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1991 Volume 2 Issue 8
1991, 3(8): 595-596
Abstract:
Methyl 3-trimethylsilylpropargyl carbonate reacted with dinucleophiles under the catalysis of palladium(0) complex to give the corresponding desilylated annulation products.
Methyl 3-trimethylsilylpropargyl carbonate reacted with dinucleophiles under the catalysis of palladium(0) complex to give the corresponding desilylated annulation products.
1991, 3(8): 597-600
Abstract:
Pentafluorobenzenesulfonyl bromide was synthesized by the reaction of pentafluorophenylmagnesium chloride with sulphur dioxide followed by bromine oxidation. The sulfonyl bromide reacted with polyfluorophenoxide to form polyfluorophenyl pentafluorobenzenesulfonates. Photolysis of pentafluorobenze-nesulfonyl bromide gave bis(pentafluorobenzene)sulfone and decafluorodiphenyl.
Pentafluorobenzenesulfonyl bromide was synthesized by the reaction of pentafluorophenylmagnesium chloride with sulphur dioxide followed by bromine oxidation. The sulfonyl bromide reacted with polyfluorophenoxide to form polyfluorophenyl pentafluorobenzenesulfonates. Photolysis of pentafluorobenze-nesulfonyl bromide gave bis(pentafluorobenzene)sulfone and decafluorodiphenyl.
1991, 3(8): 601-604
Abstract:
A convenient route for the conversion of inosine to the corresponding 6-amino, 6-methoxy and 6-ethoxy derivatives is reported. This conversion can be achieved by ammoniation or etherification of the 6-pyridinium intermediate(3) which can be readily produced under mild reaction conditions. The chemistry and characterization of these compounds are presented, A plausible mechanism of the reaction is proposed.
A convenient route for the conversion of inosine to the corresponding 6-amino, 6-methoxy and 6-ethoxy derivatives is reported. This conversion can be achieved by ammoniation or etherification of the 6-pyridinium intermediate(3) which can be readily produced under mild reaction conditions. The chemistry and characterization of these compounds are presented, A plausible mechanism of the reaction is proposed.
1991, 3(8): 605-606
Abstract:
the utility of sodium disulfite as a new sulfinatodehalogenation reagent for primary polyfluoroalkyl iodides and bromides is reallzed.
the utility of sodium disulfite as a new sulfinatodehalogenation reagent for primary polyfluoroalkyl iodides and bromides is reallzed.
1991, 3(8): 607-608
Abstract:
Polyfluoroalkylated biphenyl was obtained from reaction of benzene with RFI/Na2S2O4 using cetyltrimethylammonium bromide (CTAB) as PTC followed by dehydrogenation with DDQ in 38-43% yield.
Polyfluoroalkylated biphenyl was obtained from reaction of benzene with RFI/Na2S2O4 using cetyltrimethylammonium bromide (CTAB) as PTC followed by dehydrogenation with DDQ in 38-43% yield.
1991, 3(8): 609-610
Abstract:
Two aromatic aldehydes are found to be reduced by an unusual way by sodium borohydride in the presence of water to yield the corresponding methyl substituted aryl compounds.
Two aromatic aldehydes are found to be reduced by an unusual way by sodium borohydride in the presence of water to yield the corresponding methyl substituted aryl compounds.
1991, 3(8): 611-612
Abstract:
Ene-chtorination of the otefins bearing isopropenyl moieties has been achieved in good yieid by using catcium hypochiorite and sodium biphosphate. An efficient synthesis of San Jose ScaLe's sex pheromone is described.
Ene-chtorination of the otefins bearing isopropenyl moieties has been achieved in good yieid by using catcium hypochiorite and sodium biphosphate. An efficient synthesis of San Jose ScaLe's sex pheromone is described.
1991, 3(8): 613-616
Abstract:
1-Aryl-2-merhy1-4, 5-dihydropyrro1-3-carboxylic acid ethyl ester was observed to dehydrogenate to give 1-ary1-2-methyl-pyrro1-3-carboxylic acid ethyl ester upon irradiation in the presence of oxygen and in the presence or absence of ms-tetraphenylporphine.
1-Aryl-2-merhy1-4, 5-dihydropyrro1-3-carboxylic acid ethyl ester was observed to dehydrogenate to give 1-ary1-2-methyl-pyrro1-3-carboxylic acid ethyl ester upon irradiation in the presence of oxygen and in the presence or absence of ms-tetraphenylporphine.
1991, 3(8): 617-620
Abstract:
Efficient catalysis of functinnatized β-cyctodextrins bearing aninoatkytimino groups for atdot condensations of nitrobenzatdehydes and acetone has been effected and substantiated by preparative experiments
Efficient catalysis of functinnatized β-cyctodextrins bearing aninoatkytimino groups for atdot condensations of nitrobenzatdehydes and acetone has been effected and substantiated by preparative experiments
1991, 3(8): 621-622
Abstract:
Deacetylamijidictyol, a new dolastane diterpene was isolated from the marine brown algae Dictyota divaricata. The chemical structure was elucidated on the basis of spectral analysis.
Deacetylamijidictyol, a new dolastane diterpene was isolated from the marine brown algae Dictyota divaricata. The chemical structure was elucidated on the basis of spectral analysis.
1991, 3(8): 623-626
Abstract:
Two new neolignans, Kadsuranin G and Kadsuranin H, were isolated from Piper Kadsura (Choisy) Ohwj. Baaed on the spectroscopic analysis (UV, IR, MS, NNR, and X-ray) and chemical reactions, their structures were established as 7R, BR, 1'S, 2'R, 3'5-△8'-3, 4, 5'-trimethoxy-2'-hydroxy-1', 2', 3', 4'-tetrahydro-4'-oxo-7, 3', 8, 1'-neolignan and 7R, 8R, 1'S, 2'R, 3'S-△8'-3, 4, 5'-trimethoxy-2'-acetyloxy-1', 2', 3', 4'-tetrahydro-4'-oxo-7, 3', 8, 1'-neolignan.
Two new neolignans, Kadsuranin G and Kadsuranin H, were isolated from Piper Kadsura (Choisy) Ohwj. Baaed on the spectroscopic analysis (UV, IR, MS, NNR, and X-ray) and chemical reactions, their structures were established as 7R, BR, 1'S, 2'R, 3'5-△8'-3, 4, 5'-trimethoxy-2'-hydroxy-1', 2', 3', 4'-tetrahydro-4'-oxo-7, 3', 8, 1'-neolignan and 7R, 8R, 1'S, 2'R, 3'S-△8'-3, 4, 5'-trimethoxy-2'-acetyloxy-1', 2', 3', 4'-tetrahydro-4'-oxo-7, 3', 8, 1'-neolignan.
1991, 3(8): 627-628
Abstract:
A new polysaccharide, GBW was obtained homogeneous as determined by HPLC from the roots of Glycyrrhizia uralensis Fisch. The molecular weight was estimated to be 4000. The component sugar was identified as glucose only. The specific rotation [α]D28 (C=0.1, H2O) was +1200. The α-configuration was established by IR and 13C NMR. Methylation analysis, periodate oxidation, Smith degradation, partial hydrolysis, KI-I2 reaction and 13C NMR showed that GBW is a new (1→4)linked linear α-D-glucan. The structure is shown as 1.
A new polysaccharide, GBW was obtained homogeneous as determined by HPLC from the roots of Glycyrrhizia uralensis Fisch. The molecular weight was estimated to be 4000. The component sugar was identified as glucose only. The specific rotation [α]D28 (C=0.1, H2O) was +1200. The α-configuration was established by IR and 13C NMR. Methylation analysis, periodate oxidation, Smith degradation, partial hydrolysis, KI-I2 reaction and 13C NMR showed that GBW is a new (1→4)linked linear α-D-glucan. The structure is shown as 1.
1991, 3(8): 629-630
Abstract:
À new prenylated flavonol, maackiaflavonol, was isolated from the ethanol extract of the roots of Maackia tenuifolia. Its structure was elucidated as 7-hydrox-8-prenylflavonol by means of spectroscopic analysis (UV, IR, MS, NMR and 1H-1H COSY) and confirmed by total synthesis.
À new prenylated flavonol, maackiaflavonol, was isolated from the ethanol extract of the roots of Maackia tenuifolia. Its structure was elucidated as 7-hydrox-8-prenylflavonol by means of spectroscopic analysis (UV, IR, MS, NMR and 1H-1H COSY) and confirmed by total synthesis.
1991, 3(8): 631-632
Abstract:
The metaphosphate anion, PO3-, was detected in the negative-ion chemicalionization mass spectra of 2, 6, 7-trioxa-1-phospbabicyclo[2.2.2] octane-1-oxides.
The metaphosphate anion, PO3-, was detected in the negative-ion chemicalionization mass spectra of 2, 6, 7-trioxa-1-phospbabicyclo[2.2.2] octane-1-oxides.
1991, 3(8): 633-636
Abstract:
Two types of modified silica gels were prepared by adsorption method and bonding method respectively. Enrichment and separation of trace metal ions have been done by using the column packed with modified silica gels.
Two types of modified silica gels were prepared by adsorption method and bonding method respectively. Enrichment and separation of trace metal ions have been done by using the column packed with modified silica gels.
1991, 3(8): 637-640
Abstract:
In this paper, a linear relationship between the logarithm of capacity factor k' and normal boiling point to of the homologues has been derived, based on the basic retention equation of liquid chromatography according to statistical thermodyoamics proposed by professor Ln Peizhang and others, This equation has been verified by a large number of experimental data, all the strsight lines of lnk'--tb of bumologues for different mobile phass coaiposltion cross each other at the same point, So the intereection point equation was proposed, wbich was used to prodict the retention value, the result was satisfactory.
In this paper, a linear relationship between the logarithm of capacity factor k' and normal boiling point to of the homologues has been derived, based on the basic retention equation of liquid chromatography according to statistical thermodyoamics proposed by professor Ln Peizhang and others, This equation has been verified by a large number of experimental data, all the strsight lines of lnk'--tb of bumologues for different mobile phass coaiposltion cross each other at the same point, So the intereection point equation was proposed, wbich was used to prodict the retention value, the result was satisfactory.
1991, 3(8): 641-644
Abstract:
The experiments have proved that Os(Ⅳ) has very strong catalytic effect on the chlorate oxidation of As(Ⅲ) in perchloric acid media, and As(Ⅲ) exhibits a sensitive single-sweep oscillopolarographic wave at-0.75 V vs. SCE. The kinetics of this catalytic reaction has been investigated by the initial rate procedure. The mechanism has been proposed. A new and highly sensitive catalytic reaction-oscillopolarographic method for the determination of ultratrace amounts of osmium has been described, based on the Os(Ⅳ) catalytic effect on the reaction. The linear range of 5.0×10-11-4.4×10-9 mol/L and 6.0×10-9-1.3×10-7 mol/L Os was obtained using the fixed-time procedure and the initial rate procedure, respectively. Osmium in refined ore was analysed by this method.
The experiments have proved that Os(Ⅳ) has very strong catalytic effect on the chlorate oxidation of As(Ⅲ) in perchloric acid media, and As(Ⅲ) exhibits a sensitive single-sweep oscillopolarographic wave at-0.75 V vs. SCE. The kinetics of this catalytic reaction has been investigated by the initial rate procedure. The mechanism has been proposed. A new and highly sensitive catalytic reaction-oscillopolarographic method for the determination of ultratrace amounts of osmium has been described, based on the Os(Ⅳ) catalytic effect on the reaction. The linear range of 5.0×10-11-4.4×10-9 mol/L and 6.0×10-9-1.3×10-7 mol/L Os was obtained using the fixed-time procedure and the initial rate procedure, respectively. Osmium in refined ore was analysed by this method.
1991, 3(8): 645-648
Abstract:
A high performance liquid chromatographic assay has been developed for the simultaneous determination of five water soluble vitamins:thimine, riboflavin, niacin, pyridoxine and folic acid in cereal products and fresh vegetables. Food samples were hydrolyzed in 0.4 mol/L HCl, autoclaved at 120℃ 15 psi for 20 minutes, using a μ-Bondapak column (3.9×300mm, Waters Co.), a mobile phase of methanol-water (30:70) (0.005 mol/L heptanesulfonic acid) and a flow rate of 1.0 ml/min gave the most satisfactory separation of the five water soluble vitamins. A double channel deteetion was used: four vitamins (B5, folic acid, B2, B1) were detected hy UV spectrophotometry (254 nm) first, pyridoxine (B6) was detected by fluoromelry (EX 290nm, EM 395 nm) afterwards. Detection limits were 2, 5, 5, 2 and 5ng, linear ranges were 5-10ng, 5-50ng, 5-40ng, 5-50ng and 10-50ng for B1, B2, B5, B6 and folic acid respectively. Recoveries were 92-100%(B5), 51-52% (folic acid), 103-105% (B2), 99-100% (B6) and 91.3-102% (B1) respectively. In comparison with a reference method and checking with food composition tables, very satisfactory results were obtained by this method.
A high performance liquid chromatographic assay has been developed for the simultaneous determination of five water soluble vitamins:thimine, riboflavin, niacin, pyridoxine and folic acid in cereal products and fresh vegetables. Food samples were hydrolyzed in 0.4 mol/L HCl, autoclaved at 120℃ 15 psi for 20 minutes, using a μ-Bondapak column (3.9×300mm, Waters Co.), a mobile phase of methanol-water (30:70) (0.005 mol/L heptanesulfonic acid) and a flow rate of 1.0 ml/min gave the most satisfactory separation of the five water soluble vitamins. A double channel deteetion was used: four vitamins (B5, folic acid, B2, B1) were detected hy UV spectrophotometry (254 nm) first, pyridoxine (B6) was detected by fluoromelry (EX 290nm, EM 395 nm) afterwards. Detection limits were 2, 5, 5, 2 and 5ng, linear ranges were 5-10ng, 5-50ng, 5-40ng, 5-50ng and 10-50ng for B1, B2, B5, B6 and folic acid respectively. Recoveries were 92-100%(B5), 51-52% (folic acid), 103-105% (B2), 99-100% (B6) and 91.3-102% (B1) respectively. In comparison with a reference method and checking with food composition tables, very satisfactory results were obtained by this method.
SIMULTANEOUS DETERMINATION OF FAT SOLUBLE VITAMINS A, D3, E AND K1 IN FORTIFIED MILK POWDERS BY HPLC
1991, 3(8): 649-652
Abstract:
A high performance liquid chromatographic method for the simultaneous determination of four fat soluble vitamins: retinol (vitamin A), cholecalciferol(vitamin D), tocopherol(vitamin E) and phylloquinone(vitamin K1) in fortified milk powders and egg yolk has been developed. The method requires enzymatic hydrolysis of lipid component of the sample as a pretreatment. Several factors which influence the enzymatic hydrolysis were studied-Separation was achieved using μ-Bondapak C-18 column(3.9×300mm), 98% methanol as mobile phase, a double channel detection was selected; vitamins D3 E1 K1 were detected by UV spectrophotometry (265 nm) first, then vitamin A by fluorometry (EX 325nm, EM 480nm). The retention times of vitamin A1 D3, E and K1 4.87, 9.00, 10.58 and 15.45 min respectively. Detection limit were 0.64, 0.25, 0.50 and 0.07 ng; and the recoveries were 90.5%~103.6%, 90.0%~95.6%, 91.7%~98.8%, 91.5%~98.6%, respectively. The vitamins A, D3, E, K1 contents in foods were determined satisfactorily.
A high performance liquid chromatographic method for the simultaneous determination of four fat soluble vitamins: retinol (vitamin A), cholecalciferol(vitamin D), tocopherol(vitamin E) and phylloquinone(vitamin K1) in fortified milk powders and egg yolk has been developed. The method requires enzymatic hydrolysis of lipid component of the sample as a pretreatment. Several factors which influence the enzymatic hydrolysis were studied-Separation was achieved using μ-Bondapak C-18 column(3.9×300mm), 98% methanol as mobile phase, a double channel detection was selected; vitamins D3 E1 K1 were detected by UV spectrophotometry (265 nm) first, then vitamin A by fluorometry (EX 325nm, EM 480nm). The retention times of vitamin A1 D3, E and K1 4.87, 9.00, 10.58 and 15.45 min respectively. Detection limit were 0.64, 0.25, 0.50 and 0.07 ng; and the recoveries were 90.5%~103.6%, 90.0%~95.6%, 91.7%~98.8%, 91.5%~98.6%, respectively. The vitamins A, D3, E, K1 contents in foods were determined satisfactorily.
1991, 3(8): 653-654
Abstract:
The geometric parameters for D-Ala-D-Ala are optimized by MM, the most and next two stable conformations are obtained. According to the interaction model with target emzyme suggested by us, the traingle-relationship of it is obtained. This triangle-relationship could be found in the pharmaceuticals belong to different classes of β-actams also.
The geometric parameters for D-Ala-D-Ala are optimized by MM, the most and next two stable conformations are obtained. According to the interaction model with target emzyme suggested by us, the traingle-relationship of it is obtained. This triangle-relationship could be found in the pharmaceuticals belong to different classes of β-actams also.
1991, 3(8): 655-656
Abstract:
The influences of methanol-d4(MeOD), dimethylsulfoxide-d6 (Me2SO(D)) and dioxane(C4H8O2) solvents on the intramolecular processes are studied by NMR. It has been shown that the addition of these solvents in CdEGTA complex aqueous solution can increase the rate constant (k) of the nitrogen inversion and decrease the activation energy of this process. The linear relations between In(k) and the reciprocal of the solvent dielectric constants (1/ε) are obtained for all the three solvents.
The influences of methanol-d4(MeOD), dimethylsulfoxide-d6 (Me2SO(D)) and dioxane(C4H8O2) solvents on the intramolecular processes are studied by NMR. It has been shown that the addition of these solvents in CdEGTA complex aqueous solution can increase the rate constant (k) of the nitrogen inversion and decrease the activation energy of this process. The linear relations between In(k) and the reciprocal of the solvent dielectric constants (1/ε) are obtained for all the three solvents.
1991, 3(8): 657-658
Abstract:
Many catalysts were pcrpared by carbonization of ion exchange resin-PdCl2 complexes at high temperature in nitrogen, hydrogen atmosphere. The rates for the hydrogenation of methyl acrylate and the amounts of Pd elution of the carbonaceous products were measured and compared with those of commercial Pd/C catalyst. It indicates that the carbonaceous products are less active than Pd/C. However, the leaching of Pd from carbonaceous products is very small and much less than that from Pd/C.
Many catalysts were pcrpared by carbonization of ion exchange resin-PdCl2 complexes at high temperature in nitrogen, hydrogen atmosphere. The rates for the hydrogenation of methyl acrylate and the amounts of Pd elution of the carbonaceous products were measured and compared with those of commercial Pd/C catalyst. It indicates that the carbonaceous products are less active than Pd/C. However, the leaching of Pd from carbonaceous products is very small and much less than that from Pd/C.
1991, 3(8): 659-660
Abstract:
A series of "liquid crystal polymers with two-dimensional mesogeuic units" were synthesized by the polycondensations of the monomer 2, 5-dihydroxybenzylidene-4-phenetidine with a diacid chloride selected from a series of α, ω-bis(4-chloroformylphenyloxy)carbonylalkues. This is the first series of polymers reported under the newly proposed concept "liquid crystal polymers with two dimensional mesogenic units".
A series of "liquid crystal polymers with two-dimensional mesogeuic units" were synthesized by the polycondensations of the monomer 2, 5-dihydroxybenzylidene-4-phenetidine with a diacid chloride selected from a series of α, ω-bis(4-chloroformylphenyloxy)carbonylalkues. This is the first series of polymers reported under the newly proposed concept "liquid crystal polymers with two dimensional mesogenic units".
1991, 3(8): 661-664
Abstract:
The behavior of chloride adsorbed on Ag(100) electrode has been studied using chronoamperometric technique, and the structural transition of chloride layer has been confirmed.
The behavior of chloride adsorbed on Ag(100) electrode has been studied using chronoamperometric technique, and the structural transition of chloride layer has been confirmed.
1991, 3(8): 665-668
Abstract:
The anion of tungstoniobate was synthesized for the first time as KqNbW″O40 2H2O by the reaction of soluble potassium niobate and porous white tungstic acid in aqueous solution. The structure of the anion may be proposed reasonably to be similar to that of dodecameric anion of paratungstate, resulting from substituting of one WO6 group in paratungstate anion by one NbO4 group and leading to the formation of tungstoniobate anion according to the extreme similarity of IR and UV spectra of these two different anions. Potassium 11-tungstoniobate is soluble in wator and unstable in alkaline medium while the structure of the anion may be considered to keep unchanged in acidic medium according to the spectrophotometrical results.
The anion of tungstoniobate was synthesized for the first time as KqNbW″O40 2H2O by the reaction of soluble potassium niobate and porous white tungstic acid in aqueous solution. The structure of the anion may be proposed reasonably to be similar to that of dodecameric anion of paratungstate, resulting from substituting of one WO6 group in paratungstate anion by one NbO4 group and leading to the formation of tungstoniobate anion according to the extreme similarity of IR and UV spectra of these two different anions. Potassium 11-tungstoniobate is soluble in wator and unstable in alkaline medium while the structure of the anion may be considered to keep unchanged in acidic medium according to the spectrophotometrical results.
1991, 3(8): 669-672
Abstract:
In this paper protonation constants of the title lisand and stability constants of its coordination compounds with rare earths have been determined by potentiometric titration at 25±；0.1℃ and ionic strength of 0.10mol.dm-3 NaClO4. The coordination of rare earths with DL-alanyl-alanine has been discussed. The stability of the coordination compound shows "tetrad effect". The position for yttrium shifts from its usual Bo-Er region to the vicinity of Tb.
In this paper protonation constants of the title lisand and stability constants of its coordination compounds with rare earths have been determined by potentiometric titration at 25±；0.1℃ and ionic strength of 0.10mol.dm-3 NaClO4. The coordination of rare earths with DL-alanyl-alanine has been discussed. The stability of the coordination compound shows "tetrad effect". The position for yttrium shifts from its usual Bo-Er region to the vicinity of Tb.
