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2014 Volume 25 Issue 8
2014, 25(8): 1107-1111
doi: 10.1016/j.cclet.2014.05.016
Abstract:
Metabolism study was carried out on 12β-hydroxylveratroylzygadenine (VOG) that is a cevine-type alkaloid existing in Veratrum nigrum L. and a neurotoxic component. In order to better understand the potential mechanism of neurotoxicity of VOG, this study measured VOG-induced DNA damage in the cerebellum and cerebral cortex of mice after 7 days repetitive oral dose by using single-cell gel electrophoresis (Comet assay). High performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and applied to separate and identify in vitro and in vivo metabolites of VOG for investing the possible relationship of metabolism and neurotoxicity. In vitro experiment was carried out using rat liver microsomes, while the in vivo study was conducted on rats. The obtained results indicated that VOG might cause DNA damage in cerebellum and cerebral cortex of mice in a dosedependent manner. Hydrolysis of ester bond and O-demethylation were proposed to be themain in vivo metabolic pathways of VOG, while the major in vitro metabolic pathways were proposed as methyl oxidation to aldehyde, dehydrogenation, hydrolysis of ester bond, hydrolysis of ester bond together with acetylation, and methoxylation. O-Demethylation reaction was likely to be associated with reactive oxygen species production, leading to the DNA damage.
Metabolism study was carried out on 12β-hydroxylveratroylzygadenine (VOG) that is a cevine-type alkaloid existing in Veratrum nigrum L. and a neurotoxic component. In order to better understand the potential mechanism of neurotoxicity of VOG, this study measured VOG-induced DNA damage in the cerebellum and cerebral cortex of mice after 7 days repetitive oral dose by using single-cell gel electrophoresis (Comet assay). High performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and applied to separate and identify in vitro and in vivo metabolites of VOG for investing the possible relationship of metabolism and neurotoxicity. In vitro experiment was carried out using rat liver microsomes, while the in vivo study was conducted on rats. The obtained results indicated that VOG might cause DNA damage in cerebellum and cerebral cortex of mice in a dosedependent manner. Hydrolysis of ester bond and O-demethylation were proposed to be themain in vivo metabolic pathways of VOG, while the major in vitro metabolic pathways were proposed as methyl oxidation to aldehyde, dehydrogenation, hydrolysis of ester bond, hydrolysis of ester bond together with acetylation, and methoxylation. O-Demethylation reaction was likely to be associated with reactive oxygen species production, leading to the DNA damage.
2014, 25(8): 1112-1114
doi: 10.1016/j.cclet.2014.04.024
Abstract:
The nitrile functionality is a key building block in synthetic chemistry, and has wide applications in pharmaceuticals. However, traditional methodologies for the synthesis of nitriles are limited to harsh reaction conditions. Herein, we report a new and efficient access to aryl nitriles by an electrochemical synthesis. Compared with the conventional synthetic methods, this electrochemical synthesis is more environmentally friendly and easier to handle.
The nitrile functionality is a key building block in synthetic chemistry, and has wide applications in pharmaceuticals. However, traditional methodologies for the synthesis of nitriles are limited to harsh reaction conditions. Herein, we report a new and efficient access to aryl nitriles by an electrochemical synthesis. Compared with the conventional synthetic methods, this electrochemical synthesis is more environmentally friendly and easier to handle.
2014, 25(8): 1115-1120
doi: 10.1016/j.cclet.2014.04.018
Abstract:
A novel gem-difluoromethylenated castanospermine analogue B was designed and synthesized, starting from 3-bromo-3,3-difluoropropene and L-(-)-malic acid. The key steps involve substitution cyclization reaction and RCM reaction to construct the aza fused bicyclic framework.
A novel gem-difluoromethylenated castanospermine analogue B was designed and synthesized, starting from 3-bromo-3,3-difluoropropene and L-(-)-malic acid. The key steps involve substitution cyclization reaction and RCM reaction to construct the aza fused bicyclic framework.
2014, 25(8): 1121-1124
doi: 10.1016/j.cclet.2014.03.045
Abstract:
A yellow, alkali-clearable azo disperse dye containing a carboxylic ester moiety was readily synthesized from the reactant p-aminobenzoic acid by successive diazotization, coupling reaction, chlorination and esterification with ethanol. Then its molecular structure was characterized by FTIR, 1H NMR, 13C NMR, mass spectrometry and elemental analysis. The synthesized dye and a similar control dye containing the acylamide moiety (Ⅰ) were applied to dyeing poly(ethylene terephthalate) fabric and their washing and rubbing fastness properties with different post-treatment methods (reduction clearing and alkali clearing) were examined and compared. It is found that the ester-containing disperse dye shows good alkali-clear ability on poly(ethylene terephthalate) fabric and contaminates little to environment due to the absence of reductants, as well as low toxicity and easy recycling of the hydrolysates.
A yellow, alkali-clearable azo disperse dye containing a carboxylic ester moiety was readily synthesized from the reactant p-aminobenzoic acid by successive diazotization, coupling reaction, chlorination and esterification with ethanol. Then its molecular structure was characterized by FTIR, 1H NMR, 13C NMR, mass spectrometry and elemental analysis. The synthesized dye and a similar control dye containing the acylamide moiety (Ⅰ) were applied to dyeing poly(ethylene terephthalate) fabric and their washing and rubbing fastness properties with different post-treatment methods (reduction clearing and alkali clearing) were examined and compared. It is found that the ester-containing disperse dye shows good alkali-clear ability on poly(ethylene terephthalate) fabric and contaminates little to environment due to the absence of reductants, as well as low toxicity and easy recycling of the hydrolysates.
2014, 25(8): 1125-1131
doi: 10.1016/j.cclet.2014.03.019
Abstract:
To evaluate the effect of neutral C-H bond or electron pair of nitrogen atom with sp2 hybridization (N(sp2)) involving into the same chemical environment for anion binding, two analogous tetracationic imidazolium macrocycles, namely cyclo[2](2,6-bis-(1H-imidazol-1-yl)pyridine) [2](1,3-dimethylenebenzene) (14+), and cyclo[2](2,6-bis-(1H-imidazol-1-yl)pyridine)[2](2,6-di methylenepyridine) (24+) were studied in detail as small inorganic anion receptors. The guest anions with different shapes are Cl-, N3-, NO3-, and H2PO4-. The host-guest interactions were characterized via 1H NMR spectroscopy, electrospray ionization mass spectrometry (ESI-MS) and single crystal X-ray crystallography. The results implied that macrocyclic hosts with similar backbone but two distinct binding sites (14+ with neutral C-H vs. 24+ with N (sp2)) vary markedly in their response to anions, including the binding modes and association constants. The finding will serve to the construction of new anion receptors, even improve insights into the anion binding process in biology.
To evaluate the effect of neutral C-H bond or electron pair of nitrogen atom with sp2 hybridization (N(sp2)) involving into the same chemical environment for anion binding, two analogous tetracationic imidazolium macrocycles, namely cyclo[2](2,6-bis-(1H-imidazol-1-yl)pyridine) [2](1,3-dimethylenebenzene) (14+), and cyclo[2](2,6-bis-(1H-imidazol-1-yl)pyridine)[2](2,6-di methylenepyridine) (24+) were studied in detail as small inorganic anion receptors. The guest anions with different shapes are Cl-, N3-, NO3-, and H2PO4-. The host-guest interactions were characterized via 1H NMR spectroscopy, electrospray ionization mass spectrometry (ESI-MS) and single crystal X-ray crystallography. The results implied that macrocyclic hosts with similar backbone but two distinct binding sites (14+ with neutral C-H vs. 24+ with N (sp2)) vary markedly in their response to anions, including the binding modes and association constants. The finding will serve to the construction of new anion receptors, even improve insights into the anion binding process in biology.
2014, 25(8): 1132-1136
doi: 10.1016/j.cclet.2014.03.029
Abstract:
An environmentally benign processing approach for furfural production from xylose and xylan under verymild conditions (353-373 K) was developed with the addition of metal chlorides in ChCl-oxalic acid (a deep eutectic solvent (DES)) synthesized from cheap and renewable starting materials). ChCl-oxalic acid acted as both a Brønsted acid catalyst and a reaction medium in this catalytic route. In addition, a biphasic system with methyl isobutyl ketone as an extracting reagent (DES/MIBK) to further increase furfural yield was also proposed. This processing approach for producing furfural eliminated the large energy consumption for high pressure saturated steam and the generation of acidic effluent, which was very difficult to handle. The whole catalytic system was more environmentally friendly compared with the commercial process for furfural production.
An environmentally benign processing approach for furfural production from xylose and xylan under verymild conditions (353-373 K) was developed with the addition of metal chlorides in ChCl-oxalic acid (a deep eutectic solvent (DES)) synthesized from cheap and renewable starting materials). ChCl-oxalic acid acted as both a Brønsted acid catalyst and a reaction medium in this catalytic route. In addition, a biphasic system with methyl isobutyl ketone as an extracting reagent (DES/MIBK) to further increase furfural yield was also proposed. This processing approach for producing furfural eliminated the large energy consumption for high pressure saturated steam and the generation of acidic effluent, which was very difficult to handle. The whole catalytic system was more environmentally friendly compared with the commercial process for furfural production.
2014, 25(8): 1137-1140
doi: 10.1016/j.cclet.2014.01.024
Abstract:
Halogenated anilines have a wide range of applications in the production of pharmaceuticals and agrochemical substances, and thus it is of great importance to develop highly active and selective catalysts for the hydrogenation of halogenated nitrobenzenes. We approach this challenge by probing noble metal/non-noble metal oxide nanoparticles (NPs) catalysts. Carbon-supported Pd/SnO2 catalysts were synthesized by the chemical reduction method, and their catalytic activity was evaluated by the hydrogenation reaction of 2,4-difluoronitrobenzene (DFNB) to the corresponding 2,4-difluoroaniline (DFAN), showing a remarkable synergistic effect of the Pd and SnO2 NPs. The as-prepared Pd/SnO2/C catalysts were characterized using TEM, XRD, H2 TPD and XPS techniques. Modifications to the electronic structure of the Pd atoms through the use of SnO2 led to the suppression of the hydrogenolysis of the C-F bond and the acceleration of nitrosobenzene (DFNSB) conversion and consequently, resulted in the inhibition of the formation of reactive by-products and may be responsible for the enhancements observed in selectivity.
Halogenated anilines have a wide range of applications in the production of pharmaceuticals and agrochemical substances, and thus it is of great importance to develop highly active and selective catalysts for the hydrogenation of halogenated nitrobenzenes. We approach this challenge by probing noble metal/non-noble metal oxide nanoparticles (NPs) catalysts. Carbon-supported Pd/SnO2 catalysts were synthesized by the chemical reduction method, and their catalytic activity was evaluated by the hydrogenation reaction of 2,4-difluoronitrobenzene (DFNB) to the corresponding 2,4-difluoroaniline (DFAN), showing a remarkable synergistic effect of the Pd and SnO2 NPs. The as-prepared Pd/SnO2/C catalysts were characterized using TEM, XRD, H2 TPD and XPS techniques. Modifications to the electronic structure of the Pd atoms through the use of SnO2 led to the suppression of the hydrogenolysis of the C-F bond and the acceleration of nitrosobenzene (DFNSB) conversion and consequently, resulted in the inhibition of the formation of reactive by-products and may be responsible for the enhancements observed in selectivity.
2014, 25(8): 1141-1144
doi: 10.1016/j.cclet.2014.03.002
Abstract:
A catalyst system of Sevelamer, a phosphate-binding drug, has been prepared and used in the Knoevenagel reaction of aromatic aldehydes in water to produce substituted electrophilic alkenes. The products were obtained in excellent yields. Several novel, related catalytic systems showed promising catalytic properties for aromatic and heterocyclic aldehydes. The Sevelamer catalyst can be recovered using simple filtration and reused numerous times (up to 15 times) in the aqueous Knoevenagel reaction without any significant lowering of activity.
A catalyst system of Sevelamer, a phosphate-binding drug, has been prepared and used in the Knoevenagel reaction of aromatic aldehydes in water to produce substituted electrophilic alkenes. The products were obtained in excellent yields. Several novel, related catalytic systems showed promising catalytic properties for aromatic and heterocyclic aldehydes. The Sevelamer catalyst can be recovered using simple filtration and reused numerous times (up to 15 times) in the aqueous Knoevenagel reaction without any significant lowering of activity.
2014, 25(8): 1145-1148
doi: 10.1016/j.cclet.2014.03.023
Abstract:
12 perfluorinated compounds (PFCs) in human blood from workers in a textilemill in Shandong province and several barbershops in Tianjin were analyzed in this study. It was found that perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were the most prominent PFCs, with average concentrations of 5.73 μg/L and 5.46 μg/L for textile workers, and 2.55 μg/L and 2.84 μg/L for barbers. PFOS and perfluorohexanesulfonate (PFHxS) concentrations revealed a positive correlation in blood samples (p < 0.01), and concentrations among PFOS, perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) also revealed positive correlations (p < 0.01). The influence of gender and age on PFC concentration in blood was also investigated, and the results showed that there was no statistically significant difference between the male and female samples, as well as in samples from people with different ages. Generally speaking, the textile workers may face a higher exposure of PFCs than barbers.
12 perfluorinated compounds (PFCs) in human blood from workers in a textilemill in Shandong province and several barbershops in Tianjin were analyzed in this study. It was found that perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were the most prominent PFCs, with average concentrations of 5.73 μg/L and 5.46 μg/L for textile workers, and 2.55 μg/L and 2.84 μg/L for barbers. PFOS and perfluorohexanesulfonate (PFHxS) concentrations revealed a positive correlation in blood samples (p < 0.01), and concentrations among PFOS, perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) also revealed positive correlations (p < 0.01). The influence of gender and age on PFC concentration in blood was also investigated, and the results showed that there was no statistically significant difference between the male and female samples, as well as in samples from people with different ages. Generally speaking, the textile workers may face a higher exposure of PFCs than barbers.
2014, 25(8): 1149-1152
doi: 10.1016/j.cclet.2014.03.037
Abstract:
Lanthanum oxide (La2O3) in combination with 2,2,2-trifluoroethanol (TFE) was found to be an efficient system for the one-pot, four-component synthesis of Hantzsch polyhydroquinoline derivatives from aromatic aldehydes, dimedone, ethyl acetoacetate and ammonium acetate at ambient temperature. The catalyst is heterogeneous and reusable, hence can be separated easily and reused. The present method is featured by mild reaction conditions, use of heterogeneous catalyst, non-chromatographic purification, short reaction time and high yields, which make it an attractive route for the synthesis of polyhydroquinolines.
Lanthanum oxide (La2O3) in combination with 2,2,2-trifluoroethanol (TFE) was found to be an efficient system for the one-pot, four-component synthesis of Hantzsch polyhydroquinoline derivatives from aromatic aldehydes, dimedone, ethyl acetoacetate and ammonium acetate at ambient temperature. The catalyst is heterogeneous and reusable, hence can be separated easily and reused. The present method is featured by mild reaction conditions, use of heterogeneous catalyst, non-chromatographic purification, short reaction time and high yields, which make it an attractive route for the synthesis of polyhydroquinolines.
2014, 25(8): 1153-1156
doi: 10.1016/j.cclet.2014.05.040
Abstract:
Two new oplopane sesquiterpenes, gmelinin A (1) and gmelinin B (2), were isolated from Artemisia gmelinii Web. ex Stechm. Their structures were established by spectroscopic techniques (mainly 1D and 2D NMR) and application of the modified Mosher method.
Two new oplopane sesquiterpenes, gmelinin A (1) and gmelinin B (2), were isolated from Artemisia gmelinii Web. ex Stechm. Their structures were established by spectroscopic techniques (mainly 1D and 2D NMR) and application of the modified Mosher method.
2014, 25(8): 1157-1160
doi: 10.1016/j.cclet.2014.03.035
Abstract:
During the laboratory optimization and the late phase manufacturing studies of the cholesterol absorption inhibitor Ezetimibe 1, the formation of several stereoisomers was observed. To study the complete stereoisomer profile of Ezetimibe 1,we have synthesized and completely characterized several key stereoisomers of Ezetimibe 1 for the first time. This study will provide an access to the reference standard of these stereoisomers andmay have some implications in the development of new medicines.
During the laboratory optimization and the late phase manufacturing studies of the cholesterol absorption inhibitor Ezetimibe 1, the formation of several stereoisomers was observed. To study the complete stereoisomer profile of Ezetimibe 1,we have synthesized and completely characterized several key stereoisomers of Ezetimibe 1 for the first time. This study will provide an access to the reference standard of these stereoisomers andmay have some implications in the development of new medicines.
2014, 25(8): 1161-1164
doi: 10.1016/j.cclet.2014.03.004
Abstract:
In this paper, an efficient synthesis of 5-alkynyl-1,2,3-triazoles through a one-pot aerobic oxidative coupling reaction of various alkynes and azides has been developed. Further derivatization of 5-alkynyl-1,2,3-triazoles readily yielded 5-carbonyl-1,2,3-triazoles, 5-carboxylic-1,2,3-triazole, 5-hydroxyalkyl-1,2,3-triazoles and 5-quinoxaline-1,2,3-triazole, which provided an entry into structurally diverse 5-functionalized-1,2,3-triazoles.
In this paper, an efficient synthesis of 5-alkynyl-1,2,3-triazoles through a one-pot aerobic oxidative coupling reaction of various alkynes and azides has been developed. Further derivatization of 5-alkynyl-1,2,3-triazoles readily yielded 5-carbonyl-1,2,3-triazoles, 5-carboxylic-1,2,3-triazole, 5-hydroxyalkyl-1,2,3-triazoles and 5-quinoxaline-1,2,3-triazole, which provided an entry into structurally diverse 5-functionalized-1,2,3-triazoles.
2014, 25(8): 1165-1168
doi: 10.1016/j.cclet.2014.03.052
Abstract:
This study reports the synthesis and characterization of quinoline derivatives. The synthesized quinoline compounds were applied to the dyeing treatment of acrylic fabrics. The color fastness to washing and light of quinoline compound-dyed fabrics was examined. Human skin HaCaT cell line was also used for the skin cytotoxicity evaluation of the quinoline compound-dyed acrylic fabrics.
This study reports the synthesis and characterization of quinoline derivatives. The synthesized quinoline compounds were applied to the dyeing treatment of acrylic fabrics. The color fastness to washing and light of quinoline compound-dyed fabrics was examined. Human skin HaCaT cell line was also used for the skin cytotoxicity evaluation of the quinoline compound-dyed acrylic fabrics.
2014, 25(8): 1169-1173
doi: 10.1016/j.cclet.2014.04.006
Abstract:
A highly effective phase transfer of a quaternary ammonium gemini surfactant with ester groups ((diethylhexanedioate) diyl-α,ω-bis(dimethyl dodecyl ammonium bromide) referred to as 12-10-12) was synthesized with high yield and characterized by infrared spectroscopy, elemental analysis and 1HNMR. Then, 12-10-12 was used as a phase transfer catalyst to study the catalytic effect on the reaction of anhydrous sodium acetate and 4-methylbenzyl chloride. The possible catalytic mechanism and the influence of surfactant concentration, temperature and type are also discussed. The experimental results showed that the catalysis efficiency was more active than the traditional, single-chained surfactant, tetrabutyl ammonium bromide. It also revealed that the reaction was first-order with respect to the concentration of 4-methylbenzyl chloride. The concentration of 4-methylbenzyl chloride grew linearly with the concentration of 12-10-12 and as the reaction temperature increased. The optimum reaction time was 7 h.
A highly effective phase transfer of a quaternary ammonium gemini surfactant with ester groups ((diethylhexanedioate) diyl-α,ω-bis(dimethyl dodecyl ammonium bromide) referred to as 12-10-12) was synthesized with high yield and characterized by infrared spectroscopy, elemental analysis and 1HNMR. Then, 12-10-12 was used as a phase transfer catalyst to study the catalytic effect on the reaction of anhydrous sodium acetate and 4-methylbenzyl chloride. The possible catalytic mechanism and the influence of surfactant concentration, temperature and type are also discussed. The experimental results showed that the catalysis efficiency was more active than the traditional, single-chained surfactant, tetrabutyl ammonium bromide. It also revealed that the reaction was first-order with respect to the concentration of 4-methylbenzyl chloride. The concentration of 4-methylbenzyl chloride grew linearly with the concentration of 12-10-12 and as the reaction temperature increased. The optimum reaction time was 7 h.
2014, 25(8): 1174-1178
doi: 10.1016/j.cclet.2014.03.033
Abstract:
FeX3 (X=Cl, Br) were found to be very effective reagents and powerful catalysts for regioselective ring openings of a variety of N-tosylaziridines with them to afford the corresponding β-haloamines in good to excellent yields with high regioselectivity under mild conditions. At the same time, 13 new compounds were obtained firstly. Moreover, the β-bromoamine prepared could be transferred into β-nitroamine with NaNO2 in moderate yield.
FeX3 (X=Cl, Br) were found to be very effective reagents and powerful catalysts for regioselective ring openings of a variety of N-tosylaziridines with them to afford the corresponding β-haloamines in good to excellent yields with high regioselectivity under mild conditions. At the same time, 13 new compounds were obtained firstly. Moreover, the β-bromoamine prepared could be transferred into β-nitroamine with NaNO2 in moderate yield.
2014, 25(8): 1179-1184
doi: 10.1016/j.cclet.2014.03.049
Abstract:
The non-covalent complexes of duplexes DNA and 9 ginsenosides (1 aglycone and 8 glycosides) were investigated using electrospray ionization mass spectrometry (ESI-MS) in the gas phase. The results of relative binding affinities in negative ion mode revealed that several factors impact on the duplexbinding properties of ginsenosides. Glycosylations of 20(S)-protopanaxadiol ginsenosides at the position C-20 and 20(S)-protopanaxatriol classification at the position C-6 enhanced the fraction of bound DNA sharply. A rhamnose moiety shows little lower binding intensities than glucose at the same position. Ginsenosides of 20(S)-protopanaxatriol result in subtle higher binding affinities toward the duplex DNA than 20(S)-protopanaxadiol family. However, glycosylation with two sugar moieties does not show a higher binding affinity than with only one moiety. The collision-induced dissociation experimental data demonstrate the gas-phase stability and fragmentation patterns of the ginsenoside/DNA complexes are related to the glycoside number. Positive ion ESI mass spectra of the complexes were also recorded. The result of ESI-MS suggests that hydrogen bonds are the dominate interaction between ginsenosides and DNA. Similar results were obtained in solution-phase by UV spectroscopy, which exhibit a hyperchromism and blue-shift effect when DNA solution was titrated by individual ginsenoside.
The non-covalent complexes of duplexes DNA and 9 ginsenosides (1 aglycone and 8 glycosides) were investigated using electrospray ionization mass spectrometry (ESI-MS) in the gas phase. The results of relative binding affinities in negative ion mode revealed that several factors impact on the duplexbinding properties of ginsenosides. Glycosylations of 20(S)-protopanaxadiol ginsenosides at the position C-20 and 20(S)-protopanaxatriol classification at the position C-6 enhanced the fraction of bound DNA sharply. A rhamnose moiety shows little lower binding intensities than glucose at the same position. Ginsenosides of 20(S)-protopanaxatriol result in subtle higher binding affinities toward the duplex DNA than 20(S)-protopanaxadiol family. However, glycosylation with two sugar moieties does not show a higher binding affinity than with only one moiety. The collision-induced dissociation experimental data demonstrate the gas-phase stability and fragmentation patterns of the ginsenoside/DNA complexes are related to the glycoside number. Positive ion ESI mass spectra of the complexes were also recorded. The result of ESI-MS suggests that hydrogen bonds are the dominate interaction between ginsenosides and DNA. Similar results were obtained in solution-phase by UV spectroscopy, which exhibit a hyperchromism and blue-shift effect when DNA solution was titrated by individual ginsenoside.
2014, 25(8): 1185-1189
doi: 10.1016/j.cclet.2014.03.030
Abstract:
In this paper, a novelmagnetic solid-phase extraction method using three-dimensional graphene-based magnetic nanocomposite as adsorbent for the preconcentration of several chlorophenols from water samples prior to high-performance liquid chromatography analysis was developed. Various experimental parameters were investigated. Under the optimum conditions, the enrichment factors of the method were in the range of 186-312, and the limit of detection (S/N=3) was 0.10 ng/mL. The recoveries of the method were in the range between 85.1% and 101.2%. The developed method has been successfully applied to the determination of chlorophenols in environmental water samples.
In this paper, a novelmagnetic solid-phase extraction method using three-dimensional graphene-based magnetic nanocomposite as adsorbent for the preconcentration of several chlorophenols from water samples prior to high-performance liquid chromatography analysis was developed. Various experimental parameters were investigated. Under the optimum conditions, the enrichment factors of the method were in the range of 186-312, and the limit of detection (S/N=3) was 0.10 ng/mL. The recoveries of the method were in the range between 85.1% and 101.2%. The developed method has been successfully applied to the determination of chlorophenols in environmental water samples.
2014, 25(8): 1190-1192
doi: 10.1016/j.cclet.2014.04.007
Abstract:
A simple and efficient method was developed for the synthesis of 2,20-arylmethylene dicyclohexane-1,3-dione derivatives via the Knoevenagel-Michael cascade reactions of aromatic aldehydes and 1,3-cyclic diketones catalyzed by "Amano" lipase DF, which expands the application field of enzyme catalytic promiscuity. This protocol provides several advantages over the traditional chemical synthesis, such as simple work-up procedure, high yields (up to 94%) and environmental friendliness.
A simple and efficient method was developed for the synthesis of 2,20-arylmethylene dicyclohexane-1,3-dione derivatives via the Knoevenagel-Michael cascade reactions of aromatic aldehydes and 1,3-cyclic diketones catalyzed by "Amano" lipase DF, which expands the application field of enzyme catalytic promiscuity. This protocol provides several advantages over the traditional chemical synthesis, such as simple work-up procedure, high yields (up to 94%) and environmental friendliness.
2014, 25(8): 1193-1197
doi: 10.1016/j.cclet.2014.02.005
Abstract:
An EPDDMAC-GE polymer (hydrophilic molecule) has been synthesized based on epoxypropyl dodecyl dimethyl ammonium chloride (EPDDMAC) and gelatin. A DEEPSAC-GE polymer (hydrophobicmolecule) has been synthesized based on diethyl-2,3-epoxypropyl-[3-methyldimethoxyl] silpropyl ammonium chloride (DEEPSAC) and gelatin. Compared with initial gelatin, the gelatin modified with quaternary ammonium salts containing epoxide groups exhibits stronger antibacterial activity.
An EPDDMAC-GE polymer (hydrophilic molecule) has been synthesized based on epoxypropyl dodecyl dimethyl ammonium chloride (EPDDMAC) and gelatin. A DEEPSAC-GE polymer (hydrophobicmolecule) has been synthesized based on diethyl-2,3-epoxypropyl-[3-methyldimethoxyl] silpropyl ammonium chloride (DEEPSAC) and gelatin. Compared with initial gelatin, the gelatin modified with quaternary ammonium salts containing epoxide groups exhibits stronger antibacterial activity.
2014, 25(8): 1198-1202
doi: 10.1016/j.cclet.2014.03.005
Abstract:
This study aimed to establish a rapid analytical method to determine antioxidants in essence. A simple, efficient and practical, vortex-assisted, cloud-point extraction (VACPE) procedure is proposed for extracting and pre-concentrating four different of synthetic phenolic antioxidants (SPAs), propyl gallate (PG), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) in essence prior to high performance liquid chromatography (HPLC) analysis. The non-ionic surfactant, fatty alcohol polyoxyethylene ether-9 (AEO-9), was used as extractant and vortex-mixing was utilized to reduce extraction time and improve extraction efficiency. The effective parameters of the extraction process, such as volume of extraction solvent, pH, vortex-mixing time, equilibration temperature and time, were optimized. Under the optimum conditions, the linear range of PG, TBHQ, BHA and BHT was 8.0-800 ng/mL. All correlation coefficients of the calibration curves were higher than 0.996 and relative standard deviations (RSD, n=5) were 2.36%-5.46%. The proposed method was successfully applied to the extraction and determination of antioxidants in essence samples with satisfactory relative recoveries of 89.4%-103.5%. The results confirmed the SPAs of essence could be effectively monitored by this method and also established good reference criteria for essence.
This study aimed to establish a rapid analytical method to determine antioxidants in essence. A simple, efficient and practical, vortex-assisted, cloud-point extraction (VACPE) procedure is proposed for extracting and pre-concentrating four different of synthetic phenolic antioxidants (SPAs), propyl gallate (PG), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) in essence prior to high performance liquid chromatography (HPLC) analysis. The non-ionic surfactant, fatty alcohol polyoxyethylene ether-9 (AEO-9), was used as extractant and vortex-mixing was utilized to reduce extraction time and improve extraction efficiency. The effective parameters of the extraction process, such as volume of extraction solvent, pH, vortex-mixing time, equilibration temperature and time, were optimized. Under the optimum conditions, the linear range of PG, TBHQ, BHA and BHT was 8.0-800 ng/mL. All correlation coefficients of the calibration curves were higher than 0.996 and relative standard deviations (RSD, n=5) were 2.36%-5.46%. The proposed method was successfully applied to the extraction and determination of antioxidants in essence samples with satisfactory relative recoveries of 89.4%-103.5%. The results confirmed the SPAs of essence could be effectively monitored by this method and also established good reference criteria for essence.
2014, 25(8): 1203-1206
doi: 10.1016/j.cclet.2014.03.003
Abstract:
In this study, Yb immobilized NaY zeolite catalyst (Yb/NaY) was obtained by a hydrothermal method and characterized by XRD, BET, FT-IR, ICP-AES, and NH3-TPD. The catalyst displayed good catalytic activity when applied to the synthesis of quinoxalines via condensation of α-hydroxyketones with 1,2-diamines, and could be reused several times without any loss of catalytic activity.
In this study, Yb immobilized NaY zeolite catalyst (Yb/NaY) was obtained by a hydrothermal method and characterized by XRD, BET, FT-IR, ICP-AES, and NH3-TPD. The catalyst displayed good catalytic activity when applied to the synthesis of quinoxalines via condensation of α-hydroxyketones with 1,2-diamines, and could be reused several times without any loss of catalytic activity.
2014, 25(8): 1207-1210
doi: 10.1016/j.cclet.2014.03.048
Abstract:
We describe here a rapid process for the preparation of new 9-chloromethyl-12-aryl-10,12-dihydrobenzo[5,6]chromeno[2,3-d]pyrimidin-11-ones 5a-d and 10-chloromethyl-7-aryl-7,9-dihydrobenzo[7,8]chromeno[2,3-d]pyrimidin-8-ones 6a-d by two different methods utilizing microwave irradiation. This methodology provides better yields (72%-80%) and high purity of the title compounds.
We describe here a rapid process for the preparation of new 9-chloromethyl-12-aryl-10,12-dihydrobenzo[5,6]chromeno[2,3-d]pyrimidin-11-ones 5a-d and 10-chloromethyl-7-aryl-7,9-dihydrobenzo[7,8]chromeno[2,3-d]pyrimidin-8-ones 6a-d by two different methods utilizing microwave irradiation. This methodology provides better yields (72%-80%) and high purity of the title compounds.
