STUDIES ON THE EXCIMER FLUORESCENCE AND THE STERIC TACTICITY OF POLYPHENYLSILSESQUIOXANES

The steric tacticity of polyphenylsilsesquioxanes (PPS) was studied by exeimer fluorescence spectroscopy. It was found that the fluorescence of PPS come mainly from its intramolecular excimers, The experimental results indicated that the steric-structure of PPS is most probably cisisotactic rather than the cis-syndiotactic as suggested in the literature. With the increase in defect content monomer fluorescence intensity increases because of the enhanced mobility of phenyl groups. Molecular weights and molecular weight distributions do not affect the fluorescence spectra of PPS.     

STUDIES ON THE INTERACTION OF EPOXY POLYMERS WITH HOMOPOLYUREAS

INTRODUCTION Epoxy resins are reactive polymers which when cured with a variety of chemicals lead to a host of useful thermosets. Since the epoxide is a strained ring, it readily undergoes addition and homopolymerization. The homopolymerization is a process catalysed by acids, bases, Lewis acids, t-amines as well as by inorganic salts.     

STRUCTURE-REACTIVITY STUDIES ON THE EXTRACTION OF RARE EARTHS BY DIALKYL ISOPROPYLPHOSPHONATES

Dialkyl isopropylphosphonates with various alkyl groups are synthesized for the structure-reactivity studies on the extraction of rare earths. Steric effect of ligands on the extrac-tion behaviour of rare earth is well demonstrated due to the lanthanide contraction. Thethermodynamic functions of the extraction reaction are estimated and the influence of chem-ical structure of extractants is discussed. By the method of continuous variation as well asthe elementary analysis, the composition of the extracted species is deduced as Ln(NO_3)_3·3L.The structure of the coordination compound is further elucidated by IR and NMR spectra.The magnetic property and the differential thermal analysis of the complexes are also studied.     

THEORETICAL STUDIES ON THE CYCLOADDITION REACTION OF FLUOROKETENE WITH ETHYLIDENIMINE

ＴＨＥＯＲＥＴＩＣＡＬＳＴＵＤＩＥＳＯＮＴＨＥＣＹＣＬＯＡＤＤＩＴＩＯＮＲＥＡＣＴＩＯＮＯＦＦＬＵＯＲＯＫＥＴＥＮＥＷＩＴＨＥＴＨＹＬＩＤＥＮＩＭＩＮＥＴＨＥＯＲＥＴＩＣＡＬＳＴＵＤＩＥＳＯＮＴＨＥＣＹＣＬＯＡＤＤＩＴＩＯＮＲＥＡＣＴＩＯＮＯＦＦＬＵ...     

THE STUDIES OF THE CURING OF AN EPOXY RESIN ON COPPER WIRE BY FTIR EXTERNAL REFLECTION SPECTROSCOPY

The epoxy coating on copper wire has been studied by a modified sampling technique using Fourier transform infrared (FTIR) diffuse reflectance attachment. As the wire axis was parallel to the incident plane, a reflection spectrum of thin layer coating on a copper wire can be obtained. The study found that imidszole, especially the acetic acid treated imidazole, can be used as an effective curing catalyst of the epoxy resin on copper. This is the first report about the IR study of coatings on metal wires.     

STUDIES ON THE EXCIMER FLUORESCENCE OF POLYPHENYL GLYCIDYL ETHER AND POLYNAPHTHYL GLYCIDYL ETHER

Polyphenyl glycidyl ether (PPGE) and polynaphthyl glycidyl ether (PNGE) have beensynthesized by cationic polymerization and their structures characterized by carbon 13 NMRand 1R, etc. The fluorescence spectra of PPGE, PNGE and their corresponding monomersPGE, NGE as model compounds have been studied. In dilute solutions at room temperature,only monomer fluorescence of the chromophore is observed. Comparison between the spectraobtained from dilute solutions, concentrated solutions and solid film shows that there is excimeremission when polymer chains in solution or in film are sufficiently close to each ocher.From the concentration dependence of the excimer emission, further evidence is obtained forthe existence of interchain excimer interaction in these polymers.     

THEORETICAL STUDIES ON THE REACTION MECHANISM OF AMMONIA WITH FORMALDEHY DE

The reaction mechanism of ammonia with formaldehyde was investigated by usingthe intrinsic reaction coordinate(IRC)method on the ab initio RHF/STO-3G basis set.our results indicate that the reaction proceeds in two stages:the first step yieldsthe molecular complex and the second one is the rearrangement from molecular complex tothe reaction proauct.     

THE STUDIES ON CHELATING FIBER—THE STUDIES ON THE AMIDOXIMATION OF POLYACRYLONITRILE FIBER

The amidoximation process of commercial polyacrylonitrile fiber was studied. The results showed that it is possible to prepare a chelating fiber, which present high adsorption capability to Au^3+ and reasonable mechanical property,by the amidoximation of PAN fiber,with the increase of reaction time or agent concentration,the coversion of CN group in PAN increases rapidly at first and then increases slowly.When the reaction temperature is higher than that at which the paracrystalline region in the fiber is destroyed, the conversion of CN group increases greatly,but the mechanical property of the fiber begins to be inferior.     

STUDIES ON COMPLEXES OF RARE EARTHS WITH CROWN ETHERS(Ⅳ)SYNTHESIS AND CHARACTERIZATION OF THE COMPLEXES OF RARE EARTH NITRATES WITH 4''''-BROMO-5''''-NITROBENZO-15-CROWN-5

Six new solid complexes of macrocyclic polyether ligand 4′-bromo-5′-nitrobenzo-15-crown-5(L)withUivalent rare earth nitrates having composition of RE(NO_3)_3·L·mCH_3CN·nH_2O(RE=L_a--Nd,m=n=0,RE=Sm,Bu,m=0.1,n=1,4)have been synthesized in acetonitrile or acetone.All the isolated complexes have been char-acterized by elementary analysis,IR and UV spectra,differential thermal and thermogravimetric analysis,X-ray powderdiffraction analysis,molar conductance and measurementa of solubility in some general solventa.It shows thatcoordination number of the rare earth cation in the complexes of La,Ce,Pr and Nd nitrate is eleven.     

STUDIES ON THE KINETICS OF PROPYLENE POLYMERIZATION WITH THE COMPLEXTYPE TiCl_3 CATALYST

The active center concentration C_p, the rate constant k_p, and the activation energy of chain propagation E_p in the polymerization of propylene with complex-type TiCl_3-(C_2H_5)_2AlCl catalyst system were studied. The Mn was corrected by (?) value determined by GPC. The values thus obtained for C_p, k_p, and E_p at 50℃were 3.01 mol/mol Ti, 6.27 1/mol·sec, and 5.10 Kcal/mol respectively.The kinetic parameters were compared with those obtained from conventional TiCl_3·AlCl_2 catalyst, showing that the higher activity of the complex-type catalyst over the conventional catalyst is not only due to the higher C_p of the former, but to a greater extent due to the increase of the k_p value.     

STUDIES ON THE SYNTHESES OF FAVELINES

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STUDIES ON THE SYNTHESIS OF ISOSARCOPHYTOL-A

A precursor 9 of isosarcophytol-A(1)was prepared from(■)-farnesol(3)through 6 steps.Isosarcophytol-A(1),a cembrane-type diterpenoid,was first isolated fromustralian soft coral(Nephthea brassica)in 1982,and its structure was estab-shed as(1,3,7,11-all ■,13■)-cembra-1,3,7,11-tetraen-13-ol,an isomer ofarcophytol-A■.As far as we know,its bioactivity and synthesis have noteen reported yet.     

THE STUDIES ON CHELATING FIBER -THE STUDIES ON THE AMIDOXIMATION OF POLYACRYLONITRILE FIBER

The amidoximation process of commercial polyacrylonitrile fiber was studied. The results showed that it is possible to prepare a chelating fiber, which present high adsorption capability to Au3+ and reasonable mechanical property, by the amidoximation of PAN fiber, with the increase of reaction time or agent concentration, the coversion of CN group in PAN increases rapidly at first and then increases slowly. When the reaction temperature is higher than that at which the paracrystalline region in the fiber is destroyed, the conversion of CN group increases greatly, but the mechanical property of the fiber begins to be inferior.     

THE RETICAL STUDIES ON THE THERMOLYSIS OF THIETANE

The mechanism of the thermolysis of thietane to form ethyleneand thioformaldehyde has been studied by using ab initio SCF MO methodat STO-3G* and 3-21G* level.It has been found that there are twopossible stepwise pathways.One is to break C-C bond firstly,while theother is to break C-S bond at first.The cleavage of C-S bond is pre-ferred over that of C-C bond.     

NMR AND INFRARED SPECTROSCOPIC STUDY ON THE INTERACTION OF RARE EARTH WITH L-METHIONIHE

Five solid complexes of rare earth with L-methionine have been prepared. The interaction of rare earth with the ligand has been studied by NMR and IR spectroscopy.     

STUDIES ON THE CONSTITUENTS OF THE ROOTS OF SCUTELLARIA PLANIPES

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NMR STUDIES ON THE WEAK INTERACTION OF FOUR-MONONUCLEOTIDES WITH TRYPTAMIDE AND LEUCINAMIDE

NMR spectroscopy analysis was introduced to investigate the weak interaction of four 5'—mononucleotides with tryptamide and leucinamide. Assuming a 1∶1 complex formation, the association constants were determined by nonlinear regression analysis. The association affinity of 4 mononucleotides with tryptamide decreased in the order: G>A>C>U, indicating that purine bases stack more strongly with tryptamide than pyrimidine bases. But with leucinamide the affinity decreases in the order: G>C>A=U, suggesting an amino acid—anticodonic preferential interaction. The implication of the present data to the origin of genetic code was briefly discussed.     

STUDIES ON THE REACTION OF d-ACETAMIDCCINNAMAMIDE WITH TRIS(DIETHYLAMINO)PHOSPHINE

d-Acetamidocinnamamide do not react with P(OMe)_3, with P(NEt_2)_3 they give rise to 2-methyl-4-hydroxy-5-d-[bis(diethylamino)phosphoryl] benzyl imidazole.The pathway is studied for the formation of Ⅰ. The two intermediates(Ⅱ) are isolated.The structures of Ⅰ and Ⅱ are confirmed by IR, ~1H NMR, ~(31)P NMR, Ms.     

IR STUDIES OF THE SIDE CHAIN ALKYLATION OF TOLUENE WITH METHANOL ON ZEOLITE CATALYSTS

Surface species resulting from the decomposition of methanol on Na—、K—、Rb—、Cs—、BCs—、KCs— and KBCs—X zeolite at 420℃,and the relationship between sur-face species and the side chain alkylation selectivity from toluene with methanol have beenstudied by infrared and gas chromatographic methods.