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2011 Volume 22 Issue 2
2011, 22(2): 127-130
doi: 10.1016/j.cclet.2010.09.030
Abstract:
An efficient solvent free method for the synthesis of various 3,4-dihydropyrimidin-2(1H)-one/thiones in excellent yields using sulfonatedβ-cyclodextrine as recyclable catalyst is described. Sulfonatedβ-cyclodextrine was found to be efficient, recyclable heterogeneous catalyst and showed rate enhancements, high yields and short reaction times in this transformation.
An efficient solvent free method for the synthesis of various 3,4-dihydropyrimidin-2(1H)-one/thiones in excellent yields using sulfonatedβ-cyclodextrine as recyclable catalyst is described. Sulfonatedβ-cyclodextrine was found to be efficient, recyclable heterogeneous catalyst and showed rate enhancements, high yields and short reaction times in this transformation.
2011, 22(2): 131-134
doi: 10.1016/j.cclet.2010.10.012
Abstract:
Reaction of isatoic anhydride with aniline derivatives gave 2-amino-N-(aryl) benzamides. The latters reacted with phenyli-sothiocyanate in the presence of heteropolyacids in various solvents which afforded 3-(aryl)-2-thioxo-2,3-dihydroquinazolin-4(1H)-one derivatives. The effects of various heteropolyacids including Preyssler and Keggin on the yields and reaction times have been investigated.
Reaction of isatoic anhydride with aniline derivatives gave 2-amino-N-(aryl) benzamides. The latters reacted with phenyli-sothiocyanate in the presence of heteropolyacids in various solvents which afforded 3-(aryl)-2-thioxo-2,3-dihydroquinazolin-4(1H)-one derivatives. The effects of various heteropolyacids including Preyssler and Keggin on the yields and reaction times have been investigated.
2011, 22(2): 135-138
doi: 10.1016/j.cclet.2010.09.027
Abstract:
An attempt has been made to prepare terephthalic acid (TPA) by solvent-free oxidation of p-xylene (PX) with air over tetra(p-chlorophenylporphinato)manganese chloride (T(pCl)PPMnCl) and cobalt acetate. The co-catalysis between T(pCl)PPMnCl and Co(OAc)2 has been discovered under solvent-free conditions. TPA yield could be increased significantly when T(pCl)PPMnCl and Co(OAc)2 were used together. The addition of T(pCl)PPMnCl into the reaction mixture over Co(OAc)2 significantly accelerated the rate-determining step of the oxidation process of PX to TPA. The effect of temperature on reaction was also investigated.
An attempt has been made to prepare terephthalic acid (TPA) by solvent-free oxidation of p-xylene (PX) with air over tetra(p-chlorophenylporphinato)manganese chloride (T(pCl)PPMnCl) and cobalt acetate. The co-catalysis between T(pCl)PPMnCl and Co(OAc)2 has been discovered under solvent-free conditions. TPA yield could be increased significantly when T(pCl)PPMnCl and Co(OAc)2 were used together. The addition of T(pCl)PPMnCl into the reaction mixture over Co(OAc)2 significantly accelerated the rate-determining step of the oxidation process of PX to TPA. The effect of temperature on reaction was also investigated.
2011, 22(2): 139-142
doi: 10.1016/j.cclet.2010.10.001
Abstract:
Novel acetylene terminated silazane compounds, with three types of substituent, were synthesized by the aminolysis of dichlorosilane with 3-aminophenylacetylene (3-APA). Thermal property of the compounds is studied by thermogravimetry analysis (TGA). It shows that the acetylene terminated silazane has high temperature resistance. The char yield at 1000℃ is 77.6, 81.9 and 68.7 wt% for methyl, vinyl, and phenyl substituted silazane, respectively. The pyrolysis kinetics of the silazane is investigated by non-isothermal thermogravimetric measurement. The pyrolysis undergoes three stages, which is resolved by PEAKFIT. The kinetic parameters are calculated by the Kissinger method. The role of functionalities on the thermal resistance is discussed. The vinyl-silazane exhibits higher thermal stability because of higher cross-linking density.
Novel acetylene terminated silazane compounds, with three types of substituent, were synthesized by the aminolysis of dichlorosilane with 3-aminophenylacetylene (3-APA). Thermal property of the compounds is studied by thermogravimetry analysis (TGA). It shows that the acetylene terminated silazane has high temperature resistance. The char yield at 1000℃ is 77.6, 81.9 and 68.7 wt% for methyl, vinyl, and phenyl substituted silazane, respectively. The pyrolysis kinetics of the silazane is investigated by non-isothermal thermogravimetric measurement. The pyrolysis undergoes three stages, which is resolved by PEAKFIT. The kinetic parameters are calculated by the Kissinger method. The role of functionalities on the thermal resistance is discussed. The vinyl-silazane exhibits higher thermal stability because of higher cross-linking density.
2011, 22(2): 143-146
doi: 10.1016/j.cclet.2010.09.020
Abstract:
This paper describes the combustion synthesis of α-Fe2O3 nanopowder at much lower temperature and its catalytic activity for the one-pot preparation of 3,4-dihydropyrano[c]chromenes. The combustion derived α-Fe2O3 nanopowder was characterized by powder X-ray diffraction (PXRD), Braunauer, Emmett and Teller (BET) surface area, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Highly efficient, three-component condensation of aromatic aldehyde, malanonitrile and 4-hydroxycoumarin catalyzed by α-Fe2O3 nanoparticles at room temperature is described. The method offers an excellent alternative to the synthesis of 3,4-dihydropyrano[c]chromenes. The reactions are rapid, clean, and the products with good yield and high purity.
This paper describes the combustion synthesis of α-Fe2O3 nanopowder at much lower temperature and its catalytic activity for the one-pot preparation of 3,4-dihydropyrano[c]chromenes. The combustion derived α-Fe2O3 nanopowder was characterized by powder X-ray diffraction (PXRD), Braunauer, Emmett and Teller (BET) surface area, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Highly efficient, three-component condensation of aromatic aldehyde, malanonitrile and 4-hydroxycoumarin catalyzed by α-Fe2O3 nanoparticles at room temperature is described. The method offers an excellent alternative to the synthesis of 3,4-dihydropyrano[c]chromenes. The reactions are rapid, clean, and the products with good yield and high purity.
2011, 22(2): 147-150
doi: 10.1016/j.cclet.2010.09.021
Abstract:
Nucleophilic aromatic substitution of hydrogen in non-activated aromatic ring, a very rare phenomenon in organic chemistry, is found in ionic liquids containing Cl-as anion under mild reaction conditions. The reaction may be carried out by the addition of the halogen-bonding adduct (Br2Cl-) as nucleophile to aromatic ring carbon atom, leading to the formation of the nucleophilic substitution product.
Nucleophilic aromatic substitution of hydrogen in non-activated aromatic ring, a very rare phenomenon in organic chemistry, is found in ionic liquids containing Cl-as anion under mild reaction conditions. The reaction may be carried out by the addition of the halogen-bonding adduct (Br2Cl-) as nucleophile to aromatic ring carbon atom, leading to the formation of the nucleophilic substitution product.
2011, 22(2): 151-154
doi: 10.1016/j.cclet.2010.09.023
Abstract:
4-Arylmethylidene-4,5-dihydro-3-phenylisoxazol-5-ones were synthesized by the convenient three-component reaction of ethyl benzoylacetate, hydroxylamine and aromatic aldehydes in the presence of pyridine. The target compounds were also obtained by the reaction between 3-phenylisoxazol-5-one and aromatic aldehydes at 105℃ under solvent free condition. Yields of products depended considerably on the aldehyde used.
4-Arylmethylidene-4,5-dihydro-3-phenylisoxazol-5-ones were synthesized by the convenient three-component reaction of ethyl benzoylacetate, hydroxylamine and aromatic aldehydes in the presence of pyridine. The target compounds were also obtained by the reaction between 3-phenylisoxazol-5-one and aromatic aldehydes at 105℃ under solvent free condition. Yields of products depended considerably on the aldehyde used.
2011, 22(2): 155-158
doi: 10.1016/j.cclet.2010.09.025
Abstract:
Chiral N,N'-dialkylated cyclohexanediamine derived ligands have been synthesized and used in the asymmetric hydrogenation of aryl ketones. Optically active alcohols with up to 90% enantiomeric excess were obtained in high yields.
Chiral N,N'-dialkylated cyclohexanediamine derived ligands have been synthesized and used in the asymmetric hydrogenation of aryl ketones. Optically active alcohols with up to 90% enantiomeric excess were obtained in high yields.
2011, 22(2): 159-162
doi: 10.1016/j.cclet.2010.10.002
Abstract:
A novel approach to the synthesis of 4-phenylethynylphthalic anhydride has been described. The target compound was synthesized by Pd/Cu catalyzed Sonogashira coupling reaction between phenylacetylene and 4-bromophthalic acid which was for the first time employed as start material, followed by dehydration of 4-phenylethynylphthalic acid. Compared with traditional synthetic routes, this method provides several advantages such as readily available raw materials, convenient manipulation and high yield. The products were characterized by IR, 1H NMR, 13C NMR, MS and elemental analysis, respectively.
A novel approach to the synthesis of 4-phenylethynylphthalic anhydride has been described. The target compound was synthesized by Pd/Cu catalyzed Sonogashira coupling reaction between phenylacetylene and 4-bromophthalic acid which was for the first time employed as start material, followed by dehydration of 4-phenylethynylphthalic acid. Compared with traditional synthetic routes, this method provides several advantages such as readily available raw materials, convenient manipulation and high yield. The products were characterized by IR, 1H NMR, 13C NMR, MS and elemental analysis, respectively.
2011, 22(2): 163-166
doi: 10.1016/j.cclet.2010.09.026
Abstract:
ZrOCl2·8H2O catalyzed environmentally benign synthesis of isobenzofuran-1(3H)-ones are described. ZrOCl2·8H2O appeared to be an excellent catalyst for the condensation and reactions. Reaction of phthalaldehydic acid (2-carboxybenzaldehyde) with methylaryl and cyclic ketones was initiated by condensation and occurred in one step providing excellent yields (90-98%). (c) 2010 Published by Elsevier B.V. on behalf of Chinese Chemical Society.
ZrOCl2·8H2O catalyzed environmentally benign synthesis of isobenzofuran-1(3H)-ones are described. ZrOCl2·8H2O appeared to be an excellent catalyst for the condensation and reactions. Reaction of phthalaldehydic acid (2-carboxybenzaldehyde) with methylaryl and cyclic ketones was initiated by condensation and occurred in one step providing excellent yields (90-98%). (c) 2010 Published by Elsevier B.V. on behalf of Chinese Chemical Society.
2011, 22(2): 167-170
doi: 10.1016/j.cclet.2010.10.003
Abstract:
The thermal Claisen rearrangement of O-allyl substituted isotetronic acids 1 was successfully carried out within a glass microreactor operated with temperature at 150℃ and a flow rate of 1 mL/h. The strategy provides an efficient alternative way toβ-allyl substituted isotetronic acid derivatives 2 in high yields with much accelerated reaction speed.
The thermal Claisen rearrangement of O-allyl substituted isotetronic acids 1 was successfully carried out within a glass microreactor operated with temperature at 150℃ and a flow rate of 1 mL/h. The strategy provides an efficient alternative way toβ-allyl substituted isotetronic acid derivatives 2 in high yields with much accelerated reaction speed.
2011, 22(2): 171-174
doi: 10.1016/j.cclet.2010.09.022
Abstract:
A new friedelane-type triterpene named 3β-hydroxyfriedelane-7,12,22-trione, as well as nine known compounds were isolated from the whole stems of Drypetes laciniata Hutch. (Euphorbiaceae). Their structures were established on the basis of spectroscopic methods. The new triterpene derivative and a known saponin were tested for antimicrobial and antifungal activities and they appeared to be moderate active.
A new friedelane-type triterpene named 3β-hydroxyfriedelane-7,12,22-trione, as well as nine known compounds were isolated from the whole stems of Drypetes laciniata Hutch. (Euphorbiaceae). Their structures were established on the basis of spectroscopic methods. The new triterpene derivative and a known saponin were tested for antimicrobial and antifungal activities and they appeared to be moderate active.
2011, 22(2): 175-177
doi: 10.1016/j.cclet.2010.09.028
Abstract:
Two new benzopyran derivatives, l-[(rel 25,3R)-3,5,7-trihydroxy-3,4-dihydro-2H-chromen-2-yl]ethanone (1), and l-[(rel 2S,35)-3,5,7-trihydroxy-3,4-dihydro-2H-chromen-2-yl]ethanone (2), along with four known flavonoids, prodelphinidin C, pro-delphinidin B3, (-)-epi-gallocatechin and (+)-gallocatechin, were isolated from the stems of Gouania leptostachya DC. var. tonkinensis Pitard. Their structures were determined on the basis of spectroscopic methods including HR-ESI-MS, ID and 2D NMR. Prodelphinidin C exhibited significant inhibitory activity for α-glucosidase.
Two new benzopyran derivatives, l-[(rel 25,3R)-3,5,7-trihydroxy-3,4-dihydro-2H-chromen-2-yl]ethanone (1), and l-[(rel 2S,35)-3,5,7-trihydroxy-3,4-dihydro-2H-chromen-2-yl]ethanone (2), along with four known flavonoids, prodelphinidin C, pro-delphinidin B3, (-)-epi-gallocatechin and (+)-gallocatechin, were isolated from the stems of Gouania leptostachya DC. var. tonkinensis Pitard. Their structures were determined on the basis of spectroscopic methods including HR-ESI-MS, ID and 2D NMR. Prodelphinidin C exhibited significant inhibitory activity for α-glucosidase.
2011, 22(2): 178-180
doi: 10.1016/j.cclet.2010.09.029
Abstract:
A new benzophenone glycoside, 2,6-dihydroxy-4-O-β-D-glucopyranosylbenzophenone (1), was isolated from the leaves of guajava L. Its structure was elucidated by spectral and chemical methods. 1 showed significant activities to secretion of NO in mouse peritoneal macrophages in 10 μmol/L.
A new benzophenone glycoside, 2,6-dihydroxy-4-O-β-D-glucopyranosylbenzophenone (1), was isolated from the leaves of guajava L. Its structure was elucidated by spectral and chemical methods. 1 showed significant activities to secretion of NO in mouse peritoneal macrophages in 10 μmol/L.
2011, 22(2): 181-184
doi: 10.1016/j.cclet.2010.10.013
Abstract:
A new lignan glycoside was isolated from the n-butanol extract of the roots and rhizomes of Sinopodophyllum emodi. On the basis of spectral evidences, its structure was established and named as 4,5-didemethylpodophyllotoxin 7'-O-β-D-glucopyranoside. This compound showed cytotoxicity against four human cancer cell lines (Hela, K562, SH-SY5Y and CNE) in vitro.
A new lignan glycoside was isolated from the n-butanol extract of the roots and rhizomes of Sinopodophyllum emodi. On the basis of spectral evidences, its structure was established and named as 4,5-didemethylpodophyllotoxin 7'-O-β-D-glucopyranoside. This compound showed cytotoxicity against four human cancer cell lines (Hela, K562, SH-SY5Y and CNE) in vitro.
2011, 22(2): 185-188
doi: 10.1016/j.cclet.2010.07.031
Abstract:
Novel dopamine-derivative compound, 3,5-diamino-N-(3,4-dihydroxyphenethyl)benzamide (3,5-DAB) was prepared in two steps. In the first step dopamine hydrochloride was reacted with 3,5-dinitrobenzoyl chloride in the presence of propylene oxide. In the second step reduction of nitro groups resulted in preparation of 3,5-DAB in quantitative yield. This material was characterized using conventional spectroscopic methods such as FT-IR and 1H NMR. In addition, the redox response of a modified carbon nanotubes paste electrode of 3,5-DAB was investigated in aqueous solution at a neutral pH. The result showed that the electrode process has a guasi-reversible response, with △Ep, greater than the (59/n) mV expected for a reversible system. Finally, the diffusion coefficient for redox process in paraffin oil matrix obtained using chronoamperometry methods.
Novel dopamine-derivative compound, 3,5-diamino-N-(3,4-dihydroxyphenethyl)benzamide (3,5-DAB) was prepared in two steps. In the first step dopamine hydrochloride was reacted with 3,5-dinitrobenzoyl chloride in the presence of propylene oxide. In the second step reduction of nitro groups resulted in preparation of 3,5-DAB in quantitative yield. This material was characterized using conventional spectroscopic methods such as FT-IR and 1H NMR. In addition, the redox response of a modified carbon nanotubes paste electrode of 3,5-DAB was investigated in aqueous solution at a neutral pH. The result showed that the electrode process has a guasi-reversible response, with △Ep, greater than the (59/n) mV expected for a reversible system. Finally, the diffusion coefficient for redox process in paraffin oil matrix obtained using chronoamperometry methods.
2011, 22(2): 189-192
doi: 10.1016/j.cclet.2010.09.015
Abstract:
A method to determine water content in organic solvents was developed based on the color change of cobalt(II) nitrate in different solvents. The color-change mechanism and optimal conditions for determining the water content were investigated. The results showed that there was a good linear relationships between the absorbance of cobalt(II) complexes in organic solvents and water contents with γ in 0.9989~0.9994. This method has the advantages of low cost, good reproducibility, good sensitivity, simple in operation, fast in detection, friendly to the environment and no limitation on linear range for determining water content. It was used to determine water in samples with a satisfactory recovery in 97.81%~101.24%.
A method to determine water content in organic solvents was developed based on the color change of cobalt(II) nitrate in different solvents. The color-change mechanism and optimal conditions for determining the water content were investigated. The results showed that there was a good linear relationships between the absorbance of cobalt(II) complexes in organic solvents and water contents with γ in 0.9989~0.9994. This method has the advantages of low cost, good reproducibility, good sensitivity, simple in operation, fast in detection, friendly to the environment and no limitation on linear range for determining water content. It was used to determine water in samples with a satisfactory recovery in 97.81%~101.24%.
2011, 22(2): 193-196
doi: 10.1016/j.cclet.2010.07.032
Abstract:
A novel and very simple colorimetric and fluorometric method for selectively sensing F- was proposed based on 4-bromo-2,6-bis(hydroxymethyl)phenol (BBHMP), which is a simple and available phenolic receptor the absence of any special chromophoric function and with over wide range of anions (Cl-, Br-, I-, AcO-, HSO4-, NO3-and BzO-) in DMSO media. The colorimetric method is described for naked-eye detection of F- in the presence of the BBHMP. The BBHMP was found to show selective and sensitive fluorescence quenching response toward fluoride over than Cl-, Br-, I-, AcO-, HSO4-, NO3-and BzO-.
A novel and very simple colorimetric and fluorometric method for selectively sensing F- was proposed based on 4-bromo-2,6-bis(hydroxymethyl)phenol (BBHMP), which is a simple and available phenolic receptor the absence of any special chromophoric function and with over wide range of anions (Cl-, Br-, I-, AcO-, HSO4-, NO3-and BzO-) in DMSO media. The colorimetric method is described for naked-eye detection of F- in the presence of the BBHMP. The BBHMP was found to show selective and sensitive fluorescence quenching response toward fluoride over than Cl-, Br-, I-, AcO-, HSO4-, NO3-and BzO-.
2011, 22(2): 197-200
doi: 10.1016/j.cclet.2010.10.019
Abstract:
A new and simple capillary electrophoresis with electrochemiluminescence detection was developed for the separation and the quantification of a pair of diastereoisomeric alkaloids (ephedrine and pseudoephedrine). The limits of detection (S/N=3) were 4.5×10-8 mol/L for ephedrine and 5.2×10-8 mol/L for pseudoephedrine, respectively. The RSDs of migration time and peak area were less than 1.3 and 2.5% (n=5), respectively. The applicability of the propose method was illustrated in the determination of ephedrine and pseudoephedrine in human urine, ephedrine in nasal drops, and the monitoring of pharmacokinetics for pseudoephedrine.
A new and simple capillary electrophoresis with electrochemiluminescence detection was developed for the separation and the quantification of a pair of diastereoisomeric alkaloids (ephedrine and pseudoephedrine). The limits of detection (S/N=3) were 4.5×10-8 mol/L for ephedrine and 5.2×10-8 mol/L for pseudoephedrine, respectively. The RSDs of migration time and peak area were less than 1.3 and 2.5% (n=5), respectively. The applicability of the propose method was illustrated in the determination of ephedrine and pseudoephedrine in human urine, ephedrine in nasal drops, and the monitoring of pharmacokinetics for pseudoephedrine.
2011, 22(2): 201-204
doi: 10.1016/j.cclet.2010.07.035
Abstract:
In this research, a new poly(vinyl chloride) (PVC) membrane sensor for Ho3+ ion based on N-phenyl-2-(thiophen-2-ylmethylene)hydrazinecarbothioamide (PHC) as an ionophore was prepared. This sensor demonstrated good selectivity and sensitivity towards the holmium ion in comparison with variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The effect of membrane composition and pH on the response properties of the electrode was investigated. In detail, the suggested sensor exhibited a Nernstian behavior (with a slope of 20.4 ±0.3 mV decade-1) in the range of 1.0×10-6 to 1.0×10-2 mol/L with a detection limit of 6.2×10-7 mol/L. The response time was relatively quick in the whole concentration range (~5 s). The sensor usage was found to be at least 10 weeks in a pH range of 3.3-10.9. It was successfully applied in determination of fluoride ions in mouth wash preparations.
In this research, a new poly(vinyl chloride) (PVC) membrane sensor for Ho3+ ion based on N-phenyl-2-(thiophen-2-ylmethylene)hydrazinecarbothioamide (PHC) as an ionophore was prepared. This sensor demonstrated good selectivity and sensitivity towards the holmium ion in comparison with variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The effect of membrane composition and pH on the response properties of the electrode was investigated. In detail, the suggested sensor exhibited a Nernstian behavior (with a slope of 20.4 ±0.3 mV decade-1) in the range of 1.0×10-6 to 1.0×10-2 mol/L with a detection limit of 6.2×10-7 mol/L. The response time was relatively quick in the whole concentration range (~5 s). The sensor usage was found to be at least 10 weeks in a pH range of 3.3-10.9. It was successfully applied in determination of fluoride ions in mouth wash preparations.
2011, 22(2): 205-208
doi: 10.1016/j.cclet.2010.07.034
Abstract:
The reversible aggregation between dextran-conjugated CdSe quantum dots (Dex-CdSe-QDs) and concanavalin A (Con A) was explored based on the specific affinity of polysaccharide for Con A by resonance light-scattering technique. In this study, the aggregation of Dex-CdSe-QDs induced by Con A and sequential dissociation by glucose was determined over a wide range of dextran molecular mass (10-500 kDa). The results demonstrate that the sensitivity of lectin-dextran-modified-QDs interactions increase with dextran molecular mass, and an optimum dextran molecular mass is 500 kDa.
The reversible aggregation between dextran-conjugated CdSe quantum dots (Dex-CdSe-QDs) and concanavalin A (Con A) was explored based on the specific affinity of polysaccharide for Con A by resonance light-scattering technique. In this study, the aggregation of Dex-CdSe-QDs induced by Con A and sequential dissociation by glucose was determined over a wide range of dextran molecular mass (10-500 kDa). The results demonstrate that the sensitivity of lectin-dextran-modified-QDs interactions increase with dextran molecular mass, and an optimum dextran molecular mass is 500 kDa.
2011, 22(2): 209-212
doi: 10.1016/j.cclet.2010.10.010
Abstract:
ZnO particles about 200 nm were prepared through a facile hydrothermal method. Compared with single ozonation, the degradation efficiency of phenol increased about 23.7% and the degradation efficiency of intermediates improved about four times in the presence of ZnO at 298 K. In addition, the catalyst had good stability in the ozonation process. The influence of temperature was investigated and it was found that the better catalysis efficiency could be obtained at lower temperature.
ZnO particles about 200 nm were prepared through a facile hydrothermal method. Compared with single ozonation, the degradation efficiency of phenol increased about 23.7% and the degradation efficiency of intermediates improved about four times in the presence of ZnO at 298 K. In addition, the catalyst had good stability in the ozonation process. The influence of temperature was investigated and it was found that the better catalysis efficiency could be obtained at lower temperature.
2011, 22(2): 213-216
doi: 10.1016/j.cclet.2010.10.011
Abstract:
Synthesis and structure of Ti complex having a pair of chelating aminotropone[O-N] ligand have been reported. Calculations of density functional theory (DFT) studies suggest that bis(aminotropone) Ti complex, when activated with methylaluminoxane (MAO), have high potential for the polymerization of olefinic monomers. These theoretical studies also show that the active species derived from bis(aminotropone) Ti catalyst normally possess higher electrophilicity nature compared with those produced using bis(phenoxyimine) Ti complexes (Ti-FI catalysts) which are known as high performance olefin polymerization catalysts. Bis(aminotropone) Ti catalyst generates a catalytically active species that has higher electrophilicity than a Ti-FI catalysts.
Synthesis and structure of Ti complex having a pair of chelating aminotropone[O-N] ligand have been reported. Calculations of density functional theory (DFT) studies suggest that bis(aminotropone) Ti complex, when activated with methylaluminoxane (MAO), have high potential for the polymerization of olefinic monomers. These theoretical studies also show that the active species derived from bis(aminotropone) Ti catalyst normally possess higher electrophilicity nature compared with those produced using bis(phenoxyimine) Ti complexes (Ti-FI catalysts) which are known as high performance olefin polymerization catalysts. Bis(aminotropone) Ti catalyst generates a catalytically active species that has higher electrophilicity than a Ti-FI catalysts.
2011, 22(2): 217-220
doi: 10.1016/j.cclet.2010.09.014
Abstract:
Cross-linked β-cyclodextrin polymer/Fe3O4 composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethyl β-cyclodextrin (CM-β-CD) modified Fe3O4 nanoparticles in β-cyclodextrin alkaline solution by using epichlorohydrin as crosslinking agent. The morphology, structure and magnetic properties of the prepared composite nanoparticles were investigated by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, X-ray diffraction (XRD) measurement, thermogravimetric analysis (TGA) and Vibrating sample magnetometry (VSM), respectively.
Cross-linked β-cyclodextrin polymer/Fe3O4 composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethyl β-cyclodextrin (CM-β-CD) modified Fe3O4 nanoparticles in β-cyclodextrin alkaline solution by using epichlorohydrin as crosslinking agent. The morphology, structure and magnetic properties of the prepared composite nanoparticles were investigated by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, X-ray diffraction (XRD) measurement, thermogravimetric analysis (TGA) and Vibrating sample magnetometry (VSM), respectively.
2011, 22(2): 221-224
doi: 10.1016/j.cclet.2010.09.024
Abstract:
The promoting effect of ethanol on the synthesis of N-(2-methylphenyl)hydroxylamine from o-nitrotoluene in Zn/H2O/CO2 system was observed. By adding appropriate amount of ethanol, the selectivity of N-(2-methylphenyl)hydroxylamine increased from 71% to 90% when the reduction was carried out at 25℃ under normal pressure of CO2.
The promoting effect of ethanol on the synthesis of N-(2-methylphenyl)hydroxylamine from o-nitrotoluene in Zn/H2O/CO2 system was observed. By adding appropriate amount of ethanol, the selectivity of N-(2-methylphenyl)hydroxylamine increased from 71% to 90% when the reduction was carried out at 25℃ under normal pressure of CO2.
2011, 22(2): 225-228
doi: 10.1016/j.cclet.2010.07.030
Abstract:
The tea wastages could remove methylene blue (MB) as a cationic dye from waste water corresponding to second-order kinetic model. Thermodynamic studies showed that adsorption equilibrium constant (KL) and maximum adsorption capacities (Qmax) were increased with increasing temperature. The removal efficiency of MB for Co 0.01 mmol/L at optimum conditions was about 85%. The maximum uptake capacity (Qmax) of methylene blue in a batch reactor was 0.328,0.542 and 0.659 mmol/g at 15,25 and 40℃, respectively. The enthalpy change (△H) and entropy change (△S) were 11.356 kJ/mol and 20.563 J/(mol K), respectively.
The tea wastages could remove methylene blue (MB) as a cationic dye from waste water corresponding to second-order kinetic model. Thermodynamic studies showed that adsorption equilibrium constant (KL) and maximum adsorption capacities (Qmax) were increased with increasing temperature. The removal efficiency of MB for Co 0.01 mmol/L at optimum conditions was about 85%. The maximum uptake capacity (Qmax) of methylene blue in a batch reactor was 0.328,0.542 and 0.659 mmol/g at 15,25 and 40℃, respectively. The enthalpy change (△H) and entropy change (△S) were 11.356 kJ/mol and 20.563 J/(mol K), respectively.
2011, 22(2): 229-232
doi: 10.1016/j.cclet.2010.09.018
Abstract:
A new series of liquid crystals comprising eight heterocyclic isoflavone esters, 7-alkanoyloxy-3-[4'-(3-methylbutyloxyphenyl)]-4H-1-benzopyran-4-ones exhibiting enantiotropic nematic (N) and smectic C (SmC) phases were synthesized and investigated. The mesomorphic properties of all derivatives were investigated by means of differential calorimetry and polarized optical microscopy. Wide angle X-ray diffraction technique was employed to investigate the molecular packing associated with the intermolecular interaction as well as the correlation between the thermal behaviour of these compounds with their anisotropy properties within a mesophase.
A new series of liquid crystals comprising eight heterocyclic isoflavone esters, 7-alkanoyloxy-3-[4'-(3-methylbutyloxyphenyl)]-4H-1-benzopyran-4-ones exhibiting enantiotropic nematic (N) and smectic C (SmC) phases were synthesized and investigated. The mesomorphic properties of all derivatives were investigated by means of differential calorimetry and polarized optical microscopy. Wide angle X-ray diffraction technique was employed to investigate the molecular packing associated with the intermolecular interaction as well as the correlation between the thermal behaviour of these compounds with their anisotropy properties within a mesophase.
2011, 22(2): 233-236
doi: 10.1016/j.cclet.2010.09.016
Abstract:
In this study, the preparation of a new kind of magnetic and luminescent Fe3O4/CdTe nanocomposites was demonstrated. Superparamagnetic Fe3O4 nanoparticles were first synthesized by hydrothermal coprecipitation of ferric and ferrous ions, followed by the modification of their surfaces with tetramethylammonium hydroxide (TMAOH) and the chemical activation with aspartic acid. The surface-modified Fe3O4 nanoparticles were then covalently coated with CdTe quantum dots (QDs), which were modified with mercaptoacetic acid (MPA), to form the Fe3O4/CdTe magnetic and luminescent nanocomposites through the coordination of the amino groups on the surfaces of Fe3O4 and the carboxyl groups on CdTe QDs. The structure and properties of as-synthesized nanocomposites were characterized. It was indicated that the nanocomposites possessed structure with an average diameter of 40-50 nm, yellow-green emission feature and room temperature ferro-magnetism. Both the fluorescence and UV-vis absorption spectra of the nanocomposites showed a blue shift comparing with those of CdTe QDs. The mechanism of the blue shift was presented. The nanocomposites retained the ferromagnetic property with a saturation magnetization of 8.9 emu/g.
In this study, the preparation of a new kind of magnetic and luminescent Fe3O4/CdTe nanocomposites was demonstrated. Superparamagnetic Fe3O4 nanoparticles were first synthesized by hydrothermal coprecipitation of ferric and ferrous ions, followed by the modification of their surfaces with tetramethylammonium hydroxide (TMAOH) and the chemical activation with aspartic acid. The surface-modified Fe3O4 nanoparticles were then covalently coated with CdTe quantum dots (QDs), which were modified with mercaptoacetic acid (MPA), to form the Fe3O4/CdTe magnetic and luminescent nanocomposites through the coordination of the amino groups on the surfaces of Fe3O4 and the carboxyl groups on CdTe QDs. The structure and properties of as-synthesized nanocomposites were characterized. It was indicated that the nanocomposites possessed structure with an average diameter of 40-50 nm, yellow-green emission feature and room temperature ferro-magnetism. Both the fluorescence and UV-vis absorption spectra of the nanocomposites showed a blue shift comparing with those of CdTe QDs. The mechanism of the blue shift was presented. The nanocomposites retained the ferromagnetic property with a saturation magnetization of 8.9 emu/g.
2011, 22(2): 237-240
doi: 10.1016/j.cclet.2010.10.026
Abstract:
A series of novel poly(urethane-urea) (PUU) was synthesized from poly(lactide-co-p-dioxanone) macrodiol (HO-P(LA-co-PDO)-OH), hexamethylene diisocyanate (HDI) and butanediamine (BDA). The obtained PUU, which is recorded as P(LA-co-PDO)-PUU here, may demonstrate enhanced phase separation and thus improved shape memory property. FTIR was employed to characterize the copolymers, and the effects of NCO/OH molar ratios on Tg of PUU was investigated by means of differential scanning calorimetry (DSC). The results revealed the successful synthesis of P(LA-co-PDO)-PUU. In addition, the Tg of P(LA-co-PDO)-PUU increased from 37.9℃ to 44.2℃ with the increase NCO/OH ratios from 1.1 to 1.2. The P(LA-co-PDO)-PUU with Tg close to body temperature will have potential applications as shape memory polymers in biomedical fields, especially in minimally invasive surgery.
A series of novel poly(urethane-urea) (PUU) was synthesized from poly(lactide-co-p-dioxanone) macrodiol (HO-P(LA-co-PDO)-OH), hexamethylene diisocyanate (HDI) and butanediamine (BDA). The obtained PUU, which is recorded as P(LA-co-PDO)-PUU here, may demonstrate enhanced phase separation and thus improved shape memory property. FTIR was employed to characterize the copolymers, and the effects of NCO/OH molar ratios on Tg of PUU was investigated by means of differential scanning calorimetry (DSC). The results revealed the successful synthesis of P(LA-co-PDO)-PUU. In addition, the Tg of P(LA-co-PDO)-PUU increased from 37.9℃ to 44.2℃ with the increase NCO/OH ratios from 1.1 to 1.2. The P(LA-co-PDO)-PUU with Tg close to body temperature will have potential applications as shape memory polymers in biomedical fields, especially in minimally invasive surgery.
2011, 22(2): 241-244
doi: 10.1016/j.cclet.2010.10.014
Abstract:
Amphiphilic terpolymer (TPR) exhibits good film-forming behavior on pure water observed by means of π-A> isotherms. To gain insight into physical properties of TPR, the films have been deposited on silicon substrates at different surface pressure by Langmuir-Blodgett (LB) technique. It was found that the increase in peak intensities of stretching mode was due to orderly packing of the films. The contact angles increased with increasing surface pressure, indicating an increase in hydrophobicity due to dense packing of chains of TPR. The cyclic voltammetric measurements indicated that TPR showed good current shielding effect for electron-transfer. In a word, LB films of TPR can produce a variety of structures with varied topography, enabling us to control not only the functionality of the surface, but also the interfacial transport characteristics.
Amphiphilic terpolymer (TPR) exhibits good film-forming behavior on pure water observed by means of π-A> isotherms. To gain insight into physical properties of TPR, the films have been deposited on silicon substrates at different surface pressure by Langmuir-Blodgett (LB) technique. It was found that the increase in peak intensities of stretching mode was due to orderly packing of the films. The contact angles increased with increasing surface pressure, indicating an increase in hydrophobicity due to dense packing of chains of TPR. The cyclic voltammetric measurements indicated that TPR showed good current shielding effect for electron-transfer. In a word, LB films of TPR can produce a variety of structures with varied topography, enabling us to control not only the functionality of the surface, but also the interfacial transport characteristics.
2011, 22(2): 245-248
doi: 10.1016/j.cclet.2010.07.036
Abstract:
A one-step procedure to hydrophilize monodisperse poly (chloromethyl-styrene-co-divinylbenzene) beads has been presented with 2-hydroxy-3-[4-(hydroxymethyl)-1H-l,2,3-triazol-l-yl] propyl 2-methylacrylate (HTMA) as monomer by surface-initiated atom transfer radical polymerization (SI-ATRP). The length of the grafted poly (HTMA) chain was varied via controlling the ratio of HTMA to initiator on the surface of the beads. Using these grafted beads as the stationary phase in hydrophilic interaction chromatography, good separation was obtained for nucleosides in the mobile phase of acetonitrile-water. It was also found that the retention time and selectivity of solutes showed a positive relationship with the length of the grafted poly (HTMA) chain.
A one-step procedure to hydrophilize monodisperse poly (chloromethyl-styrene-co-divinylbenzene) beads has been presented with 2-hydroxy-3-[4-(hydroxymethyl)-1H-l,2,3-triazol-l-yl] propyl 2-methylacrylate (HTMA) as monomer by surface-initiated atom transfer radical polymerization (SI-ATRP). The length of the grafted poly (HTMA) chain was varied via controlling the ratio of HTMA to initiator on the surface of the beads. Using these grafted beads as the stationary phase in hydrophilic interaction chromatography, good separation was obtained for nucleosides in the mobile phase of acetonitrile-water. It was also found that the retention time and selectivity of solutes showed a positive relationship with the length of the grafted poly (HTMA) chain.
2011, 22(2): 249-252
doi: 10.1016/j.cclet.2010.09.031
Abstract:
The neodymium chloride complex [Nd(ONN'O)Cl(THF)]2 supported by amine-bis(phenolate) ligand was synthesized by the metathesis reaction of anhydrous NdCl3 with Li2(ONN'O)[H2ONN'O=Me2NCH2CH2N(CH2-3-Bu2t-5-Me-C6H2OH)2] in high yield. X-ray structural determination shows[Nd(ONN'O)Cl(THF)]2 complex consists of two seven-coordinate neodymium centers linked through μ-Cl bridges. And this complex was successfully used to initiate the ring-opening polymerization (ROP) of ε-caprolactone.
The neodymium chloride complex [Nd(ONN'O)Cl(THF)]2 supported by amine-bis(phenolate) ligand was synthesized by the metathesis reaction of anhydrous NdCl3 with Li2(ONN'O)[H2ONN'O=Me2NCH2CH2N(CH2-3-Bu2t-5-Me-C6H2OH)2] in high yield. X-ray structural determination shows[Nd(ONN'O)Cl(THF)]2 complex consists of two seven-coordinate neodymium centers linked through μ-Cl bridges. And this complex was successfully used to initiate the ring-opening polymerization (ROP) of ε-caprolactone.
