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1991 Volume 2 Issue 12
1991, 2(12): 907-910
Abstract:
When the mixture of CpTiCl3-KI is used, many acetals and ketals, which are difficuitly deprotected with CpTiCl3 alone, can be easily converted to the corresponding carbonyl compounds in high yield at 30℃ in Et2O.
When the mixture of CpTiCl3-KI is used, many acetals and ketals, which are difficuitly deprotected with CpTiCl3 alone, can be easily converted to the corresponding carbonyl compounds in high yield at 30℃ in Et2O.
1991, 2(12): 911-912
Abstract:
In this paper, we investigated the selective cleavage of acyclic acetals with the reagent system, ZrCl4-LiAlH4. The results indicate that this system is very useful for the cleavage of acyclic acetals to the corresponding asymmetric ethers.
In this paper, we investigated the selective cleavage of acyclic acetals with the reagent system, ZrCl4-LiAlH4. The results indicate that this system is very useful for the cleavage of acyclic acetals to the corresponding asymmetric ethers.
1991, 2(12): 913-916
Abstract:
A comparative study is made on the efficiencies of three initiators ofFe2+-H2O2, K2S2O8, KMnO4 in the grafting of acrylamide onto starch. Of the three initiators the best one is KMnO4. Moreover, the kinetic equation is also studied.
A comparative study is made on the efficiencies of three initiators ofFe2+-H2O2, K2S2O8, KMnO4 in the grafting of acrylamide onto starch. Of the three initiators the best one is KMnO4. Moreover, the kinetic equation is also studied.
1991, 2(12): 917-918
Abstract:
Synthesis of 1-(2-imidazolylazo)-2-naphthol-4-sulfonic acid is described including its physical and chemical properties and spectroscopic data. The reagent reacts with various transition metal ions to form water-soluble and colored chelates which can be decomposed by EDTA exoept cobalt chelate. Present method has good selectivity.
Synthesis of 1-(2-imidazolylazo)-2-naphthol-4-sulfonic acid is described including its physical and chemical properties and spectroscopic data. The reagent reacts with various transition metal ions to form water-soluble and colored chelates which can be decomposed by EDTA exoept cobalt chelate. Present method has good selectivity.
1991, 2(12): 919-920
Abstract:
A new route was developed for diastereoselective preparation of δ-(α-hydroxyalkyl)-αβ-unsaturated δ-lactones. A single diastereoisomer(14) of the lactone was obtained after oxidation and elimination of (12).
A new route was developed for diastereoselective preparation of δ-(α-hydroxyalkyl)-αβ-unsaturated δ-lactones. A single diastereoisomer(14) of the lactone was obtained after oxidation and elimination of (12).
1991, 2(12): 921-924
Abstract:
A modified method for preparation and purification of Schiff base and protonated Schiff base from 9-cis-retinal has been suggested. Reaction took place in chloroform phase and purification was conducted by using water to remove the excess solvent, base and acid
A modified method for preparation and purification of Schiff base and protonated Schiff base from 9-cis-retinal has been suggested. Reaction took place in chloroform phase and purification was conducted by using water to remove the excess solvent, base and acid
1991, 2(12): 925-926
Abstract:
Dihydro-1-benzoyl-1,5-benzodiazepines react with (ethoxycarbonyl)carbenes to give 4H-azirino-[1,2-a] [1,5]-benzodiazepines and unexpected new ring system 1H-pyrrolo-[1,2-a] [1,5]-benzodiazepines. Dihydro-1,5-benzothiazepines react with (ethoxycarbonyl)carbenes in cyclohexane to gire unexpected ring cleavage products ethyl (2E, 4E)-3-aryl-2-arylthiohexadienoates.
Dihydro-1-benzoyl-1,5-benzodiazepines react with (ethoxycarbonyl)carbenes to give 4H-azirino-[1,2-a] [1,5]-benzodiazepines and unexpected new ring system 1H-pyrrolo-[1,2-a] [1,5]-benzodiazepines. Dihydro-1,5-benzothiazepines react with (ethoxycarbonyl)carbenes in cyclohexane to gire unexpected ring cleavage products ethyl (2E, 4E)-3-aryl-2-arylthiohexadienoates.
1991, 2(12): 927-928
Abstract:
The optically active R-4-phenyl-2-hydroxy butyrates were prepared by esterification of the racemic acid or transesterification of the racemic ester catalyzed by lipase from Candida cyclindra (CCL) in organic media.
The optically active R-4-phenyl-2-hydroxy butyrates were prepared by esterification of the racemic acid or transesterification of the racemic ester catalyzed by lipase from Candida cyclindra (CCL) in organic media.
1991, 2(12): 929-932
Abstract:
A stereocontrolled construction of the side chain of brassinclide and homobrassinolide has been achieved via the tandem vicinal dialkylation of the pyranone moiety as a key step.
A stereocontrolled construction of the side chain of brassinclide and homobrassinolide has been achieved via the tandem vicinal dialkylation of the pyranone moiety as a key step.
1991, 2(12): 933-934
Abstract:
The rearrangement of α-substituted phenyl-α, α'-dimethoxypropanones (R1) was recently proved to he an[1, 3] siqmatropic migration of methoxy group by study of LFER, solvent effect, crossover experiment, and by other means. The rearrangement catalysed by trace of totuenesulfonic acid gave a negligible value of the Hammett reaction constant. Further experimental results show that the electronic effect of substituent on the aromatic ring for the rearrangement in neutral medium is much greater (Table 1). We propose sigmatropic migration of alkoxy group be induced by molecular polarization.
The rearrangement of α-substituted phenyl-α, α'-dimethoxypropanones (R1) was recently proved to he an[1, 3] siqmatropic migration of methoxy group by study of LFER, solvent effect, crossover experiment, and by other means. The rearrangement catalysed by trace of totuenesulfonic acid gave a negligible value of the Hammett reaction constant. Further experimental results show that the electronic effect of substituent on the aromatic ring for the rearrangement in neutral medium is much greater (Table 1). We propose sigmatropic migration of alkoxy group be induced by molecular polarization.
1991, 2(12): 935-936
Abstract:
A new sesquitcrpene was isolated from Celastrus rothornianus, its structure was clucidated mainly on the basis of spectral analysis.
A new sesquitcrpene was isolated from Celastrus rothornianus, its structure was clucidated mainly on the basis of spectral analysis.
1991, 2(12): 937-940
Abstract:
Triptolide(1) gave 2-9 under various conditions specified in the text.
Triptolide(1) gave 2-9 under various conditions specified in the text.
1991, 2(12): 941-944
Abstract:
Three-layer back-propagation neural networks were used for processing the information provided by the ultraviolet spectra of five-component mixtures, affecting the simultaneous determination of the components with satisfactory results.
Three-layer back-propagation neural networks were used for processing the information provided by the ultraviolet spectra of five-component mixtures, affecting the simultaneous determination of the components with satisfactory results.
1991, 2(12): 945-948
Abstract:
The voltammetric behavior of indigo carmine at mercury film electrode on a silver substrate (MFES) was studied in this paper. It was found that indigo carmine gave a sensitive reduction peak at a potential (Vp) of-0.11 V at pH 4.0 in aqueous solution. The MFES gave good reproducibility and life time. The peak currents (ip) depended lipearly on the concentrations of indigo carmine free 0 to 100 ng/ml.
The voltammetric behavior of indigo carmine at mercury film electrode on a silver substrate (MFES) was studied in this paper. It was found that indigo carmine gave a sensitive reduction peak at a potential (Vp) of-0.11 V at pH 4.0 in aqueous solution. The MFES gave good reproducibility and life time. The peak currents (ip) depended lipearly on the concentrations of indigo carmine free 0 to 100 ng/ml.
1991, 2(12): 949-952
Abstract:
The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid in the presence of diethylamine and ethanol have been measured by normal and third-derivative spectrophotometry. Their molar absorptivities are 70.7 l.mol-1.cm-1 for Nd and 62.5 l.mol-1.cm-1 for Er. They are 7.6 times and 14.9 times greater than those of corresponding chlorides, respectively. Use of the third-derivative spectra both eliminates the interference of Ce(Ⅳ) and increases the sensitivity for Nd and Er. Beer,s Law was obeyed from 0-10 ug/ml of Nd and Er. The method has been applied to the determination of neodymium and erbium in rare earth mixtures.
The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid in the presence of diethylamine and ethanol have been measured by normal and third-derivative spectrophotometry. Their molar absorptivities are 70.7 l.mol-1.cm-1 for Nd and 62.5 l.mol-1.cm-1 for Er. They are 7.6 times and 14.9 times greater than those of corresponding chlorides, respectively. Use of the third-derivative spectra both eliminates the interference of Ce(Ⅳ) and increases the sensitivity for Nd and Er. Beer,s Law was obeyed from 0-10 ug/ml of Nd and Er. The method has been applied to the determination of neodymium and erbium in rare earth mixtures.
1991, 2(12): 953-956
Abstract:
A sensitive and selective method has been developed for the detection of free ethacrynic acid in human urine. Using 4-(bromomethyl)-7-methoxycoumarin, ethacrynic acid was transformed into a fluorescent derivative, and was analysed by HPLC-fluorescence detector. The detection limit is 0.1ug/ml urine. The method is suitable for screening ethacrynic acid in doping control and studying its metabolism.
A sensitive and selective method has been developed for the detection of free ethacrynic acid in human urine. Using 4-(bromomethyl)-7-methoxycoumarin, ethacrynic acid was transformed into a fluorescent derivative, and was analysed by HPLC-fluorescence detector. The detection limit is 0.1ug/ml urine. The method is suitable for screening ethacrynic acid in doping control and studying its metabolism.
1991, 2(12): 957-960
Abstract:
A series of new complexes of formula Ln (acac)3 (Ph3PO)3 (where Ln3+=Nd3+, Sm3+, Eu3+, Tb3+, Ho3+) have been prepared and characterized. The coordination of two ligands with lanthanide ions are studied by IR spectra, 1H, 13C, 31P-NMR and metal-ligand charge tranafer tranaition is also discussed via electronic adaorption and luminescence spectroscopy.
A series of new complexes of formula Ln (acac)3 (Ph3PO)3 (where Ln3+=Nd3+, Sm3+, Eu3+, Tb3+, Ho3+) have been prepared and characterized. The coordination of two ligands with lanthanide ions are studied by IR spectra, 1H, 13C, 31P-NMR and metal-ligand charge tranafer tranaition is also discussed via electronic adaorption and luminescence spectroscopy.
1991, 2(12): 961-962
Abstract:
The crystat structure of {[Er2(L-Glu)2 (H2O)6] (ClO4)2·3H2O)2 has been studied by X-ray diffraction. The crystal is monoctinic with space group P21 and cell parameters a=19.987(3)Å, b=16.505(3)Å, c=11.040(2)Å, β=104.69(1)°, V=3538(1)Å3, Z=2, Dc=2.29 g. cm-3, μ=53.2 cm-1, F(000)=2384. The asymmetric unit contains two complex motecules and four centre ions. Each erbium (Ⅲ) is coordinated by five oxygen donors from four different glutamates and four oxygen donors from the aqua ligand to form a nine coordination potyhedron. The mean distances of Er-0 (carboxylate) and Er-Ow are 2.439Å and 2.416Å respectivety. The finat R and Rw are 0.043 and 0.058, respectivety.
The crystat structure of {[Er2(L-Glu)2 (H2O)6] (ClO4)2·3H2O)2 has been studied by X-ray diffraction. The crystal is monoctinic with space group P21 and cell parameters a=19.987(3)Å, b=16.505(3)Å, c=11.040(2)Å, β=104.69(1)°, V=3538(1)Å3, Z=2, Dc=2.29 g. cm-3, μ=53.2 cm-1, F(000)=2384. The asymmetric unit contains two complex motecules and four centre ions. Each erbium (Ⅲ) is coordinated by five oxygen donors from four different glutamates and four oxygen donors from the aqua ligand to form a nine coordination potyhedron. The mean distances of Er-0 (carboxylate) and Er-Ow are 2.439Å and 2.416Å respectivety. The finat R and Rw are 0.043 and 0.058, respectivety.
1991, 2(12): 963-966
Abstract:
PASCA, ESR and Microreactor, have been used to study the states and properties of coking deposits on catalyst. The results indicate that the C exists as three types of states on catalyst surface. The first and second types of carbon are the main reason of the catalyst deactivation, but the third type has a promoting role in n-C7 hydrocracking reaction. The Ss-C interacts strongly with catalyst, forming metal-carbon-support interaction (MCSI).
PASCA, ESR and Microreactor, have been used to study the states and properties of coking deposits on catalyst. The results indicate that the C exists as three types of states on catalyst surface. The first and second types of carbon are the main reason of the catalyst deactivation, but the third type has a promoting role in n-C7 hydrocracking reaction. The Ss-C interacts strongly with catalyst, forming metal-carbon-support interaction (MCSI).
1991, 2(12): 967-970
Abstract:
Na2CO3/ZrO2 catalyst shows a high activity of oxidative coupling of methane. It possesses stronger electron donor ability than that of ZrO2 catalyst. The activation of methane is supposed to relate to the O2- or O22-and O- species.
Na2CO3/ZrO2 catalyst shows a high activity of oxidative coupling of methane. It possesses stronger electron donor ability than that of ZrO2 catalyst. The activation of methane is supposed to relate to the O2- or O22-and O- species.
1991, 2(12): 971-972
Abstract:
6 kinds of IPN's PVA were synthesized by using different monomers of HEMA, MAA and MMA. The effect of adding polysaccharide was also studied. The cell growth on them were determined and compared. The results showed that the cell growth property of the IPN's PVA with hydrophobic monomer of MMA is better, and it can be improved further by adding hyaluronic acid.
6 kinds of IPN's PVA were synthesized by using different monomers of HEMA, MAA and MMA. The effect of adding polysaccharide was also studied. The cell growth on them were determined and compared. The results showed that the cell growth property of the IPN's PVA with hydrophobic monomer of MMA is better, and it can be improved further by adding hyaluronic acid.
1991, 2(12): 973-974
Abstract:
Ultrafine particle (UFP)alumina has been prepared by supereritical fluid drying process of inorganic salt with organic solvent system, which is reported for the first time. UFP-alumina prepared from this system is featured by its hish specific surface area, large pore volume, small perticle size and low bulk density.
Ultrafine particle (UFP)alumina has been prepared by supereritical fluid drying process of inorganic salt with organic solvent system, which is reported for the first time. UFP-alumina prepared from this system is featured by its hish specific surface area, large pore volume, small perticle size and low bulk density.
1991, 2(12): 975-978
Abstract:
The concept of pseudo orbital has been proposed, which includes the interactions of all the orbitals and extends the applicable limit of Fukui's frontier orbitals. An example shows that the pseudo orbital reactivity indexes are probably able to explain more complicated phenomena in chemical reactions.
The concept of pseudo orbital has been proposed, which includes the interactions of all the orbitals and extends the applicable limit of Fukui's frontier orbitals. An example shows that the pseudo orbital reactivity indexes are probably able to explain more complicated phenomena in chemical reactions.
1991, 2(12): 979-982
Abstract:
New synthetic condition in a wide temperature range from 110℃ to 190℃ was employed to crystallize DBA-VPI-5. The phase transformation of the samples prepared at different temperatures was measured by high-temperature x-ray diffraction technique.
New synthetic condition in a wide temperature range from 110℃ to 190℃ was employed to crystallize DBA-VPI-5. The phase transformation of the samples prepared at different temperatures was measured by high-temperature x-ray diffraction technique.
