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1998 Volume 9 Issue 9
1998, 9(9): 791-793
Abstract:
Reaction of 5'-O-p-methoxytritylthymidine with 1,1'-carbonyl-diimidazole gave the 3'-O-carbonylimidazolide, which was condensed in high yield with 3'-0-protected thymidine to give a dinucleoside carbonate. In the synthesis of dinucleoside carbonate, allyl can be used as a good protecting group for 3'-hydroxyl of thymidine. The condition of deprotection will not affect the carbonate bridges.
Reaction of 5'-O-p-methoxytritylthymidine with 1,1'-carbonyl-diimidazole gave the 3'-O-carbonylimidazolide, which was condensed in high yield with 3'-0-protected thymidine to give a dinucleoside carbonate. In the synthesis of dinucleoside carbonate, allyl can be used as a good protecting group for 3'-hydroxyl of thymidine. The condition of deprotection will not affect the carbonate bridges.
1998, 9(9): 795-796
Abstract:
Ketones react with hydroxylamine hydrochloride over HC00H/Si02 under microwave irradiation to afford amides in good yields.
Ketones react with hydroxylamine hydrochloride over HC00H/Si02 under microwave irradiation to afford amides in good yields.
1998, 9(9): 797-798
Abstract:
A convenient and practical synthetic route for 2,4-dibromo-5-fluorobenzoic acid is described. Two intermediates, 2,4-dibromo-5-fluorobenzonitrile and 2,4-dibromo-5-fluoro-benzamide, have not been reported before. This route can be easily industrialized.
A convenient and practical synthetic route for 2,4-dibromo-5-fluorobenzoic acid is described. Two intermediates, 2,4-dibromo-5-fluorobenzonitrile and 2,4-dibromo-5-fluoro-benzamide, have not been reported before. This route can be easily industrialized.
1998, 9(9): 799-800
Abstract:
Two novel Acetophenones, 4-(1'-geranyloxy)-2,6-dihydroxyacetophenone 1 and 4-(1'-farnesyl)-2,6-dihydroxyacetophenone 2 isolated from the fruit of Evodia merrillii and from the aerial parts of Borronia ramosa respectively, have been synthesized by starting from 2,4,6-trihydroxyacetophenone 3.
Two novel Acetophenones, 4-(1'-geranyloxy)-2,6-dihydroxyacetophenone 1 and 4-(1'-farnesyl)-2,6-dihydroxyacetophenone 2 isolated from the fruit of Evodia merrillii and from the aerial parts of Borronia ramosa respectively, have been synthesized by starting from 2,4,6-trihydroxyacetophenone 3.
1998, 9(9): 801-802
Abstract:
The new synthetic method of isoxazole derivatives was succesfully achieved. The experimental results demonstrate that thermal decomposition reactions of nitrone could take place with yields of 41~81%, to give a series of new isoxazole derivatives.
The new synthetic method of isoxazole derivatives was succesfully achieved. The experimental results demonstrate that thermal decomposition reactions of nitrone could take place with yields of 41~81%, to give a series of new isoxazole derivatives.
1998, 9(9): 803-804
Abstract:
Treatment of 3-aroylethylsydnone 1 with HC1 leads to 3-arylpyrazoline 2 or 1-aroylethyl-3-arylpyrazoline 3 under different conditions.
Treatment of 3-aroylethylsydnone 1 with HC1 leads to 3-arylpyrazoline 2 or 1-aroylethyl-3-arylpyrazoline 3 under different conditions.
1998, 9(9): 805-807
Abstract:
A convenient cyclization method for the flavans synthesis is described. BF3 was used for the first time as an efficient catalyst to effect the cyclization of 1,3-diarylpropan-l-ols.
A convenient cyclization method for the flavans synthesis is described. BF3 was used for the first time as an efficient catalyst to effect the cyclization of 1,3-diarylpropan-l-ols.
1998, 9(9): 809-812
Abstract:
Fluorinated polyether dendritic sectors 4,7 and 10 from the first to the third generations, respectively, were prepared by a convergent approach from readily available pentafluorophenol, phloroglucinol and 1,3-dibromopropane. These dendritic sectors have good solubility properties and are stable in both acidic and basic media. Hence they are useful dendritic building blocks for the preparation of functional dendrimers.
Fluorinated polyether dendritic sectors 4,7 and 10 from the first to the third generations, respectively, were prepared by a convergent approach from readily available pentafluorophenol, phloroglucinol and 1,3-dibromopropane. These dendritic sectors have good solubility properties and are stable in both acidic and basic media. Hence they are useful dendritic building blocks for the preparation of functional dendrimers.
1998, 9(9): 813-814
Abstract:
Key intermediate bis[2-amino-4,5-(15-crown-5)phenyl]diselenide was obtained by the convenient redox method. Crown-ether type host molecule containing Se-Se bond 2,11-dioxo-4,5:8,9-di(benzo[4',5']-15-crown-5)-6,7-diselena-3,10,16-triazabicyclo[10,3,l]hexadeca-1(16), 4, 8,12, 14-pentaene was synthesized with high dillution technique.
Key intermediate bis[2-amino-4,5-(15-crown-5)phenyl]diselenide was obtained by the convenient redox method. Crown-ether type host molecule containing Se-Se bond 2,11-dioxo-4,5:8,9-di(benzo[4',5']-15-crown-5)-6,7-diselena-3,10,16-triazabicyclo[10,3,l]hexadeca-1(16), 4, 8,12, 14-pentaene was synthesized with high dillution technique.
1998, 9(9): 815-816
Abstract:
Synthesis of spirobenzopyrans bearing monoazacrown at the 8-position is described.
Synthesis of spirobenzopyrans bearing monoazacrown at the 8-position is described.
1998, 9(9): 817-818
Abstract:
A stereoselective total synthesis of 6β-hydroxy-7α(H)-eudesma-4-en-3-one 1 starting from (+)-dihydrocarvone 7 has been described.
A stereoselective total synthesis of 6β-hydroxy-7α(H)-eudesma-4-en-3-one 1 starting from (+)-dihydrocarvone 7 has been described.
1998, 9(9): 819-822
Abstract:
The repeat unit of Candida kefyr IFO 0586 strain was designed, and a protected pentasaccharide was synthesized by thirteen-step reactions. Trichloroacetoxy was used as leaving group at anomeric carbon.
The repeat unit of Candida kefyr IFO 0586 strain was designed, and a protected pentasaccharide was synthesized by thirteen-step reactions. Trichloroacetoxy was used as leaving group at anomeric carbon.
1998, 9(9): 823-826
Abstract:
Methylene blue sensitized singlet oxygen oxidation of dl-a-tocopherol in dodecyl sulfate (SDS) or cetyl trimethyl ammonium bromide (CTAB) micelles led to the formation, besides a-tocopherol quinone and its epoxide, of a hitherto unknown spiro compound 6-hydroxy-2,6,8,9-tetramethyl-2-phytyl-1-oxaspiro[4,5]dec-8-en-7,10-dione.
Methylene blue sensitized singlet oxygen oxidation of dl-a-tocopherol in dodecyl sulfate (SDS) or cetyl trimethyl ammonium bromide (CTAB) micelles led to the formation, besides a-tocopherol quinone and its epoxide, of a hitherto unknown spiro compound 6-hydroxy-2,6,8,9-tetramethyl-2-phytyl-1-oxaspiro[4,5]dec-8-en-7,10-dione.
1998, 9(9): 827-828
Abstract:
Terminalic acid 1, a new hydrolysable tannin, was isolated from the fruit of Terminalia chebula. Its structure was found to be l-0-galloyl-2,4-chebuloyl-β-D-glucopyranose by chemical method and 1HNMR, 13C-NMR, 1H-1H COSY, HMQC, HMBC and FAB-MS spectral analyses.
Terminalic acid 1, a new hydrolysable tannin, was isolated from the fruit of Terminalia chebula. Its structure was found to be l-0-galloyl-2,4-chebuloyl-β-D-glucopyranose by chemical method and 1HNMR, 13C-NMR, 1H-1H COSY, HMQC, HMBC and FAB-MS spectral analyses.
1998, 9(9): 829-832
Abstract:
A new dimeric guaianolide, artselenoide, was isolated from Artemisia selengensis. Its structure was elucidated by spectroscopic methods.
A new dimeric guaianolide, artselenoide, was isolated from Artemisia selengensis. Its structure was elucidated by spectroscopic methods.
1998, 9(9): 833-834
Abstract:
WB, a new antifungal antibiotic, was isolated from the soil fungus strain 38 against Pyricularia oryzae, and its structure was elucidated as 2-[(E)-3,5-dimethyl-3,4-dihydroxy-1-eptylenyl]-4-chloro-5-oxo-6-methyl-6,7-dihydroxy-5,6,7,7,-4H-benzo[d]-2H-pyran on the basis of 1H-NMR, 13C-NMR, DEPT, HMQC, 1H-13H COSY, HMBC spectra.
WB, a new antifungal antibiotic, was isolated from the soil fungus strain 38 against Pyricularia oryzae, and its structure was elucidated as 2-[(E)-3,5-dimethyl-3,4-dihydroxy-1-eptylenyl]-4-chloro-5-oxo-6-methyl-6,7-dihydroxy-5,6,7,7,-4H-benzo[d]-2H-pyran on the basis of 1H-NMR, 13C-NMR, DEPT, HMQC, 1H-13H COSY, HMBC spectra.
1998, 9(9): 835-837
Abstract:
The optical properties of the fullerenated poly(epoxy propyl carbazole) (PEPC) have been investigated. Compared with pure PEPC, fullerenated PEPC has the same structure in the UV region of the absorption spectrum, and extends the active range to a longer wavelength. The apparent quenching of PEPC fluorescence was observed in the fullerenated polymer and it can be attributed to intramolecular excited state energy transfer.
The optical properties of the fullerenated poly(epoxy propyl carbazole) (PEPC) have been investigated. Compared with pure PEPC, fullerenated PEPC has the same structure in the UV region of the absorption spectrum, and extends the active range to a longer wavelength. The apparent quenching of PEPC fluorescence was observed in the fullerenated polymer and it can be attributed to intramolecular excited state energy transfer.
1998, 9(9): 839-842
Abstract:
The Mian Erkang capsules made by us is a high potency calcium preparation with actions of hypnosis and anti-decrepitude. Melatonin is one of the main effective components which can hypnotize, calm, relieve pain, increase the body's immunity, be used for cancer therapy, and delaydecrepitude. A rapid, sensitive, and accurate HPLC method for the determination of melatonin in Mian Erkang capsules is described in this paper.
The Mian Erkang capsules made by us is a high potency calcium preparation with actions of hypnosis and anti-decrepitude. Melatonin is one of the main effective components which can hypnotize, calm, relieve pain, increase the body's immunity, be used for cancer therapy, and delaydecrepitude. A rapid, sensitive, and accurate HPLC method for the determination of melatonin in Mian Erkang capsules is described in this paper.
1998, 9(9): 843-845
Abstract:
A flow injection chemiluminescence (CL) method for the determination of catecholamines is described which is based on their inhibition of the intensity of CL from the luminol-hypochlorite system. The hypochlorite was electrogenerated on-line by a constant current electrolysis, resulting in the elimination of the instability of the hypochlorite solution prepared from a commercial reagent of sodium hypochlorite. The detection limits are 0.6 ng/ml for dopamine, 0.8 ng/ml for adrenaline and isoprenaline. The proposed method has been successfully applied to the determination of catecholamines in pharmaceutical injections.
A flow injection chemiluminescence (CL) method for the determination of catecholamines is described which is based on their inhibition of the intensity of CL from the luminol-hypochlorite system. The hypochlorite was electrogenerated on-line by a constant current electrolysis, resulting in the elimination of the instability of the hypochlorite solution prepared from a commercial reagent of sodium hypochlorite. The detection limits are 0.6 ng/ml for dopamine, 0.8 ng/ml for adrenaline and isoprenaline. The proposed method has been successfully applied to the determination of catecholamines in pharmaceutical injections.
1998, 9(9): 847-850
Abstract:
Polysiloxane with pendant [60] fulleropyrrolidines was synthesized and used as the stationary phase for capillary gas chromatography for the first time. A preliminary investigation of its property shows that it has an excellent thermostability and a wide range of allowable operating temperature from 80℃ to 360℃.
Polysiloxane with pendant [60] fulleropyrrolidines was synthesized and used as the stationary phase for capillary gas chromatography for the first time. A preliminary investigation of its property shows that it has an excellent thermostability and a wide range of allowable operating temperature from 80℃ to 360℃.
1998, 9(9): 851-854
Abstract:
Chromium hexacyanoferrate (CrHCF) modified glassy carbon electrode (GC) in different electrolytes was studied by cyclic voltammetry and in situ FTIR spectroelectrochemistry. The results indicate that the behavior of CrHCF film can be understood in term of two structures: Cr1/3Cr(Ⅲ)Fe(Ⅱ)(CN)6 and MCr(Ⅲ)Fe(Ⅱ)(CN)6. Besides, the film exists in amorphous state: the outer layer is porous film, while the inner layer is relatively compact. According to the electrochemical reaction of CrHCF, the lattice can contract and expand with the cations' diffusion.
Chromium hexacyanoferrate (CrHCF) modified glassy carbon electrode (GC) in different electrolytes was studied by cyclic voltammetry and in situ FTIR spectroelectrochemistry. The results indicate that the behavior of CrHCF film can be understood in term of two structures: Cr1/3Cr(Ⅲ)Fe(Ⅱ)(CN)6 and MCr(Ⅲ)Fe(Ⅱ)(CN)6. Besides, the film exists in amorphous state: the outer layer is porous film, while the inner layer is relatively compact. According to the electrochemical reaction of CrHCF, the lattice can contract and expand with the cations' diffusion.
1998, 9(9): 855-857
Abstract:
The three potential surfaces for reactions of the O atom to abstract H atoms from CH2F2 and CH2Cl2 were studied using the ab initio method. The frequencies, geometries and energies of all species are calculated. The best estimates of the heat of reactions are 30.92 KJ/mol and 13.01 KJ/mol, and, the best potential barrier heights for both reactions are calculated to be 74.50 KJ/mol and 67.22 KJ/mol, respectively, the second-order rate coefficients calculated are 2.8721×10-21 and 4.2522×10-20cm3/molecule-s at 298 K, respectively.
The three potential surfaces for reactions of the O atom to abstract H atoms from CH2F2 and CH2Cl2 were studied using the ab initio method. The frequencies, geometries and energies of all species are calculated. The best estimates of the heat of reactions are 30.92 KJ/mol and 13.01 KJ/mol, and, the best potential barrier heights for both reactions are calculated to be 74.50 KJ/mol and 67.22 KJ/mol, respectively, the second-order rate coefficients calculated are 2.8721×10-21 and 4.2522×10-20cm3/molecule-s at 298 K, respectively.
1998, 9(9): 859-862
Abstract:
A new ab-initio method of computing reorganization energy (RE) for the electron transfer (ET) reaction between M-H and M+-H system is presented. Values of RE from precise RE definition and the George-Griffith-Marcus (GGM) model were obtained and compared with the RE obtained from the experimental spectroscopic data. Results show that in the gaseous phase, ET reactions by the new method can give better values than classical GGM model.
A new ab-initio method of computing reorganization energy (RE) for the electron transfer (ET) reaction between M-H and M+-H system is presented. Values of RE from precise RE definition and the George-Griffith-Marcus (GGM) model were obtained and compared with the RE obtained from the experimental spectroscopic data. Results show that in the gaseous phase, ET reactions by the new method can give better values than classical GGM model.
1998, 9(9): 863-866
Abstract:
Two competitive channels of the reaction of FO with CO were calculated by the TST-RRKM theory and the classical transition state theory, respectively. The results show that the direct channel dominates the reaction over the entire studied temperature range and the addition-elimination channel has important contributions at low temperatures. The cited reaction does not influence the fluorine regeneration and the sink of CO in the stratosphere.
Two competitive channels of the reaction of FO with CO were calculated by the TST-RRKM theory and the classical transition state theory, respectively. The results show that the direct channel dominates the reaction over the entire studied temperature range and the addition-elimination channel has important contributions at low temperatures. The cited reaction does not influence the fluorine regeneration and the sink of CO in the stratosphere.
1998, 9(9): 867-868
Abstract:
Nanofiltration of aqueous NaN03 solution with a dynamically formed Zr(IV) hydrous oxide-PAA membrane is presented. The practical transport coefficients Lp, σ, ω were obtained using relationships of the non-equilibrium thermodynamics and were used to calculate the frictional coefficients of a friction model.
Nanofiltration of aqueous NaN03 solution with a dynamically formed Zr(IV) hydrous oxide-PAA membrane is presented. The practical transport coefficients Lp, σ, ω were obtained using relationships of the non-equilibrium thermodynamics and were used to calculate the frictional coefficients of a friction model.
1998, 9(9): 869-872
Abstract:
Aluminoxanes containing both ethyl and wo-butyl groups were synthesized by the hydrolysis of Al(C2H3)3 (TEA)/A1(i-C4H9)3 (TIBA) mixtures. The aluminoxane made from the TCA/TIBA mixture of molar ratio 7:3 showed cocatalyst activity of about five times as those of ethylaluminoxane or isobutylaluminoxane for ethylene polymerization catalyzed by Cp2ZrCl2. The aluminoxane was characterized and the possible reasons for its high activity were discussed.
Aluminoxanes containing both ethyl and wo-butyl groups were synthesized by the hydrolysis of Al(C2H3)3 (TEA)/A1(i-C4H9)3 (TIBA) mixtures. The aluminoxane made from the TCA/TIBA mixture of molar ratio 7:3 showed cocatalyst activity of about five times as those of ethylaluminoxane or isobutylaluminoxane for ethylene polymerization catalyzed by Cp2ZrCl2. The aluminoxane was characterized and the possible reasons for its high activity were discussed.
1998, 9(9): 873-876
Abstract:
Cu-Ce-0 catalysts, prepared by the amorphous citrate precursor (ACP) method, were investigated by ICP, XRD and micro-reactor techniques. At low copper content of Cu-Ce-0 catalysts, fluorite structures formed at low calcining temperatures, and CuO doped into the CeO2 matrix; at high copper content, in addition to the fluorite structure, crystalline monoclinic phase CuO formed as well at high calcining temperatures. There was no other phase formed even calcined at 1000℃. The results show that only a little CuO dopes into the CeO2 matrix to form complex oxide, which promotes the catalytic activity of CO oxidation greatly. The optimum Cu-Ce-0 catalyst is composed of 15% copper by Cu/(Ce+Cu) atomic ratio, and calcined at 700℃ for 4h. The phase compositions include the crystalline CuO and the active complex oxide with fluorite structure. The formulation of the active complex oxide is Cu0.06Ce0.94O1.94.
Cu-Ce-0 catalysts, prepared by the amorphous citrate precursor (ACP) method, were investigated by ICP, XRD and micro-reactor techniques. At low copper content of Cu-Ce-0 catalysts, fluorite structures formed at low calcining temperatures, and CuO doped into the CeO2 matrix; at high copper content, in addition to the fluorite structure, crystalline monoclinic phase CuO formed as well at high calcining temperatures. There was no other phase formed even calcined at 1000℃. The results show that only a little CuO dopes into the CeO2 matrix to form complex oxide, which promotes the catalytic activity of CO oxidation greatly. The optimum Cu-Ce-0 catalyst is composed of 15% copper by Cu/(Ce+Cu) atomic ratio, and calcined at 700℃ for 4h. The phase compositions include the crystalline CuO and the active complex oxide with fluorite structure. The formulation of the active complex oxide is Cu0.06Ce0.94O1.94.
A New High Efficiency Green Luminescent Material—the System Al2O3-B2O3 Containing Ce3+ and Tb3+ Ions
1998, 9(9): 877-880
Abstract:
To obtain high efficiency luminescent materials, the system Al2O3-B2O3 containing Ce3+ and Tb3+ ions with variation of B203-content, has been prepared by Al203, H3B03, Ce02 and Tb407 under reducing atmosphere at 1250;æ. It is notable that the brightness of the sample with appropriate composition is similar to that of commercial phosphorous containing Ce3+ and Tb3+, indicating that a new high efficency green luminescent material was obtained with appropriate B203-content.
To obtain high efficiency luminescent materials, the system Al2O3-B2O3 containing Ce3+ and Tb3+ ions with variation of B203-content, has been prepared by Al203, H3B03, Ce02 and Tb407 under reducing atmosphere at 1250;æ. It is notable that the brightness of the sample with appropriate composition is similar to that of commercial phosphorous containing Ce3+ and Tb3+, indicating that a new high efficency green luminescent material was obtained with appropriate B203-content.
1998, 9(9): 881-884
Abstract:
Reaction of Zn(Cl04)2·6H2O with septadentate 2,6-bis[bis(2-benzimidazolyIme-thyl) amino methyl]-4-methylphenol(Hbbap) and sodium isonicotinate yielded a dinuclear zinc complex [Zn2(bbap) (Iso) (Hiso)] (ClO4)2·[Zn2 (bbap) (Iso) (H20)] (ClO4)2·4H20(la·lb·4H20). Hiso is isonicotinic acid and Iso is isonicotinate anion. The structure has been established by X-ray crystallography and shows that the two zinc ions are bridged by the phenoxy unit of bbap ligand, and the presence of unusual monodentate O-coordination of carboxylate group from isonicotinic acid. The coordination geometry around the zinc ion is approximately trigonal bipyramidal.
Reaction of Zn(Cl04)2·6H2O with septadentate 2,6-bis[bis(2-benzimidazolyIme-thyl) amino methyl]-4-methylphenol(Hbbap) and sodium isonicotinate yielded a dinuclear zinc complex [Zn2(bbap) (Iso) (Hiso)] (ClO4)2·[Zn2 (bbap) (Iso) (H20)] (ClO4)2·4H20(la·lb·4H20). Hiso is isonicotinic acid and Iso is isonicotinate anion. The structure has been established by X-ray crystallography and shows that the two zinc ions are bridged by the phenoxy unit of bbap ligand, and the presence of unusual monodentate O-coordination of carboxylate group from isonicotinic acid. The coordination geometry around the zinc ion is approximately trigonal bipyramidal.
