Protonation versus Oxonium Salt Formation: Basicity and Stability Tuning of Cyanoborate Anions

Anhydrous H[BH₂(CN)₂] crystallizes from acidic aqueous solutions of the dicyanodihydridoborate anion. The formation of H[BH₂(CN)₂] is surprising as the protonation of nitriles requires strongly acidic and anhydrous conditions but it can be rationalized based on theoretical data. In contrast, [BX(CN)₃]⁻ (X=H, F) gives the expected oxonium salts (H₃O)[BX(CN)₃] while (H₃O)[BF₂(CN)₂]/H[BF₂(CN)₂] is unstable. H[BH₂(CN)₂] forms chains via N−H⋅⋅⋅N bonds in the solid state and melts at 54 °C. Solutions of H[BH₂(CN)₂] in the room‐temperature ionic liquid [EMIm][BH₂(CN)₂] contain the [(NC)H₂BCN−H⋅⋅⋅NCBH₂(CN)]⁻ anion and are unusually stable, which enabled the study of selected spectroscopic and physical properties. [(NC)H₂BCN−H⋅⋅⋅NCBH₂(CN)]⁻ slowly gives H₂ and [(NC)H₂BCN−BH(CN)₂]⁻. The latter compound is a source of the free Lewis acid BH(CN)₂, as shown by the generation of [BHF(CN)₂]⁻ and BH(CN)₂⋅py.     

常见阴离子的毛细管电泳迁移行为

以5mmol／L铬酸钠-0．5mmol／L十四烷基三甲基溴化铵为背景电解质溶液,研究了33种阴离子的有效迁移率与极限当量电导及正构羧酸的有效迁移率与碳数的关系。结果表明阴离子的有效迁移率随极限当量电导的增加而增加;C2～C7的正构—元羧酸和C2～C10的正构二元羧酸同系物的有效迁移率的倒数与碳数呈正比,线性相关系数大于0．997。     

Effect of Several Anions on Fe-Based Catalyst for Fischer-Tropsch Synthesis

The influence of several anions on Fe-based Fischer-Tropsch catalyst,used in the synthesis of light olefins from synthesis gas,was studied.The results indicated that the addition of anions resulted in the reduction of catalytic activity.When the anion content in the catalyst was 500 ppm,the influence of different anions on the catalysis activity was as follows:S~(2-)>Cl~->SO_4~(2-)>NO_3~-.The addition of S~(2-)improved the selectivity of total hydrocarbons in the products,and Cl~- reduced this selectivity but increased the olefin content in the total hydrocarbons at the same time.When the contents of S~2 and Cl~- in the catalyst were less than 50 ppm,their influence could be ignored.The XRD results indicated that the addition of anions reduced the contents ofα-Fe and Fe_3C,which were the active components in the catalyst.     

几个分子和负离子的QCI势能曲线

用ＱＣＩＳＤ（Ｔ）／６３１１＋Ｇ（３ｄｆ，２ｐ）（简称ＱＣＩ）计算了ＢＨ－（２Π），ＢＦ－（２Π），ＢＨ（１∑），ＢｅＨ－（１∑），ＢｅＦ－（１∑）和ＢＦ（１∑）的较完整的势能曲线，探讨了这些体系的稳定性和解离过程．同时用Ｍｏｒｓｅ函数和ＥＲ函数拟合得到势能曲线，用拟合结果计算谐性频率和非谐性频率，并与已有的实验数据（ＢＨ和ＢＦ分子）进行比较，由此考察了ＱＣＩ理论方法在远离平衡构型时的可靠性．对于因单参考态近似导致的反常势能曲线进行了ＣＡＳＳＣＦ计算．还比较了ＱＣＩ和Ｇ２理论中标准的ＭＰ２（ｆｕｌ）／６３１平衡几何构型及其对ＱＣＩ总能量的影响．     

Effect of Protonation on the Solution and Phase Behavior of Aqueous Sodium Myristate

Aqueous sodium myristate solutions have been shown to have unusually low dynamic tensions (1-10 mN/m) under pulsating area conditions. These solutions have no sharp solubility limit, evidently because they are protonated (or "hydrolyzed") to form the much less soluble myristic acid and acid soaps. With no added electrolytes, the protonation fraction is 1% or less. The apparent protonation equilibrium "constant" increases with increasing concentration, indicating strong solution nonidealities, in addition to micellization. This protonation seems to affect the solution and phase behavior of aqueous sodium myristate strongly, as evidenced by the effect of added NaOH. Ion-selective electrodes (for Na(+) and H(+)) and conductimetry indicate that at 25 degrees C dissolved surfactant concentrations keep increasing well after dispersed particles are observed (2 mM). A cmc of about 4.5 mM, micelles of aggregation number n=70 and counterion binding parameter beta=0.7 are inferred from these techniques. The cmc of sodium myristate increases slightly with temperature from 25 to 45 degrees C. FTIR analysis of the filtered particles indicates that the dispersed particles are mainly acid soaps for concentrations less than 6 mM. With 10 mM NaOH, the particles observed above 2 mM consist mostly of sodium myristate. From both conductivity and IR data, the solubility of sodium myristate in water at 25 degrees C is estimated to be about 6 mM, and as expected, it increases with increasing temperature and decreases with increasing sodium ion concentration. Copyright 2000 Academic Press.     

Ion Exchange and Protonation Equilibria of an Amphoteric Ion-exchange Resin in the Presence of Simple Salt

The influence of simple salts on the ion exchange and protonation equilibria of an amphoteric ion-exchange resin, which has strong base and weak acid moieties in a single functional group fixed onto the styrene-DVB matrix, has been investigated. Concentrations of ionic species in the amphoteric ion-exchange resin in equilibrium with various sodium salt solutions were estimated by (23)Na NMR spectroscopy. For the NaClO(4) system, the ratio of sodium ion concentration in the resin phase to that in the equilibrium solution was greater than 1 and increased with a decrease in the salt concentration. In contrast to an ordinary cation-exchange resin, the ion exchange behavior of Mg(2+) and Ca(2+) on the amphoteric ion-exchange resin showed a marked dependence on the kinds of salts: the distribution coefficients for the NaCl system were independent of the salt concentration, while the log D vs. log[Na(+)] plots for the NaClO(4) system showed linear relationships with slopes being neither -2 nor 0. Apparent protonation constants of the carboxylate in the functional group of the resin in equilibrium with NaClO(4) solutions were greater than those with NaCl solutions. The ion exchange and protonation properties of the amphoteric ion-exchange resin were elucidated on the basis of the information about the salt concentrations in the resin phase estimated by the NMR method.     

On the Dissociation of Aromatic Radical Anions in Solution

A new theoretical formulation is given for the reaction rate and path for the important reaction class of aromatic radical anion dissociation in solution [Ar? X]^?.→Ar^.+X^?, and is illustrated for the case of the cyanochlorobenzene radical anion [CN? Φ? Cl]^?. in dimethylformamide. Among the theory's novel features is the inclusion of the conical intersection aspect of this ground electronic state problem, which is key in allowing the reaction to occur and which has a significant impact on the reaction barrier height. Reasonable agreement with the experimental rate is found.     

Simple Estimates for Eutectic Behavior

A simple formula is derived for the eutectic point of an A–B system in terms of the monomer melting points and melting enthalpies. This estimate is tested on several non-ionic or ionic systems, with or without common ions, including choline chloride/urea mixtures. The results are compared with the Schröder-van Laar equation.     

中草药中几种阴离子的初级形态分析研究

本文报道几种中草药中常见非金属成分（阴离子）的离子色谱分析结果，研究了它们在原药及浸汁中的分布，改进了样品处理方法。     

Optically Active Hexaazamacrocycles: Protonation Behavior and Chiral‐Anion Recognition

The protonation features of two optically active 22‐membered hexaazamacrocycles possessing one ( L1 ) or two ( L2 ) (R,R)‐cyclohexane‐1,2‐diamine moieties have been studied by means of potentiometric ¹H‐ and ¹³C‐NMR techniques. This study allows the determination of the basicity constants and the stepwise protonation sites. The presence of the cyclohexane decreases the protonation ability, and this effect can be explained in terms of conformational and electrostatic factors. Binding of different chiral dicarboxylates has been studied by potentiometry. Macrocycle L2 presents higher anion‐complexation equilibrium constants than L1 . The stability of the diastereoisomeric complexes depends on the pH, and the structures of the macrocycles and anions. Receptor L1 ⋅6 H⁺ shows moderate D ‐selectivity towards tartrate anion, whereas L2 ⋅6 H⁺ exhibits a good preference for N‐Ac‐D ‐aspartate. Both protonated L1 and L2 form strong complexes with N‐Ac‐glutamate, and the stoichiometry of the complex depends on the degree of protonation and the absolute configuration of the anion. For this last anion, both azamacrocycles exhibit a clear D ‐preference.     

离子色谱快速柱检测简单基质样品中的无机阴离子

为实现简单基质样品中常规阴离子的快速分析,选用Dionex IonPac AS22-fast(4mm×150mm)离子交换色谱柱,通过优化流速、淋洗液浓度等色谱条件,使F-、Cl-、NO3-、NO2-、Br-、PO43-、SO42-7种常规阴离子在3.5min内分离完全,实现简单基质样品中常规阴离子的快速测定。     

二乙氧基丙烯酰胺甲氧基硫代磷酸酯(DAMT)的合成及应用

二乙氧基丙烯酰胺甲氧基硫代磷酸酯;膨胀型阻燃剂;极限氧指数;扫描电子显微镜     

Protonation of N-alkenylacrylamides

Protonation of N-alkenylacrylamides and medium effects on the protonation direction were studied theoretically (DFT calculations) and experimentally (IR spectroscopy). In crystal, N-alkenylacrylamide hydrochlorides exist in the O-protonated form in contrast to acrylamide hydrochloride which exists in the N-protonated form.     

Protonation of carbethoxypyrroles

The PMR and UV spectra of the bases and conjugate acids of carbethoxy derivatives of pyrrole were investigated. The conjugate acids of 3-carbethoxypyrroles in 22–25 N H₂SO₄ have the -pyrrolene structure, which corresponds to protonation of these compounds at the 5-C atom of the pyrrole ring. The protonation of 2-carbethoxypyrroles under the same conditions proceeds through the formation of an intermediate form, which is converted to the stable cation form in several hours. The stable form of the conjugate acid of 3,4-dimethyl-2-carbethoxypyrrole has the -pyrrolene structure, which corresponds to the addition of a proton to the unsubstituted 5-C ring carbon atom. The structures of the stable forms of the conjugate acids of 2-carbethoxypyrroles that are substituted in the 5 position of the methyl group correspond to protonation of these compounds at the nitrogen atom of the pyrrole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 336–341, March, 1972.     

Synthesis and Hydrodynamic Behavior of Stoichiometric Complexes of Cationic Polyelectrolytes with Amphiphilic Anions

Complexation of poly(N,N-dimethyl-N-benzyl-N-methacryloyloxyethyl)ammonium chloride with oppositely charged amphiphilic compounds was studied. The solubility and hydrodynamic properties of the resulting complexes in chloroform, methanol, and chloroform-hexane and chloroform-toluene mixtures were determined.     

钒取代Keggin型杂多酸的多层组装和电催化性能研究

用层层组装的方法在4-氨基苯甲酸预修饰的玻碳电极上交替沉积过渡金属钒取代的杂多酸H₃PW₆V₆O₆-40(简称PW₆V₆)和联吡啶锇取代的聚乙烯吡啶(QPVP-Os).用表面等离子体共振(SPR)技术和循环伏安(CV)法对多层膜进行了表征.结果表明,多层膜的生长均匀,平均厚度为2.88nm.还研究了多层膜对亚硝酸根(NO₂^-)和溴酸根(BrO₃^-)的催化还原活性.