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2004 Volume 15 Issue 6
2004, 15(6): 631-634
Abstract:
A convenient and rapid approach for the synthesis of piperamide alkaloids 1a~h by the recently developed one-flask Ramberg-Bäcklund reaction was described. The synthesis of 1e was reported for the first time.
A convenient and rapid approach for the synthesis of piperamide alkaloids 1a~h by the recently developed one-flask Ramberg-Bäcklund reaction was described. The synthesis of 1e was reported for the first time.
2004, 15(6): 635-638
Abstract:
An efficient poly(ethylene glycol) (PEG)-supported liquid-phase parallel approach to di(aryloxyacetyl)thiosemicarbazides is described. PEG-bound phenol reacted with chloroacetic acid to afford PEG-bound phenyloxyacetic acid, which was readily converted into corresponding phenyloxyacetyl chloride. Subsequent nucleophilic substitution with ammonium thiocyanate followed by addition of aryloxyacetic acid hydrazides gave PEG-bound di(aryloxyacetyl)thiosemi-carbazides, which were easily cleaved to give the resulting library of 1-aryloxyacetyl-4-(4'-methoxylcarbonylphenyloxyacetyl)thiosemicarbazides in good to high yield and high purity.
An efficient poly(ethylene glycol) (PEG)-supported liquid-phase parallel approach to di(aryloxyacetyl)thiosemicarbazides is described. PEG-bound phenol reacted with chloroacetic acid to afford PEG-bound phenyloxyacetic acid, which was readily converted into corresponding phenyloxyacetyl chloride. Subsequent nucleophilic substitution with ammonium thiocyanate followed by addition of aryloxyacetic acid hydrazides gave PEG-bound di(aryloxyacetyl)thiosemi-carbazides, which were easily cleaved to give the resulting library of 1-aryloxyacetyl-4-(4'-methoxylcarbonylphenyloxyacetyl)thiosemicarbazides in good to high yield and high purity.
2004, 15(6): 639-640
Abstract:
A series of UV-curable liquid crystalline diacrylates were synthesized by using 4, 4'-(terephthaloyldioxy) dibenzoic acid as a mesogen unit.
A series of UV-curable liquid crystalline diacrylates were synthesized by using 4, 4'-(terephthaloyldioxy) dibenzoic acid as a mesogen unit.
2004, 15(6): 641-642
Abstract:
A rapid and efficient method for synthesis of unsymmetrical ketones under microwave irradiation is reported.
A rapid and efficient method for synthesis of unsymmetrical ketones under microwave irradiation is reported.
2004, 15(6): 643-645
Abstract:
The sodium borohydride reduction of aldehydes and ketones to corresponding alcohols has been accomplished via the use of ionic liquids. The alcohols are easily obtained with excellent yields and the ionic liquid BMImBF4 could be reused.
The sodium borohydride reduction of aldehydes and ketones to corresponding alcohols has been accomplished via the use of ionic liquids. The alcohols are easily obtained with excellent yields and the ionic liquid BMImBF4 could be reused.
2004, 15(6): 646-648
Abstract:
three kinds of N-(diisopropyloxyphosphoryl) amino acids containing hydroxyl group were prepared in high yield by using diisopropyl phosphite as the phosphorylating agent, sodium hypochlorite as the chlorinating agent and tetrabutyl ammonium bromide as the phase transfer catalyst in basic aqueous media.
three kinds of N-(diisopropyloxyphosphoryl) amino acids containing hydroxyl group were prepared in high yield by using diisopropyl phosphite as the phosphorylating agent, sodium hypochlorite as the chlorinating agent and tetrabutyl ammonium bromide as the phase transfer catalyst in basic aqueous media.
2004, 15(6): 649-651
Abstract:
An efficient and practical radical chain deoxygenation method by phosphorus centered radicals generated from hypophosphorous acid was developed in the synthesis of analogues of paclitaxel.
An efficient and practical radical chain deoxygenation method by phosphorus centered radicals generated from hypophosphorous acid was developed in the synthesis of analogues of paclitaxel.
2004, 15(6): 652-654
Abstract:
N-Phosphoryl peptide libraries were constructed by transformation from homo-oligopeptide libraries, which was synthesized by self-assembly of amino acids with the assistance of phosphorus oxychloride. Electrospray ionization mass spectrometry (ESI-MS) was used to monitor the reaction.
N-Phosphoryl peptide libraries were constructed by transformation from homo-oligopeptide libraries, which was synthesized by self-assembly of amino acids with the assistance of phosphorus oxychloride. Electrospray ionization mass spectrometry (ESI-MS) was used to monitor the reaction.
2004, 15(6): 655-658
Abstract:
Jacobsen's catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times.
Jacobsen's catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times.
2004, 15(6): 659-660
Abstract:
A new phytosterone named passionsterone 1 has been isolated from the roots of Passiflora wilsonii, along with the known compound 24R-ethyl-5α-cholestane-3β, 6α-diol 2. The structure of passionsterone 1 was elucidated as 24R-ethyl-5α-cholestane-3β, 6α-diol-23-one by spectroscopic means.
A new phytosterone named passionsterone 1 has been isolated from the roots of Passiflora wilsonii, along with the known compound 24R-ethyl-5α-cholestane-3β, 6α-diol 2. The structure of passionsterone 1 was elucidated as 24R-ethyl-5α-cholestane-3β, 6α-diol-23-one by spectroscopic means.
2004, 15(6): 661-663
Abstract:
A novel bromophenol was isolated from ethanolic extract of the brown alga Leathesia nana S.et G. The structure was elucidated as (E)-3-(2, 3-dibromo-4, 5-dihydroxyphenyl)-2-methyl- propenal by spectroscopic methods including IR, HREIMS, 1D and 2D NMR techniques.
A novel bromophenol was isolated from ethanolic extract of the brown alga Leathesia nana S.et G. The structure was elucidated as (E)-3-(2, 3-dibromo-4, 5-dihydroxyphenyl)-2-methyl- propenal by spectroscopic methods including IR, HREIMS, 1D and 2D NMR techniques.
2004, 15(6): 664-666
Abstract:
A novel terpenoid, named lappulanocarpine A 1 was isolated from the alcoholic extract of the whole plant of Lappula anocarpa. Its structure was characterized by 1D-, 2D-NMR and HR-ESIMS.
A novel terpenoid, named lappulanocarpine A 1 was isolated from the alcoholic extract of the whole plant of Lappula anocarpa. Its structure was characterized by 1D-, 2D-NMR and HR-ESIMS.
2004, 15(6): 667-670
Abstract:
The application of phenylfluorone (PF)-Mo(VI) complex as a spectroscopic probe is studied. In the presence of OP microemulsion at pH 3.04, PF-Mo(VI) complex combines protein rapidly to form a stable compound and the absorbance at 527 nm is in proportion to the concentration of protein in the range 0~16 μg mL-1 for bovine serum albumin (BSA). OP microemuslion media is introduced into protein determination, it has increased markedly the sensitivity of the system. The molar absorption coefficient was 5.98(106 L mol-1 cm-1 for BSA. The assay, with sensitivity, simplicity and tolerance to many foreign substances, is applied to the determination of protein in samples with satisfactory results. Moreover, the binding number of BSA with the complex, which is determined by molar ratio and slope ratio methods, is in good agreement.
The application of phenylfluorone (PF)-Mo(VI) complex as a spectroscopic probe is studied. In the presence of OP microemulsion at pH 3.04, PF-Mo(VI) complex combines protein rapidly to form a stable compound and the absorbance at 527 nm is in proportion to the concentration of protein in the range 0~16 μg mL-1 for bovine serum albumin (BSA). OP microemuslion media is introduced into protein determination, it has increased markedly the sensitivity of the system. The molar absorption coefficient was 5.98(106 L mol-1 cm-1 for BSA. The assay, with sensitivity, simplicity and tolerance to many foreign substances, is applied to the determination of protein in samples with satisfactory results. Moreover, the binding number of BSA with the complex, which is determined by molar ratio and slope ratio methods, is in good agreement.
2004, 15(6): 671-674
Abstract:
The interaction between heparin and neutral red was investigated by molecular spectroscopic methods. The change of all spectra suggested that positively charged neutral red had interacted with negatively charged heparin. The study of influence factors indicated that electrostatic force and hydrophobic bond might be involved in the interaction. The total binding number per disaccharide unit and intrinsic binding constant were obtained using Scatchard model.
The interaction between heparin and neutral red was investigated by molecular spectroscopic methods. The change of all spectra suggested that positively charged neutral red had interacted with negatively charged heparin. The study of influence factors indicated that electrostatic force and hydrophobic bond might be involved in the interaction. The total binding number per disaccharide unit and intrinsic binding constant were obtained using Scatchard model.
2004, 15(6): 675-678
Abstract:
The use of chiral organophosphorus derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the 31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The method is accurate, reliable and convenient.
The use of chiral organophosphorus derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the 31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The method is accurate, reliable and convenient.
2004, 15(6): 679-682
Abstract:
This paper, for the first time, reports a method that can be used as a highly sensitive probe for singlet oxygen (1O2) and superoxide anion (O2-) in vitro or in vivo. FCLA(3, 7-dihydro-6-{4-[2-(N'-(5-fluoresceinyl)thioureido)ethoxy]phenyl}-2-methylimidazo{1, 2-a}pyrazin-3-one sodium salt), a chemiluminescence (CL) analysis reagent, has been reported to sensitively react with 1O2 and O2- to emit photons with a spectral peak of 525nm. In this work, when human serum albumin (HSA) was added into FCLA solution to enhance the CL intensity, approximately 20 times, compared to that without HSA. The enhanced CL had the same 525 nm spectral peak, identical to that without HSA. By gradually reducing the molecular oxygen content in the solution, we find that the auto-oxidation of oxygen molecules dissolved in the solution plays an important role in the CL process. Based on these experimental evidences, we propose a novel and highly sensitive detection method of 1O2 and O2-, which may have a great potential in chemical and medical applications.
This paper, for the first time, reports a method that can be used as a highly sensitive probe for singlet oxygen (1O2) and superoxide anion (O2-) in vitro or in vivo. FCLA(3, 7-dihydro-6-{4-[2-(N'-(5-fluoresceinyl)thioureido)ethoxy]phenyl}-2-methylimidazo{1, 2-a}pyrazin-3-one sodium salt), a chemiluminescence (CL) analysis reagent, has been reported to sensitively react with 1O2 and O2- to emit photons with a spectral peak of 525nm. In this work, when human serum albumin (HSA) was added into FCLA solution to enhance the CL intensity, approximately 20 times, compared to that without HSA. The enhanced CL had the same 525 nm spectral peak, identical to that without HSA. By gradually reducing the molecular oxygen content in the solution, we find that the auto-oxidation of oxygen molecules dissolved in the solution plays an important role in the CL process. Based on these experimental evidences, we propose a novel and highly sensitive detection method of 1O2 and O2-, which may have a great potential in chemical and medical applications.
2004, 15(6): 683-686
Abstract:
This paper described a highly sensitive chemiluminescence detection system for micro-chip electrophoresis (MCE) based on luminol-hydrogen peroxide reaction catalyzed by the metal ions. The micro-chip was composed of poly(dimethylsiloxane) (PDMS) and glass, and was fabricated by micro-machining technology. The surface of channels was dynamically modified by polydimethylacrylamide (PDMA) in order to eliminate unhomogeneous electroosmotic flow (EOF) of the PDMS/glass chip, adsorption of molecules, and improve hydrophobicity on PDMS surface. The detection modes, reagent mix procedures and reaction conditions were optimized and the detection limit of 5 x 10-11 mol/L for cobalt (II) was achieved by MCE with chemiluminescence detection, which was about four orders of magnitude more sensitive than that reported in the reference.
This paper described a highly sensitive chemiluminescence detection system for micro-chip electrophoresis (MCE) based on luminol-hydrogen peroxide reaction catalyzed by the metal ions. The micro-chip was composed of poly(dimethylsiloxane) (PDMS) and glass, and was fabricated by micro-machining technology. The surface of channels was dynamically modified by polydimethylacrylamide (PDMA) in order to eliminate unhomogeneous electroosmotic flow (EOF) of the PDMS/glass chip, adsorption of molecules, and improve hydrophobicity on PDMS surface. The detection modes, reagent mix procedures and reaction conditions were optimized and the detection limit of 5 x 10-11 mol/L for cobalt (II) was achieved by MCE with chemiluminescence detection, which was about four orders of magnitude more sensitive than that reported in the reference.
2004, 15(6): 687-690
Abstract:
A new cobalt(Ⅱ) complex with tridentate ligand 2, 6-bis (benzimidazol- 2-yl)pyridine has been synthesized by microwave irradiation method and characterized by elemental analysis, electrochemical and spectral methods. The binding of the complex with calf thymus DNA has also been investigated by absorption and fluorescence spectra.
A new cobalt(Ⅱ) complex with tridentate ligand 2, 6-bis (benzimidazol- 2-yl)pyridine has been synthesized by microwave irradiation method and characterized by elemental analysis, electrochemical and spectral methods. The binding of the complex with calf thymus DNA has also been investigated by absorption and fluorescence spectra.
2004, 15(6): 691-694
Abstract:
The photoisomerization of trans-stilbene was studied in the water in oil (W/O) micro-emulsion formed by SDS (sodium dodecyl sulfate), n-C5H11OH (1-pentanol) and H2O. The experimental results show that after 2-minute UV-irradiation, the yield of cis-stilbene is higher in W/O microemulsion than in homogeneous solvent-n-C5H11OH.
The photoisomerization of trans-stilbene was studied in the water in oil (W/O) micro-emulsion formed by SDS (sodium dodecyl sulfate), n-C5H11OH (1-pentanol) and H2O. The experimental results show that after 2-minute UV-irradiation, the yield of cis-stilbene is higher in W/O microemulsion than in homogeneous solvent-n-C5H11OH.
2004, 15(6): 695-698
Abstract:
The novel sol-gel SnO2/Al2O3 catalysts for selective catalytic reduction NO by propene under lean burn condition were investigated. The results showed that the maximum NO conversion was 82% on the SnO2/Al2O3 (5%Sn) catalyst, and the presence of H2O and SO2 improved the catalytic activity at low temperature. The catalytic activity of NO2 reduction by propene is much higher than that of NO at the entire temperature range, and the maximum NO2 conversion reached nearly 100% around the temperature 425℃.
The novel sol-gel SnO2/Al2O3 catalysts for selective catalytic reduction NO by propene under lean burn condition were investigated. The results showed that the maximum NO conversion was 82% on the SnO2/Al2O3 (5%Sn) catalyst, and the presence of H2O and SO2 improved the catalytic activity at low temperature. The catalytic activity of NO2 reduction by propene is much higher than that of NO at the entire temperature range, and the maximum NO2 conversion reached nearly 100% around the temperature 425℃.
2004, 15(6): 699-702
Abstract:
A novel kinetic mechanism of esterification reaction of 1-hexanoic acid with 1-butanol, catalyzed by lipase, was studied in water-in-oil microemulsions. The microemulsions were formed by alkyl polyglucoside C10G1.54/1-butanol/cyclohexane/phosphate buffer solution. The result shows that when the ratio of mol concentration of 1-butanol to 1-hexanoic acid is about 3.0, the initial rate V0 get the maximum values. This phenomenon was explained by the modified fishlike phase diagrams.
A novel kinetic mechanism of esterification reaction of 1-hexanoic acid with 1-butanol, catalyzed by lipase, was studied in water-in-oil microemulsions. The microemulsions were formed by alkyl polyglucoside C10G1.54/1-butanol/cyclohexane/phosphate buffer solution. The result shows that when the ratio of mol concentration of 1-butanol to 1-hexanoic acid is about 3.0, the initial rate V0 get the maximum values. This phenomenon was explained by the modified fishlike phase diagrams.
2004, 15(6): 703-706
Abstract:
Hydrogen molybdenum bronze (HxMoO3) can be electrodeposited on platinum and oxidized in two steps to the hydrogen molybdenum bronze with less amount of hydrogen HyMoO3 (y3 when platinum electrode is cycled from -0.2 to 1.3V (vs. SCE) in 0.05 mol/L Na2MoO4+0.5 mol/L H2SO4 solution. During the formation of HxMoO3, the electrochemical reduction of molybdate existing in the form of polymolydate is reversible and is about a five-electron transfer reaction.
Hydrogen molybdenum bronze (HxMoO3) can be electrodeposited on platinum and oxidized in two steps to the hydrogen molybdenum bronze with less amount of hydrogen HyMoO3 (y
2004, 15(6): 707-710
Abstract:
In this paper, the effect of ionic liquids on the CaCO3 crystal growth has been studied for the first time. The obtained CaCO3 crystals were charactered by the X-ray diffraction and scanning electron micrographs. The results showed that the control ability of ionic liquids for CaCO3 crystals growth was dependent on the counter anion very much.
In this paper, the effect of ionic liquids on the CaCO3 crystal growth has been studied for the first time. The obtained CaCO3 crystals were charactered by the X-ray diffraction and scanning electron micrographs. The results showed that the control ability of ionic liquids for CaCO3 crystals growth was dependent on the counter anion very much.
2004, 15(6): 711-713
Abstract:
A novel method based on continuous wavelet transform (CWT) for predicting the number and location of helices in membrane proteins is presented. The PDB code of 1yst is chosen as an example to describe the prediction of transmembrane helices (HTM) by using CWT. The results indicate that CWT is a promising approach for the prediction of HTM.
A novel method based on continuous wavelet transform (CWT) for predicting the number and location of helices in membrane proteins is presented. The PDB code of 1yst is chosen as an example to describe the prediction of transmembrane helices (HTM) by using CWT. The results indicate that CWT is a promising approach for the prediction of HTM.
2004, 15(6): 714-716
Abstract:
Polyoxometalates (POMs) α-K8 H6[Si2W18Ti6O77] (Si2W18Ti6) loaded starch nanop-articles have been prepared and structurally characterized by elemental analyses, IR spectra and 29Si spectroscopy. The particle size of Si2W18Ti6/starch was estimated by a Transmission electron microscope (TEM) and a 1000HSA MALVIRN Zetasizer instrument. The result shows that the polyoxometalate retained the parent structure after encapsulated by starch microspheres.
Polyoxometalates (POMs) α-K8 H6[Si2W18Ti6O77] (Si2W18Ti6) loaded starch nanop-articles have been prepared and structurally characterized by elemental analyses, IR spectra and 29Si spectroscopy. The particle size of Si2W18Ti6/starch was estimated by a Transmission electron microscope (TEM) and a 1000HSA MALVIRN Zetasizer instrument. The result shows that the polyoxometalate retained the parent structure after encapsulated by starch microspheres.
2004, 15(6): 717-720
Abstract:
The multiwall carbon nanotube (MWCNT) bonded to 2, 9, 16, 23-tetraamino manganese phthalocyanine (TAMnPc) was obtained by covalent functionalization, and its chemical structure was characterized by TEM. The photoconductivity of single-layered photoreceptors, where MWCNT bonded by TAMnPc (MWCNT-b-TAMnPc) served as the charge generation material (CGM), was also studied.
The multiwall carbon nanotube (MWCNT) bonded to 2, 9, 16, 23-tetraamino manganese phthalocyanine (TAMnPc) was obtained by covalent functionalization, and its chemical structure was characterized by TEM. The photoconductivity of single-layered photoreceptors, where MWCNT bonded by TAMnPc (MWCNT-b-TAMnPc) served as the charge generation material (CGM), was also studied.
2004, 15(6): 721-724
Abstract:
Dy0.8Sr0.2FeO3 nano powder, a synthetic oxide, is made by sol-gel method from metal nitrate and diethylenetriaminepentaacetic acid (DTPA), and the processing parameters are optimized. The process of the preparation, thermal decomposition and the property of the powder are studied by TG-DTA, IR, TEM, and XRD. The diameter of the average grain is about 70 nm. This new technique can be used in the preparation and the studying of na'no materials in the complex oxide system.
Dy0.8Sr0.2FeO3 nano powder, a synthetic oxide, is made by sol-gel method from metal nitrate and diethylenetriaminepentaacetic acid (DTPA), and the processing parameters are optimized. The process of the preparation, thermal decomposition and the property of the powder are studied by TG-DTA, IR, TEM, and XRD. The diameter of the average grain is about 70 nm. This new technique can be used in the preparation and the studying of na'no materials in the complex oxide system.
2004, 15(6): 725-728
Abstract:
Mixture formed from sonicating TiCl4 and Si(OEt)4 in the absence of water is used as precursor and hydrolyzed by using a long-chain organic ammonium bromide as a structure-directing agent. The product, titania-silica, is of mesoporous structure and characterized with SEM, FT-IR, BET, XRD and so on.
Mixture formed from sonicating TiCl4 and Si(OEt)4 in the absence of water is used as precursor and hydrolyzed by using a long-chain organic ammonium bromide as a structure-directing agent. The product, titania-silica, is of mesoporous structure and characterized with SEM, FT-IR, BET, XRD and so on.
2004, 15(6): 729-732
Abstract:
Polyurea microcapsules about 2.5μm in diameter containing phase change material for thermal energy storage application were synthesized and characterized by interfacial polycondensation method with toluene-2, 4-diisocyanate and ethylenediamine as monomers in an emulsion system. Hexadecane was used as a phase change material and OP, which is nonionic surfactant, and used as an emulsifier. The chemical structure and thermal behavior of the microcapsules were investigated by FTIR and thermal analysis respectively. The results show encapsulated hexadecane has a good potential as a solar energy storage material.
Polyurea microcapsules about 2.5μm in diameter containing phase change material for thermal energy storage application were synthesized and characterized by interfacial polycondensation method with toluene-2, 4-diisocyanate and ethylenediamine as monomers in an emulsion system. Hexadecane was used as a phase change material and OP, which is nonionic surfactant, and used as an emulsifier. The chemical structure and thermal behavior of the microcapsules were investigated by FTIR and thermal analysis respectively. The results show encapsulated hexadecane has a good potential as a solar energy storage material.
2004, 15(6): 733-736
Abstract:
The synthesis of ZnO prickly spheres using precipitation followed by heating treatment was investigated. Zn(OH)2 precursor was prepared by precipitation process using Zn(CH3COO·2·2H2O in mixed 1-propanol-water solvent. Sodium dodecyl sulfate (SDS) as the anionic surfactant was added to control the morphology. The size and structure of ZnO prickly spheres were studied using XRD, TEM and SEM. The results showed that the morphologies and size of the spheres strongly depended on the volume ratio of 1-propanol/water and molar ratio of SDS/Zn2+. ZnO prickly spheres composed of nanorods could be obtained, when the volume ratio of 1-propanol/water=2:3 and the molar ratio of Zn2+/SDS≈450:1.
The synthesis of ZnO prickly spheres using precipitation followed by heating treatment was investigated. Zn(OH)2 precursor was prepared by precipitation process using Zn(CH3COO·2·2H2O in mixed 1-propanol-water solvent. Sodium dodecyl sulfate (SDS) as the anionic surfactant was added to control the morphology. The size and structure of ZnO prickly spheres were studied using XRD, TEM and SEM. The results showed that the morphologies and size of the spheres strongly depended on the volume ratio of 1-propanol/water and molar ratio of SDS/Zn2+. ZnO prickly spheres composed of nanorods could be obtained, when the volume ratio of 1-propanol/water=2:3 and the molar ratio of Zn2+/SDS≈450:1.
2004, 15(6): 737-740
Abstract:
Following hydrothermal synthesis process, MCM-41 was synthesized by using cetyltriethylammonium bromide as templating agent. The experimental results showed that MCM-41 with pore diameter in the range of 4-7 nm can be obtained by adjusting nSurf./nSi. It was proved that cetyltriethylammonium bromide is an effective templating agent for increasing pore diameter of molecular sieve MCM-41.
Following hydrothermal synthesis process, MCM-41 was synthesized by using cetyltriethylammonium bromide as templating agent. The experimental results showed that MCM-41 with pore diameter in the range of 4-7 nm can be obtained by adjusting nSurf./nSi. It was proved that cetyltriethylammonium bromide is an effective templating agent for increasing pore diameter of molecular sieve MCM-41.
2004, 15(6): 741-744
Abstract:
In this paper, formamide was firstly used as plasticizer to prepare thermoplastic starch (TPS), which could suppress the retrogradation of TPS by X-ray diffractometry (XRD) and show a good flexibility, but was weaker than conventional glycerol-plasticized TPS (GPTPS). When urea was introduced into plasticizer, both the retrogradation and mechanical properties were ameliorated. The tensile stress, strain and energy break of TPS plasticized by urea (wt. 20%) and formamide (wt.10%), respectively, reached 4.83 MPa, 104.6% and 2.17 N·m (Newton?meter) after it had been stored at relative humidity (RH) 30% for one week.
In this paper, formamide was firstly used as plasticizer to prepare thermoplastic starch (TPS), which could suppress the retrogradation of TPS by X-ray diffractometry (XRD) and show a good flexibility, but was weaker than conventional glycerol-plasticized TPS (GPTPS). When urea was introduced into plasticizer, both the retrogradation and mechanical properties were ameliorated. The tensile stress, strain and energy break of TPS plasticized by urea (wt. 20%) and formamide (wt.10%), respectively, reached 4.83 MPa, 104.6% and 2.17 N·m (Newton?meter) after it had been stored at relative humidity (RH) 30% for one week.
2004, 15(6): 745-748
Abstract:
The alcoholysis mechanism of 1, 2-thiazetidine-1, 1-dioxide with methanol, in which the relatively stable product is sulfonate ester, has been investigated by quantum chemical method. Our calculations indicate the reaction for alcoholysis of 1, 2-thiazetidine-1, 1-dioxide proceeds via two possible mechanisms:concerted and stepwise. In the stepwise mechanism, two possible reaction pathways can be followed while only one possible reaction pathway can be followed in the concerted mechanism.
The alcoholysis mechanism of 1, 2-thiazetidine-1, 1-dioxide with methanol, in which the relatively stable product is sulfonate ester, has been investigated by quantum chemical method. Our calculations indicate the reaction for alcoholysis of 1, 2-thiazetidine-1, 1-dioxide proceeds via two possible mechanisms:concerted and stepwise. In the stepwise mechanism, two possible reaction pathways can be followed while only one possible reaction pathway can be followed in the concerted mechanism.
2004, 15(6): 749-752
Abstract:
For the Na+I2 collision system, theoretical study is performed on the QCISD(T) level by using ab initio method. The ab initio potential energy surfaces are got and on them the long-lived complexes are found and optimized. These results verify the crossed molecule beam experimental phenomenon and the detailed geometry structures are given for the first time. The role of the complexes in the reaction path is also described in detail.
For the Na+I2 collision system, theoretical study is performed on the QCISD(T) level by using ab initio method. The ab initio potential energy surfaces are got and on them the long-lived complexes are found and optimized. These results verify the crossed molecule beam experimental phenomenon and the detailed geometry structures are given for the first time. The role of the complexes in the reaction path is also described in detail.
2004, 15(6): 753-756
Abstract:
A quantitative structure-property relationship (QSPR) was made for the prediction of the hyperpolarizabilities(β) of para-disubstituted benzenes with the nonlinear optical properties, and the βcal2 calculated by this model accorded better with the experimental values (βexpt) compared with the βcal1 calculated at the CPHF/6-31G*//HF/STO-3G level of theory, especially when β was big.
A quantitative structure-property relationship (QSPR) was made for the prediction of the hyperpolarizabilities(β) of para-disubstituted benzenes with the nonlinear optical properties, and the βcal2 calculated by this model accorded better with the experimental values (βexpt) compared with the βcal1 calculated at the CPHF/6-31G*//HF/STO-3G level of theory, especially when β was big.
