Table of Content

24 June 1980, Volume 1 Issue 1

   Next Issue

Preface

THE MECHANISM OF La³⁺-NaY ION-EXCHANGE REACTION

Hsu Rhu-reg, Yu Guozhen, Lu Yuqi, Feng Shouhua, Chang Wencui

1980, 1(1):  1-8. 

Asbtract ( )   PDF (420KB) ( )  

Related Articles | Metrics

As is well known,the mechanism of La³⁺- NaY ion-exchange reaction reviewed by H.S.Sherry has been mainly ascribed into two steps.The second step of them called the slow step is proposed as the rate-controlling step in the whole reaction with respect to the stripping of water molecules from the hydrated La³⁺ion in the large cavity in relation with the replacement of Na⁺by La³⁺in the β-cage.The corresponding activation energy can be estimated by the enthaly of hydration of La³⁺ion.Although the assumption of the rate-controlling step is reasonable,there is still lack of exact experimental evidence.It is to make a deeper understanding of the slow step by means of experimental devices.The arrangement of measurement condition at elevated temperature may facilitate the systematical study of the behaviour of this kind of ion-exchange reaction.The present authors have investigated the slow step at an elevated temperature in three aspects;1.To measure the ion-exchange isotherm,for La³⁺-NaY system at 100℃and 180℃ respectively.2.To investigate the degree of ion-exchange of individual LnYat 180℃ and to compare the results with the enthalpy of hydration of Ln³⁺ions.3.To evalute the rate-constant and apparent activation energy of the slow step at elevated temperature from our experimental data.As a result,a more rational mechanism of La³⁺-NaYion-exchange reaction is proposed.Ⅰ.La(H₃O)₉³⁺+ NaY(s)→La(H₂O)₉³⁺Na(SI)F(s)+Na⁺Ⅱ.La(H₂O)₉³⁺(in large cavity)+La(H₂O)₉³⁺Na (SI)Y(s)→La(H₂O)₉³⁺LaY(s)+Na⁺Eq-Ⅱ should consist of the following two consecutive reactions;Ⅱ-A.La(H₂O)₉³⁺(in large cavity)→La³⁺+9H₂OⅡ-B.La³⁺+ La (H₃O)₉³⁺Na(SI)F(s)→La(H₂O)³⁺LaY(s)+Na⁺Eq-Ⅱ-Ais the rate-controlling step for this ion exchange reaction.

Articles

ESTIMATION OF STABILITY CONSTANTS OF METAL COMPLEXES

Chen Yude

1980, 1(1):  9-16. 

Asbtract ( )   PDF (527KB) ( )  

Related Articles | Metrics

Eight methods have been proposed for the estimation of stability constants of complexes as follows;1.lgK₁=Az²/r+Bx±+C.2.The linear relationship between lgK₁of two similar metal ions with a series of ligands.3.The linear relationship between lgK₁of two similar ligands with a series of metal ions.4.The linear relationship between lgK₁and ∑pK_afor complexes of one metal ion with a series of similar ligands.5.The linear relationship between lgK₁and x± for a series of metal ions with similar z²/r.6.The linear relationship between lgK₁and z²/r for a series of metal ions with similar x.7.The stability constants show the same "normal" variation as z²/r and x for the metal series.8.Ligands with larger∑pK_abind strongly to metals with larger z²/r and ligands with smaller x bind strongly to metals with larger xEight methods have been proposed for the estimation of stability constants of complexes as follows;

Preface

COMPLEX FORMATION OF Th(edta)CHELATE WITH SOME AMINO-ACIDS

Luo Qinhui, Meng Jingxia

1980, 1(1):  17-22. 

Asbtract ( )   PDF (462KB) ( )  

Related Articles | Metrics

The solutions containing equimolar thorium nitrate,EDTA and an amino-acid (serine,threonine,leucine,or a-amino-isobutyric acid) have been investigated potentiometrically.The results indicate the formation of 1:1:1 mixed ligand chelates.The formation constants logK_ThYL^ThY at 30°±0.1℃ and ionic strength μ=0.15 (KNO₃) have been calculated.The order of stabilities in terms of the secondary ligand amino-acids,is as follows.a-amino-isobuturic>leucine>threonine=serine.This order agrees with that of the basicity of the amino-acids and can be represented by a linear equation

STUDIES ON THE COMPLEX OF Y(NCS)₃AND DIBENZO-18-CROWN-6-I--SYNTHESIS AND CHARACTERIZATION

Wang Genglin, Zhang Yunshi, Yao Xinkan, Yan Shiping, Wang Lianyuan

1980, 1(1):  23-28. 

Asbtract ( )   PDF (466KB) ( )  

Related Articles | Metrics

The complex of Y(NCS)₃and dibenzo-18-crown-6 has been prepared in solid state and characterized by elemental analyses,X-ray diffraction,infrared and ultraviolet spectra,as well as thermogravimetric (TG) and differential thermal analyses (DTA).The complex formed is proved to be Y (dibenzo-18-crown-6) (NCS)₃Besides,a brief discussion on the conditions of complexation by rare earth elements with crown ethers was performed.

Articles

THE DETERMINATION OF THERMODYNAMIC PARAMETERS ASSOCIATED WITH THE FORMATION OF SOME METAL-ASPARAGINE COMPLEXES

Zhong Shan, Yang Weida

1980, 1(1):  29-34. 

Asbtract ( )   PDF (534KB) ( )  

Related Articles | Metrics

Equilibrium constants for the formation of Co²⁺,Ni²⁺,Cu²⁺,Zn²⁺and Cd²⁺bis-complexes of asparagine have been determined potentiometri-cally at an ionic strength of 0.1 and at 10°,15°,20°,25°,30℃.At all the temperatures studied,the Gibbs free energy changes increase in the Order Cu²⁺<Ni²⁺<Zn²⁺<Co⁹⁺<Cd²⁺.The enthalpy and entropy changes for the bis-species are calculated from the temperature coefficient data.The primary driving force favoring the formation of the corresponding complexes in solution has been discussed.

pH-METRIC DETERMINATION OF Ni(Ⅱ)-IMDA-HBG AND Ni(Ⅱ)-Tart-HBG SYSTEMS--STUDIES ON N-o-HYDROXYBENZYLGLYCINE (HBG) AND ITS COMPLEXES--Ⅱ

Zhang Hualin

1980, 1(1):  35-43. 

Asbtract ( )   PDF (631KB) ( )  

Related Articles | Metrics

The addition reaction of Ni (Ⅱ)-Iminodiacetic acid (IMDA) with HBG and the displacement reaction of Ni(Ⅱ)-Tartaric acid (Tart) with HBG as well as the complexation of Ni(Ⅱ) with HBGwere studied by pH--metrically in aqueous solution at 30.0±0.1℃in the presence of 0.1M potassium chloride.The equilibrium constants of addition reaction and displacement reaction (k₁₁₁and k_r1),the over-all formation constants of two mixed-ligand complexes (β₁₁₁) as well as the step-wise formation constants of Ni(Ⅱ)-HBGchelate (k₁₀₁,k₁₀₂) and the over-all formation constant of Ni(Ⅱ)-Tart chelate (β₁₂₀) were determined.The results are summarized as follows;Ni(Ⅱ)-IMDA-HBG.lgk₁₁₁7.10,lgβ₁₁₁15.36;Ni(Ⅱ)-Tart-HBG:lg k_r15.13,lgβ₁₁₁ 12.68,lgβ₁₂₀7.55;Ni(Ⅱ)-HBG: lgk₁₀₁9.07,lgk₁₀₂5.54,lgβ₁₂₀14.61.The pHtitration curves,the stability of mixed-ligand complexes and Ni(Ⅱ)-HBGchelate as well as the possible chelated-form of Ni(Ⅱ)-Tart chelate in basic condition were discussed.

STUDY ON THE MIXED-LIGAND COMPLEXES IN THE SYSTEM OF NIOBIUM-(5-Br-PADAP)-HYDROXY ACID

Shi Huiming, He Xiwen, Chang Guizhu

1980, 1(1):  44-52. 

Asbtract ( )   PDF (688KB) ( )  

Related Articles | Metrics

A ternary complex of Nb with 5-Br-PADAP and tartrate ion has been investigated as a sensitive and selective system for the spectrophoto-metric determination of Nb.The molar ratio of the three components in the complex is estimated to be Nb: 5-Br-PADAP: Tar=1:1:1 and the possible structure of the mixed ligand complex is proposed.Anew method has been developed for the rapid determination of Nb in steels without separated Nb from its accompanying elements

SPECTROPHOTOMETRIC DETERMINATION OF LIGHTER AND HEAVIER RARE EARTHS AND YTTRIUM BY USING CHLOROPHOSPHONAZO--Ⅲ

Cai Ruxiu, Luo Qingyao, Li Xinyi, Li Qingxiang, Shi Guangzhao, Zeng Yune

1980, 1(1):  53-60. 

Asbtract ( )   PDF (730KB) ( )  

Related Articles | Metrics

The color reactions of α-type and β-type of rare earths with chloro-phosphoaazo Ⅲ have been studied in this paper.Under a certain experimental condition,a-type of heavier rare earths (Gd to Lu) chelates of chlorophosphonazo Ⅲ can be converted to β-type.The tendency of the conversion of chelates of yttrium is the largest.The corresponding chelates of lighter rare earths (La to Eu) do not convert to β-type under the same condition.Masking effect of Zn-EDTA and Zn-CyDTA can be utilized to enlarge the difference of color reactions.Amethod for spectrophotome-tric determination of lighter and heavier rare earths,and yttrium in HCl-NaAc buffer solution has been suggested.Lighter rare earths can be determined in the presence of heavier rare earths at 684nm,pH 2.9-3.4,using Zn-CyDTAas the masking agent.Heavier rare earths and yttrium can be determined respectively in the presence of lighter rare earths at 740nm in tke range of pH2.8-3.6 and pH1.8-2.4,using Zn-EDTA+ NaFa nd NaF as a masking agent respectively.

Preface

RESEARCH ON 2,6-DISUBSTITUTED BENZO-BISOXAZOLES--Ⅰ

Kao Chen-heng, Zhou Yimin, Wang Mingzhen, Pan Jiaxing, Fan Xiuju

1980, 1(1):  61-65. 

Asbtract ( )   PDF (325KB) ( )  

Related Articles | Metrics

Eight of the 2,6-Di-substituted benzo-[1,2d;4,5d']-bisoxazoles as well as eight of the 2,6-Di-substituted benzo-[1,2d;5,4d']-bisoxazoles are synthesized.Their m.p.,λ_maxof UVspectra and fluorescence emission spectra,as well as laser properties are given in tables.

SYNTHESIS OF HIGHER PRIMARY ALKANOLS

Yang Shih-hsien, Chen Ju-yu, Liu Zhun, Chen Jinlong, Wang Likun, Shi Guozhu

1980, 1(1):  66-70. 

Asbtract ( )   PDF (397KB) ( )  

Related Articles | Metrics

Five new 7-oxo-alkanoic acids,R-CO-(CH₂)₆-COOH (Where R=CH₃-(CH₂)₁₃,CH₃(CH₂)₁₅,CH₃(CH₂)₁₇,CH₃(CH₂)₂₀and CH₃(CH₂)₃₂),have been prepared by the reaction of carboxylic chlorides with 1-morpholino -1-cyclohexene.The acids thus formed were reduced twice by first Huang-Minion modification of the Wolff-Kishner method and then lithium aluminum hydride,giving the corresponding higher primary alkanols.We studied the necessary conditions of the reaction of long chain acyl chlorides with 1-morpholino-l-cyclohexene in the presence of triethyl amine and successfully prepared the 7-oxo-alkanoic acids.

Articles

STUDIES ON NITROXIDES--Ⅰ--THE SYNTHESIS AND REACTIONS OF PIPERIDINE NITROXIDES

Liu Yu-cheng, Jiang Zhiqin

1980, 1(1):  71-80. 

Asbtract ( )   PDF (578KB) ( )  

Related Articles | Metrics

In this paper an improved procedure on the oxidation of 4-oxo-2,2,6,6-tetramethylpiperidine to 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl is described.The improved method gave high yields of the radical product within a much shortened time.The reaction between 4-oxo-2,2,6,6-tetramethylpiperidine-l-oxyl with hydroxylamine hydrochloride under different pHconditions was studied.It was found that under basic conditions (pH 9-11),the oxime of the radical was obtained,under neutral conditions (pH 7-8),the Beckmann rearrangement product of the oxime was obtained,while under acidic conditions (pH 2-5),a nonradical product was obtained in the form of a hydrochloride which had the molecular formula of C₉H₁₈N₂O₂·HCl.4-oxo-2,2,6,6-tetramethylpiperidine-l-oxyl could be readily reduced by ascorbic acid to the corresponding hydroxylamine.The electron spin resonance spectra of the nitroxides in the solid state and their mass spectra were recorded.

THE SHORT-CIRCUIT CUR RENT IN THE INNER LAYERS OF POLY CRYSTALLINE PHOTOELECTROCHEMICAL ELECTRODESTH

Dong Qinghua, Cha Chuan-sin, Gao Cuiqin, Fei Zhenming, Jian Cuiying

1980, 1(1):  81-90. 

Asbtract ( )   PDF (725KB) ( )  

Related Articles | Metrics

The existence of short-circuit current in the inner layers of poly-crystalline photoelectrochemical electrodes was postulated.Principle and experimental method for the measurement of such current ("dark current") were laid out and tested with simulated electrode system and actual polycrystalline photoelectrochemical electrodes.It was found that both open-circuit voltage and output characteristics of photoelectrodes are affected by dark current,whose magnitude depends heavily on the method of electrode fabrication.So it seems proper to suggest that polycrystalline photoelectrochemical electrodes should be made as compact as possible.

Preface

THE CURING THEORY OF A_a-B_b,C_cTYPE COPOLYCONDENSATION

Tang Aoqing, Tang Xinyi, Li Yuwei, Zhao Donghui, Qian Baogong

1980, 1(1):  91-96. 

Asbtract ( )   PDF (452KB) ( )  

Related Articles | Metrics

On the basis of probability method,the present authors obtain the equations for describing the sol-gel distribution behavior and the critical condition for gelation of A_a-B_b,C_ctype copolycondensation system. With the aid of equations mentioned above,we also obtain the equations for describing the limit-curves of curing region.The equation for lower-limit curve of curing region is given byand the equations for upper limit-curve of the curing region are given by (a-1)(b-1)r_b+(a-1)(c-1)r_c=1 and the equations for upper limit curve of the curing region are given by   Where n_b=(a-1)(b-1) and K is a parameter in relation to the relative reactivities of B an d C groups and r_band r_cin turn denote the stoichiometric ratio of Bto A and C to Agroups respectively.The copolycondensation of adipic acid butylene glycol-trimethylol propane has been carried out with different r_band r_cvalues and the corresponding gelation phenomena have been observed.The theoretical limit-curves of curing region and the observed values are nearly in coincidence with each other.

Articles

STUDIES ON THE ULTRAHIGH MOLECULAR WEIGHT POLYETHYLENE FROM HIGHLY ACTIVE CATALYTIC POLYMERIZATION OF ETHYLENE

Lin Shangan, Lu Yun, Wang Haihua, Chang Qixing, Liang Kuiming, Xu Jiarui, Luo Huayou, Liao Kairong

1980, 1(1):  97-104. 

Asbtract ( )   PDF (2744KB) ( )  

Related Articles | Metrics

The physical properties of ultrahigh molecular weight of polyethylene (UMWPE) obtained from highly active polymerization of ethylene have heen studied-with various instrumental methods.The morphology of initial polymer was observed by scanning electron microscope.The transmitting electron micrograph shows morphology of supermolecular fibrillar fringe of polymer.The melting and cooling crystallization processes of initial (nascent) polyethylene powder of various molecular weight were studied by the aid of polarimetric microscope with the result that the spherulite size increases with molecular weight.The crystallinity of initial polyethylene powder or its annealed heat molded specimen increases with increasing molecular weight (by X-ray diffraction,DTA,inverse gas chromatographic and density determination),while the crystallite size decreases with it.The crystalling melting temperature T_m(determined by DTA and inverse gas chromatographic method) of UMWPE initial powder is about 8-12℃ higher than that of PEwith ordinary molecr.lar weight (M_W≌10×10⁴).The thermomechenical curves show that above T_mthe UMWPE molded specimens present a nonflowing rubery elastic state untill the higher viscoflowing temperature is reached.The oxidation degradation behavior has been investigated with DTAand TGmethods.Besides,the extinguished impact strength and anti-abrassion properties of UMWPEspecimens have been determined.The scanning electron micrographs for the textures of the cross-section cleavage surfaces of impacted molded specimen of polyethylene with M_W=10×10⁴and M_W=126×10⁴were interpreted from the viewpoint of molecular chain aggregation.

LINEAR COMBINATIONS OF BOND ORBITALS MO METHOD AND THE ELECTRONIC STRUCTURE OF CONJUGATED MOLECULES

Zhao Shen

1980, 1(1):  105-116. 

Asbtract ( )   PDF (736KB) ( )  

Related Articles | Metrics

A new MOmethod consisting of linear combinations of bond orbitals (LCBO)has been proposed to treat the electronic structures of linear and cyclic conjugated molecules.General expressions for the wave functions and energies of MO's of some homologous series were obtained.

THE DETERMINATION OF THE STABILITY CONSTANTS OF METAL-CROWN ETHER COMPLEXES BY FLUORIMETRIC METHOD

Wang Genglin, Jiang Zonghui

1980, 1(1):  117-120. 

Asbtract ( )   PDF (271KB) ( )  

Related Articles | Metrics

The stability constaut of Tl⁺complex of 18-crown-6 iu methauol solution was determined by the fluorescent quenching of Tl⁺.Those of Na⁺,K⁺and La³⁺complexes were determined by competitive coordination.The values of logKfor Na⁺and K⁺measured by this method were found in excellent agreement with those determined potentiometrically using ion selective electrodes.The value of logKfor La³⁺was found to be higher than that determined calorimetricallg by Izatt.It is proposed that this discrepancy may be caused by the difference of water content in me-thanol.

STUDIES ON POLAROGRAPHIC CATALYTIC WAVES

Kao Sheau-shya

1980, 1(1):  121-130. 

Asbtract ( )   PDF (759KB) ( )  

Related Articles | Metrics

In the present paper the research works on polarographic catalytic waves done by the Group of Electroanalytical Chemistry in Chemistry Department of Peking University have been reviewed.The polarographie catalytic waves of 25 elements investigated were summarized in Table I,together with their catalytic systems,sensitivities,characteristics and analytical applications.The,catalytic waves are sensitive and selective enough for trace analysis of semiconductor materials,high-purity metals,alloys,minerals,ores,waters,soils and so forth.The mechanisms of the catalytic waves,such as compositions and stability constants of the catalytic-active complexes,the rate constants of the chemical reactions and the phenomena of adsorption etc.were studied by the methods: of messuring the catalytic currents,hanging mercury drop,i-t corves,cyclic voltam-metry,current integr ation and radioactive tracer.The polarographic catalytic waves of rare earths are now being carried on.