二(2-乙基己基)磷酸萃取亮氨酸平衡研究

萃取平衡;二乙基己基磷酸;二(2-乙基己基)磷酸萃取亮氨酸平衡研究     

二(2-乙基己基)磷酸萃取L-精氨酸

二(乙基己基)磷酸;二(2-乙基己基)磷酸萃取L-精氨酸     

二(2-乙基己基)磷酸对氨基酸的萃取平衡

二（２－乙基己基）磷酸对氨基酸的萃取平衡曹汉瑾,王德宝,刘沛妍,吴子生,严忠（东北师范大学化学系,长春,１３００２４）关键词氨基酸,二（２－乙基己基）磷酸,萃取平衡,分配比迄今为止,有关氨基酸溶剂萃取的文献报道还不多［１～３］．本实验以二（２－乙基己...     

二价金属离子萃取速率常数与软硬酸碱规则

用上升液滴法测定了２－乙基己基膦酸单（２－乙基己基）酯－正辛烷从硝酸介质中萃取镁、钙、锌、镍、铜和铅等二价金属离子的正向初始速率，建立了速率方程，计算出正向萃取反应的速率常数、活化能及活化熵，首次将软硬酸碱规则与金属溶萃取速率常数关联。结果表明，在萃取机理相同时，萃取速率常数的大小与金属离子的软硬酸碱标度一致，即萃取过程中，作为酸的被萃取金属离子，其硬度越大，萃取速率常数亦越大，萃取反应的活化能…     

二-(2-乙基己基)磷酸在不同稀释剂中对钼(Ⅵ)的萃取

考察了Mo(VI)在盐酸水相与二-(2-乙基己基)磷酸的不同稀释剂有机相间的分配平衡,观察到萃取平衡常数按正辛烷、四氯化碳、苯、氯仿、1,2-二氯乙烷、甲苯、甲基异丁基酮的次序递减,萃合物的组成也按这一顺序呈现规律性变化.文中将这些结果与稀释剂极性进行了关联,得到萃取平衡常数与稀释剂的极性参数E_T间良好的线性关系.此外,本文还提出了H_2MoO_4的酸、碱式解离常数分别为0.158和1.21×10(-13).     

二-(2-乙基己基)磷酸-煤油液膜萃取锌(Ⅱ)的动力学分析

锌离子;二乙基己基磷酸;迁移动力学;二-(2-乙基己基)磷酸-煤油液膜萃取锌(Ⅱ)的动力学分析     

二-（2-乙基己基）磷酸P204与三烷基叔胺N235协同萃取钼

研究了P204（二-(2-乙基己基)磷酸, HA）和N235（三烷基胺, R3N）二元体系在HCl介质中对金属钼的萃取,结果表明P204和N235混合萃取剂在萃取钼时存在协同效应,并且在N235摩尔分数为0.7时协萃系数为2.24;考察了溶液酸度、P204或N235浓度及温度对萃取钼的影响,确定了协萃络合物为(R3NH)3•HMo8O26•2(HA),并比较了负载前后有机相的红外光谱。     

萃取剂HDEHP在不同稀释剂中的聚合性质

HDEHP在惰性稀释剂中由于分子间氢键作用易形成二聚体[1 ] ,其二聚常数已有报道[2 ] ,但很不一致。由于萃取动力学、液—液界面性质都与萃取剂在有机相中的存在状态密切相关 ,本文研究了不同稀释剂中 HDEHP的聚合性质 ,并实现了二聚常数与稀释剂物理常数间的定量关联。实　验　部　分一 .试剂和仪器HDEHP,工业品 ,经提纯纯度大于 99% ;氯仿、苯、甲苯、环己烷、四氯化碳、甲基异丁基酮 ,均为分析纯 ;正辛烷 ,化学纯。TOA p H计 ,日本岛津 ;KS恒温振荡器 ,山东大学化学院金工室改装 ;FTS 16 5红外光谱仪 ,美国 Bio- Rad公司。二 .…     

二-(2-乙基己基)磷酸与仲壬基苯氧基取代乙酸混合体系对稀土元素的萃取

考察了二-(2-乙基己基)磷酸(D2EHPA,H2A2)和仲壬基苯氧基取代乙酸(CA100,H2B2)混合体系在HCl介质中对15种镧系元素(除钷)及钇的萃取性能,计算了稀土元素间的分离系数,并比较了混合萃取体系与D2EHPA单独萃取体系对稀土元素的分离能力.研究了D2EHPA-CA100混合体系对镧的协同萃取机理,用斜率法和恒摩尔法探讨了萃取反应方程式,考察了酸度、萃取剂浓度及温度对萃取性能的影响.结果表明:D2EHPA-CA100混合体系对镧系元素的协同效应随原子序数的增加而减弱.在适当的萃取剂配比下,此混合体系对某些稀土元素的分离能力优于D2EHPA,可用于这些稀土元素的分离.D2EHPA-CA100混合体系协同萃取镧的萃合物组成为LaH5A6B2,反应为吸热反应.     

The Concept of Hard and Soft Acids and Bases as Applied to Multi-Center Chemical Reactions

Many chemical bonds of differing types and strengths have recently been regarded by Pearson^[1] as representing partnerships between (Lewis) acids and (Lewis) bases. Most acceptor molecules or ions (acids) can be placed in one or other of two categories, graphically termed “Hard” and “Soft”. There are also two broad categories of donor molecules or ions (bases) which can also be termed Hard and Soft. On the whole, strong chemical bonds are partnerships between either a Hard base and a Hard acid or a Soft base and Soft acid, whereas weaker bond types most usually result in cases of either Hard base-Soft acid or Soft base-Hard acid interactions. The present paper shows how this concept of acidity and basicity can be applied in the interpretation of multi-center chemical reactions involving interconnected acid-base relationships. In particular, fourcenter substitutions and additions involving cooperative attack by nucleophiles and electrophiles at various chemical bonds have been examined, and a conclusion is reached that especially reactive patterns of reactants can be developed if the substrates contain bonds between either a hard acid and a soft base, or a soft acid and a hard base. Indeed, the arguments can be elaborated to provide two distinct Rules which should be of interest in the interpretation of metal-ion assisted reactions and in the design of novel syntheses.     

二（2—乙基己基）单硫代磷酸萃取铟的研究

目前采用二(2-乙基己基)磷酸(D2EHPA)从硫酸溶液中萃取铟在生产上虽获得广泛应用,但反萃取又转入盐酸体系,腐蚀刺激性较强.改用D2EHMTPA萃取铟可能较好,有关这方面的研究至今尚未见报道,本文从硫酸溶液中考察了D2EHMTPA萃取铟的性能,并与D2-EHPA和二(2-乙基己基)二硫代磷酸(D2EHDTPA)作比较,以了解这类萃取剂结构上的差别对萃取铟的影响,这对选择及合成高效能萃取剂分子也是有意义的,还应用斜率法、饱和法确定了萃取平衡反应及萃合物组成,根据IR与NMR探讨了D2EHMTPA萃取铟的机理。     

The use of a polymer inclusion membrane in flow injection analysis for the on-line separation and determination of zinc

This paper reports the first use of a polymer inclusion membrane (PIM) for on-line separation in flow injection analysis (FIA) involving simultaneous extraction and back-extraction. The FIA system containing the PIM separation module was used for the determination of Zn(II) in aqueous samples in the presence of Mg(II), Ca(II), Cd(II), Co(II), Ni(II), Cu(II), and Fe(III). The Fe(III) and Cu(II) interferences were eliminated by off-line precipitation with phosphate and on-line complexation with chloride, respectively. The concentration of Zn(II) was determined spectrophotometrically using 4-(2-pyridylazo) resorcinol (PAR). The optimal composition of the PIM consisted of 40% (m/m) di(2-ethlyhexyl) phosphoric acid (D2EHPA) as carrier, 10% (m/m) dioctyl phthalate (DOP) as plasticizer and 50% (m/m) poly(vinyl chloride) (PVC) as the base polymer. The optimized FIA system was characterized by a linear calibration curve in the range from 1.0 to 30.0 mg L⁻¹ Zn(II), a detection limit of 0.05 mg L⁻¹ and a relative standard deviation of 3.4% with a sampling rate of 4 h⁻¹. Reproducible results were obtained for 20 replicate injections over a 5 h period which demonstrated a good membrane stability. The FIA system was applied to the determination of Zn(II) in pharmaceuticals and samples from the galvanizing industry and very good agreement with atomic absorption spectrometry was obtained.     

A study of the nature of coordination in metal monothiocarbamates based on infrared spectroscopy and the HSAB concept

The nature of coordination in metal monothiocarbamates is shown to depend on the hardness or softness of the metal ton. Thus, the monothiocarbamate ion acts as a monodentate ligand with metal-sulphur bending when the metal ion is a soft acid while it acts as a bidentate ligand when the metal ion is a hard acid; it can exhibit either behaviour when the metal ion is a borderline acid. In dialkyltin and dialkylmonocholorotin complexes, the monothiocarbamate ion acts as a bidentate ligand with strong Sn-S bonding while in trialkyl-or triaryl-tin complexes it acts essentially as a monodentate ligand. Thus, R₃Sn(I) seems to be a soft or borderline acid while R₂Sn(II) is a hard acid.     

Extraction of lutetium(III) from aqueous solutions by employing a single fibre‐supported liquid membrane

Transport behaviour of Lu(III) across a polypropylene hollow fibre‐supported liquid membrane containing di(2‐ethylhexyl)phosphoric acid (DEHPA) in dihexyl ether as a carrier has been studied. The donor phase was LuCl₃ in the buffer solution consisting of 0.2 M sodium acetate at pH 2.5–5.0. A miniaturised system with a single hollow fibre has been operated in a batch mode. The concentration of Lu(III) was determined by indirect voltammetric method using Zn–EDTA complex. The effect of pH and volume of the donor phase, DEHPA concentration in the organic (liquid membrane) phase, the time of extraction and the content of the acceptor phase on the Lu(III) extraction and stripping behaviour was investigated. The results were discussed in terms of the pertraction and removal efficiency, the memory effect and the mean flux of Lu(III). The optimal conditions for the removal of ¹⁷⁷Lu(III) from labelled ¹⁷⁷Lu‐radiopharmaceuticals were discussed and identified. The removal efficiency of Lu(III) greater than 99% was achieved at pH of the donor phase between 3.5 and 5.0 using DEHPA concentration in the organic phase of 0.47 M and the ratio of the donor to the acceptor phase of 182.     

The Fukui function of an atom in a molecule: A criterion to characterize the reactive sites of chemical species

The principle of hard and soft acids and bases is interpreted as the result of two opposing tendencies, one related to the charge transfer process (chemical potential equalization principle), and the other one related to the reshuffling of the electronic density (maximum hardness or minimum softness principle). A local version of the principle is elucidated by assuming that these tendencies are dominated by the local properties rather than by the global properties of the molecule. This principle is used together with the Fukui function of the atoms in the molecule to characterize the reactive sites. The results presented for the nucleophilic addition to the pyridinium ion, and for the electrophilic substitution on pyridine oxide show the usefulness of these concepts in describing the inherent reactivity of chemical species.     

Cloud point extraction equilibrium of lanthanum(III), europium(III) and lutetium(III) using di(2-ethylhexyl)phosphoric acid and Triton X-100

The cloud point extraction behaviors of lanthanoids(III) (Ln(III) = La(III), Eu(III) and Lu(III)) with and without di(2-ethylhexyl)phosphoric acid (HDEHP) using Triton X-100 were investigated. It was suggested that the extraction of Ln(III) into the surfactant-rich phase without added chelating agent was caused by the impurities contained in Triton X-100. The extraction percentage more than 91% for all Ln(III) metals was obtained using 3.0 × 10⁻⁵ mol dm⁻³ HDEHP and 2.0% (v/v) Triton X-100. From the equilibrium analysis, it was clarified that Ln(III) was extracted as Ln(DEHP)₃ into the surfactant-rich phase. The extraction constant of Ln(III) with HDEHP and 2.0% (v/v) Triton X-100 were also obtained.     

The use of a polymer inclusion membrane in a paper-based sensor for the selective determination of Cu(II)

A disposable paper-based sensor (PBS) is described for the determination of Cu(II) in natural and waste waters at approximately 2 cents per measurement. The device makes use of a polymer inclusion membrane (PIM) to provide the selectivity for Cu(II). The PIM consists of 40 wt% di(2-ethlyhexyl) phosphoric acid (D2EHPA) as the carrier, 10 wt% dioctyl phthalate (DOP) as a plasticizer, 49.5 wt% poly(vinyl chloride) (PVC) as the base polymer and 0.5 wt% (m m⁻¹) 1-(2′-pyridylazo)-2-naphthol (PAN) as the colourimetric reagent. High selectivity under mildly acidic conditions (HCl, pH 2.0) is achieved for Cu(II) in the presence of frequently encountered metal ions in natural and waste waters such as Fe(III), Al(III), Zn(II), Cd(II), Pb(II), Ca(II), Mg(II), and Ni(II).