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1.
The crystalline isotypic solvates Rb4Sn4·2NH3, Cs4Sn4·2NH3, and Rb4Pb4·2NH3 have been synthesized using the direct reduction of elemental tin or tetraphenyltin, respectively, with heavier alkali metals or the dissolution of the binary phase RbPb in liquid ammonia. These compounds contain the cluster ions [Sn4]4– or [Pb4]4– respectively. This is the first time that[Tt4]4– ions (Tt = tetrels) are detected as result of a solution reaction. The accommodation of the ammonia molecules, which build up ion‐dipole interactions to alkali metal cations, requires some modifications of the crystal structures compared to the binary phases RbSn, CsSn, and RbPb. The tetrahedral [Tt4]4– anions have a slightly lower coordination by Rb+ or Cs+ cations and, furthermore, the intercluster distances show a remarkable increase.  相似文献   

2.
    
Zusammenfassung Geeignete Glaselektroden können in wäßrigen sowie nichtwäßrigen Lösungsmittelsystemen zur Messung der Aktivität des protonierten Lösungsmittels verwendet werden. Aus elektrisch hochleitfähigen Gläsern hergestellte Glaselektroden sprechen demzufolge in flüssigem Ammoniak bei einer Meßtemperatur von –34° C quantitativ auf die Aktivität des protonierten Ammoniaks (NH4 +) an. Es wird gezeigt, daß sich die Kaliumsalze von sehr schwachen Säuren (Alkohole, sterisch gehinderte Phenole) unter Verwendung dieser Meßkette mit einem Ammoniumsalz titrieren lassen. Es lassen sich auch Säuren mit Kaliumamid titrieren, das durch laufendes Einbringen von metallischem Kalium ins Meßgut erzeugt wird.
Summary Adequate glass electrodes behaving as protodes in. aqueous systems respond to the protonated solvent in liquid ammonia at –34° C and can therefore be used to measure the activity of NH4 +. Titrations of the potassium salts of very weak acids (alcohols, sterically hindered phenols) are performed in this solvent using glass electrodes. Acids may also be titrated with potassium amide generated by a step-by-step introduction of potassium into the sample solution.
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3.
The behavior of Li/La glass electrodes as specific ion sensors for NH 4 + and Na+ cations in liquid ammonia solutions at –40°C has been assessed using concentration cells with transference. The measurement of emf's of cells with very high resistances due to glass at –40°C has been overcome partly by the use of thinly blown Li/La glass and mainly through the design and use of a floating shield emf measuring system. For solutions of NH4NO3, NH4I, NH4BF4, and NH4Cl almost linear pNH4 vs. emf responses were observed between pNH4 0 and 5; for NH4NO3 solutions the slope (40±1 mV/pNH4) was invariant for substantial increases in Na+ concentrations. Solutions of NaNO3, NaCN, NaClO4, NaNCS, NaN3, and NaNO2 gave almost linear pNa vs. emf responses but the slopes were markedly dependent upon the NH 4 + concentration. Estimates of the mean molal ion activity coefficients for nitrate solutions were obtained from earlier transference data: ±(NaNO3)=0.14±0.02 and ±(NH4NO3)=0.30±0.03 at 10 molal concentration in fair agreement with earlier data.  相似文献   

4.
Guanidinium-selective membrane electrodes were constructed with dibenzo-24-crown-8, dibenzo-27-crown-9, tribenzo-27-crown-9 or dibenzo-30-crown-10. The detection limits and selectivity coefficients towards different interfering ions, such as Li+, Na+, K+, NH+4, Mg2+ and Ca2+ were determined. The electrode with dibenzo-27-crown-9 shows linear response over the range 10?1–10?4 M, with selectivity coefficients about 10?2 for most alkali and alkaline earth metal ions.  相似文献   

5.
Controlling vapour pressure is necessary for the viability of aqueous ammonia solutions in commercial applications such as refrigeration. In this study, Gibbs ensemble Monte Carlo (GEMC) simulations were used to calculate the vapour–liquid equilibrium (VLE) of ammonia–water–MCl mixtures, M = Na or Cs, within the isobaric–isothermal- (NpT-) ensemble. The results indicate that in the presence of alkali metal additives, there is a non-negligible ‘salting-in’ effect for ammonia in the liquid phase. Experimental measurements of the liquid phase concentration of ammonia confirm the GEMC results i.e. the vapour loss rates in systems containing ionic additives is slightly lower. Gibbs ensemble Monte Carlo simulations also indicate that ammonia prefers to solvate aqueous cations as a result of electrostatic interactions. Ab-initio calculations show that the M+–ammonia complex is energetically more stable than the M+–water complex. The difference in the binding free energy Δ(ΔG bind(M+–NH3)?ΔG bind(M+–H2O)) depends on the size of the cation and is highest for the smallest tight cations (e.g. Li+) and lowest for the most polarisable cations (Cs+).  相似文献   

6.
Catalytic benzene C?H activation toward selective phenol synthesis with O2 remains a stimulating challenge to be tackled. Phenol is currently produced industrially by the three‐steps cumene process in liquid phase, which is energy‐intensive and not environmentally friendly. Hence, there is a strong demand for an alternative gas‐phase single‐path reaction process. This account documents the pivotal confined single metal ion site platform with a sufficiently large coordination sphere in β zeolite pores, which promotes the unprecedented catalysis for the selective benzene hydroxylation with O2 under coexisting NH3 by the new inter‐ligand concerted mechanism. Among alkali and alkaline‐earth metal ions and transition and precious metal ions, single Cs+ and Rb+ sites with ion diameters >0.300 nm in the β pores exhibited good performances for the direct phenol synthesis in a gas‐phase single‐path reaction process. The single Cs+ and Rb+ sites that possess neither significant Lewis acidic?basic property nor redox property, cannot activate benzene, O2, and NH3, respectively, whereas when they coadsorbed together, the reaction of the inter‐coadsorbates on the single alkali‐metal ion site proceeds concertedly (the inter‐ligand concerted mechanism), bringing about the benzene C?H activation toward phenol synthesis. The NH3‐driven benzene C?H activation with O2 was compared to the switchover of the reaction pathways from the deep oxidation to selective oxidation of benzene by coexisting NH3 on Pt6 metallic cluster/β and Ni4O4 oxide cluster/β. The NH3‐driven selective oxidation mechanism observed with the Cs+/β and Rb+/β differs from the traditional redox catalysis (Mars‐van Krevelen) mechanism, simple Langmuir‐Hinshelwood mechanism, and acid?base catalysis mechanism involving clearly defined interaction modes. The present catalysis concept opens a new way for catalytic selective oxidation processes involving direct phenol synthesis.  相似文献   

7.
A capillary electrophoretic (CE) method has been optimized for the separation of some common alkali and alkaline-earth metal cations in anti-asthmatic homeopathic liquid pharmaceutical preparations. Separation was carried out on a 74 cm (62.5 cm to the detector) × 75 μm ID fused silica capillary at a potential of 25 kV and 25 °C. Baseline separation of NH4 +, K+, Ca2+, Na+, Mg2+ and Li+ was achieved in less than 4.5 min. The proposed method was applied for the determination of the above-mentioned ions in homeopathic liquid formulations. Limits of quantitation (LOQ) observed were 1.5 ppm for NH4 +, Ca2+ and Mg2+ 0.8 ppm for Na+, 1.6 ppm for K+, and 0.4 ppm for Li+. During electrophoresis, the ingredients used in the preparation of homeopathic formulation did not interfere with the cations examined.  相似文献   

8.
The thermal decomposition of pure ammonium heptamolybdate tetrahydrate (AHMT), and doped with Li+, Na+ and K+ ions was investigated using thermogravimetry, differential thermal analysis, infrared and X-ray diffraction techniques. Results obtained revealed that the decomposition of AHMT proceeded in three decomposition stages in which both NH3 and H2O were released in all stages. The presence of 0.5 mol % alkali metal ions enhances the formation of the intermediateb (NH4)2MO7O22·2H2O while the decomposition of this intermediate into MoO3 is slightly affected in the presence of all dopant concentrations used. The infrared absorption spectra of the thermal products of AHMT treated with 10 mol% alkali metal ions (AMI) at 350°C indicated a reduction of some Mo6+ ions. By heating of AHMT above 500°C in presence of 5 or 10 mol % of AMI, a solid-solid interaction between alkali metal oxides and MoO3 giving rise to well crystallized alkali metal molybdates. finally the activation energies accompanied various decomposition stages were calculated.  相似文献   

9.
Indirect ultraviolet detection was conducted in ultraviolet‐absorption‐agent‐added mobile phase to complete the detection of the absence of ultraviolet absorption functional group in analytes. Compared with precolumn derivatization or postcolumn derivatization, this method can be widely used, has the advantages of simple operation and good linear relationship. Chromatographic separation of Li+, Na+, K+, and NH4+ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid/organic solvent as the mobile phase, in which imidazolium ionic liquids acted as ultraviolet absorption reagent and eluting agent. The retention behaviors of four kinds of cations are discussed, and the mechanism of separation and detection are described. The main factors influencing the separation and detection were the background ultraviolet absorption reagent and the concentration of hydrogen ion in the ion chromatography‐indirect ultraviolet detection. The successful separation and detection of Li+, Na+, K+, and NH4+ within 13 min was achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.02, 0.11, 0.30, and 0.06 mg/L, respectively. A new separation and analysis method of alkali metal ions and ammonium by ion chromatography with indirect ultraviolet detection method was developed, and the application range of ionic liquid was expanded.  相似文献   

10.
Summary The response of cation-sensitive glass electrodes to univalent cations in ethanol-water mixtures shows increasing e.m.f. values with increasing fractions of ethanol for Na+, K+, Cs+, Rb+, Li+, and NH4 +, but anomalous behavior for H+. The calculated selectivity of the glass electrode for metal ions over the hydrogen ion thus increases sharply over the range of 10–70 weight % ethanol. It is suggested that sodium rather than hydrogen ion may be adopted as the reference ion for the definition of selectivity ratios in mixed solvents.
Zusammenfassung Die Ansprechbarkeit von kation-empfindlichen Glaselektroden auf einwertige Kationen (Na+, K+, Cs+, Rb+, Li+, NH4 +) in Äthanol-Wassergemischen weist mit steigendem Äthanolgehalt steigende E.M.K.-Werte auf; H+ zeigt ein abweichendes Verhalten. Die berechnete SelektivitÄt der Glaselektrode für Metallionen nimmt daher im Bereich von 10–70% Äthanol stark zu. Es wird empfohlen, für die Definition von SelektivitÄtsverhÄltnissen in Lösungsmittelgemischen Na+ an Stelle von H+ als Bezugsion zu verwenden.
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11.
We report the first solvate structure of the silicide anion Si44–, which provides circumstantial evidence of the stability of the highly charged anion in liquid ammonia solutions. The solvate Rb1.2K2.8Si4 · 7NH3 crystallized from a mixture of the ternary compound K6Rb6Si17 with the transition metal complex [(C6H5)3P]2Ni(CO)2 [bis(triphenylphosphine)dicarbonylnickel] in the presence of the chelating agents 18‐crown‐6 (1,4,7,10,13,16‐hexaoxacyclooctadecane) and [2.2.2]cryptand (4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane) in liquid ammonia. Single X‐ray diffraction analysis confirms the presence of the Si44– anion in the crystal structure of Rb1.2K2.8Si4 · 7NH3, which represents the first solvate compound of the naked tetrasilicide tetraanion. All five crystallographically independent cation positions show mixed occupancy by Rb+ and K+.  相似文献   

12.
Under ammonia chemical ionization (CI) conditions triarylpropenones undergo hydrogen radical-induced olefinic bond reduction on metal surfaces, resulting in [M + 2H + NH4]+ ions corresponding to the ammonium adduct of the saturated ketone. The decomposition of the adduct ions, [MNH4]+ and [M + 2H + NH4]+, was studied by collision-induced dissociation mass-analysed ion kinetic energy (CID-MIKE) spectroscopy in a reverse geometry instrument. From the CID-MIKE spectra of the [MNH4]+, [M + 2H + NH4]+, [MND4]+ and [M + 2D + ND4]+ ions it is clear that the fragmentation of the adduct ions involves loss of NH3 followed by various cyclization reactions resulting in stable condensed ring systems. Elimination of ArH and ArCHO subsequent to the loss of NH3 and formation of aroyl ion are characteristic decomposition pathways of the [MNH4]+ ions, whereas elimination of ArCH3 and formation of [ArCH2]+ are characteristic of the [M + 2H + NH4]+ ions of these propenones.  相似文献   

13.
The thermal reactions of cationic 3d transition‐metal hydrides MH+ (M=Sc–Zn, except V and Cu) with ammonia have been studied by gas‐phase experiments and computational methods. There are three primary reaction channels: 1) H2 elimination by N? H bond activation, 2) ligand exchange under the formation of M(NH3)+, and 3) proton transfer to yield NH4+. Computational studies of these three reaction channels have been performed for the couples MH+/NH3 (M=Sc–Zn) to elucidate mechanistic aspects and characteristic reaction patterns of the first row. For N? H activation, σ‐bond metathesis was found to be operative.  相似文献   

14.
Measurements of both a thermodynamic and kinetic nature establish that an 18-crown-6 derivative incorporating a ‘chiral diethyleneglycol’ unit in the shape of a 2,5-anhydro-D-mannitol residue forms extremely strong complexes with alkali metal, NH+4, and RNH+3 ions.  相似文献   

15.
16.
The thermal decomposition of nitritocobaltate(III) of the silver group of general formula M2Ag[Co(NO2)6] (where M = K+, NH+4, Rb+ or Cs+) has been investigated. Based on the thermal curves of the investigated compounds and chemical and diffractometric analysis, the mechanism of thermal decomposition has been determined. The results obtained indicate that the decomposition proceeds in three stages. As a result of decomposition in the first stage (300°C), nitrates of alkali metals, metallic silver and Co3O4 are formed. In the second stage (500°C), a partial decomposition of nitrates to alkali metal oxides occurs, and in the third stage the products are alkali metal oxides, silver and Co3O4. This paper also presents the dependence of the decomposition temperature of nitritocobaltates(III) of the silver group on the ionic radius of the outer-sphere cation.  相似文献   

17.
The electrode characteristics of ion-selective electrodes (ISEs) for K+, Na+, NH4 +, and Ca2+ based on bilayer film coatings, where the inner layer films are electroactive electropolymerized ones and the outer layer films are composed of conventional ion-sensitive materials, have been examined. These ISEs of the coated-wire electrode type have no conventional internal reference solution and reference electrode, but the inner films may be considered to function as the “internal standard solution.” The ion selectivity coefficients and the activity range showing Nernstian response were almost comparable to those of conventional liquid-membrane electrodes. The bilayer-coated ISEs showed insensitivity to O2 and CO2, long-term stability, and little drift. It was also found that the electrode performance is practically unchanged after sterilization in an autoclave. The results demonstrate that the bilayer-coated ISEs examined are promising for the determination of K+, Na+, NH4 +, or Ca2+ activity in biological and environmental systems.  相似文献   

18.
The structures of the major adduct ions formed in ammonia chemical ionization of thirteen aliphatic and aromatic ketones have been studied by mass analysed ion kinetic energy spectrometry. The [M+NH3+H]+ ion is shown to have a protonated carbinolamine structure, [M+2NH3+H]+ to be a protonated carbinolamine with hydrogen-bonded ammonia and [2M+NH3+H]+ to be, at least in part, a protonated carbinolamine with hydrogen-bonded ketone. These structures may imply a nucleophilic addition of ammonia at the carbonyl of the ketone-ammonium ion complex. An unusual hydroxy migration is seen in the internal rearrangement of the [2M+NH3+H]+ ion leading to the formation of a protonated imine.  相似文献   

19.
Cs2Ba(O3)4 · 2 NH3, the First Ionic Alkaline Earth Metal Ozonide Cs2Ba(O3)4 · 2 NH3 is the first ionic ozonide containing an alkaline earth metal cation. Its synthesis has been achieved via partial cation exchange of CsO3 dissolved in liquid ammonia. According to a single crystal X‐ray structure determination (Pnnm; a = 6.312(2) Å, b = 12.975(3) Å, c = 8.045(2) Å; Z = 2; R1 = 4.6%; 848 independent reflections) ozonide anions, cesium cations and ammonia molecules form a CsCl‐type arrangement, where Cs+ and NH3 occupy one half of the cation sites, each. Ba2+ is coordinated by four ozonide groups and two ammonia molecules. Because of a short hydrogen bond to one of the terminal oxygen atoms, the respective O–O‐distance in the ozonide ion is longer than the other. The shortest intermolecular O–O‐distance ever observed in ionic ozonides has been found in this compound, which can be taken as a first clue for the radical ozonide anion to dimerize like the isoelectronic SO2 does.  相似文献   

20.
Black soldier fly (BSF) larvae (Hermetia illucens), feeding on leachate from decaying vegetable and food scrap waste, increase ammonia (NH4+) concentration five- to sixfold relative to leachate unprocessed by larvae. NH4+ in larva-processed leachate reached levels as high as ∼100 mM. Most of this NH4+ appears to have come from organic nitrogen within the frass produced by the larvae as they fed on leachate. In nitrate-enriched solutions, BSF larvae also facilitate dissimilatory nitrate reduction to ammonia. The markedly higher concentration of NH4+ recovered in leachates processed with BSF larvae and concomitant diversion of nutrients into insect biomass (itself a valuable feedstock) indicate that the use of BSF larvae in processing leachate of decaying organic waste could be advantageous in offsetting capital and environmental costs incurred in composting.  相似文献   

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