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Nitrogen-rich phosphazene-based covalent organic framework was synthesized for efficient Pb2+ removal from aqueous solution. The N-CPF exhibits an exceedingly high Pb2+ uptake capacity of 816 mg g−1 and a fast adsorption rate.

A visible-light-induced four-component reaction of vinylcyclopropanes

A new and powerful visible-light-induced difunctionalization of the C-C σ-bond of alkylidenecyclopropanes via a ring-opening process was developed. Importantly, acyl chlorides are used as both acyl and Cl sources. This strategy provides an effective route for the difunctionalization of the C-C bond with an acyl radical and Cl− to construct a new C-C bond and a C-Cl bond in one pot. In addition, it has a wide range of substrates and can tolerate various functional groups.

A method for the preparation of 3-alkylated spiro[4.5]trienones

The efficient transition-metal-free alkylation/cyclization of activated alkenes using Hantzsch ester derivatives as effective alkyl reagents was described.

A novel and facile method for the Ag-catalyzed regioselective 1,6-hydroarylation of para-quinone methides (p-QMs) with anilines and phenols has been established, and a broad range of anilines (primary secondary, tertiary), phenols and p-QMs are well tolerated.

A mild and efficient Zn(II)-catalyzed regioselective 1,6-hydroarylation of para-quinone methides (p-QMs) with electron-rich arenes protocol is reported. A variety of electron-rich arenes and para-quinone methides are well tolerated under mild conditions, delivering a broad range of triarylmethanes in good to excellent yields. The present method also works well for the hydroarylation of p-QMs with other nucleophiles, such as aniline, indole and phenol derivatives, offering the corresponding triarylmethanes with good yields under the standard conditions. The possible mechanism for the formation of C(sp

A simple and efficient method for the regioselective thiolation of p-quinone methides with sodium aryl/alkyl sulfinates has been established using an acid/phosphine-induced radical route under transition-metal-free conditions. A broad range of sodium aryl/alkyl sulfinates and p-quinone methides (p-QMs) are compatible for the reaction, giving the expected products with good to excellent yields. Control experiments were also performed to gain insights into the generation mechanism of thiyl radicals and hydrogen-atom transfer process. This protocol provides a safe and feasible way for the formation of carbon-sulfur bonds.

Heterocyclic compounds, especially oxygen-containing heterocyclic compounds, are crucial moieties in bioactive compounds and drug leads. Substituted chroman-4-ones are a kind of the most significant structural skeletons. Herein, we report a visible-light-induced dual acylation of alkenes for constructing 3-substituted chroman-4-ones, which undergoes a radical tandem cyclization reaction through carbon-carbon bond cleavage of oxime esters by a nitrogen-centered radical strategy. A series of 3-substituted chroman-4-ones were prepared with up to 86% yield.

An efficient, cheap and green protocol for the highly regioselective 1,6-hydroarylation of para-quinone methides (p-QMs) with indoles at the C-3 position has been established by phosphoric acid catalysis in water under transition-metal-free reaction conditions. A wide range of indole derivatives and para-quinone methides (p-QMs) are compatible for the reaction, affording the corresponding 1,6-hydroarylation products with good to excellent yields. The possible mechanism of the reaction has been explored through step-by-step control experiments. The protocol is convenient for practical applications, leading to a safe, green and feasible way for the formation of C-3 diarylmethyl functionalized indole derivatives.

A copper-catalyzed diphenylation of P(O)-OH bonds with cyclic diaryliodonium salts is described. Valuable 2'-iodo substituted biaryl phosphinic/phosphoric acid esters were obtained in good to excellent yields, which could be further transformed to diversified building blocks for the synthesis of bioactive compounds, pharmaceuticals and functional materials.

A simple and efficient method for the silver-catalyzed regioselective phosphorylation of

A convenient and efficient visible-light-induced tandem acylation/cyclization of

A visible-light-mediated tandem cyanoalkylsulfonylation/cyclization of alkynoates with cycloketone oxime compounds for the preparation of 3-cyanoalkylsulfonylcoumarins via SO

As we all know, organic phosphorus compounds have high application values in chemical industries. Compared with traditional compounds with P-X (X = Cl, Br, I) and P-H bonds, phosphorylation reagents containing P(O)-OH bonds are stable, environmentally friendly, and inexpensive. However, in recent years, there have been few studies on the selective functionalization of P(O)-OH bonds for the fabrication of P-C and P-Z bonds. In general, four-coordinated P(O)-OH compounds have reached coordination saturation due to the phosphorus atom center, but cannot evolve the phosphorus coordination center through intra-molecular tautomerization; however, the weak coordination effects between the P=O bond and transition metals can be utilized to activate P(O)-OH bonds. This review highlights the most important recent contributions toward the selective functionalization of P(O)-OH bonds via cyclization/cross coupling/esterification reactions using transition metals or small organic molecules as the catalyst.

A simple and efficient method for the regioselective thiolation of

A novel and convenient visible light-catalyzed tandem radical cyclization of

To establish an extraction method for fenvaleric acid (FA) enantiomers using l-iso-butyl-l-tartaric esters and hydroxypropyl-β-cyclodextrin (HP-β-CD) as chiral selector, the distribution of FA enantiomers was examined in methanol aqueous solution containing HP-β-CD and 1,2-dichloroethane organic solution containing l-iso-butyl-l-tartaric esters. The influences of the concentration of l-iso-butyl-l-tartaric esters and HP-β-CD, organic diluent, pH, extraction temperature and the concentration of methanol aqueous solution on the partition coefficient (k) and separation factor (α) of FA were investigated. The experiment results showed that the complex formed by l-iso-butyl-l-tartaric esters with S-enantiomer is stabler than that with R-enantiomer. With the increase of the concentration of l-iso-butyl-l-tartaric ester, k and α increased; With the increase of the concentration of HP-β-CD, k increased firstly, and then decreased, but α increased all the while, k was the highest when the concentration of HP-β-CD was 4 mmol L−1. 1,2-dichloroethane organic diluent was better than the others. With the increase of pH, k and α decreased; with further increasing concentration of methanol aqueous solution, k and α decreased, k and α were the highest when the concentration of methanol aqueous solution was 10%. The extraction temperature had a great influence on k and α, too.

The effect of acid concentration, time and temperature of modification on the magnesium removal from sepiolite modified by hydrochloric acid, sulfuric acid and nitric acid and on its effectiveness as an active matrix for FCC catalysts, were investigated. The modified sepiolite was characterized by XRD, SEM and N2 adsorption. The results show that the removal of magnesium, specific surface area, and pore specific volume of modified sepiolite are improved with increasing acid concentration, treating time and treating temperature. Hydrochloric acid appears preferable to the modification of sepiolite. The suitable acid modification conditions of sepiolite for FCC catalysts are 80 for 2.5 h with 1 mol L-1 HCl acid, under which the removal of magnesium in sepiolite is 27 %. With the modified sepiolite as an active matrix for FCC catalysts, the specific surface area, pore specific volume and mesopore pore specific volume of the catalysts can increase effectively, the catalysts exhibit excellent heavy-metal resisting performance and better cracking properties as a result of the introduction of magnesium oxide from the modified sepiolite.

To evaluate the effect of ditching for drain on the control of the breed of Oncomelania hupensis snails in beaches of Dongting Lake.From November, 2009 to November, 2012, an 0. hupensis snail infested beach of the Yueyang jail and an O. hupensis snail infested beach of Junshan District were selected as research fields in the eastern Dongting Lake area, and the former, as the intervention field, was performed with the ditching for drain by excavators and the latter, as the control field, was not.Before the project implemented, the average soil moisture contents on the beaches in dry seasons of the two fields were both about 35.56%. After the project implemented, in the intervention field, the average soil moisture content was 26.53% which was significantly lower than that (35.56%) in the control field (F = 6.53, P0.05). The underground water levels in different heights in the intervention field were lower than those in the control field (χ2 = 33.33, P0.05). Before the project implemented, the natural death rates of the snails were 0.98% and 0.89% in the two research fields respectively (P0.05), and after the project implemented (in 2012), no adult and young snails were found in the interventional field, but in the control field, the average densities of living snails and young snails were 29.37 snails/0.1 m2 and 213 ± 108.45 snails/0.1 m2 respectively.The intervention of ditching for drain can decrease the soil moisture contents quickly and change the ecological condition, therefore, can control the breed of O. hupensis snails in the beaches of Dongting Lake.

Based on chemical thermodynamics and mass balance, countercurrently fractional chiral extraction by hollow fiber membrane was investigated. The mathematical modules for the relation of chiral extraction yield and product optical purity with number of transfer units by chiral extraction with hollow fiber membrane were established, and the modules were simulated by visual basic(VB) proceduce. The results show that, the difference in free energy between two diastereomeric complexes formed by R- and S-enantiomer with chiral selector,—Δ(ΔG), is the force of separation of enantiomers. It is necessary to separate enantiomers, where one of the extraction factors is above 1, and the other is below 1. Under certain phase ratio, chiral separation depends on separation factor and number of transfer units. The experimental result is in agreement with the theoretical value.

The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the binary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles were evaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticles is between 130–180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yield and size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that the yields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at the cloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solution and attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coincides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.

Distribution behavior of terbutaline enantiomers was examined in the aqueous and organic solvent of a two-phase system containing L-dibenzoyltartaric acid and lipophilic phase transfer reagent of Na-tetraphenylborate. The influences of pH, organic solvents, concentrations of Na-tetraphenylborate and L-dibenzoyltartaric acid on the partition coefficients and enantioselectivity of terbutaline enantiomers, were investigated. The results show that tetraphenylborate lipophilic anion and terbutaline enantiomers form two lipophilic salt complexes, which facilitates the solubility of the enantiomers in the organic phase. L-dibenzoyltartaric acid forms more stable complexes with enantiomer II than with enantiomer I. Enantioselectivity and partition coefficient increase with the addition of the length of alkyl chain of alcohols. pH and concentrations of lipophilic anion and L-dibenzoyltartaric acid influence them obviously and differently.

Asymmetric esterification of racemic mandelic acid (MA) was conducted in 1,2-dichloroethane using lipase Novozym 435 as catalyst. Different alcohols were screened for esterification to achieve high conversion and enantioselectivity. The results show that ethanol is the best alcohol substrate among tested alcohols, and long-chain alcohols show lower enantioselectivities. The effect of substrate concentrations on esterification with ethanol was studied, and the result indicates an alcohol inhibition. To examine the mechanism of the alcohol chain length effect, the ping-pong bi-bi mechanism with competitive alcohol inhibition was applied to build a model. By comparing the kinetic parameters of methanol, ethanol, butanol, heptanol, and octanol, it was found that both the Michaelis constant and the inhibition constant of alcohol increase with the increase in alcohol chain length, indicating that the balance between nucleophilicity and the inhibition effect is the possible reason for the highest conversion and enantioselectivity as shown by ethanol.

In the past decade, ionic liquids have received great attention owing to their potential as green solvent alternatives to conventional organic solvents. In this work, hydrophobic achiral ionic liquids (1-butyl-3-methylimidazolium-hexafluorophosphate([bmim][PF6]), 1-octyl-3methylimidazolium tetrafluoroborate([omim][BF4 ])) were used as solvents in chiral liquid–liquid extraction separation of mandelic acid (MA) enantiomers with β-cyclodextrin (β-CD) derivatives as hydrophilic chiral selectors preferentially forming complexes with (R)-enantiomers. Factors affecting the separation efficiency were optimised, namely the type of the extraction solvents and β-CD derivatives, concentrations of the β-CD derivatives and MA enantiomers, pH, and temperature. Excellent enantioseparation of MA enantiomers was achieved in the ionic liquid aqueous two-phase extraction systems under the optimal conditions of pH 2.5 and temperature of 5 ◦ Cw ith the maximum enantioselectivity (α) of 1.74. The experimental results demonstrated that the ionic liquid aqueous two-phase extraction systems with a β-CD derivative as the chiral selector have a strong chiral recognition ability, which might extend the application of ionic liquids in chiral separation. c 2013 Institute of Chemistry, Slovak Academy of Sciences

Two new chiral stationary phases, 2,3-di-O-acetyl-6-O-trimethylsilyl-β-cyclodextrin (DATBCD) and 2, 6-di-O-trimethylsilyl-3-O-acetyl-β-cyclodextrin (DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β-cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β-cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer (k 1) and separation factor(α)of α-phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.

Asymmetric esterification of racemic mandelic acid (MA) was conducted in 1,2-dichloroethane using lipase Novozym 435 as catalyst. Different alcohols were screened for esterification to achieve high conversion and enantioselectivity. The results show that ethanol is the best alcohol substrate among tested alcohols, and long-chain alcohols show lower enantioselectivities. The effect of substrate concentrations on esterification with ethanol was studied, and the result indicates an alcohol inhibition. To examine the mechanism of the alcohol chain length effect, the ping-pong bi-bi mechanism with competitive alcohol inhibition was applied to build a model. By comparing the kinetic parameters of methanol, ethanol, butanol, heptanol, and octanol, it was found that both the Michaelis constant and the inhibition constant of alcohol increase with the increase in alcohol chain length, indicating that the balance between nucleophilicity and the inhibition effect is the possible reason for the highest conversion and enantioselectivity as shown by ethanol.

The inclusion complex formation of zopiclone with beta-yclodextrin was studied by using phase solubility method, and the formation constant for zopiclone-beta-cyclodextrin was determined. The solubility of zopiclone and the formation constant were enhanced with the increase in beta-cyclodextrin concentration and pH. The effect of temperature on the reaction was studied through thermodynamics, and the changes in entropy deltaS, enthalpy deltaH and free energy deltaG of the reaction were all negative, suggesting that the inclusion complexation is exothermic and can spontaneously occur by the balance of enthalpy driving and entropy opposing. The inclusion complex of zopiclone and beta-cyclodextrin was prepared by a method of solidgrinding, Stable inclusion complex in solid state was characterized by IR spectra and DTA. Results showed that zopiclone-delta-cyclodextrin conclusion complex could be formed, and beta-cyclodextrin is a desirable solubilizer for zopiclone.

The effect of acid concentration, time and temperature of modification on the magnesium removal from sepiolite modified by hydrochloric acid, sulfuric acid and nitric acid and on its effectiveness as an active matrix for FCC catalysts, were investigated. The modified sepiolite was characterized by XRD, SEM and N2 adsorption. The results show that the removal of magnesium, specific surface area, and pore specific volume of modified sepiolite are improved with increasing acid concentration, treating time and treating temperature. Hydrochloric acid appears preferable to the modification of sepiolite. The suitable acid modification conditions of sepiolite for FCC catalysts are 80 for 2.5 h with 1 mol L-1 HCl acid, under which the removal of magnesium in sepiolite is 27 %. With the modified sepiolite as an active matrix for FCC catalysts, the specific surface area, pore specific volume and mesopore pore specific volume of the catalysts can increase effectively, the catalysts exhibit excellent heavy-metal resisting performance and better cracking properties as a result of the introduction of magnesium oxide from the modified sepiolite., U radu je istraživano djelovanje koncentracije kiseline, vremena i temperature modificiranja na uklanjanje magnezija iz sepiolita, kao i na djelotvornost aktivne matrice FCC-katalizatora pripravljenog korištenjem solne, sumporne i dušične kiseline. Modificirani sepiolit je bio karakteriziran rendgenskom difrakcijom praškastih uzoraka, pretražnom elektronskom mikroskopijom te adsorpcijom N2. Dobiveni rezultati ukazuju na povećanje uklanjanja magnezija, specifične površine i volumena pora modificiranog sepiolita s povišenjem koncentracije kiseline, vremena i temperature reakcije. Uvjeti pogodni za kiselinsko modificiranje sepiolita jesu 80 °C tijekom 2,5 sata te c(HCl) = 1,0 mol dm-3, pri čemu se postiže 27-postotno uklanjanje magnezija. Korištenjem modificiranog sepiolita kao aktivne matrice FCC katalizatora, povećana je specifična površina, volumen pora te volumen mezopora katalizatora. Također, tako pripravljeni katalizatori iskazuju odličnu otpornost na kontaminaciju teškim kovinama te bolja krekirajuća svojstva kao posljedicu uklanjanja magnezijeva oksida iz sepiolita.

To establish a resolution method for alpha-cyclohexyl mandelic acid enantiomers by enantioselective extraction and to observe the effects of all kinds of tartaric esters, pH, the concentration of D-tartaric esters and beta-cyclodextrin on the enantioselectivity.Resolution of alpha-cyclohexyl mandelic acid enantiomers by enantioselective extraction with tartaric esters and beta-cyclodextrin has been studied.The distribution behavior of alpha-cyclohexyl mandelic acid enantiomers in the separation system was studied. The effects of all kinds of tartaric esters, pH, the concentration of D-tartaric esters and beta-cyclodextrin on the enantioselectivity has been examined in the two-phase.Results showed that the complex formed by D-iso-butyl-D-tartaric ester with R enantiomer is stabler than that with S enantiomer. With the increase of pH, the partition coefficient and separation factor decreased. The concentration of beta-cyclodextrin and D-tartaric ester had visible effect on the enantioselectivity.

The performance of adsorption of tea polyphenol and caffine with polyamide resin was investigated. The results obtained by spectrophotometry and HPLC show that the ability of adsorption of tea polyphenol with polyamide is stronger than that of caffine, in which hydrogen bond plays a very important role. The adsorption amount of caffine is 2.65 mg.g-1 with 7.5% adsorption ratio when 100 mL of 0.71 g.L-1 caffine is adsorbed on polyamide resine, but the adsorption amount of tea polyphenol is up to 148.13 mg.g-1 with 85% adsorption ratio when 700 mL of 1.98 g.L-1 tea polyphenol is adsorbed on polyamide resine. The dilution ratios of caffine and tea polyphenol are 74% and 90%, respectively, when they are diluted by 85% alcohol. The static adsorptions of caffine and tea polyphenol on polyamide resine reach equilibrium quickly in 80 min, and the plots of adsorption kinetics are nearly linear. Tea polyphenol and caffine are successfully separated on polyamide resine, and the obtained product contains more than 96% of tea polyphenol and 80% of EGCC with caffine less than 2.8%.

Volatile oil was extracted from Cuminum cyminum L. by using steam distillation. More than sixty peaks were separated and 49 compounds were identified by gas chromatography-mass spectrometry (GC-MS). The relative amounts of the components were determined by area normalization method. Among the 49 compounds identified, there were 16 hydrocarbons and 32 oxygenated compounds. The main compnents were cuminal and safranal (accounting for 32.26% and 24.46% respectively in the components identified). The other nine compounds with contents all over 1%, were monterpenes, sesquiterpenes, aromatic aldehydes and aromatic oxides etc. The other components with relatively small amounts were chiefly terpenes, terpenols, terpenals, terpenones, terpene esters and aromatic compounds. It is good to separate polar and apolar components in the volatile oil from Cuminum cyminum L. on the GC capillary column of moderate polarity.