Category: 14098-44-3

The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.14098-44-3, Name is Benzo-15-crown-5, molecular formula is C14H20O5. In a Article£¬once mentioned of 14098-44-3, Quality Control of: Benzo-15-crown-5

On the facilitating effect of neutral macrocyclic ligands on the ion transfer across the interface between aqueous and organic solutions – Part III. Competitive facilitated ion-transfer

A theoretical equation of the reversible current-potential curves is derived for the competitive ion-transfer of two kinds of cations present in an aqueous (w) phase simultaneously facilitated by a macrocyclic ligand (L) present in an organic (o) phase. Especially, for the two limiting cases, i.e. case (A): c*Mj (j = 1, 2)?c*L and case (B): c*L?c*Mj (where c*Mj and c*L denote the bulk concentrations of cation Mj in the w-phase and of L in the o-phase, respectively), simple explicit expressions are derived and a method analyzing the facilitated waves is presented. Furthermore, the main part of the theoretical predictions obtained is verified experimentally at 25C by using the ion-transfer-polarographic method with the electrolyte dropping electrode, for the following four combinations: (i) competitive cations: protonated alanine and H+, L: benzo-18-crown-6 ether; (ii) Na+ and Li+, benzo-15-crown-5 ether; (iii) K+ and Na+, dibenzo-18-crown-6 ether; and (iv) Na+ and Ba2+, dibenzo-24-crown-8 ether.

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Ethynylpyrene Linked Benzocrown Ethers as Fluorescent Sensors for Metal Ions

Substances containing ethynylpyrenes linked to either one or four benzocrown ethers were synthesized, and their absorption and fluorescence spectroscopic responses to metal ions were assessed. Addition of metal perchlorates to solutions of these substances promotes short wavelength shifts in their absorption and fluorescence maxima and increases in their fluorescence intensities. The magnitudes of the fluorescence intensity increases are dependent on the ring size and number of the crown ether and the nature of the metal cation. Association constants for complex formation were calculated using fluorescence intensity versus concentration data. Analysis using Job’s plots showed that the substances containing one benzocrown ether moiety form 1:1 complexes with metal ions. Results of experiments employing repeated addition and removal of Mg(ClO4)2 demonstrate that the ON-OFF fluorescence response can be repeated at least three times. Results of molecular orbital calculations show that complexation with metal ions lowers the energies of both the pi and pi* levels of the ethynylpyrene moiety and that in some cases the vacant orbital on the metal becomes the LUMO of the complex. An explanation of the spectroscopic changes promoted by metal ions is proposed in terms of electrostatic repulsion and structural regulation.

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14098-44-3, Name is Benzo-15-crown-5, molecular formula is C14H20O5, belongs to chiral-catalyst compound, is a common compound. In a patnet, once mentioned the new application about 14098-44-3, Computed Properties of C14H20O5

A three dimensional network of iodide ions and iodine molecules in the crystal structure of [Pr(benzo-15-crown-5)2]I21

Black polyhedra of [Pr(benzo-15-crown-5)2]I21 were grown from an ethanol / dichlormethane solution of PrI3, benzo-15-crown-5 and I2. The crystal structure (orthorhombic, P2 1cn, a = 1201.1(1), b = 2168.3(1), c = 2571.1(1) pm, Z = 4) is built up from sandwich like cations [Pr(benzo-15-crown-5)2]3+ and polyiodide anions I213-. This unique polyiodide anion exhibits a complex connection pattern of iodide ions and iodine molecules with variable bond lengths forming a complicated network.

Balanced chemical reaction does not necessarily reveal either the individual elementary reactions by which a reaction occurs or its rate law.Computed Properties of C14H20O5. In my other articles, you can also check out more blogs about 14098-44-3

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Reference of 14098-44-3, Catalysts are substances that increase the reaction rate of a chemical reaction without being consumed in the process. 14098-44-3, Name is Benzo-15-crown-5, molecular formula is C14H20O5. In a Article£¬once mentioned of 14098-44-3

Electrochemical modification of benzo-15-crown-5 ether on a glassy carbon electrode for alkali metal cation recognition

Benzo-15-crown-5 (B15C5) was covalently immobilized on a glassy carbon (GC) electrode and its complexation ability with alkali metal cations was studied. A mixture of 4?-aminobenzo-15-crown-5 and NaNO2 was prepared to generate diazotized B15C5, and a GC electrode was immersed in the mixture. By potential cycling between 0.0 and -0.8 V, the diazotized B15C5 was reduced electrochemically and reacted with the carbon atoms at the electrode surface to form the B15C5 layer on the GC electrode. Cyclic voltammetry and scanning tunneling microscopy were used to characterize the B15C5 layer. The surface amount of B15C5 groups increased by repeating the potential cycles, and reached a saturated value within 20 cycles. STM observation reveals that a monolayer or sub-monolayer of B15C5 was formed. The adsorption behavior of alkali metal cations to the B15C5 layer on GC electrode was examined by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The order of adsorption constants was K+ > Na+ > Rb+ > Li + > Cs+, indicating cooperative association between K+ and B15C5 groups at the modified electrode surface.

The proportionality constant is the rate constant for the particular unimolecular reaction. the reaction rate is directly proportional to the concentration of the reactant. I hope my blog about 14098-44-3 is helpful to your research., Reference of 14098-44-3

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The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.14098-44-3, Name is Benzo-15-crown-5, molecular formula is C14H20O5. In a Article£¬once mentioned of 14098-44-3, Computed Properties of C14H20O5

In situ one-pot formation of crown ether functionalized polysulfone membranes for highly efficient lithium isotope adsorptive separation

A unique one-pot polymer synthesis and membrane formation technique was developed to fabricate polysulfone-graft-4?-aminobenzo-15-crown-5-ether (PSf-g-AB15C5) membranes for lithium isotope adsorptive separation. This is, the reaction system and the preparation of casting solution were integrated into one step without separation and purification of the product. Herein, PSf-g-AB15C5 was prepared by the grafting reaction of AB15C5 and chloromethylated polysulfone (CMPSf). The viscosity of reaction solution was controlled by the grafting time. The reaction solution with a certain viscosity or at a certain grafting time as a casting solution was in-situ cast to porous membranes through non-solvent induced phase separation (NIPS). Results showed that the resultant membrane structures changed gradually from macrovoids to sponge-like with the viscosity increase of the reaction solution, which is attributed to the grafting and self-crosslinking of PSf-g-AB15C5 polymers. This endows the membranes can be formed even at a very low polymer solution concentration of 10%. Interestingly, the sponge-like crosslinked networks displayed a strong mechanical strength at the range of 2.12?3.72 MPa. Moreover, all membranes showed high porosity. Especially, the membrane with the reaction time of 20 h exhibited a remarkable porosity of 85.2%. These porous membranes promoted the effective adsorption between Li+ ions and crown ether groups and led to a high distribution coefficient. A remarkable equilibrium separation factor of 6Li+/7Li+ up to 1.055 was obtained from the membrane containing 0.521 mmol g?1 of the immobilization crown ether, which is much higher than the acceptable industrial scale separation factor of 1.03. Due to the higher affinity of 6Li+ to crown ether than 7Li+, 6Li+ and 7Li+ were enriched in the membrane phase and the solution phase, respectively. Therefore, the membrane shows a great potential in the development of green and highly efficient membrane chromatography for lithium isotope adsorptive separation applications.

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Nuclear Magnetic Resonance Studies of Some Sodium Ion Complexes with Crown Ethers and <2>Cryptands in Various Solvents

Sodium-23 and carbon-13 NMR were used to study sodium ion complexes with crown ethers 15C5, B15C5, and 18C6 as well cryptands C211, C221, C222, and C222B in water and in a number of nonaqueous solvents.The stabilities of the complexes varied in the order Na+*18C6 > Na+*15C5 > Na+*B15C5.In most cases the cationic exchange between the free and complexed sites was rapid.However, in the NaBPh4 – 18C6 – THF and NaBPh4 – 18C6 – dioxolane systems the exchange was slow enough to observe two 23Na resonances in solutions containing an excess of the sodium salt.Two signals merged when NaBPh4 was replaced by NaClO4 or NaI.In all solvents studied the four cryptands formed stable complexes with the sodium ion.The limiting chemical shifts showed some solvent dependence in the 30 to -70 deg C temperature range.The chemical shift of the complexed sodium ion moved downfield in the order Na+*C222 < Na+*C222B < Na+*C221 < Na+*C211. If you are interested in 14098-44-3, you can contact me at any time and look forward to more communication.Related Products of 14098-44-3

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Reference of 14098-44-3, Catalysts are substances that increase the reaction rate of a chemical reaction without being consumed in the process. 14098-44-3, Name is Benzo-15-crown-5, molecular formula is C14H20O5. In a Article£¬once mentioned of 14098-44-3

Benzoaza-15-crown-5 ethers: Synthesis, structure, and complex formation with metal and ethylammonium ions

enzoaza-15-crown-5 ethers containing one or two nitrogen atoms in different positions of the macrocycle and bearing different substituents at these atoms were synthesized. The structures of azacrown ethers and their metal complexes were studied by X-ray diffraction. The stability constants of the complexes of azacrown ethers with Na+, Ca2+, Ba2+, Ag+, Pb2+, and EtNH3+ ions were determined by 1H NMR titration in MeCN-d3. In free benzoazacrown ethers containing secondary nitrogen atoms bound to the benzene ring, as well as in N-acetyl derivatives, the N atoms are sp2-hybridized and have a planar geometry. The nitrogen lone pairs on the p orbitals are efficiently conjugated to the benzene ring or the carbonyl fragment of the acetyl group, which is unfavorable for the complex formation. In addition, the formation of complexes with benzoazacrown ethers containing secondary nitrogen atoms is hindered because the hydrogen atoms of the NH groups are directed to the center of the macrocyclic cavity. In benzoazacrown ethers bearing N-alkyl substituents or secondary nitrogen atoms distant from the benzene ring, the N atoms show a substantial contribution of the sp3-hybridized state and have a pronounced pyramidal configuration, which promotes the complex formation. The lead and calcium cations form the most stable complexes due to the high affinity of Pb2+ ions for O, N-containing ligands, a high charge density on these ions, and the better correspondence of the cavity size of the 15-membered macrocycles to the diameter of the Ca2+ ion. An increase in the stability of the complexes is observed mainly in going from monoazacrown ethers to diazacrown ethers containing identical substituents at the N atoms and in the following series of substituents: C(O)Me < H < Me < CH2CO2Et. In the case of the CH2CO2Et substituents, the carbonyl oxygen atom is also involved in the coordination to the cation. The characteristic features of the complexing ability of N-alkylbenzomonoaza- 15-crown-5 ethers bearing the nitrogen atom conjugated to the benzene ring show that macro- cyclic ligands having this structure are promising as selective and efficient complexing agents for metal cations. The proportionality constant is the rate constant for the particular unimolecular reaction. the reaction rate is directly proportional to the concentration of the reactant. I hope my blog about 14098-44-3 is helpful to your research., Reference of 14098-44-3

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Terminal uranium(V)-nitride hydrogenations involving direct addition or Frustrated Lewis Pair mechanisms

Despite their importance as mechanistic models for heterogeneous Haber Bosch ammonia synthesis from dinitrogen and dihydrogen, homogeneous molecular terminal metal-nitrides are notoriously unreactive towards dihydrogen, and only a few electron-rich, low-coordinate variants demonstrate any hydrogenolysis chemistry. Here, we report hydrogenolysis of a terminal uranium(V)-nitride under mild conditions even though it is electron-poor and not low-coordinate. Two divergent hydrogenolysis mechanisms are found; direct 1,2-dihydrogen addition across the uranium(V)-nitride then H-atom 1,1-migratory insertion to give a uranium(III)-amide, or with trimesitylborane a Frustrated Lewis Pair (FLP) route that produces a uranium(IV)-amide with sacrificial trimesitylborane radical anion. An isostructural uranium(VI)-nitride is inert to hydrogenolysis, suggesting the 5f1 electron of the uranium(V)-nitride is not purely non-bonding. Further FLP reactivity between the uranium(IV)-amide, dihydrogen, and triphenylborane is suggested by the formation of ammonia-triphenylborane. A reactivity cycle for ammonia synthesis is demonstrated, and this work establishes a unique marriage of actinide and FLP chemistries.

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(Oligo)thienyl-imidazo-benzocrown ether derivatives: Synthesis, photophysical studies and evaluation of their chemosensory properties

A series of novel (oligo)thienyl-imidazo-benzocrown ethers were synthesised through a simple method and evaluated as fluorimetric chemosensors for transition metal cations. Interaction with Ni2+, Pd2+, and Hg2+ in ACN/DMSO solution (99:1) was studied by absorption and emission spectroscopy. Chemoselectivity studies in the presence of Na + were also carried out and a fluorescence enhancement upon chelation (CHEF) effect was observed following Hg2+ complexation. Considering that most systems using fluorescence spectroscopy for detecting Hg2+ are based on the complexation enhancement of the fluorescence quenching (CHEQ) effect, the present work represents one of the few examples for sensing of Hg2+ based on a CHEF effect.

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The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.14098-44-3, Name is Benzo-15-crown-5, molecular formula is C14H20O5. In a Article£¬once mentioned of 14098-44-3, name: Benzo-15-crown-5

Molecular Complexes of Crown Ethers with 2,4,6-Trinitrotuluene

Molecular complexation of six crown ethers with 2,4,6-trinitrotoluene has been studied using spectral methods.The association constants have been evaluated using PMR shift method.All these ethers form 1:1 complexes in 1,2-dichloroethane.The major contribution to the interaction arises from n and ? electrons.The 1H and 13C NMR studies provide some insight into the relative orientation of the donor and acceptor molecules in solution.

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