二甲基甲酰胺-二氧六环混合溶剂中KBr,KSCN及KClO_4的电导研究

本文报告了KBr、KSC N、KClO_4和KI在二甲基甲酰胺(DMF)和1,4-二氧六环混合溶剂中的电导测定值、溶剂的粘度和溶液的密度,按Pitts,Fuoss1978和Lee-Wheaton电导方程拟合实验数据得出溶液的无限稀释摩尔电导A_o,离子缔合常数K_α和正负离子间的距离参数R。对三个方程的适用性和溶液中离子-离子-溶剂分子间的相互作用作了初步讨论。     

PrOH-H2O混合溶剂中LiCl,NaCl的电导研究

本文设计并制作一套可搅拌U型电导池, 并用其测定了LiCl, NaCl在PrOH-H2O二元混合溶剂中的摩尔电导。应用Fuoss-Onsager电导方程关联得到Λ。, a°及Ka, 并据此探讨了LiCl, NaCl-PrOH-H2O的微观结构及相互作用。     

四种深共融溶剂的性质:密度、电导率、动力粘度及折光率

制备了四种四丁基氯化铵类深共融溶剂,包括四丁基氯化铵:丙酸[TBAC:2PA]、四丁基氯化铵:乙二醇[TBAC:2EG]、四丁基氯化铵:聚乙二醇[TBAC:2PEG]、四丁基氯化铵:苯乙酸[TBAC:2PAA].在288.15-338.15 K温度范围内,测定了它们的密度、电导率、动力粘度及折光率.讨论了温度对密度、电导率、动力粘度及折光率等性质的影响.通过经验方程估算了深共融溶剂的热膨胀系数、分子体积、标准摩尔熵及晶格能等热力学性质参数.利用Vogel-Fulcher-Tamman (VFT)方程和Arrhenius方程,将测量的电导率和动力粘度对温度拟合,得到了动力粘度和电导率随温度变化方程式.有关研究对深共融溶剂的工业化应用具有重要意义.     

四丁基氟化铵在H2O-DMF中的电导研究

测量了298.15~328.15 K温度范围内四丁基氟化铵在20(wt)%~80(wt)%H2O/DMF混合溶液中的电导率,测得的电导率分别通过Kray-Bray方程和Shedlovsky方程分析,推导出了四丁基氟化铵在H2O-DMF混合溶液中的摩尔极限电导、缔合常数和离解常数,并计算出缔合反应的热力学参数(△Ga,△Ha,△Sa);同时探讨了温度和混合溶剂的组成对摩尔极限电导、缔合常数和热力学参数的影响。     

H2O-C2H5OH-MX(NaCl等)体系中离子缔合和活度

用桥式电路测定了H_2O-C_2H_5OH-NaCl体系的摩尔电导, 并用Lee-Wheaton模型回归出H_2O-C_2H_5OH-NaCl(KCl、CsCl、KBr)体系的离子缔合常数、极限摩尔电导和距离参数, 并求出缔合反应标准自由焓。结果表明离子缔合能力的顺序为Cs~+>K~+>Na~+, Cl~->Br~-, 此四种盐在乙醇中都形成溶剂分开型离子对。并用液上空间气相色谱法测定了水-乙醇-(NaCl、KCl、KBr)体系中溶剂的活度, 用改进的Pitzer-Li公式计算了此体系的活度系数, 计算时考虑了盐在低介电常数溶剂中的离子缔合, 结果表明这种处理是合适的。还表明离子缔合程度随着乙醇浓度上升而加大, 以及盐的存在对水呈盐溶效应而对乙醇呈盐析效应。     

关于摩尔电导率的数学定义式

摩尔电导率Λｍ 是物理化学中的一个比较重要的概念。ＩＵＰＡＣ建议的Λｍ 数学定义式不能完全反映Λｍ 的物理含义。在使用过程中 ,特别是在不同的单位制一起使用时 ,Λｍ 的计算结果和单位与Λｍ 原始定义相背。本文提出了一种新的Λｍ 数学定义式 ,该式更贴近Λｍ 原始定义 ,更能反映Λｍ 的物理含义。1　电导和摩尔电导率　　在物理化学中把电解质溶液的导电能力定义为 :　　定义 1[1]:电导Ｇ=κ( Ａｌ) ( 1)　　　　　Ｇ :电导 (Ｓ)　　　　　κ:电导率 (Ｓ·ｃｍ- 1或Ｓ·ｍ- 1)　　　　　Ａ :电极的面积 (ｃｍ2 或ｍ2 )　　　　　ｌ…     

电导法测定杂多酸在非水溶液中的离解常数

本文以电导法测定了１２－磷钨、１２－硅钨酸在一些醇、酯、醛、酮等含氧有机溶剂以及乙腈中的离解常数，得到的结果表明，两种酸在同种溶液中的离解常数接近，磷钨酸的略高，同一种酸在不同溶剂中的离解常数则与溶剂的介电常数有密切关系。在醚中，因杂多酸与溶剂发生缔合作用，用电导法得不到其离散常数。     

颗粒增强复合材料电导性能研究

将弹性理论中的变换场概念引入电磁学领域,并从第一性原理出发,通过拟合颗粒的边界条件和Fourier分析,建立了确定颗粒增强复合材料内电场的积分方程,在此基础上对其电导率做了研究,其理论结果与实验结果比较吻合。该方法不再受颗粒形状及体系结构的限制,为研究复合材料的电导性能开辟了新途径。     

新型低共熔溶剂的制备、表征及物性研究

以氯化1-丁基-3-甲基咪唑鎓([Bmim]Cl)和二元羧酸为原料,由不同摩尔比混合制备了一类新型低共熔溶剂,采用红外光谱对[Bmim]Cl和二元羧酸之间的作用进行了分析。分别测定了其粘度、电导率、密度、折射率等物理性质,并研究了温度、二元羧酸结构和摩尔比对这些物理性质的影响。结果表明,新型低共熔溶剂的粘度随温度的升高而降低,电导率随温度的升高而增加。温度对两者的影响可以采用VTF方程进行精确地拟合。新型低共熔溶剂的密度随温度的升高而呈线性下降。对新型低共熔溶剂的过量摩尔体积进行计算的结果表明,过量摩尔体积均为正值,二元羧酸对过量摩尔体积的贡献远大于[BMIM]Cl,而结构特性的贡献多于物理作用。折射率和密度随二元羧酸碳数的变化趋势基本相似。     

混合电解质的电导测定

电导测定为研究离子与离子之间的缔合效应、离子与溶剂的相互作用及溶剂结构提供了一个有效手段 .目前 ,电解质水溶液、电解质非水溶剂体系的电导数据却很缺乏 ,而混合电解质体系的电导测定在理论及应用方面都很重要 .作为全面系统地考察金属氯化物的混合电解质的电导性质变化规律 ,前文已测定了 Na Cl- KCl- H2 O体系 [1] 、 Na Cl- Rb Cl- H2 O体系及 KCl- Rb Cl- H2 O体系的电导值 [2 ] ,本文用自行设计的电导池测定了 Ca Cl2 - H2 O,Ca Cl2 - Na Cl- H2 O,Ca Cl2 - KCl- H2 O体系在 2 98.1 5 K时的低浓度电导数据 ,探讨了…     

Ferromagnetic heterotrinuclear Cu-Ni complexes of a compartmental chiral Schiff base

Nickel(II) and copper(II) acetate react with the trinucleating compartmental Schiff base H(4)L (H(4)L = 6,6'-(E)-3,3'-(ethane-1,2-diyl)bis(1-(2-((E)-3-bromo-5-chloro-2-hydroxybenzylideneamino)ethyl)imidazolidine-3,2-diyl)bis(2-bromo-4-chlorophenol)) to produce the heterotrinuclear complexes [Ni(2)CuL(OAc)(2)]·0.25H(2)O·2.5MeOH (1·0.25H(2)O·2.5MeOH) and [NiCu(2)L(OAc)(2)]·3.25H(2)O·0.5MeOH (2·3.25H(2)O·0.5MeOH) as a function of the Ni(OAc)(2)?:?Cu(OAc)(2) molar ratio. The crystal structures of H(4)L, 1·0.25H(2)O·2.5MeOH and 2·3.25H(2)O·0.5MeOH could be solved. The free ligand presents two stereogenic methine groups on the imidazolidine heterocycles. X-Ray diffraction studies on H(4)L determined that the solved crystal structure corresponds to a racemate formed by the (2R,2'R) and (2S,2'S) enantiomers, without detecting the (2R,2'S) diastereoisomer. The crystal structures of both heterotrinuclear complexes reveal that Ni(II) has a preference for the central ligand pocket, showing that this cavity discriminates between Ni(II) and Cu(II) when both species are present in the reaction medium. These results are validated by DFT calculations. As a consequence of the coordination, 1·0.25H(2)O·2.5MeOH and 2·3.25H(2)O·0.5MeOH are also chiral, but crystallise as racemates. In addition to their asymmetric methine groups, these complexes present four other stereogenic centres: the four coordinated imidazolidine N atoms. The luminescent properties of the ligand and both complexes were analysed, showing that the presence of the metals partially inhibits the emission of the ligand and apparently tunes the position of the secondary fluorescence emission band. The magnetic characterisation of 1·0.25H(2)O·2.5MeOH and 2·3.25H(2)O·0.5MeOH was also performed, showing the ferromagnetic behaviour of both complexes.     

间羟基苯甲酸邻菲啰啉稀土三元配合物的合成、表征和抗菌活性研究

本文用间羟基苯甲酸、邻菲口罗啉与碳酸稀土合成了四种新的固体三元配合物,通过元素分析、摩尔电导、红外光谱、Ｘ射线粉末衍射、差热－热重分析等手段,确定配合物的组成为：Ｌｎ（ｐｈｅｎ）Ｌ３,（Ｌｎ＝Ｌａ,Ｇｄ,Ｄｙ,Ｙ;Ｌ＝ｍ－ＨＯ－Ｃ６Ｈ４ＣＯＯ－）,并对配合物的某些性质进行了研究。     

废茶油的精制及其合成生物柴油的研究

本文以废茶油为原料,经过脱胶脱酸等预处理后与甲醇进行酯交换反应制取生物柴油.探讨了反应时间、反应温度、醇-油摩尔比和催化剂用量等因素对废茶油-甲醇酯交换反应的影响,并且采用正交实验优化合成条件,确定了反应的最佳操作条件以及影响反应的关键因素.研究结果表明,酯交换反应进行的最佳反应条件为:醇油摩尔比为25:1、催化剂用量为油重的1.0%、反应时间为30min、反应温度为60℃,茶油酸甲酯产率77.34%.     

Ion association of lithium bromide,chloride and picrate and of sodium picrate in 2-propanol at 25°C. I. Conductance measurements

The molar conductances of lithium bromide, chloride and picrate, and of sodium picrate have been determined as a function of salt concentration in 2-propanol solvent at 25°C. Values of the limiting molar conductance, Λ₀, and ion pair formation constant K_A have been calculated for each of these salts using both the Fuoss 1978 and the Lee and Wheaton conductance equations. Both of these equations yield comparable results for the present systems. The limiting conductances found here are compored with those reported for lithium chloride in 1-propanol and acetone and with those for the picrates in acetone and 2-butanone, all solvents of comparable dielectric constants. The Rasaiah-Friedman square mound potential, h_+?/kT, has been calculated for each salt using the approach of Justice and Justice. These values for 2-propanol have been compared with those for lithium chloride in 1-propanol and in acetone and for the picrates in acetone and 2-butanone.     

A Study on the Gonductance of KBr. KSCN. KClO4 and KI in the Mixed Solvent of Dimethylformamide and 1,4-Dioxane

This paper reports the measured conductance of KBr,KSCN.KClO4 and KI in the mixed solvent of DMF with 1,4-dioxane at various ratios,the viscosity of the mixed solvent and the density of the salt solution.According to the conductance equations,namely,Pitts equation,Fuoss-1978 equation and Lee-Wheaton equation,the experi-.mental data were fitted on computer to get the limit molar conductance of salt at infinite dilution the ionic association constant Ka,and the distance parameter between cation and anion R.The suitability of the theoretical equations and the interaction of ion-ion-solvent molecule were discussed.     

Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone

Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L(1)) and semicarbazone (L(2)) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L)(2)(SO(4)) and Cu(L)(2)(SO(4)) [where L=L(1) and L(2)] which are of five coordinated square pyramidal geometry.     

Dianionic complexes with hexacoordinate silicon(IV) or germanium(IV) and three bidentate ligands of the hydroximato(2-) type: syntheses and structural characterization in the solid state

Reaction of Si(OMe)(4) with acetohydroxamic acid or benzohydroxamic acid and HNMe(2) (molar ratio 1:3:2) in MeCN yielded dimethylammonium fac-tris[acetohydroximato(2-)]silicate (fac-5) and N,N-dimethylacetamidinium fac-tris[benzohydroximato(2-)]silicate (fac-8), respectively. Reaction of Si(OMe)(4) with benzohydroxamic acid and HNMe(2) (molar ratio 1:3:2) or ethane-1,2-diamine (molar ratio 1:3:1) in MeOH gave dimethylammonium fac-tris[benzohydroximato(2-)]silicate-methanol (fac-6.MeOH) and ethane-1,2-diammonium mer-tris[benzohydroximato(2-)]silicate-dimethanol (mer-9.2MeOH), respectively. Reaction of Ge(OMe)(4) with benzohydroxamic acid and HNMe(2) (molar ratio 1:3:2) in MeOH resulted in the formation of dimethylammonium fac-tris[benzohydroximato(2-)]germanate-methanol (fac-7.MeOH). Single-crystal X-ray diffraction studies showed that the Si(Ge)-coordination polyhedra of the racemic hexacoordinate silicon (germanium) compounds fac-5, fac-6.MeOH, fac-7.MeOH, fac-8, and mer-9.2MeOH are distorted octahedra. All compounds were additionally characterized by solid-state VACP/MAS NMR studies ((13)C, (15)N, (29)Si). The structural investigations were complemented by computational studies of the dianions of fac-5 and mer-5.     

Spectroscopic studies of transition metal complexes with a N-donor tetradentate(N4) 12-membered macrocylic ligand

Chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), ruthenium(III), iridium(III), palladium(II) and platinum(II) complexes were synthesized with a 12-membered 1,4,7,10-tetraazadodeca-5,6,11,12-tetraene macrocylic ligand (L) and characterized by elemental analysis, molar conductance, magnetic susceptibility, IR, electronic, EPR and M?ssbauer [Fe(III)] spectral studies. The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature for M(L)Cl2 complexes [where M=Mn(II), Co(II), Ni(II), Cu(II)], 1:1 electrolytes for M'(L)Cl3 complexes [where M'=Cr(III), Fe(III), Ru(III) and Ir(III)] and 1:2 electrolytes for M'(L)Cl2 complexes [where M'=Pd(II) and Pt(II)]. Thus, the complexes may be formulated as [M(L)C1(2)], [M'(L)C1(2)]C1 and [M'(L)]C1(2), respectively [where L=ligand]. All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Pd(II) and Pt(II) complexes which were four coordinate, square planar and diamagnetic.     

Preparation of sulfonyl aromatic polyamides and copolyamides by means of di- or triphenyl phosphite

High molecular-weight aromatic polyamides were obtained by the direct polycondensation reaction of 4,4′-sulfonyldibenzoic acid (SDA) with various aromatic diamines, by means of di- (DPP) or triphenyl phosphite (TPP) in N-methyl-2-pyrrolidone (NMP)-pyridine solution containing metal salts such as LiCl and CaCl₂. The factors affecting the phosphorylation reaction were investigated, in particular for the reaction of SDA and 4,4′-oxydianiline (ODA). For the polymerization by means of TPP, the optimum conditions are: molar ratio of TPP to diacid, higher than 2.3; concentration of metal salts, 8 wt % LiCl or 6 wt % CaCl₂; reaction temperature, 100°C; and monomer concentration, 0.4 mol/L. For the polymerization by means of DPP, the optimum conditions are: molar ratio of DPP to diacid, higher than 3.8; concentration of metal salts of 8 wt % LiCl or 10 wt % CaCl₂; reaction temperature, 110°C; and monomer concentration, 0.4 mol/L. Copolyamides were also prepared from the reaction of ODA with the mixed diacids of SDA and other dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalene dicarboxylic acid by using TPP and DPP as the condensing agents.     

Optimization of enzymatic production of biodiesel from castor oil in organic solvent medium

We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent and two commercial lipases, Novozym 435 and Lipozyme IM, as catalysts. For this purpose, a Taguchi experimental design was adopted considering the following variables: temperature (35–65°C), water (0–10 wt/wt%), and enzyme (5–20 wt/wt%) concentrations and oil-to-ethanol molar ratio (1∶3 to 1∶10). An empirical model was then built so as to assess the main and cross-variable effects on the reaction conversion and also to maximize biodiesel production for each enzyme. For the system containing Novozym 435 as tatalyst the maximum conversion obtained was 81.4% at 65°C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1∶10. When the catalyst was Lipozyme IM, a conversion as high as 98% was obtained at 65°C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1∶3.