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1991 Volume 2 Issue 2
1991, 2(2): 95-98
Abstract:
A short synthesis starting from 4-imidazolylmethanol (2) was developed for the phosphonoisostere of histidine, α-amino-β-(4-imidazolyl)-ethylphosphosphonic acid, His (P) (1). The synthesis features Wittig-Horner reaction of aldehyde (4) with diphosphonate (5) followed by selective detritylation with 50% formic acid.
A short synthesis starting from 4-imidazolylmethanol (2) was developed for the phosphonoisostere of histidine, α-amino-β-(4-imidazolyl)-ethylphosphosphonic acid, His (P) (1). The synthesis features Wittig-Horner reaction of aldehyde (4) with diphosphonate (5) followed by selective detritylation with 50% formic acid.
1991, 2(2): 99-100
Abstract:
A series of estrone derivatives of amino acids and peptides have been synthesized by different coupling reagents and the binding affinity of deblocked derivatives to the estrogen receptor of rats uteri have been measured by a comptetive radiometric binding assay.
A series of estrone derivatives of amino acids and peptides have been synthesized by different coupling reagents and the binding affinity of deblocked derivatives to the estrogen receptor of rats uteri have been measured by a comptetive radiometric binding assay.
1991, 2(2): 101-102
Abstract:
3-Acetyltropolone was reacted with 2-aminobenzaldehydes to afford 3-(2-quinolyl) tropolones. 2-Acetyl-7-methylaminotropone and 2-acetyl-7-ethylamino-tropone were respectively reacted with 2-aminobenzaldehydes to give the corres-ponding 2-(2-quinolyl)-7-methylaminotropones and 2-(2-quinolyl)-7-ethylaminotro-pones, which after treatment with sodium hydroxide solution also afforded 3-(2-quinolyl) tropolones.
3-Acetyltropolone was reacted with 2-aminobenzaldehydes to afford 3-(2-quinolyl) tropolones. 2-Acetyl-7-methylaminotropone and 2-acetyl-7-ethylamino-tropone were respectively reacted with 2-aminobenzaldehydes to give the corres-ponding 2-(2-quinolyl)-7-methylaminotropones and 2-(2-quinolyl)-7-ethylaminotro-pones, which after treatment with sodium hydroxide solution also afforded 3-(2-quinolyl) tropolones.
1991, 2(2): 103-106
Abstract:
A new preparation method of the N-ethyl 7, 17-seco C19-diterpenoid alkaloids (5) and (6) by pyrolysis of the N-oxides (3) and (4), respectively, in anhydrous diglyme is described. A probable reaction mechanism for the pyrolysis is presented and studied preliminarily.
A new preparation method of the N-ethyl 7, 17-seco C19-diterpenoid alkaloids (5) and (6) by pyrolysis of the N-oxides (3) and (4), respectively, in anhydrous diglyme is described. A probable reaction mechanism for the pyrolysis is presented and studied preliminarily.
1991, 2(2): 107-110
Abstract:
Reaction of heterocycle substituted telluronium salts with aromatic aldehydes under mild conditions gave corresponding chalcones. In the presence of dibutyl telluride, 2-bromomethyl-5-nitrofuran condensed easily with aromatic aldehydes in THF to afford corresponding olefin derivatives as one-pot reaction.
Reaction of heterocycle substituted telluronium salts with aromatic aldehydes under mild conditions gave corresponding chalcones. In the presence of dibutyl telluride, 2-bromomethyl-5-nitrofuran condensed easily with aromatic aldehydes in THF to afford corresponding olefin derivatives as one-pot reaction.
1991, 2(2): 111-114
Abstract:
A formal synthesis of the natural growth promoting steroid brassinolide is described, which involves construction of side chain by 1, 3-sulfoxide-hydroxyl transposition with methylation from (24S)-22-E-24-sulfoxide 6 and (24R)-22-E-24-sulfoxide 9, respectively to (22S)-23-E-24-methyl compound 4.
A formal synthesis of the natural growth promoting steroid brassinolide is described, which involves construction of side chain by 1, 3-sulfoxide-hydroxyl transposition with methylation from (24S)-22-E-24-sulfoxide 6 and (24R)-22-E-24-sulfoxide 9, respectively to (22S)-23-E-24-methyl compound 4.
1991, 2(2): 115-118
Abstract:
A series of α-amino acids are obtained in 72-96% optical yields by alkylation of the ketimine derived from (+)-2-hydroxy-pinan-3-one and (-)-menthyl glycinate followed by hydrolysis of the alkylated intermediates with mineral acid. The double asymmetric induction are explained by the transition model of lithium enolate.
A series of α-amino acids are obtained in 72-96% optical yields by alkylation of the ketimine derived from (+)-2-hydroxy-pinan-3-one and (-)-menthyl glycinate followed by hydrolysis of the alkylated intermediates with mineral acid. The double asymmetric induction are explained by the transition model of lithium enolate.
1991, 2(2): 119-120
Abstract:
4, 4'-Oxybis (benzoic acid) (Ⅰ) is an important monomer for making synthetic resin, heat resistant film and liquid crystal fiber, etc. It has been synthesized either by the oxidation of 4, 4'-dimethyl diphenyl ether, or by the electrophilic substitution of diphenyl ether, those substituents introduced into the benzene ring can be further transformed into carboxylic groups. Diphenyl ethers are usually prepared from phenols and halobenzenes through Ullmann resction. Due to the high reaction temerature (usually above 200℃), long time heating and the formation of isomers, it is difficult to obtain pure products in high yields.
4, 4'-Oxybis (benzoic acid) (Ⅰ) is an important monomer for making synthetic resin, heat resistant film and liquid crystal fiber, etc. It has been synthesized either by the oxidation of 4, 4'-dimethyl diphenyl ether, or by the electrophilic substitution of diphenyl ether, those substituents introduced into the benzene ring can be further transformed into carboxylic groups. Diphenyl ethers are usually prepared from phenols and halobenzenes through Ullmann resction. Due to the high reaction temerature (usually above 200℃), long time heating and the formation of isomers, it is difficult to obtain pure products in high yields.
1991, 2(2): 121-122
Abstract:
An antitumour complex, cis-diammineplatinum (Ⅱ) ascorbate, has been synthesized and its X-ray structure is given. Quantum chemistry calculation compared with its diaminecyclohexane derivatives indicates that they have different electron distribution.
An antitumour complex, cis-diammineplatinum (Ⅱ) ascorbate, has been synthesized and its X-ray structure is given. Quantum chemistry calculation compared with its diaminecyclohexane derivatives indicates that they have different electron distribution.
1991, 2(2): 123-124
Abstract:
In the presence of equimolar triethylamine, vicinal dibromides were found to be easily debrominated by dibutyl telluride, forming the corresponding olefins.
In the presence of equimolar triethylamine, vicinal dibromides were found to be easily debrominated by dibutyl telluride, forming the corresponding olefins.
1991, 2(2): 125-126
Abstract:
Borohydride exchange resin-transition metal (Co, Ni, Cu,) compound systems reduced C=C double to C-C single bond in ethanol.
Borohydride exchange resin-transition metal (Co, Ni, Cu,) compound systems reduced C=C double to C-C single bond in ethanol.
1991, 2(2): 127-130
Abstract:
Aromatic nitro compounds are reduced to correspouding amiues in ethanol by borohydride exchauge resin (BER) in the presence of transition metal (Pd, Co, Ni, Cu) compounds as catalysts.
Aromatic nitro compounds are reduced to correspouding amiues in ethanol by borohydride exchauge resin (BER) in the presence of transition metal (Pd, Co, Ni, Cu) compounds as catalysts.
1991, 2(2): 131-132
Abstract:
The photoinduced reactions of aryl halides with carbazolyl nitrogen anion, in dimethyl sulfoxide, yield the corresponding N-arylated products. These reactions are suggested in terms of the SRNl mechaism of nucleophilic substitution.
The photoinduced reactions of aryl halides with carbazolyl nitrogen anion, in dimethyl sulfoxide, yield the corresponding N-arylated products. These reactions are suggested in terms of the SRNl mechaism of nucleophilic substitution.
1991, 2(2): 133-134
Abstract:
Reaction of (Z)-Crotyldiisopinocampheylborane with a series of aldehydes have been examined, and the ratio of erythro to threo products varies from 20:1 to 1:1. The results are discussed in detail.
Reaction of (Z)-Crotyldiisopinocampheylborane with a series of aldehydes have been examined, and the ratio of erythro to threo products varies from 20:1 to 1:1. The results are discussed in detail.
1991, 2(2): 135-138
Abstract:
Polydimethylsilylenes bearing pyrenyl groups exhibit emissions from twisted intramolecular charge transfer state between the aromatic ring and the silicon backbone both in polar and nonpolar solvents.
Polydimethylsilylenes bearing pyrenyl groups exhibit emissions from twisted intramolecular charge transfer state between the aromatic ring and the silicon backbone both in polar and nonpolar solvents.
1991, 2(2): 139-140
Abstract:
The initial stage of silver deposition has been investigated using the microelectrode technique A disc shaped nucleus can be obtained on glassy carbon microelectrodes and the instanta-neous nucleation model applies for the process.
The initial stage of silver deposition has been investigated using the microelectrode technique A disc shaped nucleus can be obtained on glassy carbon microelectrodes and the instanta-neous nucleation model applies for the process.
1991, 2(2): 141-142
Abstract:
A new method of zeroing anisotropy spectrofluorometry has been developed. When a mixture of two components is determined by anisotropy spectrofluorimetric method, and the excitation wavelength is selected at the intersection points of the apparent excitation spectra corresponding to I⊥ and I// for the component A, then its anisotropy values are zero, and the measured anisotropy values can thus be used for the determination of the component B & vice versa. This method had been used for the simultaneous determination of a binary mixture of rhodamine B and pyronine G, and the determination of rhodamine B in a ternary mixture of rhodamine 6G, rhodamine S and rhodamine B using the common intersection points of I⊥ and I// excitation spectra of rhodamine 6G and rhodamine S as the excitation wavelength. The results are quite satisfactory.
A new method of zeroing anisotropy spectrofluorometry has been developed. When a mixture of two components is determined by anisotropy spectrofluorimetric method, and the excitation wavelength is selected at the intersection points of the apparent excitation spectra corresponding to I⊥ and I// for the component A, then its anisotropy values are zero, and the measured anisotropy values can thus be used for the determination of the component B & vice versa. This method had been used for the simultaneous determination of a binary mixture of rhodamine B and pyronine G, and the determination of rhodamine B in a ternary mixture of rhodamine 6G, rhodamine S and rhodamine B using the common intersection points of I⊥ and I// excitation spectra of rhodamine 6G and rhodamine S as the excitation wavelength. The results are quite satisfactory.
1991, 2(2): 143-146
Abstract:
Application of Frequency-Spectrum analysis to a. c. oscillopolarogram using Fourier transform technique is given in this paper. Harmonic equations of E-t curve of base solution are derived. The measurement of concentration of the depolarizer by means of the second and third harmonic potentials were also described.
Application of Frequency-Spectrum analysis to a. c. oscillopolarogram using Fourier transform technique is given in this paper. Harmonic equations of E-t curve of base solution are derived. The measurement of concentration of the depolarizer by means of the second and third harmonic potentials were also described.
1991, 2(2): 147-150
Abstract:
In this paper a new electrochemical method "Reciprocal a. c. oscillololarography" is discussed. Both principle and experimental work are described.
In this paper a new electrochemical method "Reciprocal a. c. oscillololarography" is discussed. Both principle and experimental work are described.
1991, 2(2): 151-152
Abstract:
Kalman's Filter Technique for the separation of overlapping incisions of an a. c. oscillopolarogram is presented, the experimental verifications were carried out in various systems with the ions of Pb2+, Tl+, In3+ and Cd2+. The results showed that the concentration of the depolarizer can be determined directly and easily with this technique in the presence of interference elements.
Kalman's Filter Technique for the separation of overlapping incisions of an a. c. oscillopolarogram is presented, the experimental verifications were carried out in various systems with the ions of Pb2+, Tl+, In3+ and Cd2+. The results showed that the concentration of the depolarizer can be determined directly and easily with this technique in the presence of interference elements.
1991, 2(2): 153-154
Abstract:
This paper reports a new method of titration for very weak acids and bases using the appearance of incisions on oscillopolarogram to indicate the end-point. This method has the advantages of rapidity, simplicity, no indicator needed as well as good precision.
This paper reports a new method of titration for very weak acids and bases using the appearance of incisions on oscillopolarogram to indicate the end-point. This method has the advantages of rapidity, simplicity, no indicator needed as well as good precision.
1991, 2(2): 155-156
Abstract:
Polarization-resonance synchronous scan luminescence spectrometry is a combination of polarization technique and synchronous scan luminescence spectrometry. Polarized light was employed in this method. Because of the nature that scattered light is completely polarized, the interference of scattered light will be suppressed. Therefore, the method sensitivity of the method can be increased nearly fourfold.
Polarization-resonance synchronous scan luminescence spectrometry is a combination of polarization technique and synchronous scan luminescence spectrometry. Polarized light was employed in this method. Because of the nature that scattered light is completely polarized, the interference of scattered light will be suppressed. Therefore, the method sensitivity of the method can be increased nearly fourfold.
1991, 2(2): 157-160
Abstract:
Solvent effect on the conformations of α, ω-bis (4-nitrophenoxy)-alkanes with different chain Lengths (Nn) was studied by UV spectra. In poor solvents such as EG-H2O and THF-H2O, with the water content higher than 50%, the K-bands of N4, N5, N6and N10 in the UV absorption spectra shifted to longer wavelengths as compared with 4-nitrophenoxyethane (N0). It is suggested that in poor solvents the two aromatic groups are close to each other in parallel, forming ground state complexes. The K-band of N4 showed a blue shift from that of N0 when the water content was around 5%, probably attributable to a conformation with the nitro group of one benzene ring siting on the plane of the other benzene ring.
Solvent effect on the conformations of α, ω-bis (4-nitrophenoxy)-alkanes with different chain Lengths (Nn) was studied by UV spectra. In poor solvents such as EG-H2O and THF-H2O, with the water content higher than 50%, the K-bands of N4, N5, N6and N10 in the UV absorption spectra shifted to longer wavelengths as compared with 4-nitrophenoxyethane (N0). It is suggested that in poor solvents the two aromatic groups are close to each other in parallel, forming ground state complexes. The K-band of N4 showed a blue shift from that of N0 when the water content was around 5%, probably attributable to a conformation with the nitro group of one benzene ring siting on the plane of the other benzene ring.
1991, 2(2): 161-162
Abstract:
The photoanodic characteristics of layer-structured n-InSe were investigated in polysulfide solution as a solid-liquid junction photoelectro-chemical cell (PEC). A quantum yield approaching about 90% and a photocurrentdensity as high as 30 mA/cm2 were obtained. But the stabilization experiment demonstrates that about 8% of the photocurrent is attributed to a photoanodic corrosion ceaction.
The photoanodic characteristics of layer-structured n-InSe were investigated in polysulfide solution as a solid-liquid junction photoelectro-chemical cell (PEC). A quantum yield approaching about 90% and a photocurrentdensity as high as 30 mA/cm2 were obtained. But the stabilization experiment demonstrates that about 8% of the photocurrent is attributed to a photoanodic corrosion ceaction.
1991, 2(2): 163-166
Abstract:
The possibility of co-deposition of Li (Ⅰ) and RE (Ⅲ) has been estimated by both theoretical analysis and experimental study on the influences of temperature and concen-tration of chloride on the deposition potential. Both the electrochemical and electrolytic results clearly show that Li (Ⅰ) and RE (Ⅲ) can co-deposit on the Al-Cu electrode under selected conditions.
The possibility of co-deposition of Li (Ⅰ) and RE (Ⅲ) has been estimated by both theoretical analysis and experimental study on the influences of temperature and concen-tration of chloride on the deposition potential. Both the electrochemical and electrolytic results clearly show that Li (Ⅰ) and RE (Ⅲ) can co-deposit on the Al-Cu electrode under selected conditions.
1991, 2(2): 167-168
Abstract:
The luminophors MeO-SiO2:Eu3+, Bi3+ and MeO-SiO2Bi3+ (Me=Mg. Sr) were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica. The optimum composition and synthesis conditions were obtained by studying the excitation and emission spectra and the effects of energy transfer from the Bi3+ ions to the Eu3+ ions.
The luminophors MeO-SiO2:Eu3+, Bi3+ and MeO-SiO2Bi3+ (Me=Mg. Sr) were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica. The optimum composition and synthesis conditions were obtained by studying the excitation and emission spectra and the effects of energy transfer from the Bi3+ ions to the Eu3+ ions.
1991, 2(2): 169-170
Abstract:
Several chiral mixed-ligand complexes have been synthesized and their efficiency as catalysts for the asymmetric synthesis of chrysanthemic acid tested.
Several chiral mixed-ligand complexes have been synthesized and their efficiency as catalysts for the asymmetric synthesis of chrysanthemic acid tested.
1991, 2(2): 171-174
Abstract:
Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc (Sc6Cl12Co). Based on the analysis of the composition of the molecular orbitals and bond orders, it was pointed out that the interstitial transition metal atom Co in the octahedral Sc skeleton forms strong covalent bond with six Sc atoms and the bonding of Sc-Cl is mainly ionic in character. There are nine valence molecular orbitals in the cluster.
Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc (Sc6Cl12Co). Based on the analysis of the composition of the molecular orbitals and bond orders, it was pointed out that the interstitial transition metal atom Co in the octahedral Sc skeleton forms strong covalent bond with six Sc atoms and the bonding of Sc-Cl is mainly ionic in character. There are nine valence molecular orbitals in the cluster.
1991, 2(2): 175-176
Abstract:
The effects of Triton X-100 (TX100), a nonionic surfactant, on Belousov-Zhabotinsky reactions (B-Z reactions), including H2SO4+malonic acid (MA)+KBrOs+Mn2+ and H2SO4+gallic acid (GA)+KBrO3 systems, have been investigated. The results showed that the oscillation parameters (the induction period, average oscillation period, oscillation lasting time) in these B-Z reactions were changed suddenly near the critical micelle concen-tration (CMC) of TX100. The results were explained according to the mechanism of B-Z reaction and the properties of micelles of the surfactant.
The effects of Triton X-100 (TX100), a nonionic surfactant, on Belousov-Zhabotinsky reactions (B-Z reactions), including H2SO4+malonic acid (MA)+KBrOs+Mn2+ and H2SO4+gallic acid (GA)+KBrO3 systems, have been investigated. The results showed that the oscillation parameters (the induction period, average oscillation period, oscillation lasting time) in these B-Z reactions were changed suddenly near the critical micelle concen-tration (CMC) of TX100. The results were explained according to the mechanism of B-Z reaction and the properties of micelles of the surfactant.
1991, 2(2): 177-178
Abstract:
A new Belousov-Zhabotinsky oscillator induced by Triton X-100 (a nonionic surfactant) with glucose as the organic substrate and Ce4+ as the catalyst has been reported in this paper.
A new Belousov-Zhabotinsky oscillator induced by Triton X-100 (a nonionic surfactant) with glucose as the organic substrate and Ce4+ as the catalyst has been reported in this paper.
1991, 2(2): 179-180
Abstract:
K4H2PMo9V3O40·18H2O, Mr=2169.68, tetragonal, space group P4/mnc, a=b=12.515 (3), c=17.636 (7) A;z=2;V=2762 (2) A3;F (000)=2206;Dc=2.81g/cm3;μ=28.8/cm (MoKα=0.71069 A). The central PO4 is disordered in the (PMo9V3O40) 6. P-O=1.511A. M (M=Mo or V) is 7 coordinate, M-O=1.62-2.48A. K is 7 coordinate, K-O=2.85-3.10A.
K4H2PMo9V3O40·18H2O, Mr=2169.68, tetragonal, space group P4/mnc, a=b=12.515 (3), c=17.636 (7) A;z=2;V=2762 (2) A3;F (000)=2206;Dc=2.81g/cm3;μ=28.8/cm (MoKα=0.71069 A). The central PO4 is disordered in the (PMo9V3O40) 6. P-O=1.511A. M (M=Mo or V) is 7 coordinate, M-O=1.62-2.48A. K is 7 coordinate, K-O=2.85-3.10A.
1991, 2(2): 181-184
Abstract:
Combinations of alkaline earth Ba and Sr in place of alkali with Pr and Ce which have stronger oxidation power may result in catalysts with better stability and activity. Studies on the optimization of Ba-Pr binary system were carried out with catalysts whose Ba/(Ba+Pr) atomic ratio are from 0 to 0.56, optimal selectivity was realized at BaPrO3 which remains the constant reactivity, CH4 conversion 20% and selectivity 57%, during run of 100h at the condition of 1083K and CH4:O2=5:1. Studies on the correlation of reactivity with composition of catalyst demonstrate that there is a synergism between basicity and oxidation power. XRD patterns show that Ba and Sr cations insert into lattices of PrO1.8 and CeO2 respectively, and suppress their combustion power. Kinetic measurements support the suggestion:the rate-determining-step of title reaction be breaking of C-H bond of methane on PrO1.8 phase.
Combinations of alkaline earth Ba and Sr in place of alkali with Pr and Ce which have stronger oxidation power may result in catalysts with better stability and activity. Studies on the optimization of Ba-Pr binary system were carried out with catalysts whose Ba/(Ba+Pr) atomic ratio are from 0 to 0.56, optimal selectivity was realized at BaPrO3 which remains the constant reactivity, CH4 conversion 20% and selectivity 57%, during run of 100h at the condition of 1083K and CH4:O2=5:1. Studies on the correlation of reactivity with composition of catalyst demonstrate that there is a synergism between basicity and oxidation power. XRD patterns show that Ba and Sr cations insert into lattices of PrO1.8 and CeO2 respectively, and suppress their combustion power. Kinetic measurements support the suggestion:the rate-determining-step of title reaction be breaking of C-H bond of methane on PrO1.8 phase.
1991, 2(2): 185-188
Abstract:
The cathodic wave of vitamin C has not been reported in the literature so far. Its E½ was found at-1.85 volt vs. Ag/AgCl (25℃) in the base solution of 0.1mol/L Bu4NI. Various electrochemical and spectral techniques were used for studying the electrode reaction. They all showed that the electrode reaction was quasi-reversible while C was more than 1.0×10-6mol/L and mainly adsorptive while C was less than 1.0×10-6mol/L at a mercury electrode. The electron transfer number was 2 and the electron transfer coefficient 0.57. Using DPP techniques, the linear response range was 5.0×10-7-2.0×10-3mol/L and the detection limit 1×10-7mol/L.
The cathodic wave of vitamin C has not been reported in the literature so far. Its E½ was found at-1.85 volt vs. Ag/AgCl (25℃) in the base solution of 0.1mol/L Bu4NI. Various electrochemical and spectral techniques were used for studying the electrode reaction. They all showed that the electrode reaction was quasi-reversible while C was more than 1.0×10-6mol/L and mainly adsorptive while C was less than 1.0×10-6mol/L at a mercury electrode. The electron transfer number was 2 and the electron transfer coefficient 0.57. Using DPP techniques, the linear response range was 5.0×10-7-2.0×10-3mol/L and the detection limit 1×10-7mol/L.
