Bi-ionic membrane potential across a liquid anion-exchange membrane containing triphenyltin chloride

Potentiometric selectivities of a liquid anion-exchange membrane containing triphenyltin chloride (TPTCl) to several inorganic anions were evaluated via measurements of the membrane potential of a bi-ionic system, also called bi-ionic membrane potential. Addition of TPTCl to the liquid anion-exchange membrane, based on the quaternary ammonium salt, gave rise to a quite different selectivity pattern from the so-called Hofmeister anion series observed for the liquid anion-exchange membrane. An additivity rule of the bi-ionic membrane potential was observed to hold for the liquid anion-exchange membrane containing TPTCl. Thus, the following multiple chain rule was derived for selectivity coefficients; k_1,n^pot = k_1,2^pot · k_2,3^pot … k_i,(i+1)^pot … k_n−1,n^pot where k_i,i+1^pot is the selectivity coefficient of the membrane for the (i + 1)th ion over the ith ion.     

Synthesis of a Tweezer—like Bis（Phenylthiapropoxy）calix[4]—arene as a Cation／π Enhanced Sensor for Ion—Selective Electrodes

Two novel 25,27-dihydroxy-26,28-bis(3-phenylthiapropxy)-calix[4]arene(3) and 25,27-dihydroxy-26,28-bis(3-phenylthiapropoxy)-5,11,17,23-tetra-tert-butylcalix[4] arene (4) were synthesized for the evaluation of their ion-selectivity in ion-selective electrodes(ISEs).ISEs based on 3 and 4 as neutral ionophores were prepared,and their selectivity coefficients for Ag^ (lg KAg,M^pot)were investigated against other alkali metal,alkaline-earth metal,aluminum,thallium(Ⅰ）,Lead and some transition metal ions using the separate solution method (SSM).These ISEs showed excellent Ag^ seletivity over most of the interfering cations examined,except for Hg^2 and Fe^2 having relative smaller interference(lg KAg,M^pot≤-2.1).     

An investigation of Prussian Blue analogues by Mössbauer spectroscopy and magnetic susceptibility

The Mössbauer spectra and magnetic susceptibilities have been obtained for a series of Prussian Blue analogues of general formula M_j^A[M^B(CN)₆]_k·mH₂O where M^A and M^B are transition metal ions, j and k vary with the oxidation states of M^A and M^B and m typically has values from 8 to 14. The compounds were prepared from the hexacyano acids or with large quaternary ammonium counterions and are therefore not contaminated with alkali cations. In each analogue, A or B is iron and the second metal is Mn, Cu, Co, Cr or Ru. In each case it was possible to assign the site (A or B), oxidation state and spin state to each transition metal ion. This group of compounds are all class II mixed valence species from their colours, but do not show evidence of linkage isomerism or redox changes compared to the starting materials. The Mössbauer linewidths are consistent with the Ludi model of Prussian Blue.     

Characterization of bis(alkylamine)mercury cations from mercury nitrate surfaces by using an ion trap secondary ion mass spectrometer

Mercury-cyclohexylamine (R-NH₂, where R = c-C₆H₁₁) ions having the composition Hg(R-NH)₂H⁺ can be formed by exposing the surface of Hg(NO₃) _{n = 1,2} salts to gaseous primary amines and then sputtering the surface with a primary ion beam (ReO ₄ ^? ). The resultant ions can be stabilized and detected using an ion trap secondary ion mass spectrometer (IT-SIMS) instrument, which provides collisional stabilization that facilitates their observation. Isolation of the Hg(R-NH)₂H⁺ ions followed by collisional activation produces daughter ions corresponding to (C₆H₁₀NH₂)⁺ and Hg(R-NH)⁺. These assignments were supported by deuterium labeling experiments, which resulted in the formation of Hg(R-NH)(R-NH-d ₁₁)H⁺ and Hg(R-NH)₂H⁺. The existence of the Hg(R-NH)₂ compounds on the surface was verified using Raman spectroscopy, which showed a strong absorption at 590 cm^?1 that corresponded to Hg-N stretching. Analogous ions could be formed with n-hexylamine, but no Hg-bearing ions were formed when starting with a secondary or a tertiary amine. This indicates that only primary amines will react with Hg-nitrate surfaces in this manner. Hg-amine ions could not be formed starting with other Hg salts: chloride, iodide, thiocyanate, sulfate, and oxide. These results suggest that surface derivatization using amines, coupled with an IT-SIMS instrument, may offer an approach for determining inorganic metal speciation on surfaces.     

Calcium ion selective membrane electrode

The calcium salts of the mono- and diesters of [4-(1,1,3,3-tetramethylbutyl)phenyl phosphoric acid] have been prepared, and the individual esters as well as mixtures of the esters have been used with several varieties of polyvinyl chloride to construct macro membrane electrodes selective to calcium ions. These electrodes have been calibrated by using solutions of CaCl₂ and Ca ion buffers. The mixed ester electrodes showed Nernstian response in the concentration range 10^-1 to 10^-7M; the diester electrodes showed Nernstian response down to 7.9 x 10^-8M. The detection limit of the mixed ester electrode was 10^-8M, whereas that of the diester electrode was 7.9 x 10^-9M. Contrary to these results, the monoester electrodes showed unsatisfactory behavior. The responses of both the mixed ester and diester electrodes to calcium ions were not affected by the presence of sodium, potassium, or other divalent ions. Only ferric and lanthanum ions showed interferences with the electrode response to calcium ions. p]The electrode response was independent of pH in the approximate range 5–8 at a CaCl₂ concentration of 10^-4M. As the Ca ion concentration was increased, the range of pH independence widened to approximately 4–8. The dynamic response time constant of the mixed ester electrode was in the range 0.7–1.5 sec, whereas that of the diester electrode was in the range 0.5–0.75 sec.     

The Stability Constants of Some Benzo-15-Crown-5 And Naphtho-15-Crown-5 Derivatives

Abstract

The stability constants for the complexes of several benzo-15-crown-5 and naphtho-15-crown-5 derivatives containing various substituents in the aromatic ring have been determined in methanol. The potentiometric method with glass ion-selective electrodes has been employed. The stability constants have been compared to the selectivity coefficients (log k^pot _K,Na ) of membrane electrodes based on the mentioned compounds. No significant relationship has been stated.     

Effect of amines on the ceric ion-initiated polymerization of vinyl monomers. II. Polymerization of acrylonitrile by ceric ion in presence of various substituted amines

The effect of various substituted amines on the polymerization of acrylonitrile initiated by ceric ammonium sulfate has been studied in aqueous solution at 30°C. It was found that the secondary and tertiary amines considerably increased the rate of polymerization, whereas the primary amines seemed to have no effect at all. From the kinetic studies it was found that the overall polymerization rate R_p is independent of ceric ion concentration and can be expressed by the equation: R_p = k₁ [amine] [monomer] + k₂[monomer]², where k₁ and k₂ are constants (involving different rate constants). The accelerating effect of the amines was attributed to a redox reaction between the ceric ion and the amine involving a single electron transfer, the relative activity of the different amines being thus dependent on the relative electron-donating tendency of the substituents present in the amine. The mechanism of the polymerization is discussed on the basis of these results, and various kinetic constants are evaluated.     

Protonation constants and thermodynamic properties of amines for post combustion capture of CO2

The leading process for the post combustion capture (PCC) of CO₂ from coal-fired power stations and hence reduction in greenhouse gases involves capture by aqueous amine solutions. Of the reactions that occur in solution, which include CO₂ hydration, de-protonation of carbonic acid, amine protonation and carbamate formation, the protonation of the amine in the absorber and its subsequent de-protonation in the stripper involve the greatest enthalpy changes. In this study, protonation constants (reported as log₁₀ K_prot) of selected series of primary, secondary and tertiary alkanolamines/amines over the temperature range 288–318 K are reported. Selected series studied involve primary, secondary and tertiary mono-, di- and tri-alkanolamines, secondary amines including heterocyclic species, and both –CH₂OH and –CH₂CH₂OH substituted piperidines. van’t Hoff analyses have resulted in the standard molar enthalpies, ΔH_m^o, and molar entropies, ΔS_m^o, of protonation. Trends in ΔH_m^o are correlated with systematic changes in composition and structure of the selected series of amines/alkanolamines, while ΔH_m^o–ΔS_m^o plots generated linear correlations for the mono-, di-, and tri-alkanolamines, the –CH₂OH and –CH₂CH₂OH substituted piperidines, and the alkylamines. These relationships provide a guide to the selection of an amine(s) solvent for CO₂ capture, based on a greater difference in log₁₀ K_prot between the absorber and stripper temperatures.     

CpIr-catalyzed N-alkylation of amines with alcohols. A versatile and atom economical method for the synthesis of amines

A versatile and highly atom economical catalytic system consisting of [Cp^∗IrCl₂]₂/NaHCO₃ (Cp^∗=pentamethylcyclopentadienyl) for the N-alkylation of amines with primary and secondary alcohols as alkylating reagents has been developed. For example, the reaction of equimolar amounts of aniline and benzyl alcohol in the presence of [Cp^∗IrCl₂]₂ (1.0 mol % Ir) and NaHCO₃ (1.0 mol %) in toluene at 110 °C gives N-benzylaniline in 94% yield. The present catalytic system is applicable to the N-alkylation of both primary and secondary amines, and only harmless water is produced as co-product. A wide variety of secondary and tertiary amines can be synthesized with high atom economy under mild and less-toxic conditions. One-pot sequential N-alkylation leading to tertiary amines bearing three different substituents is also described.     

Molar excess volumes of ternary mixtures of nonelectrolytes

Molar excess volumes V^E_ijk of methylenebromide i + pyridine j + β-picoline (k, cyclohexane (i) + pyridine (j) + β-picoline(K), benzene(i)+toluene(j)+1,2-dichloroethane(k), benzene(i) + 0-xylene(j) + 1,2-dichloroethane(k) and benzene(i) + p-xylene(j) + 1,2-dichloroethane(k) mixtures have been determined dilatometrically at 298.15 K. The data have been examined in terms of Sanchez and Lacombe theory and the graph-theoretical approach, and it is found that they are described well by the latter. Self- and cross-volume interaction coefficients V_jk, V_jjk and V_jkk, etc., have also been evaluated and the values utilised to study molecular interactions between the jth and kth molecular species in the presence of the ith in these i + j + k mixtures.     

Molar excess enthalpies of ternary mixtures of non-electrolytes

Molar excess enthalpies, H^E_ijk(T₁, x_i, x_j), for methylenebromide (i)+pyridine (j)+β-picoline (k); pyridine (i)+β-picoline (j)+cyclohexane (k); benzene (i)+toluene (j)+1,2-dichloroethane (k); benzene (i)+o-xylene (j)+1,2-dichloroethane (k); and benzene (i)+p-xylene (j)+1,2-dichloroethane (k) mixtures have been measured calorimetrically as a function of temperature and composition. The data have been analysed in terms of the Sanchez and Lacombe theory and using an approach employing the “graph theoretical” concept of connectivity parameters to characterize its pure components. It has been observed that the H^E_ijk (T, x_i, x_j) data calculated from the “graph theoretical” approach using ³ξ values based on δ^v considerations (that take into consideration the valency of individual atoms of the molecular graph constituent components) best reproduces the corresponding experimental H^E_ijk data.     

Magnesium Ion Selective Electrodes Based on β-Diketone Compounds

Abstract

The ion selectivities for poly(vinyl chloride) (PVC)-matrix membrane ion-selective electrodes based on seven lipophilic diketone compounds were examined. All the electrodes based on the tested five β-diketone cómpounds exhibited clear Mg²′-selectivity under high pH conditions (pH10). Especially, the electrode based on 2-acetyl-1-tetralone shows excellent Mg²⁺-selectivity, and the selectivity coefficients of the Mg²+ -electrode to Ca²+, K⁺ and K⁺ (log K^pot _{mg, ca} log K^pol _mg.k and log K^pot _Mg.Na) in pH 10 solution were ?2.2, ?1.9 and ?2.7, respectively. This elecrode gave a response slope of about 60 mV/pMg²⁺ ranging from 1 × 10^?2 to 2 × 10^?2, which corresponds to twice the usual Nernstian theoretical responce slope for the divalent cation. This phenomenon is advantageous for the acccurate determination of Mg²⁺.     

Interlayer reactions of the silver molybdate Ag6Mo10O33

Silver molybdate Ag₆Mo₁₀O₃₃ exchanges silver ions for organic cations, particularly surface-active agents such as long-chain n-alkylammonium ions C_nH_2n+1NH⁺₃. The alkylammonium ions penetrate between the layers and aggregate as bimolecular structures. The alkyl chains in the interlayer are not in all-trans conformation but are isomerized into conformers with gauche-bonds. These chains aggregate as gauche-blocks because the polar chain ends (NH⁺₃ and NH₂ groups) interacting with the molybdate layer cannot be close-packed. The specially favored formation and pronounced stability of gauche-blocks impede the quantitative exchange of the silver ions. No more than 20% of the silver ions are exchanged by alkylammonium nitrate. The gauche-blocks are stabilized by additional uptake of alkylamine molecules. Silver molybdate also reacts with alkylamine and forms long-spacing complexes with long segments of the alkyl chains perpendicular to the layers.     

On tertiary BOx± ions in HF-plasma SNMS

The effect of plasma electron impact on negative secondary ions is investigated by example of a sputtered H₃BO₃/Cu powder pellet. O^–, BO^–, BO⁺, and B⁺ tertiary ions, fractured from strongly forward focussed secondary BO₂ ^– ions, are identified by their kinetic energies. Since most of them are accepted by the ion optics, this process may affect quantification in HF-plasma SNMS.     

Determination of molar ratio of primary secondary and tertiary amines in polymers by applying derivatization and NMR spectroscopy

A trifluoroacetic acid derivatization combined with ¹H NMR spectroscopy method for determining the molar ratio of primary, secondary, and tertiary amines in small molecules and polymers was discussed. Amines reacted with trifluoroacetic acid to form their salts RNH₃⁺, R₂NH₂⁺, and R₃NH⁺. The ¹H NMR signals of these protonated amines (NH₃⁺, NH₂⁺, and NH⁺) were separated well in the spectra. Based on the integration of these protonated amine signals, the molar ratio of primary, secondary, and tertiary amines can be calculated.     

Effect of solvent on the free energy of activation of S_N2 reaction between phenacyl bromide and amines

The kinetics of SN2 reaction between phenacyl bromide and various amines in 12 different solvents were studied. Solvent effects on the rate of this reaction and free energy of activation, ΔG# , were interpreted by applying the Abraham-Kam-let-Taft (AKT) equation. UK solvent polarity (π1*), solvent hydrogen-bond basicity (β1) and Hildebrand cohesive density energy (δH2) are those parameters which increase the rate constant and decrease ΔG# , while solvent hydrogen-bond acidity (α1) will have the compensatory effect. A comparison among obtained values of second rate constants, k2, for different amines in a given solvent indicates that the amine reactivities are highly dependent on their structures. The consequent decrease of the rate constant for different amines in any given solvent was found to be: primary > secondary> tertiary. This order results from steric effects of amines.     

proton transfers of substituted ammonium salts—XIII : N-inversion of piperidines in aqueous acidic solutions

The kinetics of the nitrogen inversion of 1,2-dimethyl-(2); 1,4-dimethyl-(8); 1-trans(2,6)-trimethyl-(4); 1,4-cis(2,6)-tetramethyl-(7) and 1,2,2,6,6-pentamethyl-(5)piperidines have been investigated in aqueous acidic solution (pH = 6.5–8.5) at 33° by dynamic NMR. In all cases, two isomeric cations AH⁺ and BH⁺ are observed in acidic conditions (pH<6?), and the nitrogen inversion is brought to the NMR time scale as a result of a progressive deprotonation of the cations into their conjugate amines on increasing the pH. Low rate constants K_A are obtained for α-substituted or unsubstituted compounds (k_A ?10³ s^?1), except for piperidine 5 where the rate constant k_A = 4.3 × 10⁵ s^?1 is of the same order of magnitude as the one found for tertiary acyclic amines.     

Measurement of state-to-state rotational transfer rates in collision of I2*(B 0u+, υ = 15, j) with 3He, 4He,Ne, Ar,H2, D2 and I2

The selective laser excitation and induced fluorescence observation technique has been used to study rotationally inelastic collisions of I₂^*(B 0_u⁺, υ = 15,j) with I₂, ³He, ⁴He, Ne, Ar, H₂ and D₂. For each collision partner, several initial rotational levels ranging from j_i = 12 up to j_i = 146 have been excited. For purely rotational transfer within the υ = 15 level, our data are perfectly consistent with energy sudden (eventually corrected) scaling laws. Thus, any thermally averaged rate constant, k(j_i → j_f), can be expressed as a function of the basis rate constants k(l → 0). Furthermore, these k(l → 0) are found to follow simple empirical fitting laws. Consequently any k(j_i → j_f) can be predicted given a set of two or three fitting parameters. Collisions with relatively heavy particles (I₂, Ar and Ne) are well described by using the inverse power fitting law k(l → 0) = b[l(l+1)]^?γ, where b = 1.7, 1.2 and 1.2×10^?10 cm³ s^?1 and γ = 1.08, 1.02 and 1.17 for I₂^*-Ne, I₂^*-Ar and I₂^*-I₂ collisions respectively. For collisions with light particles (³He, ⁴He, H₂ and D₂), k(l → 0) shows a sharp decrease with l which can be accounted for by a hybrid power-exponential fitting law k(l → 0) = b[l(l+1)]^?γ exp[-l(l+1)/l^* (l^*+1)], where b = 0.84, 0.71, 2.77 and 2.78×10^?10 cm³ s^?1l⁺ = 20.6, 23.1, 18.8 and 31.4, and γ = 0.66, 0.66, 0.78 and 0.91 for I₂^*-³He, I₂^*-He, I₂^*-H₂ and I₂^*-D₂ collisions, respectively. We confirm that the rotational transfer dynamics in heavy molecules is mainly governed by angular momentum exchange.     

Heterogeneous electron-transfer kinetics for some multiply bonded dirhenium complexes

Standard electrochemical rate constants k^ex_ob have been measured for the two sequential one-electron oxidations of triply-bonded dirhenium(II) complexes Re₂X₄(PR₃)₄, where X = Cl or Br, and PR₃ = a monodentate tertiary phosphine, and also for allied complexes in methylene chloride, acetonitrile, and N,N-dimethylformamide at platinum electrodes. The objective is to explore the possible dependence of k^ex_ob upon the known differences in the structural changes accompanying electron transfer. Although significant and even substantial variations in k^ex_ob were observed for closely related redox couples, the reactivity trends appear to be chiefly a consequence of differences in electrostatic work terms at the metal/solution interface. Comparisons are made with recent results for mononuclear organometallic redox couples.     

Fluorimetric method for the determination of long-chain amines in water

A method is presented for the determination of long-chain quaternary ammonium salts, tertiary amines and secondary amines in water or aqueous raffinates, based on their extraction and fluorimetric determination as amine salts with Eosine Yellowish in toluene-hexanol (4:1) as solvent. No interferences were obtained from metal ions, or chloride, nitrate or phosphate ions when a back-washing method was applied to the sample extract. The method allows the determination of long-chain tertiary amines down to 4 ppM.