PHOTOPOLYMERIZATION IN THE MICELLAR SYSTEMSⅡ THE CATALYSIS OF PKT FUNCTIONAL MICELLE*

A kind of cationic compounds, having benzophenone end group and various length chain (PKT) (BP-CH_2N+R_2R'·X~-, R&R' different chain iength alkyl group) were used as photosensitizers. Various BP/TEA systems have been used for study, The efficiency of MMA photopolymerization initiated by them shows PKT>BP in homogeneous water solution and PKT> BP/CTAB in micellar water solution. The results obtained indicate that catalytic effects of PKT type functional micelles are far greater than that of common micelle with the enhancement of polymerization rate over 10 times compared with BP in water solution. The catalytic role, reaction character of PKT, effect of counter ions and retarding effect of oxygen have also been discussed.     

光照对高铁酸盐溶液稳定性的影响

The effects of light wave on the stability of fen'ate solution have been examined. The results showed that UV-light accelerates the decomposition of ferrate with decomposition rate 1.6 times as much as that in dark whereas infrared light has only unclear effect on the stability of ferrate, with decomposition rate 1.1 times as much as in dark. The polythene container is found to the best for preservation of ferrate solution in dark.     

MECHANISM OF ELECTROCHEMILUMINESCENCE OF THE NEW REAGENT 6-(2-HYDROXY-DIETHYLAMINOPHENYLAZO)-2, 3-DIHYDRO-1, 4-PHTHALAZINE-1, 4-DIONE CATALYZED BY SILVER (Ⅰ)

The electrochemi luminescence of a new reagent 6-<2-hydroxy-4-diethylaminophenylazo>-2, 3-dihydro-1, 4-phthatazine-1, 4-dione in basic aqueous solution was studied. Trace amount of silver showed significant effect on the efficiency of light emission of HDEA during a positive trigonometrical wave pulse was exerted on the electrodes In the present paper, the ecl spectra of HDEA have been measured. λ_(max) is 410 nm. The reaction of HDEA chemiluminescence and the circular voltammetry, ultraviolet-visible spectrometry for the system have been investigated. The possible mechanism of the ecl of HDEA-KCL-KOH-Ag(I) system has been proposed.     

KINETIC AND APPLICATION: STUDIES ON THE REACTION SYSTEM OF OSMIUM(Ⅳ)-ARSENIC(Ⅲ)-CHLORATE

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.     

~(13)C NMR SUBSTITUENT EFFECTS IN A SERIES OF 2-PHENYL BENZOTHIAZOLES

According to ~(13)C NMR determinations and analyses of 14 compounds of 2-phenyl benzothiazole, we have studied the substituent effects on aromatic hetero rings. The different substituents have effects on the charge densities in the molecules. We have also analyzed the structural factors of effects on ~nJ_(13C-1H). The perturbations of benzothiazole to benzene ring were studied by the method of comparison analysis. The substituent induced chemical shifts of benzothiazole were obtained. The experiential calculations of ~(13)C chemical shifts for aromatic carbons have been done, the calculated velues agreed with the experimental ones. The theoretical calculations for the compounds 2, 3, 9 have been made using the EHMO method (the Enlarged Hiickel Molecular Orbital Method). The relationships between the ~(13)C experimental chemical shifts and the total charge densities of the corresponding carbon atoms were obtained by the regression analysis. The correlation coefficient is—0.96.     

PHOTOREDUCTION OF ALKYL VIOLOGENS AND POLYVlOLOGENS IN 2-PROPANOL AQUEOUS SOLUTION

In order to study the effect ofalkyl chain length and the polymer effect on the photoreduction behavior of some viologens, a series of alkyl viologen, polyviologen and bisviologen compounds have been synthesized. In the presence of excess 2-propanol, the initial photoreduction of alkyl viologens and polyviologens follow the peudo--seeond--order reaction, the calculated rate constants are related to the alkyl chain length: In addition, the intramoleeular association of radical cations of polyviologens has been found even in dilute solution. However the extent of association is varied with the aikyl chain length. The observed polymer effect of polyviologens in the photoreduetion is significant which can be explained in terms of the nature of second order reaction.     

脂族酰基过氧化物分解动力学的分研究 III: 过氧化3,5,5-三甲基己酰在萃中的解动力学和机理

The kinetics of decomposition of 3, 5, 5-trimethylhexanoyl peroxide (1) in benzene has been studied at 30, 40 and 50`C and the cage effect of decomposition has been determined by scavenging method. The relative amounts of the main products of decomposition of 1 at 50`C with change of initial concentration have been determined. The results showed that the decomposition of 1 followed first plus three halves order kinetics as reported for lauroyl peroxide (2), but had a larger cage effect of 0.6. The mechanism of decomposition of 1 is practically the same as what we have proposed for 2. The faster rate and larger cage effect but less induced decomposition of 1 than that of 2 are attributed to the branching of the molecule of 1, especially to the presence of β-methyl group, which causes a larger entropy increase in the transition state.     

Studies on PNPP Hydrolysis Catalyzed by Schiff Base Cobalt（Ⅱ） Complexes

Two cobalt（Ⅱ） complexes of the Schiff base with morpholino or aza-crown ether pendants, CoL^1 and CoL^2, as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester （PNPP）. The analysis of specific absorption spectra of the hydrolytic reaction systems indicates that key intermediates, made up of PNPP and Co（Ⅱ） complexes, have been formed in reaction processes of the PNPP catalytic hydrolysis. The mechanism of PNPP catalytic hydrolysis has been proposed based on the analytic result of specific absorption spectrum. A kinetic mathematical model, applied to the calculation of the kinetic parameter of PNPP catalytic hydrolysis, has been established based on the mechanism proposed. The acid effect of buffer solution, structural effect of the complexes, and effect of temperature on the rate of PNPP hydrolysis catalyzed by the complexes have been also discussed.     

COPOLYMER OF 1-(ACETYLSALICYLYLOXY)ETHYL METHACRYLATE AND ITS HYDROLYSIS

The copolymers of 1-(acetylsalicylyloxy)ethyl methacrylate (HEMA-ASA) with methacrylicacid (MA) have been prepared and their hydrolysis in dioxane-H_2.O either in acdic or alkaline medium,at 60℃or 37℃have been investigated. It is found that the chief product of hydrolysis is alwaysaspirin with minor amount of salicylic acid. Due to its neighbouring group effect, the hydrolysisrate of (HEMA-ASA)-MA copolymer markedly depends on its composition and the pH value ofhydrolysis medium, i.e. the hydrolysis rate increases with increasing mole fraction of MA in the copoly-mer and pH value of hydrolysis medium.     

A STUDY ON THE MORPHOLOGY AND PROPERTIES OF IPP/IIR BLENDS

The effect of isobutylene-isoprene rubber (IIR) on the crystallizing behavior of isotactic polypropylene (IPP) as well as the morphology of the blends in relation with its properties have been studied by DSC, WAXD, polarized light microscope, SEM and mechanical properties test. The experimental results show that IIR has slight influence on melting point, crystallinity, crystallization rate of IPP. It seems certain that IIR has not entered into IPP phase in melt state. IIR has retarding action on the growth of IPP crystal and is an effective nucleating agent of IPP spherulites. The impact strength of the blend increases rapidly with IIR content more than 30 parts; the tensile strength of the blend, however, decreases as IIR content increases. The temperature and time of alter heat-treatment also have great influence on the impact strength of the blend. The impact strength of IPP/IIR (100/20) heat-treated at about 130℃for 2h is 5 times as high as that of the untreated blend.     

Determination of chloride ion by electrochemiluminescence and investigation of the mechanism

The electrochemiluminescence (ECL) of luminol in aqueous alkaline solution was studied.Trace amounts of chloride showed significant effect on the efficiency of light emission of luminol as a posi-tive trigonometrical wave pulse was exerted on the solution. The detection limit for the chloride is5.0 ×10~(-6) mol/L and the linear calibration range extends up to 1.0 ×10~(-2) mol/L; the relative standarddeviation for 1.0 ×10~(-5) mol / L chloride is 5%. The influencing factors for chloride determination arealso discussed. The possible mechanism for the electrochemiluminescence reaction may be due to theoxidation of chloride ion in the solution to ClO~-, and the latter acts on luminol and then gives outluminescence. The method has been applied to determine the total chloride in tap water with satisfactoryresults.     

Study on Frequency Doubling Scattering and Second—Order Scattering Spectra of Heparin—Methylene Blue System

Binding of heparin with methylene blue(MB) in pH5.7 Britton-Robinson buffer can result in a significant enhancement of frequency doubling scattering (FDS) and second-order scattering (SOS).Their maximum scattering wavelengths(λmax) appear at 350nm for FDS and 700nm for SOS,respectively.The optimum conditions of the reaction,the influencing factors and the relationship between the two scattering intensities and the concentration of heparin have been investigated.The new methods for the determination of trace amounts of heparin bassed on the FDS and SOS methods have been developed,which exhibit high sensitivities.The detection limits of heparin are 4.36ng/mL for the FDS method and 3.55ng/mL for the SOS method,respectively.Both of the methods have fairly godd selectivity and ware applied to the determination of heparin in sodium heparinate injection samples with satisfactory results.Moreover,the relative mechamisms have also been discussed.     

TARNISH AND PROTECTION OF SILVER DEPOSIT——MECHANISM AND METHOD

The mechanism of tarnish caused by exposure to light and Na_2S solution treatment on silver-electroplated deposit and the antitarnish effects of various antitarnish agents have been investigated in this paper. The results showed that 1-phenyl-5-mercaptotetrazole (PMTA) has excellent antitarnish effect for UV light and H_2S tests.The studies of XPS and AES and UV absorption spectra showed that PMTA can absorb effectively UV light and form a dense surface film which can prevent effectively the reactions between silver deposit with corrosive media.Antitarnish surface film could be composed of a polynuclear coordination polymeric compound with structure unit approximate to [Ag_3(PMTA)]. according to the depth dependence of percent component (C%) and sputtering time.     

A STUDY OF METHANE OXIDATIVE COUPLING OVER La-Th-O MIXED OXIDE CATALYSTS

The compositions and structures of La-Th-O mixed oxides as well astheir catalytic activity for methane oxidative coupling have been studied bymeans of XRD,XPS and IR.The results indicated that the solid solution ofLa_xTh_(1-x)O_(2-&)with the fluorite structure was formed in the range of 0≤x≤0.6and it was the main active phase for oxidative coupling of methane(OCM).     

Study on the Atomization Process of Lithium in Electrothermal Atomic Absorption Spectrometry

A new method for determining the kinetic order and activation energy for atom formation in electrothermal atomic absorption spec-trometry is proposed. The assumption of first order kinetics for atom formation and the steady-state approximation which appeared in the previous models is avoided in the proposed method. The kinetic parameters for atom formation of Li have been obtained, and the effect of the amount of analysed sample, ashing temperature, atomization temperature, heating rate, gas flow and tube surface on the atomization of Li has also been investigated.     

Electrolessly Plated Ni-Zn（Fe）-P Alloy and Its Corrosion Resistance Properties

The autocatalytic deposition of Ni-Zn(Fe)-P alloys has been carried out on substrate of carbon steel from a bath containing nickel sulfate, zinc sulfate, sodium hypophosphite, sodium citrate and boric acid. The effects of pH and the molar ratio of NiSO4/ZnSO4 on the deposition rate and the composition of deposits have been studied. It was found that the presence of zinc sulfate in the bath has an inhibitory effect on the alloy deposition. The structure and the surface morphology of Ni-Zn(Fe)-P coatings were characterized with XRD and SEM, respectively. The alloys plated under the experimental conditions consisted of an amorphous phase coexisting with a crystalline cubic Ni phase (poly-crystalline). The surface morphology of the coating is dependent on the deposition parameters. The corrosion resistance of the Ni-Zn(Fe)-P deposits was examined via mass loss tests and anodic polarization measurements, respectively. The results show that the surface morphologies of the deposits and the corrosion resistance of the deposits have been improved. The results of mass loss tests almost accord with those of anodic polarization measurements. The corrosion mechanisms of Ni-Zn(Fe)-P alloys in NaCl and NaOH solutions were investigated by means of EDX. The deposit immersed in an NaCI or an NaOH solution contains more content of oxygen and less contents of the metals(except Fe) than that placed in air, which shows that the NaCl or NaOH solution can accelerate the oxidation of the deposit.     

Effect of mass transfer limitations on catalyst performance during reduction and carburization of iron based Fischer-Tropsch synthesis catalysts

Existence of intraparticle mass transfer limitations under typical Fischer-Tropsch synthesis has been reported previously,but there is no suitable study on the existence of intraparticle diffusion limitations under pretreatment steps (reduction and activation) and their effect on catalytic performance for iron based catalysts.In this study,Fe-Cu-La-SiO2 catalysts were prepared by co-precipitation method.To investigate the intraparticle mass transfer limitation under reduction,activation and reaction steps,and its effect on catalytic performance,catalyst pellets with different sizes of 6,3,1 and 0.5 mm have been prepared.All catalysts were calcined,pretreated and tested under similar conditions.The catalysts were activated in hydrogen (5%H2in N2) at 450℃ for 3 h and exposed to syngas (H2/CO=1) at 270℃ and atmospheric pressure for 40 h.Afterwards,FTS reaction tests were performed for approximately 120 h to reach steady state conditions at 290℃,17 bar and a feed flow (syngas H2/CO=1) rate of 3 L/h (STP).Using small pellets resulted in higher CO conversion,FT reaction rate and C5+ productivity as compared with larger pellets.The small pellets reached steady state conditions just 20 h after starting the reaction.Whereas for larger pellets,CO conversion,FT reaction rate and C5+ productivity increased gradually,and reached steady state and maximum values after 120 h of operation.The results illustrate that mass transfer limitations exist not only for FTS reaction but also for the reduction and carburization steps which lead to various phase formation through catalyst activation.Also the results indicate that some effects of mass transfer limitations in activation step,can be compensated in the reaction step.The results can be used for better design of iron based catalyst to improve the process economy.     

STEADY-STATE AND TIME-RESOLVED FLUORESCENCE STUDY OF TRIPLE EXCIPLEX IN THE SYSTEM OF POLYACENAPHTHALENE AND TEREPHTHALIC DIMETHYLESTER

Triple exciplex formed between polyacenaphthalene and terephthalic dimethylester (TDE) has been studied by means of the steady-state and time-resolved fluorescence spectra. The theoretical model of the triple exciplex formation for a flexible polymer chain in a dilute solution has been proposed. The fluorescence decays of the monomer, the exciplex and the triple exciplex obey a double exponential rule in the pbotophysical processes of the triple exciplex formation. The association rate constant of the exciplex formation is k_3=6.0×10~9s~(-1)(mol/L)~(-1); the association rate constant of the triple exciplex formation is k_6=5.2×10~7s~(-1). A mechanism for the triple exciplex formation from the exciplex to the triple exciplex has been proved through the noncrystal films corresponding to the same concentrations of the solution systems and the fluorescence lifetimes of the intramolecular excimer.     

Kinetic study on the ligand exchange reactions between bis(alkylxanthato)palladium(II)and bis(N,N-dialkyldithiocarbamato)palladium(II)by high-performance liquid chromatography

The rate constants and equilibrium constants of ligand exchange reactions between his(alkylxanthato)palladium(Ⅱ),Pd(S_2COR)_2(R=Am,n-Hex,Bz),and bis(N,N-dialkyldithiocarbamato)palladium(Ⅱ),Pd(S_2CNR_2)_2(K=Et,n-Pr,n-Bu),in chloroform solution have been determined ina temperature range of 20—50°C by means of high-performance liquid chromatography.It was foundthat both the forward and reverse reactions are of second order.All of the equilibrium constants Kdetermined are 10.3±1.0,much greater than the value(K=4)calculated statistically which indicatesthat the ternary complexes are more stable than the binary complexes.The experimental resultsrevealed that the reaction rate decreases with the increase in the size of R and R~1 groups and the latterare more remarkable,consistent with the deduction of steric effect.The activation parameters ofthe reactions have been calculated.In reaction series(11)and(12)(in the text)the isokinetic tempera-tures B=390±8K and β=346±15 K have been observed respectively.A plausiblemechanism in-volving an eight-membered ring intermediate has been proposed on the basis of experimental results.     

Mechanism and Kinetics for the Reaction of NCS and OH Radicals

The mechanism and dynamical properties for the reaction of NCS and OH radicals have been investigated theoretically. The minimum energy paths (MEP) of the reaction were calculated using the density functional theory(DFT) at the B3LYP/6-311 G^** level, and the energies along the MEP were further refined at the QCISD(T)/6-311 G^** level. As a result, the reaction mechanism of the title reaction involves three channels, producing HCS NO and HNC SO products, respectively. Path Ⅰ and path Ⅱ are competitive, with some advantages for path Ⅰ in kinetics. As for path Ⅲ, it looks difficult to react for its high energy barrier. Moreover, the rate constant have been calculated over the temperature range of 8190-2500K using canonical variational transition-state theory (CVT). It was found that the rate constants for both path Ⅰ and path Ⅱ are negatively dependent on temperature, which is similarwith the experimental results for reactions of NCS with NO and NO2, and the variational effect for the rate constant calculation olavs an important role in whole temperature range.