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2009 Volume 26 Issue 10
2009, 26(10): 1129-1133
Abstract:
A new type of combined catalyst of Lewis acids,Me3SiCl and InCl3·4H2O,that can catalyze Friedel-Crafts alkylation reaction between POE and PS in the molten state was studied. The existence of grafted copolymer was testified by FTIR. SEM micrographs show that the size of the domains was decreased from 3～ 4 μm to less than 1 μm when the combined catalyst was added. Because the in-situ generated PS-g-POE copolymer could act as a compatibilizer in the blending system,the mechanical properties of the reacted blends were improved notably compared to that of the physical blends. For example,after compatibilization,the Izod impact strength of the m(POE):m(PS) blend (40:60) was increased from 1.9 kJ/m2 to 9.7 kJ/m2 and its elongation at break increased from 3.4% to 46.3%. The complex viscosity of the reacted blends within the low frequency range showed a higher value than that of the physical blends,indicating the increased interactions between POE and PS.
A new type of combined catalyst of Lewis acids,Me3SiCl and InCl3·4H2O,that can catalyze Friedel-Crafts alkylation reaction between POE and PS in the molten state was studied. The existence of grafted copolymer was testified by FTIR. SEM micrographs show that the size of the domains was decreased from 3～ 4 μm to less than 1 μm when the combined catalyst was added. Because the in-situ generated PS-g-POE copolymer could act as a compatibilizer in the blending system,the mechanical properties of the reacted blends were improved notably compared to that of the physical blends. For example,after compatibilization,the Izod impact strength of the m(POE):m(PS) blend (40:60) was increased from 1.9 kJ/m2 to 9.7 kJ/m2 and its elongation at break increased from 3.4% to 46.3%. The complex viscosity of the reacted blends within the low frequency range showed a higher value than that of the physical blends,indicating the increased interactions between POE and PS.
2009, 26(10): 1134-1138
Abstract:
Chitosan-graft-poly(D,L-lactide)(CS-g-PLA) copolymers were obtained by means of microwave-irradiation and graft copolymerization via ring opening polymerization using stannous octoat(Sn(oct)2) as catalyst without any organic solvent. Through orthogonality experiment the best synthesis conditions were optimized as follows:reaction power 10 W,reaction temperature 120 ℃,reaction time 15 min,the amount of catalyst n(lactide):n(Sn(oct)2)=1 000:1. The products were characterized by FTIR,1H NMR,XRD and DTG. These results show that microwave-assisted ring-opening polymerization can produce a CS-g-PLA copolymer successfully and rapidly. The average degree of polymerization of polylactide branch chains in the graft copolymer was 17.46. Compared with CS,the grafting destroyed the original crystallinity of chitosan,and the onset temperature of degradation and thermal stability of the products descended. The feed ratio n(D,L-LA)/n(aminoglucoside) had a strong influence on the structure and properties of the CS-g-PLA copolymer,and higher feed ratio led to the copolymer with a higher average degree of polymerization of polylactide branch chains,and a lower crystallinity and an onset temperature(246 ℃) of degradation,lower than that of CS of 253 ℃.
Chitosan-graft-poly(D,L-lactide)(CS-g-PLA) copolymers were obtained by means of microwave-irradiation and graft copolymerization via ring opening polymerization using stannous octoat(Sn(oct)2) as catalyst without any organic solvent. Through orthogonality experiment the best synthesis conditions were optimized as follows:reaction power 10 W,reaction temperature 120 ℃,reaction time 15 min,the amount of catalyst n(lactide):n(Sn(oct)2)=1 000:1. The products were characterized by FTIR,1H NMR,XRD and DTG. These results show that microwave-assisted ring-opening polymerization can produce a CS-g-PLA copolymer successfully and rapidly. The average degree of polymerization of polylactide branch chains in the graft copolymer was 17.46. Compared with CS,the grafting destroyed the original crystallinity of chitosan,and the onset temperature of degradation and thermal stability of the products descended. The feed ratio n(D,L-LA)/n(aminoglucoside) had a strong influence on the structure and properties of the CS-g-PLA copolymer,and higher feed ratio led to the copolymer with a higher average degree of polymerization of polylactide branch chains,and a lower crystallinity and an onset temperature(246 ℃) of degradation,lower than that of CS of 253 ℃.
2009, 26(10): 1139-1143
Abstract:
Gel polymer electrolytes with ionic liquid [BMIM]Cl-ZnCl2 and an aprotic solvent were prepared via in situ free radical polymerization from vinyl monomers MA,MMA or HEMA as matrix and studied. The structure and properities of the products were studied by means of FTIR,AC,and TG. The interactions and structure changes of the composites were investigated by FTIR. The combination of a Lewis acid ionic liquid,[BMIM]Cl-ZnCl2 with aprotic solvent PC or DMC strongly increased the ionic conductivity in comparison with the neat ionic liquid,which showed a highly ionic conductivity of up to 2.83×10-3 S/cm at room temperature. And the activation energies of ions were calculated according to VTF equation. The gel polymer electrolytes exhibited high decomposition temperatures of above 275 ℃.
Gel polymer electrolytes with ionic liquid [BMIM]Cl-ZnCl2 and an aprotic solvent were prepared via in situ free radical polymerization from vinyl monomers MA,MMA or HEMA as matrix and studied. The structure and properities of the products were studied by means of FTIR,AC,and TG. The interactions and structure changes of the composites were investigated by FTIR. The combination of a Lewis acid ionic liquid,[BMIM]Cl-ZnCl2 with aprotic solvent PC or DMC strongly increased the ionic conductivity in comparison with the neat ionic liquid,which showed a highly ionic conductivity of up to 2.83×10-3 S/cm at room temperature. And the activation energies of ions were calculated according to VTF equation. The gel polymer electrolytes exhibited high decomposition temperatures of above 275 ℃.
2009, 26(10): 1144-1148
Abstract:
Molecularly imprinted polymeric microspheres(MIPMs) were prepared by a one-step swelling polymerization method in an aqueous system with polystyrene microspheres obtained by emulsifer-free polyme-rization as seeds and Chlorpyrifos as template molecules. The selective binding characteristics of the MIPMs were evaluated by ultraviolet spectrometry. The infrared spectrum(IR) of the polymer further indicated that there were some functional groups in the moleculary imprinted polymer which could interact with the template. Subsequent morphological characterization of the MIPMs by means of scanning electron microscopy(SEM) shows that the diameters were between 0.5～3 μm(2～3 μm for UMIPMs),and surface rugosity and high porosity facilitated the approaching of the template to the binding sites,so as to obtain high load,affinity and selectivity for the template molecules. Scatchard analysis suggests that during MIPMs recognition of Chlorpyrifos,there were two classes of binding sites. The calculated dissociation constant KD1 and apparent maximum number Bmax1 of binding sites with high affinity were 0.526 mmol/L and 35.91 μmol/g respectively,while KD2 and Bmax2 of binding sites with low affinity were 2.19 mmol/L and 83.87 μmol/g.
Molecularly imprinted polymeric microspheres(MIPMs) were prepared by a one-step swelling polymerization method in an aqueous system with polystyrene microspheres obtained by emulsifer-free polyme-rization as seeds and Chlorpyrifos as template molecules. The selective binding characteristics of the MIPMs were evaluated by ultraviolet spectrometry. The infrared spectrum(IR) of the polymer further indicated that there were some functional groups in the moleculary imprinted polymer which could interact with the template. Subsequent morphological characterization of the MIPMs by means of scanning electron microscopy(SEM) shows that the diameters were between 0.5～3 μm(2～3 μm for UMIPMs),and surface rugosity and high porosity facilitated the approaching of the template to the binding sites,so as to obtain high load,affinity and selectivity for the template molecules. Scatchard analysis suggests that during MIPMs recognition of Chlorpyrifos,there were two classes of binding sites. The calculated dissociation constant KD1 and apparent maximum number Bmax1 of binding sites with high affinity were 0.526 mmol/L and 35.91 μmol/g respectively,while KD2 and Bmax2 of binding sites with low affinity were 2.19 mmol/L and 83.87 μmol/g.
2009, 26(10): 1149-1153
Abstract:
A novel acidic N-thioacyl thioglycolic acid functionalized triethylentetramine crosslinked PVC resin was preparated from PVC,triethylenetetramine,CS2 and ClCH2COONa and characterized by FTIR and elemental analysis. Adsorption properties of the resin for Hg2+ were investigated under different conditions such as pH,temperature,contact time and the initial concentration of Hg2+. The results show that the adsorption of the resin for Hg2+ could rapidly reach balance,and it displayed a higher capacity when pH was about 2.0. The adsorption capacity of the resin for Hg2+ reached 3.330 mmol/g at 35 ℃ and 17.66 mmol/L Hg2+. The adsorption process was fitted to Langmuir and Freundlich isotherms in the studied concentration range. The loaded resin with Hg2+ was regenerated in an efficiency of 99.2% via 0.2 mol/L HNO3-10% thiourea.
A novel acidic N-thioacyl thioglycolic acid functionalized triethylentetramine crosslinked PVC resin was preparated from PVC,triethylenetetramine,CS2 and ClCH2COONa and characterized by FTIR and elemental analysis. Adsorption properties of the resin for Hg2+ were investigated under different conditions such as pH,temperature,contact time and the initial concentration of Hg2+. The results show that the adsorption of the resin for Hg2+ could rapidly reach balance,and it displayed a higher capacity when pH was about 2.0. The adsorption capacity of the resin for Hg2+ reached 3.330 mmol/g at 35 ℃ and 17.66 mmol/L Hg2+. The adsorption process was fitted to Langmuir and Freundlich isotherms in the studied concentration range. The loaded resin with Hg2+ was regenerated in an efficiency of 99.2% via 0.2 mol/L HNO3-10% thiourea.
2009, 26(10): 1154-1158
Abstract:
A composite adsorbent based on acrylic acid,acrylamide,montmorillonite and sodium humate was prepared,and the effects of pH value,contact time,and initial Pb2+ concentration on removing Pb2+ from the aqueous solution by the composite adsorbent were evaluated. The adsorption mechanism of Pb2+ onto the as-prepared adsorbent was discussed. Under the conditions of pH=6.00,contact time of 2 h,an initial Pb2+ concentration of 0.01 mol/L and an amount of adsorbent of 0.10 g,the adsorption capacity of the as-prepared adsorbent for Pb2+ was found to be 364.05 mg/g and the adsorption system reached equilibrium within 15 min. Compared with Ca-montmorillonite and other adsorbents reported,the as-prepared composite adsorbent has a higher adsorption capacity and a faster adsorption rate.
A composite adsorbent based on acrylic acid,acrylamide,montmorillonite and sodium humate was prepared,and the effects of pH value,contact time,and initial Pb2+ concentration on removing Pb2+ from the aqueous solution by the composite adsorbent were evaluated. The adsorption mechanism of Pb2+ onto the as-prepared adsorbent was discussed. Under the conditions of pH=6.00,contact time of 2 h,an initial Pb2+ concentration of 0.01 mol/L and an amount of adsorbent of 0.10 g,the adsorption capacity of the as-prepared adsorbent for Pb2+ was found to be 364.05 mg/g and the adsorption system reached equilibrium within 15 min. Compared with Ca-montmorillonite and other adsorbents reported,the as-prepared composite adsorbent has a higher adsorption capacity and a faster adsorption rate.
2009, 26(10): 1159-1164
Abstract:
Eight novel fluorine-containing PhTX-12 derivatives were prepared from the intermediate obtained via one-pot Ugi four-component solvent-free reactions by the simple removal of the protecting groups in the presence of trifluoroacetic acid. Their structures were identified by 1H NMR,13C NMR and HRMS or MS. Preliminary bioassays indicate that compound 6b showed 44% and 42% mortality rates against Heliothis armigera and Pieris rapae respectively at a concentration of 100 mg/L.
Eight novel fluorine-containing PhTX-12 derivatives were prepared from the intermediate obtained via one-pot Ugi four-component solvent-free reactions by the simple removal of the protecting groups in the presence of trifluoroacetic acid. Their structures were identified by 1H NMR,13C NMR and HRMS or MS. Preliminary bioassays indicate that compound 6b showed 44% and 42% mortality rates against Heliothis armigera and Pieris rapae respectively at a concentration of 100 mg/L.
2009, 26(10): 1165-1168
Abstract:
The salicylaldehyde-type glutamate Schiff bases(Ⅱ) were obtained first by the reactions of chlorinated salicylaldehyde,bromide salicylaldehyde and L-glutamates and their esters,and then the schiff bases were reduced by NaBH4 to produce halogenated o-hydroxybenzyl-glutamates and their esters(Ⅲ). The structures of the products were confirmed by 1H NMR,IR,MS and elemental analysis. The results of preliminary bioassay show that at a mass concentration of 0.05%,p-halo-o-hydroxybenzyl-glutamates had obvious antimicrobial activity against E.coli,with an inhibition rate of as high as 97%,but has less effective to M.albicans or S.aureus. The methyl esters,such as p-halo-o-hydroxybenzyl-glutamate methylesters,had obvious antimicrobial avtivity against M.albicans,with an inhibition rate of as high as 100%,but was less effective to E.coli or S.aureus,indicating that the antibacterial properties of the title compounds have an obvious selecti-vity and specificity. p-Chloride-o-hydroxybenzyl-glutamate methylester,p-bromide-o-hydroxybenzyl-glutamate methylester are fine antibacterial compounds for M.aureus.
The salicylaldehyde-type glutamate Schiff bases(Ⅱ) were obtained first by the reactions of chlorinated salicylaldehyde,bromide salicylaldehyde and L-glutamates and their esters,and then the schiff bases were reduced by NaBH4 to produce halogenated o-hydroxybenzyl-glutamates and their esters(Ⅲ). The structures of the products were confirmed by 1H NMR,IR,MS and elemental analysis. The results of preliminary bioassay show that at a mass concentration of 0.05%,p-halo-o-hydroxybenzyl-glutamates had obvious antimicrobial activity against E.coli,with an inhibition rate of as high as 97%,but has less effective to M.albicans or S.aureus. The methyl esters,such as p-halo-o-hydroxybenzyl-glutamate methylesters,had obvious antimicrobial avtivity against M.albicans,with an inhibition rate of as high as 100%,but was less effective to E.coli or S.aureus,indicating that the antibacterial properties of the title compounds have an obvious selecti-vity and specificity. p-Chloride-o-hydroxybenzyl-glutamate methylester,p-bromide-o-hydroxybenzyl-glutamate methylester are fine antibacterial compounds for M.aureus.
2009, 26(10): 1169-1173
Abstract:
A clean and efficient method has been developed for N-alkylation of amines catalyzed by Ni-Sn/Al2O3 with alcohol as the alkylation agent and solvent as well as hydrogen-donor. For all the reactions,the temperature was 180 ℃,the pressure was 1.5 MPa,and the flow rate was 1.0 mL/min. The structure of the catalyst was confirmed by X-ray diffraction(XRD) and transmission electron microscopy(TEM). The yields of N-alkylation amines were measured by gas chromatography(GC) while their structures were confirmed by gas chromatography-mass spectrometry(GC-MS). The results show that this catalyst has a great conjoint effect for all the reactions in in-situ hydrogenation for N-alkylation,including dehydrogenation of alcohol and hydrogenation of imine intermediates. The total yields of all the N-alkylation products were quite high,and some even greater than 99%. The catalyst had a long life of more than 480 h.
A clean and efficient method has been developed for N-alkylation of amines catalyzed by Ni-Sn/Al2O3 with alcohol as the alkylation agent and solvent as well as hydrogen-donor. For all the reactions,the temperature was 180 ℃,the pressure was 1.5 MPa,and the flow rate was 1.0 mL/min. The structure of the catalyst was confirmed by X-ray diffraction(XRD) and transmission electron microscopy(TEM). The yields of N-alkylation amines were measured by gas chromatography(GC) while their structures were confirmed by gas chromatography-mass spectrometry(GC-MS). The results show that this catalyst has a great conjoint effect for all the reactions in in-situ hydrogenation for N-alkylation,including dehydrogenation of alcohol and hydrogenation of imine intermediates. The total yields of all the N-alkylation products were quite high,and some even greater than 99%. The catalyst had a long life of more than 480 h.
2009, 26(10): 1174-1179
Abstract:
Chiral Salen Mn(Ⅲ) complex was axially coordinated on diamine or polyamines modified Zirconium poly(styrene-isopropenyl phosphonate)-phosphates(ZPS-IPPA) by a covalent grafting method. All the supported heterogeneous chiral Salen Mn(Ⅲ) complexes prepared were characterized by FT-IR,diffusion reflection UV-Vis,XPS,SEM and TEM. The supported catalyst was applied to the enantioselective epoxidation of α-methylstyrene with NaClO and m-CPBA as oxidants. The results confirm that the activity of the supported catalyst was lower than that of the homogeneous chiral Salen Mn( Ⅲ). However,its enantioselecti-vity was higher than that of the homogeneous one. A conversion of 68% and an e.e. of 99% of epoxide were obtained when α-methylstyrene was oxidized by NaClO for 24 h at 0 ℃ in the presence of 4-PPNO. The catalysts were easily recovered by filtration and could be reused for at least eight times with little loss of activity and enantioselectivity.
Chiral Salen Mn(Ⅲ) complex was axially coordinated on diamine or polyamines modified Zirconium poly(styrene-isopropenyl phosphonate)-phosphates(ZPS-IPPA) by a covalent grafting method. All the supported heterogeneous chiral Salen Mn(Ⅲ) complexes prepared were characterized by FT-IR,diffusion reflection UV-Vis,XPS,SEM and TEM. The supported catalyst was applied to the enantioselective epoxidation of α-methylstyrene with NaClO and m-CPBA as oxidants. The results confirm that the activity of the supported catalyst was lower than that of the homogeneous chiral Salen Mn( Ⅲ). However,its enantioselecti-vity was higher than that of the homogeneous one. A conversion of 68% and an e.e. of 99% of epoxide were obtained when α-methylstyrene was oxidized by NaClO for 24 h at 0 ℃ in the presence of 4-PPNO. The catalysts were easily recovered by filtration and could be reused for at least eight times with little loss of activity and enantioselectivity.
2009, 26(10): 1180-1183
Abstract:
The total synthesis of the title compound 10 was accomplished from 3,5-dimethoxybenzoic acid(1) and p-hydroxybenzaldehyde(6). In the process,esterification,reduction,bromination and Wittig-Horner reaction were performed. Compound 5 was then synthesized in a high yield. Treatment of compound 5 with the protection product of compound 6 afforded the key compound 8. The target compound 10 was successfully synthesized through deprotection and bionic oxidative coupling. The structure of compound 10 was confirmed by 1H NMR,13C NMR,IR,and HRMS. In conclusion,resveratrol (E)-dehydrodimer-11,11',13,13'-tetramethyl ether was synthesized through the new method in a total yield of 48.93%.
The total synthesis of the title compound 10 was accomplished from 3,5-dimethoxybenzoic acid(1) and p-hydroxybenzaldehyde(6). In the process,esterification,reduction,bromination and Wittig-Horner reaction were performed. Compound 5 was then synthesized in a high yield. Treatment of compound 5 with the protection product of compound 6 afforded the key compound 8. The target compound 10 was successfully synthesized through deprotection and bionic oxidative coupling. The structure of compound 10 was confirmed by 1H NMR,13C NMR,IR,and HRMS. In conclusion,resveratrol (E)-dehydrodimer-11,11',13,13'-tetramethyl ether was synthesized through the new method in a total yield of 48.93%.
2009, 26(10): 1184-1188
Abstract:
Twelve new ferroceneacyl benzimidazoles were prepared by the reaction of ferrocenesulfonylchloride or ferrocenylcarbonylchloride with 1H-benzimidazole derivatives. The structures of as-synthesized benzimi-dazoles were confirmed by IR,1H NMR,Elemental analysis and MS. The results show that the reaction of benzimidazole derivatives containing active hydrogen with ferroceneacylchloride gave ferroceneacyl benzimi-dazole in good yields.
Twelve new ferroceneacyl benzimidazoles were prepared by the reaction of ferrocenesulfonylchloride or ferrocenylcarbonylchloride with 1H-benzimidazole derivatives. The structures of as-synthesized benzimi-dazoles were confirmed by IR,1H NMR,Elemental analysis and MS. The results show that the reaction of benzimidazole derivatives containing active hydrogen with ferroceneacylchloride gave ferroceneacyl benzimi-dazole in good yields.
2009, 26(10): 1189-1193
Abstract:
4-Alkoxy-biphenyl-4'-carboxy-lates(2-n) was synthesized by introducing a benzyl ring on the side of alkoxy chain of chromen-2-one-6-yl 4-alkoxy benzoates(1-n). The liquid crystalline and gelation of compound 2-n were determined. Comparing with compound 1-n,compound 2-n exhibits enantiotropic nematic phase and can form gels with various organic solvents. The critical gel concentrations in various solvents were determined and the three-dimensional network structure consisting of xerogel fibrils was observed with a scanning electron microscope. Conclusively,intermolecular interactions around lactone moiety having a broad shape and a large dipole moment play important roles in enhancing the broad gelling ability.
4-Alkoxy-biphenyl-4'-carboxy-lates(2-n) was synthesized by introducing a benzyl ring on the side of alkoxy chain of chromen-2-one-6-yl 4-alkoxy benzoates(1-n). The liquid crystalline and gelation of compound 2-n were determined. Comparing with compound 1-n,compound 2-n exhibits enantiotropic nematic phase and can form gels with various organic solvents. The critical gel concentrations in various solvents were determined and the three-dimensional network structure consisting of xerogel fibrils was observed with a scanning electron microscope. Conclusively,intermolecular interactions around lactone moiety having a broad shape and a large dipole moment play important roles in enhancing the broad gelling ability.
2009, 26(10): 1194-1199
Abstract:
Six sulfonium photoacid generators(PAGs) which were used in 248 nm photoresists were synthesized,some of which were innovated by our lab for the first time. The synthesis method is very simple and environment-friendly,with high yields at the same time. All the PAGs were identified by IR,HNMR and UV. The max wavelengths of ultraviolet absorption are between 250 nm and 285 nm,and the absorption region are so wide that these PAGs can be used extensively. We used rhodamine B and ultraviolet spectrophotometer to evaluate the acid-generation efficiency of the PAGs in acetonitrile because rhodamine B will change colour by the change of acid concentration. The PAGs synthesized by thioxanthen-9-one and isopropylthioxanthen-9-one were choosed as the best ones. We also studied how the solvent affect the acid-generation by fluorescence,and found that the acid-generation efficiency would be depressed by the decrease of the solvent's polarity. All the work about the PAGs can provide an important reference to 248 nm photoresists.
Six sulfonium photoacid generators(PAGs) which were used in 248 nm photoresists were synthesized,some of which were innovated by our lab for the first time. The synthesis method is very simple and environment-friendly,with high yields at the same time. All the PAGs were identified by IR,HNMR and UV. The max wavelengths of ultraviolet absorption are between 250 nm and 285 nm,and the absorption region are so wide that these PAGs can be used extensively. We used rhodamine B and ultraviolet spectrophotometer to evaluate the acid-generation efficiency of the PAGs in acetonitrile because rhodamine B will change colour by the change of acid concentration. The PAGs synthesized by thioxanthen-9-one and isopropylthioxanthen-9-one were choosed as the best ones. We also studied how the solvent affect the acid-generation by fluorescence,and found that the acid-generation efficiency would be depressed by the decrease of the solvent's polarity. All the work about the PAGs can provide an important reference to 248 nm photoresists.
2009, 26(10): 1200-1205
Abstract:
A purine nucleotide derivative,6-chloro-2-aminopurine nucleoside triphosphate,was synthesized in four steps and characterized with 1H NMR,31P NMR,13C NMR,EA and IR. Its ultraviolet properties at various pH values were studied. The pKa value of the compound was determined by the curves of UV abso-rption dependency on pH,which was 1.44. Hydrolysis of the nucleotide derivative under the catalysis of potato apyrase was studied. The competion of the ATP analogue with ATP for potato apyrase' active site was proved to be mixed prohibition mechanism.
A purine nucleotide derivative,6-chloro-2-aminopurine nucleoside triphosphate,was synthesized in four steps and characterized with 1H NMR,31P NMR,13C NMR,EA and IR. Its ultraviolet properties at various pH values were studied. The pKa value of the compound was determined by the curves of UV abso-rption dependency on pH,which was 1.44. Hydrolysis of the nucleotide derivative under the catalysis of potato apyrase was studied. The competion of the ATP analogue with ATP for potato apyrase' active site was proved to be mixed prohibition mechanism.
2009, 26(10): 1206-1210
Abstract:
Pyrazol-3,4-dihydropyrimidines were synthesized by one-pot Biginelli cyclocondensation of substituted-4-formylpyrazole,ethyl acetoacetate,urea or thiourea and ferric choride(in molar ratio of 1:3:3:1) in ethanol,under traditional heating or microwave irradiation conditions,while ferric chloride was used as a catalyst. The structures of all the products were characterized by elemental analysis,IR,1H NMR and 13C NMR. The mechanism of the reaction and the spectra of all the compounds were also discussed. The method of microwave irradiation showed some advantages,such as a shorter reaction time and a higher yield,which is a new approach for synthesizing this kind of compounds.
Pyrazol-3,4-dihydropyrimidines were synthesized by one-pot Biginelli cyclocondensation of substituted-4-formylpyrazole,ethyl acetoacetate,urea or thiourea and ferric choride(in molar ratio of 1:3:3:1) in ethanol,under traditional heating or microwave irradiation conditions,while ferric chloride was used as a catalyst. The structures of all the products were characterized by elemental analysis,IR,1H NMR and 13C NMR. The mechanism of the reaction and the spectra of all the compounds were also discussed. The method of microwave irradiation showed some advantages,such as a shorter reaction time and a higher yield,which is a new approach for synthesizing this kind of compounds.
2009, 26(10): 1211-1215
Abstract:
Polyborosilazane(PBSZ),a novel precursor of SiBNC ceramic,was synthesized via polycondensation approach with a yield of about 90%(mass fraction) from dichloromethylsilane(MeHSiCl2),boron trichloride(BCl3) and hexamethydisilazane((CH3)3SiNHSi(CH3)3). Precursors with different softening points can be obtained by altering the dosage of MeHSiCl2. Rheological study shows that PBSZ melt is a typical shear thinning fluid. The shear rate,the flow index,the apparent viscosity and the viscous flow activation energy are 10~110 s-1,0.83~0.90,440~2 460 Pa·s,and 142 kJ/mol,respectively. The as-synthesized polyborosilazane shows a good melt-spinning processability and continuous fibers with diameter 20 μm and length1 600 m can easily be obtained.
Polyborosilazane(PBSZ),a novel precursor of SiBNC ceramic,was synthesized via polycondensation approach with a yield of about 90%(mass fraction) from dichloromethylsilane(MeHSiCl2),boron trichloride(BCl3) and hexamethydisilazane((CH3)3SiNHSi(CH3)3). Precursors with different softening points can be obtained by altering the dosage of MeHSiCl2. Rheological study shows that PBSZ melt is a typical shear thinning fluid. The shear rate,the flow index,the apparent viscosity and the viscous flow activation energy are 10~110 s-1,0.83~0.90,440~2 460 Pa·s,and 142 kJ/mol,respectively. The as-synthesized polyborosilazane shows a good melt-spinning processability and continuous fibers with diameter 20 μm and length1 600 m can easily be obtained.
2009, 26(10): 1216-1221
Abstract:
A new 3D supramolecular compound,[Co2(Dpq)2(btec)(H2O)6]·2H2O,was obtained from the hydrothermal reaction of cobalt(Ⅱ) nitrate with mixed ligands [1,2,4,5-benzenetetracarboxylate(btec) and dipyrido[3,2-d:2',3'-f]quinoxaline(Dpq)],and characterized by elemental analysis,IR,TG and single-crystal X-ray diffraction. The results reveal that the compound belongs to the monoclinic system with P21/c space group. The cell parameters are a=0.897 8(5) nm,b=2.982 2(16) nm,c=0.705 8(4) nm,β=94.199(6)°,V=1.884 8(18) nm3,Z=2,R1=0.035 0,wR2=0.079 6. The Co(Ⅱ) is coordinated with two nitrogen atoms of one Dpq molecule,one oxygen atom from the bridging ligand btec,and three oxygen atoms from coordinated water molecules,respectively,rendering a six-coordinate mode in a distorted octahedron geometry. Two adjaceut Co(Ⅱ) ions are linked by the bridging ligand btec to construct a dinuclear unit. The 3D supramolecular network of the title compound is formed through hydrogen bonds and π-π stacking interactions. Moreover,the electrochemical properties of carbon paste electrode modified by the compound(Co-CPE) were studied,and the results indicate that the Co-CPE exhibited one-electron redox wave in potential range of 600 to -300 mV due to the metal cobalt ion redox Co(Ⅱ)/Co(Ⅲ). The Co-CPE has good electrocatalytic activity toward the oxidation of nitrite in a 0.1 mol/L HAc-NaAc solution.
A new 3D supramolecular compound,[Co2(Dpq)2(btec)(H2O)6]·2H2O,was obtained from the hydrothermal reaction of cobalt(Ⅱ) nitrate with mixed ligands [1,2,4,5-benzenetetracarboxylate(btec) and dipyrido[3,2-d:2',3'-f]quinoxaline(Dpq)],and characterized by elemental analysis,IR,TG and single-crystal X-ray diffraction. The results reveal that the compound belongs to the monoclinic system with P21/c space group. The cell parameters are a=0.897 8(5) nm,b=2.982 2(16) nm,c=0.705 8(4) nm,β=94.199(6)°,V=1.884 8(18) nm3,Z=2,R1=0.035 0,wR2=0.079 6. The Co(Ⅱ) is coordinated with two nitrogen atoms of one Dpq molecule,one oxygen atom from the bridging ligand btec,and three oxygen atoms from coordinated water molecules,respectively,rendering a six-coordinate mode in a distorted octahedron geometry. Two adjaceut Co(Ⅱ) ions are linked by the bridging ligand btec to construct a dinuclear unit. The 3D supramolecular network of the title compound is formed through hydrogen bonds and π-π stacking interactions. Moreover,the electrochemical properties of carbon paste electrode modified by the compound(Co-CPE) were studied,and the results indicate that the Co-CPE exhibited one-electron redox wave in potential range of 600 to -300 mV due to the metal cobalt ion redox Co(Ⅱ)/Co(Ⅲ). The Co-CPE has good electrocatalytic activity toward the oxidation of nitrite in a 0.1 mol/L HAc-NaAc solution.
2009, 26(10): 1222-1226
Abstract:
Surface desorption atmospheric chemical ionization mass spectrometry(SDAPCI-MS) was used to directly determine pesticide residue on the surface of vegetables without any toxic chemical contamination. Three carbamate pesticides,carbofuran,isoprocarb and methomyl,were determined,and the structure of the molecular ions of each analyte was confirmed by collision-induced dissociation(CID) to exclude the fake positive conclusion. The results show that the carbofuran and methomyl exhibit protonated molecular ion signals at m/z 222 and m/z 163 respectively,but the isoprocarb displays free radical cation signal at m/z 193 under these conditions. The tandem mass spectrometry shows that the fragmentation regularity of the three carbamate pesticides coincide with their molecular structures. The detection limit of this method was found to be less than 1.0×-14g/cm2,and the detection time less than 1 s. SDAPCI-MS is a good method to inspect bulk samples nondestructively without sample pretreatment.
Surface desorption atmospheric chemical ionization mass spectrometry(SDAPCI-MS) was used to directly determine pesticide residue on the surface of vegetables without any toxic chemical contamination. Three carbamate pesticides,carbofuran,isoprocarb and methomyl,were determined,and the structure of the molecular ions of each analyte was confirmed by collision-induced dissociation(CID) to exclude the fake positive conclusion. The results show that the carbofuran and methomyl exhibit protonated molecular ion signals at m/z 222 and m/z 163 respectively,but the isoprocarb displays free radical cation signal at m/z 193 under these conditions. The tandem mass spectrometry shows that the fragmentation regularity of the three carbamate pesticides coincide with their molecular structures. The detection limit of this method was found to be less than 1.0×-14g/cm2,and the detection time less than 1 s. SDAPCI-MS is a good method to inspect bulk samples nondestructively without sample pretreatment.
2009, 26(10): 1227-1231
Abstract:
Inhibition behavior of brass corrosion by sodium diethyldithiocarbamate(SDDTC) in 3%(mass fraction) NaCl solution was investigated by means of mass-loss method,electrochemical impedance spectro-scopy(EIS) and potentiodynamic polarization. The mass-loss results show that SDDTC had an inhibition efficiency of up to 95% in a 3% NaCl solution at a concentration of 120×10-4%. The EIS results indicate that the Rp value of brass electrodes initially increased with the increase of SDDTC concentration and immersion time,reaching a maximum at 120×10-4% and 72 h. After that,the Rp value decreased slightly with further increase of SDDTC concentration and immersion time. Potentiodynamic polarization results reveal that the inhibitor had simultaneous inhibitory effects on both anodic and cathodic behavior of brass in a 3% NaCl solution.
Inhibition behavior of brass corrosion by sodium diethyldithiocarbamate(SDDTC) in 3%(mass fraction) NaCl solution was investigated by means of mass-loss method,electrochemical impedance spectro-scopy(EIS) and potentiodynamic polarization. The mass-loss results show that SDDTC had an inhibition efficiency of up to 95% in a 3% NaCl solution at a concentration of 120×10-4%. The EIS results indicate that the Rp value of brass electrodes initially increased with the increase of SDDTC concentration and immersion time,reaching a maximum at 120×10-4% and 72 h. After that,the Rp value decreased slightly with further increase of SDDTC concentration and immersion time. Potentiodynamic polarization results reveal that the inhibitor had simultaneous inhibitory effects on both anodic and cathodic behavior of brass in a 3% NaCl solution.
2009, 26(10): 1232-1235
Abstract:
The adsorption behavior of glycine(GLY) on the surface of FeCO3 film and its inhibition mechanism in sodium bicarbonate solution were studied by polarization curves and electrochemical impedance spectrum(EIS). Results indicate that GLY forms multi-layer on the surface of pre-corrosion A3 steel and there is a desorption process. The inhibition mechanism is geometric blocking effect and inhibition effect is better at a concentration of 100 mg/L. The adsorption is spontaneous,and the Gibbs free energy is -27.408 kJ/mol at a low concentration of GLY,and is -13.152 kJ/mol at a high concentration of GLY.
The adsorption behavior of glycine(GLY) on the surface of FeCO3 film and its inhibition mechanism in sodium bicarbonate solution were studied by polarization curves and electrochemical impedance spectrum(EIS). Results indicate that GLY forms multi-layer on the surface of pre-corrosion A3 steel and there is a desorption process. The inhibition mechanism is geometric blocking effect and inhibition effect is better at a concentration of 100 mg/L. The adsorption is spontaneous,and the Gibbs free energy is -27.408 kJ/mol at a low concentration of GLY,and is -13.152 kJ/mol at a high concentration of GLY.
2009, 26(10): 1236-1240
Abstract:
The anodic material of Li1+xV3O8 was synthesized with Li2CO3 and NH4VO3 as the reactants under different conditions. The effects of the reactant dispersion and the calcining temperature on the structure,morphology and electrochemical properties of the products were investigated. XRD,IR and SEM experiments show that the sample synthesized at 550 ℃ from the precursor obtained with ultrasonically treating reactants in anhydrous ethanol has low crystallinity,small grain size and homogeneous morphology. And it has low polarization,more lithium insertion/extraction sites and good cyclability. Its discharge capacity reaches 268 mA·h/g in the 2nd cycle at a discharge rate of 0.5 C and still retains 210 mA·h/g after 100 cycles.
The anodic material of Li1+xV3O8 was synthesized with Li2CO3 and NH4VO3 as the reactants under different conditions. The effects of the reactant dispersion and the calcining temperature on the structure,morphology and electrochemical properties of the products were investigated. XRD,IR and SEM experiments show that the sample synthesized at 550 ℃ from the precursor obtained with ultrasonically treating reactants in anhydrous ethanol has low crystallinity,small grain size and homogeneous morphology. And it has low polarization,more lithium insertion/extraction sites and good cyclability. Its discharge capacity reaches 268 mA·h/g in the 2nd cycle at a discharge rate of 0.5 C and still retains 210 mA·h/g after 100 cycles.
2009, 26(10): 1241-1243
Abstract:
The oxidative degradation of sesbania gum by Fenton reagent was studied. The effects of amounts of H2O2 and Fe2+,reaction time,temperature and pH value on the decreasing rate of the viscosity was investigated. The result shows that the appropriate dosage ratio of H2O2 to Fe2+ was 2:1. The decreasing ratio of viscosity reached 90% at a low temperature within a short reaction time. In addition,the changing of pH value had little effect on the degradation performance of Fenton reagent,indicating the high oxidative degradability of sesbania gum by Fenton reagent.
The oxidative degradation of sesbania gum by Fenton reagent was studied. The effects of amounts of H2O2 and Fe2+,reaction time,temperature and pH value on the decreasing rate of the viscosity was investigated. The result shows that the appropriate dosage ratio of H2O2 to Fe2+ was 2:1. The decreasing ratio of viscosity reached 90% at a low temperature within a short reaction time. In addition,the changing of pH value had little effect on the degradation performance of Fenton reagent,indicating the high oxidative degradability of sesbania gum by Fenton reagent.
2009, 26(10): 1244-1246
Abstract:
Silicon dioxide sol was synthesized from inorganic salt precursor,tetraethylorthosilioate by hydro-lysis and condensation in water. The thermal stabilities and micro-structure of PMMA/SiO2 hybrid materials were characterized with TEM,DSC and TG. The studies reveal that the diameter of the particles was about 100 nm. The glass transition temperature of the PMMA/SiO2 hybrid materials disappeared when ω(SiO2) was more than 20%,and the thermal decomposition temperature increased by 110 ℃. The forming of homogeneous inter-penetrated network between the organic phase and the inorganic phase demonstrated the miscibility of the two species had been improved.
Silicon dioxide sol was synthesized from inorganic salt precursor,tetraethylorthosilioate by hydro-lysis and condensation in water. The thermal stabilities and micro-structure of PMMA/SiO2 hybrid materials were characterized with TEM,DSC and TG. The studies reveal that the diameter of the particles was about 100 nm. The glass transition temperature of the PMMA/SiO2 hybrid materials disappeared when ω(SiO2) was more than 20%,and the thermal decomposition temperature increased by 110 ℃. The forming of homogeneous inter-penetrated network between the organic phase and the inorganic phase demonstrated the miscibility of the two species had been improved.
2009, 26(10): 1247-1249
Abstract:
With Zn(Ac)2·2H2O,Fe(NO3)3·9H2O and NaOH as raw materials,Fe3+-doped ZnO was prepared by hydrothermal method. The structure and morphology were investigated by means of X-ray diffrac-tion and scanning electron microscopy. The measurements indicated that the Fe3+-doped ZnO was rod like. The UV diffuse reflectance absorbent properties were detected on a UV-Lambda35 spectrophotometer. The results showed that the Fe3+-doped ZnO had strong absorption in UV and visible regions. Photodegradation of dyes in an aqueous solution was investigated with Fe3+-doped ZnO as a photocatalyst. The results showed that Fe3+-doped ZnO had better degradation properties than pure ZnO.
With Zn(Ac)2·2H2O,Fe(NO3)3·9H2O and NaOH as raw materials,Fe3+-doped ZnO was prepared by hydrothermal method. The structure and morphology were investigated by means of X-ray diffrac-tion and scanning electron microscopy. The measurements indicated that the Fe3+-doped ZnO was rod like. The UV diffuse reflectance absorbent properties were detected on a UV-Lambda35 spectrophotometer. The results showed that the Fe3+-doped ZnO had strong absorption in UV and visible regions. Photodegradation of dyes in an aqueous solution was investigated with Fe3+-doped ZnO as a photocatalyst. The results showed that Fe3+-doped ZnO had better degradation properties than pure ZnO.
2009, 26(10): 1250-1252
Abstract:
The electrospray ionization(ESI) mass spectrometry was used to study the fragmentation pathway of kaempferol. The fragmentation pathway of kaempferol was also theoretically studied by means of Density Functional Theory(DFT). The structures of all the fragment ions and the corresponding bond dissociation energies(BDEs) were analyzed by virtue of DFT at ROB3LYP/6-311 ++ G(2d,2p)/B3LYP/6-31G(d) levels. Based on the comparison with the calculated BDEs,the structure and the origin of each fragment ion were determined,and then the whole fragmentation pathway was deduced. The calculated results show that the fragment ions at m/z 284.7,256.7,228.7,210.7,184.8,168.7 and 150.7 of kaempferol mainly formed by the cleavage of the C ring. And the BDE of fragment ion at m/z 210.7 is the lowest,while the BDE of fragment ion at m/z 150.7 is the highest,suggesting that the former is evidently easier to form from the parent ion,and the latter is comparatively more difficult to form.
The electrospray ionization(ESI) mass spectrometry was used to study the fragmentation pathway of kaempferol. The fragmentation pathway of kaempferol was also theoretically studied by means of Density Functional Theory(DFT). The structures of all the fragment ions and the corresponding bond dissociation energies(BDEs) were analyzed by virtue of DFT at ROB3LYP/6-311 ++ G(2d,2p)/B3LYP/6-31G(d) levels. Based on the comparison with the calculated BDEs,the structure and the origin of each fragment ion were determined,and then the whole fragmentation pathway was deduced. The calculated results show that the fragment ions at m/z 284.7,256.7,228.7,210.7,184.8,168.7 and 150.7 of kaempferol mainly formed by the cleavage of the C ring. And the BDE of fragment ion at m/z 210.7 is the lowest,while the BDE of fragment ion at m/z 150.7 is the highest,suggesting that the former is evidently easier to form from the parent ion,and the latter is comparatively more difficult to form.
