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1998 Volume 9 Issue 5
1998, 9(5): 415-416
Abstract:
A series of title compounds were synthesized by the addition reaction of dialkyl-α-hydroxyphosphonates and phenyl isocyanate under base catalysis. All new compounds have been identified by 1H NMR, 31P NMR, IR and elemental analysis.
A series of title compounds were synthesized by the addition reaction of dialkyl-α-hydroxyphosphonates and phenyl isocyanate under base catalysis. All new compounds have been identified by 1H NMR, 31P NMR, IR and elemental analysis.
1998, 9(5): 417-420
Abstract:
The reduction of diacyl diselenides by samarium diiodide led to the production of samarium acylselenolates, which reacted with α,β-unsaturated esters or nitriles to give β-selenoesters or selenonitriles under mild and neutral conditions.
The reduction of diacyl diselenides by samarium diiodide led to the production of samarium acylselenolates, which reacted with α,β-unsaturated esters or nitriles to give β-selenoesters or selenonitriles under mild and neutral conditions.
1998, 9(5): 421-422
Abstract:
The chloromethylation reaction of substituted titanocenes (η5-C5H5)(η5-C5H4CRR' C6H4X)TiCl2 1 in the presence of polyformaldehyde and dry hydrogen chloride is reported.
The chloromethylation reaction of substituted titanocenes (η5-C5H5)(η5-C5H4CRR' C6H4X)TiCl2 1 in the presence of polyformaldehyde and dry hydrogen chloride is reported.
1998, 9(5): 423-425
Abstract:
Methoxycarbonylation was performed on 1-heptene, 1-octene and 1-dodecene with Co(acac)2 catalyst in the presence of UV light under ambient conditions.
Methoxycarbonylation was performed on 1-heptene, 1-octene and 1-dodecene with Co(acac)2 catalyst in the presence of UV light under ambient conditions.
1998, 9(5): 427-430
Abstract:
Allylic alcohols react with aryl iodides in the presence of tri-n-butylamine and a catalytic amount of a silica-bound bidentate sulfur palladium (0) complex to form 3-arylaldehydes or ketones in good yields.
Allylic alcohols react with aryl iodides in the presence of tri-n-butylamine and a catalytic amount of a silica-bound bidentate sulfur palladium (0) complex to form 3-arylaldehydes or ketones in good yields.
1998, 9(5): 431-432
Abstract:
Synthesis of an optically active intermediate 4b for the A-ring of 1α,25-dihydroxyvitamin D3 analogs has been achieved in eight steps, starting from readily available, inexpensive D-(+)-xylose.
Synthesis of an optically active intermediate 4b for the A-ring of 1α,25-dihydroxyvitamin D3 analogs has been achieved in eight steps, starting from readily available, inexpensive D-(+)-xylose.
1998, 9(5): 433-434
Abstract:
Anti-HIV agent (±)-calanolide A has been synthesized by a four-step approach starting from phloroglucinol, including the Pechmann reaction, Friedel-Crafts acylation, cyclization, chromenylation and Luche reduction.
Anti-HIV agent (±)-calanolide A has been synthesized by a four-step approach starting from phloroglucinol, including the Pechmann reaction, Friedel-Crafts acylation, cyclization, chromenylation and Luche reduction.
1998, 9(5): 435-437
Abstract:
In the continuation of our study on the Serratia marcescens O-antigen, two disaccharides 8 and 13, corresponding to the key intermediates of oligosaccharides related to the S. marcescens O10 antigen, were synthesized by the trichloroacetate method. Their structures and compositions were characterized by 1H NMR, 13C NMR, 2D NMR and IR, FAB-MS spcctra.
In the continuation of our study on the Serratia marcescens O-antigen, two disaccharides 8 and 13, corresponding to the key intermediates of oligosaccharides related to the S. marcescens O10 antigen, were synthesized by the trichloroacetate method. Their structures and compositions were characterized by 1H NMR, 13C NMR, 2D NMR and IR, FAB-MS spcctra.
1998, 9(5): 439-442
Abstract:
A new methodology was advanced that mesogenic cores appeared after the formation of urethane groups and during the monomer-to-polymer transition. A new diphenol monomer, bis(4'-hydroxy-phenyl)-toluene-2,4-diurethane (BHPTU), was obtained by the reaction of 2,4-tolulene diisocyanate with hydroquinone in dioxane or N,N-dimethyl-acetamide. The reaction process was monitored by FTIR, and the product was investigated by 1HNMR and elemental analysis (EA). A liquid crystalline poly(urethane-ester) was obtained using the BHPTU monomer.
A new methodology was advanced that mesogenic cores appeared after the formation of urethane groups and during the monomer-to-polymer transition. A new diphenol monomer, bis(4'-hydroxy-phenyl)-toluene-2,4-diurethane (BHPTU), was obtained by the reaction of 2,4-tolulene diisocyanate with hydroquinone in dioxane or N,N-dimethyl-acetamide. The reaction process was monitored by FTIR, and the product was investigated by 1HNMR and elemental analysis (EA). A liquid crystalline poly(urethane-ester) was obtained using the BHPTU monomer.
1998, 9(5): 443-445
Abstract:
Biodegradable poly(Glc-alt-Asp) was synthesized by ring-opening polymerization of the monomer 3-(S)-[(benzyloxycarbonyl)methyl]-morpholine-2,5-dione and subsequent catalytic hydrogenation. Copolymers of the monomer with glycolide, D,L-lactide and L-lactide were also prepared.
Biodegradable poly(Glc-alt-Asp) was synthesized by ring-opening polymerization of the monomer 3-(S)-[(benzyloxycarbonyl)methyl]-morpholine-2,5-dione and subsequent catalytic hydrogenation. Copolymers of the monomer with glycolide, D,L-lactide and L-lactide were also prepared.
1998, 9(5): 447-450
Abstract:
Transformation of living ring-opening metathesis polymerization into coordination polymerization by converting the titanacyclobutane group attached to a polynorbomene chain into titanocene alkoxide has been used for the synthesis of polynorbornene-poly(ethylene-co-propylene) block copolymer. Preliminary characterizations of the copolymerization products by solvent extraction and 13C NMR spectrum are reported.
Transformation of living ring-opening metathesis polymerization into coordination polymerization by converting the titanacyclobutane group attached to a polynorbomene chain into titanocene alkoxide has been used for the synthesis of polynorbornene-poly(ethylene-co-propylene) block copolymer. Preliminary characterizations of the copolymerization products by solvent extraction and 13C NMR spectrum are reported.
Synthesis on Multifunctional Groups and MultibranchedCompounds Ⅷ. Synthesis of Dendritic Polyestrone
1998, 9(5): 451-453
Abstract:
In this article, using the four-directional core and quaternary carbon branching point, a dendritic polyestrone with twelve estrone units was synthesized by convergent strategy. Its structure was confirmed by IR and NMR spectra.
In this article, using the four-directional core and quaternary carbon branching point, a dendritic polyestrone with twelve estrone units was synthesized by convergent strategy. Its structure was confirmed by IR and NMR spectra.
1998, 9(5): 455-458
Abstract:
In view of the isosterism of the sulfonyl (-S02-) and phosphoryl groups [-P(0)(0R)-, R=H, CH3, C2H5, etc], two new types of ureas, N-(N-aryl-O-alkyl phosphoryl)-N'-(4, 6-dimethoxy pyrimidin-2-yl) ureas 2 and N-(N-aryI-N-alkyl phosphoryl)-N'-(4, 6-dimethoxy pyrimidin-2-yl) ureas 3,were synthesized by treating N-(arylaminochlorophosphoryl)-N'-(4,6-dimethoxy pyrimidinyl-2-) ureas 4 with alcohols or amines. Compounds 4 were obtained by reacting dichlorophosphoryl isocyanate with 4,6-dimethoxy-2-aminopyrimidine, and then with aromatic amines. The enzyme tests (in vitro) indicated that compounds 2 and 3 were two novel classes of acetolactate synthase (ALS) inhibitors, which showed that the phosphoryl group, [-P(0)(0R)-], or[-P(0)(NHR)-], was a good bioisostere of the sulfonyl group (-S02-) in sulfonylurea.
In view of the isosterism of the sulfonyl (-S02-) and phosphoryl groups [-P(0)(0R)-, R=H, CH3, C2H5, etc], two new types of ureas, N-(N-aryl-O-alkyl phosphoryl)-N'-(4, 6-dimethoxy pyrimidin-2-yl) ureas 2 and N-(N-aryI-N-alkyl phosphoryl)-N'-(4, 6-dimethoxy pyrimidin-2-yl) ureas 3,were synthesized by treating N-(arylaminochlorophosphoryl)-N'-(4,6-dimethoxy pyrimidinyl-2-) ureas 4 with alcohols or amines. Compounds 4 were obtained by reacting dichlorophosphoryl isocyanate with 4,6-dimethoxy-2-aminopyrimidine, and then with aromatic amines. The enzyme tests (in vitro) indicated that compounds 2 and 3 were two novel classes of acetolactate synthase (ALS) inhibitors, which showed that the phosphoryl group, [-P(0)(0R)-], or[-P(0)(NHR)-], was a good bioisostere of the sulfonyl group (-S02-) in sulfonylurea.
1998, 9(5): 459-461
Abstract:
The possible excited state decomposition reactions (dehydrogensulfidation, dehydration, and dehydrogenation) of the four tautomers of monothioformic acid have been investigated by ab initio methods with 6-31G** basis sets at the CIS level. The activation energies of the four excited state reactions are 42.57,42.49,56.90,47.73 kcal/mol, and are respectively lower than that of the ground states by 24.52,24.98, 27.28,and 21.10 kcal/mol.
The possible excited state decomposition reactions (dehydrogensulfidation, dehydration, and dehydrogenation) of the four tautomers of monothioformic acid have been investigated by ab initio methods with 6-31G** basis sets at the CIS level. The activation energies of the four excited state reactions are 42.57,42.49,56.90,47.73 kcal/mol, and are respectively lower than that of the ground states by 24.52,24.98, 27.28,and 21.10 kcal/mol.
1998, 9(5): 463-464
Abstract:
A three-dimensional diagram shows that the association constants (Ka) for the inclusion of a- and β-CD with substituted benzene are mainly correlated with the molar refraction (Rm) and hydrophobic constant (πx)of the substituents of guest compounds. It reveals that the inclusion of cyclodextrin with the substituted benzene is dominantly driven by van der Waals forces and hydrophobic interactions.
A three-dimensional diagram shows that the association constants (Ka) for the inclusion of a- and β-CD with substituted benzene are mainly correlated with the molar refraction (Rm) and hydrophobic constant (πx)of the substituents of guest compounds. It reveals that the inclusion of cyclodextrin with the substituted benzene is dominantly driven by van der Waals forces and hydrophobic interactions.
1998, 9(5): 465-467
Abstract:
Three grayanane diterpenoids 1-3 were isolated from Pieris formosa. 1 was identified as a new natural product and 2 and 3 as known grayanoside C and grayanotoxin ⅹⅧ on the basis of spectral analysis.
Three grayanane diterpenoids 1-3 were isolated from Pieris formosa. 1 was identified as a new natural product and 2 and 3 as known grayanoside C and grayanotoxin ⅹⅧ on the basis of spectral analysis.
1998, 9(5): 469-470
Abstract:
Two new phloroglucinol glycosides, 2,6-dihydroxy-3,5-dimethyl-l-isobutyrylbenzene-4-0-β-D-glucoside and 2,6-dihydroxy-3,5-dimethyl-l-(2-methylbutyryl) benzene-4-O-β-D-glucoside were isolated from Hypericum japonicum. Their structures were determined by spectroscopic and chemical methods.
Two new phloroglucinol glycosides, 2,6-dihydroxy-3,5-dimethyl-l-isobutyrylbenzene-4-0-β-D-glucoside and 2,6-dihydroxy-3,5-dimethyl-l-(2-methylbutyryl) benzene-4-O-β-D-glucoside were isolated from Hypericum japonicum. Their structures were determined by spectroscopic and chemical methods.
1998, 9(5): 471-472
Abstract:
A novel chemiluminescence (CL) sensor for H202 combined with flow injection analysis is described in this paper. H202 is sensed by the CL reaction with luminol and Co2+ bleeding from the ion exchange column with immobilized reagents by hydrolysis. The calibration graph is linear and falls between the range of 4×l0-8 to 1×10-5 mol/L. A complete analysis could be performed in 1 min. The system was reused for over 50 hours.
A novel chemiluminescence (CL) sensor for H202 combined with flow injection analysis is described in this paper. H202 is sensed by the CL reaction with luminol and Co2+ bleeding from the ion exchange column with immobilized reagents by hydrolysis. The calibration graph is linear and falls between the range of 4×l0-8 to 1×10-5 mol/L. A complete analysis could be performed in 1 min. The system was reused for over 50 hours.
1998, 9(5): 473-476
Abstract:
The effects of 2.8% Cd on the electrochromic properties of NiOxHy film were studied. The film was electrodeposited on both the polished Ni plate and conductive ITO glass to study its electrochemical and optical characteristics respectively. It was found that Cd could decrease the working voltage and increase the oxygen evolution voltage as well as the transmittance difference of colored and bleached states of the film. However, it has little effect on the kinetic process.
The effects of 2.8% Cd on the electrochromic properties of NiOxHy film were studied. The film was electrodeposited on both the polished Ni plate and conductive ITO glass to study its electrochemical and optical characteristics respectively. It was found that Cd could decrease the working voltage and increase the oxygen evolution voltage as well as the transmittance difference of colored and bleached states of the film. However, it has little effect on the kinetic process.
1998, 9(5): 477-479
Abstract:
This paper presents a new model for the calculation of the standard entropies of solid complex silicates as follows.SO298=53.630Φ1+9.91Φ2-72.81 J/kmol (R=0.9915, Sd:5.39) Sixty complex silicates have been investigated,and good agreement was found between the estimated and experimental entropy values.
This paper presents a new model for the calculation of the standard entropies of solid complex silicates as follows.SO298=53.630Φ1+9.91Φ2-72.81 J/kmol (R=0.9915, Sd:5.39) Sixty complex silicates have been investigated,and good agreement was found between the estimated and experimental entropy values.
1998, 9(5): 481-482
Abstract:
A tetranuclear copper (Ⅰ) complex of the ditholate ligand fused with a TTF moiety has been synthesized and characterized crystallographically. This is the first example of a metal cluster coordinated with the new type ligand. The complex shows interesting redox and radical properties.
A tetranuclear copper (Ⅰ) complex of the ditholate ligand fused with a TTF moiety has been synthesized and characterized crystallographically. This is the first example of a metal cluster coordinated with the new type ligand. The complex shows interesting redox and radical properties.
1998, 9(5): 483-485
Abstract:
The title dinuclear complex structure was determined by X-ray diffraction.
The title dinuclear complex structure was determined by X-ray diffraction.
1998, 9(5): 487-490
Abstract:
Well-defined Si- and Ti-MCM-41 mesoporous molecular sieves were synthesized in high yields through the halogen anion mediated S+X-I+ assembly in the presence of cetylpyridinium bromide as template. The spectroscopy characterization of the as-synthesized samples confirmed that Ti (Ⅳ) could be isolated in the lattice positions of the MCM-41 mesostructure by this method.
Well-defined Si- and Ti-MCM-41 mesoporous molecular sieves were synthesized in high yields through the halogen anion mediated S+X-I+ assembly in the presence of cetylpyridinium bromide as template. The spectroscopy characterization of the as-synthesized samples confirmed that Ti (Ⅳ) could be isolated in the lattice positions of the MCM-41 mesostructure by this method.
1998, 9(5): 491-494
Abstract:
Seven compounds containing tin-copper bonds, namely [Ph2P(CH2)nPPh2](CuSnPh3)2(n=1-4) and (Ph2PR)CuSnPh3 (R=Ph, Bu, Am), have been synthesized. Tin-119 Moessbauer spectra for these compounds were determined. The results have shown that the QS values for these compounds are all zero, the IS values are between 1.32 and 1.38mm/s, and the oxidation state of tin is +4.
Seven compounds containing tin-copper bonds, namely [Ph2P(CH2)nPPh2](CuSnPh3)2(n=1-4) and (Ph2PR)CuSnPh3 (R=Ph, Bu, Am), have been synthesized. Tin-119 Moessbauer spectra for these compounds were determined. The results have shown that the QS values for these compounds are all zero, the IS values are between 1.32 and 1.38mm/s, and the oxidation state of tin is +4.
1998, 9(5): 495-496
Abstract:
The heat capacity of Na2W2O7(s) has been measured using the drop calorimetry method with a high temperature calorimeter HT1000 in the temperature range of 273-974K. The results can be represented by the equation Cp0/J K-1 mol1=229.50+8.5052×l0-2T-3.83373×l06T-2.
The heat capacity of Na2W2O7(s) has been measured using the drop calorimetry method with a high temperature calorimeter HT1000 in the temperature range of 273-974K. The results can be represented by the equation Cp0/J K-1 mol1=229.50+8.5052×l0-2T-3.83373×l06T-2.
1998, 9(5): 497-499
Abstract:
Reaction of Cu(C104)2·6H20 with tripodal ligand tris(2-benzimidazolylmethyl) amine (ntb) and sodium isonicotinate (Iso) yielded a mononuclear complex [Cu(ntb)(Iso)]C104·3.5H20. The structure has been established by X-ray crystallography. The Cu (·Ⅱ) atom is in a distorted trigonal bipyramidal environment with three benzimidazole N atoms of ntb defining the equatorial plane, one amine N atom of ntb, and one O atom of the carboxylate group of isonicotinate occupying the axial positions.
Reaction of Cu(C104)2·6H20 with tripodal ligand tris(2-benzimidazolylmethyl) amine (ntb) and sodium isonicotinate (Iso) yielded a mononuclear complex [Cu(ntb)(Iso)]C104·3.5H20. The structure has been established by X-ray crystallography. The Cu (·Ⅱ) atom is in a distorted trigonal bipyramidal environment with three benzimidazole N atoms of ntb defining the equatorial plane, one amine N atom of ntb, and one O atom of the carboxylate group of isonicotinate occupying the axial positions.
1998, 9(5): 501-504
Abstract:
Highly oriented pyrolytic graphite (HOPG) is the substrate often used in scanning tunneling microscopy (STM). It is well known that STM images of the basal plane of HOPG show some unusual structural patterns. In this letter, we present in situ STM images of some unusual features on HOPG in solutions, including normal or abnormal chain-like features and hexagonal or oblique superperiodic structures. These features emerge both next to and apart from the step of HOPG.
Highly oriented pyrolytic graphite (HOPG) is the substrate often used in scanning tunneling microscopy (STM). It is well known that STM images of the basal plane of HOPG show some unusual structural patterns. In this letter, we present in situ STM images of some unusual features on HOPG in solutions, including normal or abnormal chain-like features and hexagonal or oblique superperiodic structures. These features emerge both next to and apart from the step of HOPG.
1998, 9(5): 505-508
Abstract:
A new heteropoly complex has been prepared and characterized by chemical analysis, IR spectrum, UV spectrum, X-ray powder diffraction and thermal analysis.
A new heteropoly complex has been prepared and characterized by chemical analysis, IR spectrum, UV spectrum, X-ray powder diffraction and thermal analysis.
