn^Ⅱ） without any solvent.The catalytic activity was significantly depended on the transition metal introduced in polyoxometalates.[（n-C₄H₉）₄N]₃H₇GeW₉Mn₃（H₂O）₃O₃₇ exhibited the highest catalytic activity with 94.9%conversion for epichlorohydrin and 98%selectivity for chloropropylene carbonate in 3 h.Plausible mechanism was proposed based on the results.     

Melamine-(H_2SO_4)_3 and PVP-(H_2SO_4)_n as solid acids:Synthesis and application in the first mono-and di-nitration of bisphenol A and other phenols

Melamine and poly vinylpyrrolidone（PVP） reacted with neat sulfuric acid readily to form two new organic solid acids namely melamine-（H₂SO₄）₃ and PVP-（H₂SO₄）_n.These solid acids were used for the first nitration of bisphenol A as well as other phenols in the presence of NH₄NO₃.Mono- and di-nitro bisphenol A have been characterized with IR and ¹H NMR techniques.     

Explicating the Role of Metal Centers in Porphyrin-Based MOFs of PCN-222（M） for Electrochemical Reduction of CO2

The porphyrin-based MOFs formed by combining Zr₆ clusters and porphyrin carboxylic acids with clear M-N₄ active centers show unique advantages in electrocatalytic reduction of CO₂（CO₂RR）. However, its conductivity is still the bottleneck that limits its catalytic activity due to the electrical insulation of the Zr cluster. Therefore, the porphyrin-based MOFs of PCN-222（M）(M = Mn, Co, Ni, Zn) with explicit M-N₄ coordination were combined with...     

Regeneration of C4H10 dry reforming catalyst by nonthermal plasma

Carbon deposition via coke formation is one of the critical problems causing catalyst deactivation during the reforming of hydrocarbons.An effort was made to regenerate the catalyst（Ni/7-alumina） by oxidation methods.Two approaches were carried out for the regeneration of the deactivated catalyst.The first one involves the plasma treatment of the deactivated catalyst in the presence of dry air over a temperature range of 300～500℃,while the second one only the thermal treatment in the same temperature range.The performance of the regenerated catalyst was evaluated in terms of C₄H₁₀ and CO₂ conversions and the physicochemical characteristics were examined using a surface area analyzer,an elemental analyzer,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.It was observed that the carbon deposit （coke） on the catalyst was about 9.89 wt%after reforming C₄H₁₀ for 5 h at 540℃.The simple thermal treatment at 400℃reduced carbon content to 6.59 wt%whereas it was decreased to 3.25 wt%by the plasma and heat combination.The specific surface area was fully restored to the original state by the plasma-assisted regeneration at 500℃.As far as the catalytic activity is concerned,the fresh and regenerated catalysts exhibited similar C₄H₁₀ and CO₂ conversion efficiencies.     

Synthesis of pillar[7]arene

The first synthesis of pillar[7]arene is reported with two methods.Method A:the FeCl₃-catalyzed condensation reaction of 1,4- dimethoxybenzene（1） with paraformaldehyde in CHCl₃ gave dimethoxypillar[7]arene（3）.Method B:the p-toluenesulfonic acid catalyzed condensation reaction of 2,5-bis（benzyloxymethyl）-1,4-dimethoxybenzene（2） in CH₂Cl₂ gave compound 3.Demethylation of 3 with BBr₃ gave pillar[7]arene（4）.The pillar[7]arene might be a perspective macrocyclic host in host-guest chemistry.     

Single- and few-layer 2H-SnS2 and 4H-SnS2 nanosheets for high-performance photodetection

The properties of two-dimensional（2D） materials are highly dependent on their phase and thickness. Various phases exist in tin disulfide（SnS₂）, resulting in promising electronic and optical properties. Hence,accurately identifying the phase and thickness of SnS₂ nanosheets is prior to their optoelectronic applications. Herein, layered 2H-SnS₂ and 4H-SnS₂ crystals were grown by chemical vapor transportation and the crystalline phase of SnS₂ w...     

Spectrophotometric study of the charge transfer complexes of 4′-nitrobenzo-15-crown-5 and benzo-15-crown-5 with iodine in nonaqueous solvents

The formation of charge transfer complex between iodine with 4’-nitrobenzo-15-crown-5（NB15C5） and benzo-15-crown-5 （B15C5） is investigated spectrophotometrically in chloroform and dichloromethane（DCM） solutions at 25℃.The pseudo-first-order rate constants for the transformation process were evaluated from the absorbance-time data and found to vary in the order of DCM > CHCl₃.The values of the formation constant,K_f,for each complex are evaluated from Benesi-Hilebrand equation. Stability of the resulting complex in two solvents was also found to vary in the order of DCM > CHCl₃.     

Promoting effect of chloride ions on selective oxidation of methanol to methyl formate over zirconia-supported ruthenium oxide catalysts

The effect of chloride ions on a monoclinic ZrO₂-supported RuO_x（RuO_x/m-ZrO₂） catalyst with a Ru surface density of 0.3 Ru/nm² was studied in the selective oxidation of methanol to methyl formate（MF） at a low temperature of 373 K.The m-ZrO₂ support was Cl-free,and Cl^- ions were introduced into the RuO_x/m-ZrO₂ catalyst by impregnation with zirconium oxychloride or ammonium chloride and subsequent thermal treatment in air at 673 K.The structures of these catalysts were characterized by X-ray diffraction,Raman and X-ray photoelectron spectroscopies.Their reducibility was probed by temperature-programmed reduction in H₂.The RuO_x domains were present as highly dispersed RuO₄^2- structure on m-ZrO₂ with similar reducibility for the RuO_x/m-ZrO₂ samples irrespective of modification with or without Cl^- ions.Introduction of appropriate amounts of zirconium oxychloride into RuO_x/m-ZrO₂ led to a remarkable increase in the methanol oxidation rate and MF selectivity,whereas introduction of ammonium chloride or zirconyl nitrate significantly inhibited the catalytic performance of RuO_x/m-ZrO₂.The promoting effect of Cl^- ions derived from zirconium oxychloride can be tentatively attributed to their roles in facilitating the adsorption of methanol and desorption of MF product or its intermediates.This finding provides novel insights into the promoting effect of Cl ions on oxides-based catalysts for selective oxidation reactions.     

Crystallization and morphology of star-shaped polyethylenoxyde-b-polycaprolactone under high pressure carbon dioxide

Atomic force microscopy（AFM）,wide-angle X-ray diffraction（WAXD） and differential scanning calorimetry are used to analyze the crystallization morphology and melting behavior of 4-arm PEO-b-PCL under high-pressure CO₂.It is demonstrated that CO₂ has certain effect on the melting and crystallization behavior of the samples.After crystallization under CO₂ at 4 MPa,spherulites with concentric ring-banded structure are formed which are composed of crystals with periodic thickness variation,and the band distance decreases with increasing treatment pressure.Due to the plasticization effect of CO₂,depression of the melting temperature is observed with sorption of CO₂ in polymers.     

Photocatalytic activity of different morphology BiPO4 supported on zeolite

Highly efficient sheet-like Bi PO₄/zeolite and ball-flower-like Bi PO₄/zeolite had been successfully synthesized by a standard hydrothermal method.The addition of assistant reagent in the hydrothermal system is promising to obtain special morphology.The assistant reagent（EDTA） acts as a growth modifier of crystal.The possible formation mechanisms of sheet-like Bi PO₄/zeolite and ball-flower-like Bi PO₄/zeolite were schematically discussed.A detailed study of sheet-like Bi PO₄/zeolite and ball-flower-like Bi PO₄/zeolite impacted on the photodecoloration methylene blue（MB） solution showed that the composite had a highly reusable and stable property for long-run photocatalytic application.     

Magnetic graphene nanocomposite as an efficient catalyst for hydrogenation of nitroarenes

Graphene-Fe₃O₄ nanocomposite（G-Fe₃O₄） was synthesized by a chemical co-precipitation method which was used as an efficient catalyst for the reduction of nitroarenes with hydrazine hydrate.The method has been applied to a broad range of compounds with different properties and the yields were in the range of 75%-92%.The G-Fe₃O₄ catalyst can be readily recovered and reused 5 times without significant loss of the catalytic activity.     

In-situ hydrothermal synthesized γ-Al2O3/O-g-C3N4 heterojunctions with enhanced visible-light photocatalytic activity in water splitting for hydrogen

In this work,γ-Al₂O₃ and hydrogen peroxide treated g-C₃N₄（O-g-C₃N₄） were combined through a novel in-situ hydrothermal method to form heterojunction structured photocatalysts.These photocatalysts were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,Fourier transform infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy（PL）.FT-IR results indicate that oxygen functional groups can be grafted on the surface of O-g-C₃N₄ by hydrogen peroxide treatment.The visible light photocatalytic hydrogen evolution rate was investigated in 10 vol% TEOA aqueous solution.The optimal Al₂O₃ mass content is set to be 20 wt% and the corresponding hydrogen evolution rate is 1288 μmol/h/g which is approximately 6,3 folds that of pristine g-C₃N₄ and O-g-C₃N₄ respectively and 1.6 folds that of mechanical mixed composite with the same Al₂O₃ mass content.The photocurrent density–time curves were carried out under visible light illumination for four on–off cycles.The electrochemical impedance spectroscopy（EIS） measurements verified the enhanced separation efficiency of electron–hole pairs.This work raised a new method to form the heterojunction structured photocatalysts and achieved a remarkable improvement of the photocatalytic activity in water splitting for hydrogen under visible light irradiation.