Category: 33100-27-5

Chemistry is the science of change. But why do chemical reactions take place? Why do chemicals react with each other? The answer is in thermodynamics and kinetics.In a document type is Article, the author is D’Aprano, Alessandro and a compound is mentioned, 33100-27-5, 1,4,7,10,13-Pentaoxacyclopentadecane, introducing its new discovery. 33100-27-5

Solvent Effects on Complexation of Crown Ethers with LiClO4, NaClO4 and KClO4 in Methanol and Acetonitrile

The thermodynamic formation constants Kf for complexation of Li+, Na+ and K+ with the crown ethers 12C4 and 15C5 have been determined in methanol and acetonitrile at 25 deg C using precision conductivity data.The method permits evaluation of very small Kf values (e.g., Kf = 6.98 mol-1-dm3 for LiClO4 + 12C4 in methanol) as well as fairly large values (e.g., Kf 0 2.73*104 mol-1-dm3 for NaClO4 + 15C5 in acetonitrile).The determination fo Kf values from condcutivity data takes into consideration the often neglected ion pair formation of both the uncomplexed and the complexed cations.Our results for Kf are generally consistent with previously reported values based on potentiometry, calorimetry, and polarography, but there are significant differences in several cases which we attribure to neglect of ion association both for uncomplexed or “free” cation Ka and the macrocyclic complexed cation Ka2.Our results are also consistent with the well known concept relating the magnitude of Kf to both the cavity diameter and ion-solvent interactions.Limiting molar conductivities Lambda2 for the complex salt (M-crown ether) (ClO4) in both solvents were generally found to be smaller or very close to the corresponding quantity Lambda1 for the binary MClO4-solvent system.However, in methanol, single ion limiting molar conductivities for the cationic complexes lambda2 exhibit anomalous behavior which is attributed to solvation differences between “free” cations and complexed cations. – Key words: Electrolytic, molar and ionic conductance; ion pair and complex ion formation; 12-crown-4; 15-crown-5; lithium, sodium and potassium perchlorate; acetonitrile; methanol; solvation effects; ion solvation; Gibbs energies of transfer.

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Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane. In a document type is Article, introducing its new discovery., 33100-27-5

Crown ether adducts of light alkali metal triphenylsilyls: Synthesis, structure and hydrosilylation catalysis

Alkali metal triphenylsilyls [Li(12-crown-4)SiPh3]¡¤(thf)0.5(2), [Na(15-crown-5)SiPh3]¡¤(thf)0.5(3) and [K(18-crown-6)SiPh3(thf)] (4) were synthesized using 1,1,1-trimethyl-2,2,2-triphenyldisilane (Ph3SiSiMe3) and isolated in high yields. Solid state structures were determined by single crystal X-ray diffraction. These alkali metal silyls catalyzed the regioselective hydrosilylation of 1,1-diphenylethylene to give the anti-Markovnikov product. The presence of crown ethers enhanced the reactivity of the metal silyls in hydrosilylation catalysis.

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In an article, published in an article,authors is Baglioni, Piero, once mentioned the application of 33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane,molecular formula is C10H20O5, is a conventional compound. this article was the specific content is as follows.33100-27-5

Electron Spin Resonance and Electron Spin-echo Modulation Studies of 5-Doxylstearic Acid and N,N,N’,N’-Tetramethylbenzidine Photoionization in Sodium Dodecylsulphate Micelles. Effects of 15-Crown-5 and 18-Crown-6 Ether addition

Electron spin-echo modulation (e.s.e.m.) and electron spin resonance (e.s.r.) spectra of the photogenerated N,N,N’,N’-tetramethylbenzidine (TMB) cation radical and 5-doxylstearic acid (5-DSA) in frozen micellar solutions of sodium dodecylsulphate containing 15-crown-5 and 18-crown-6 ethers in D2O and H2O have been studied as a function of the crown ether concentrations.Modulation effects due to 5-DSA interactions with water deuteriums give direct evidence that both crown ethers are mainly located at the micellar interface and that their interaction causes a decrease of hydration of the micellar interface.Modulation effects from TMB+ interaction with water deuteriums indicate that the TMB molecule moves toward the interfacial region when the sodium cation is complexed by the crown ether to decrease the local ionic strength in the interfacial region.The efficiency of charge separation upon TMB photoionization increases ca. 10percent with crown ether addition, and correlates with the increased TMB+-water interactions.The sodium cation complexation by the crown ether to change the charge distribution and ionic strength at the micellar interface seems to cause the interfacial hydration changes that promote the photoionization efficiency.

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Chemistry is the science of change. But why do chemical reactions take place? Why do chemicals react with each other? The answer is in thermodynamics and kinetics.In a document type is Review, 33100-27-5, the author is Ellis, Bobby D. and a compound is mentioned, 33100-27-5, 1,4,7,10,13-Pentaoxacyclopentadecane, introducing its new discovery.

Stable compounds containing heavier group 15 elements in the +1 oxidation state

This review provides an oxidation state model that emphasizes the similarities in the structural features, bonding and reactivities of molecules containing main group elements in a particular oxidation state. Using this model, the syntheses, structural features and selected aspects of the chemistry of stable compounds containing group 15 elements (pnictogens) in the +1 oxidation state are examined. Molecular types that are considered include: triphosphenium salts, phosphamethine cyanine dyes, phosphide anions, certain pnictaalkenes, certain phosphinidenes and their heavier analogues, among others. Theoretical models are presented to rationalize the factors that render such molecules stable.

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33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane, molecular formula is C10H20O5, belongs to chiral-catalyst compound, is a common compound. In a patnet, assignee is DOW AGROSCIENCES LLC33100-27-5, once mentioned the new application about 33100-27-5

ALKYLATION OF PICOLINAMIDES WITH SUBSTITUTED CHLOROACYLALS UTILIZING A CROWN ETHER CATALYST

A process for the alkylation of picolinamides with substituted chloroacylals to produce a structure of Formula (III), wherein the reaction is performed in the presence of a phase-transfer catalyst and an inorganic halide co-catalyst.

Each elementary reaction can be described in terms of its molecularity, the number of molecules that collide in that step. The slowest step in a reaction mechanism is the rate-determining step.you can also check out more blogs about 33100-27-5, 33100-27-5

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Chemistry is the science of change. But why do chemical reactions take place? Why do chemicals react with each other? The answer is in thermodynamics and kinetics.In a document type is Article, the author is Cundari, Thomas R. and a compound is mentioned, 33100-27-5, 1,4,7,10,13-Pentaoxacyclopentadecane, introducing its new discovery. 33100-27-5

Rhenium-oxo-bis(acetylene) anions. Structure, properties, and electronic structure. Comparison of Re-O bonding with that in other rhenium-oxo complexes

Reduction of Re(O)I(RC?CR)2 (2) or [Re(O)(RC?CR)2]2 by two electrons gives Re(O)(RC?CR)2Na (R = Me, 1a; Et, 1b; Ph, 1c). Compounds 1 are unusual oxo complexes, being highly nucleophilic and strongly reducing. X-ray structures of 1a-crypt and 1c-2MeCN reveal Re(O)(RC?CR)2 units, as isolated anions in the former but, in the latter, connected via Na-O-Na bridges into centrosymmetric dimers. The acetylene ligands lie in a plane that is roughly perpendicular to the Re – O bond, but the C?C vectors are splayed rather than parallel. The bond lengths and angles about rhenium are quite similar in the two structures, and quite close to the values found for 2 in which the splaying occurs to accommodate the iodide ligand. Reduction of 2a to 1a¡¤crypt causes a lengthening of the Re-O bond from 1.697(3) to 1.745(7) A and a drop in nuReO from 975 to 869 cm-1, both indicative of a decrease in the Re-O bond order. The Re-C distances and C?C stretching frequencies both decrease on reduction, indicating increased Re ? acetylene back-bonding in 1. Effective core potential calculations on Re(O)(HC?CH)2- (A), Re(O)H(HC?CH)2 (B), Re(O)Cl4- (C), and Re(O)F5 (D) have been performed with excellent agreement between the calculated structures and experimental crystallographic data (A and B are models for 1 and 2). The Re-O bonds in the high-oxidation-state oxo complexes C and D follow the classical Ballhausen-Gray picture, with little mixing between the Re-O orbitals and orbitals on other ligands. In contrast, the frontier molecular orbitals in A and B exhibit significant delocalization over the rhenium, the oxygen, and the acetylene ligands. In A, the HOMO is an orbital largely Re dx(2)-y(2) in character, accounting for the high nucleophilicity at rhenium in 1. The second-highest molecular orbital, only 0.8 eV below the HOMO, has significant Re-O ?-antibonding and Re-acetylene ?-back-bonding character, which provides a rationalization for the reduced Re-O bond order and strong back-bonding observed. There is also a ligand-based nonbonding orbital delocalized over the oxo and the acetylene ligands, as observed in other three-coordinate compounds involving acetylenes. Connections between the calculated electronic structure and the chemistry of 1 are emphasized.

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Chemistry is the science of change. But why do chemical reactions take place? Why do chemicals react with each other? The answer is in thermodynamics and kinetics.In a document type is Article, the author is Cusack, Paul A. and a compound is mentioned, 33100-27-5, 1,4,7,10,13-Pentaoxacyclopentadecane, introducing its new discovery. 33100-27-5

Synthetic and Structural Studies of Tin(IV) Complexes of Crown Ethers

Fourteen inorganic tin(IV) and organotin(IV) complexes of crown ethers (L), of general formulae SnX4*L*2H2O, SnCl4*L*4H2O*nCHCl3 ( n = 0 or 1), (SnR2X2)n*L*2H2O ( n = 1 or 2), and (SnPh3X)2*L*2H2O, have been synthesised.The structure and bonding in these adducts are discussed in terms of their i.r. and 119Sn Moessbauer spectroscopic data.These suggest co-ordination to the tin either by one or more of the polyether O atoms, or by the water molecules of hydration (the crown ether acting as a second-sphere ligand).The latter structure is confirmed by a single-crystal X-ray determination of Sn(OH2)2Cl4*18-crown-6*2H2O*CHCl3.The crystals are monoclinic, space group P21/n, with a = 10.315(6), b = 13.630(8), c = 20.649(13) Angstroem, and beta = 94.68(5) deg.The structure was solved using multisolution direct methods and refined by least squares to R = 0.062 (R’ = 0.068) for 3142 observed diffractometer data.The water molecules within the octahedral Sn(OH2)2Cl4 units are found to be cis to each other and are involved in an extensive hydrogen-bonding scheme.The latter links together the 18-crown-6 molecules, unco-ordinated water molecules, and Sn(OH2)2Cl4 octahedra, to give hydrogen-bonded chains which run parallel to the b axis.

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33100-27-5. Chemistry is an experimental science, and the best way to enjoy it and learn about it is performing experiments.Introducing a new discovery about 33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane

Recent developments in green membrane-based extraction techniques for pharmaceutical and biomedical analysis

Monitoring of target analytes (e.g., pharmaceuticals, endogenous compounds) present in biological samples usually requires a preliminary step toward analyte isolation from surrounding matrix and enrichment for trace analysis. Evident developments have been recently made to introduce novel ?green? analytical approaches (which keep the requirements of Green Analytical Chemistry ? GAC) being effective, economical, eco-friendly, and amenable to hyphenated analytical instrumentations. Modern membrane-based extraction techniques provide the smart options against classical sample preparations e.g., liquid-liquid extraction (LLE).These approaches are more stable and allow trace determination of analytes in complex matrices (e.g., biological samples), with high extraction recovery and selectivity. Simultaneously, drawbacks of LLE such as large consumption of organic solvents and the need for tedious handling are eliminated. This paper thoroughly overviews important features and applications of membrane- based extraction techniques with special focus on pharmaceutical and biomedical analysis since 2013. Different driving forces of mass transfer across the membrane were summarized and membrane-based extraction techniques were described along with their advantages/disadvantages as well.

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Chemistry is an experimental science, and the best way to enjoy it and learn about it is performing experiments.Introducing a new discovery about 33100-27-5, 33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane, molecular formula is C10H20O5.

Crown Ethers as Transthyretin Amyloidogenesis Inhibitors

Transthyretin (TTR) is a tetrameric protein found in human serum and associated with amyloid diseases. Because the tetramer dissociation and misfolding of the monomer precede amyloid fibril formation, development of a small molecule that binds to TTR and stabilizes the TTR tetramer is an efficient strategy for the treatment of amyloidosis. Here, we report our discovery of the anti-TTR amyloidogenesis activities of crown ethers. X-ray crystallographic analysis, binding assay, and chemical cross-linking assay showed that 4?-carboxybenzo-18C6 (4) stabilized the TTR tetramer by binding to the allosteric sites on the molecular surface of the TTR tetramer. In addition, 4 synergistically increased the stabilization activity of diflunisal, one of the most potent TTR amyloidogenesis inhibitors. These experimental evidences establish that 4 is a valuable template compound as an allosteric inhibitor of TTR amyloidogenesis.

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Chemistry is the experimental science by definition. We want to make observations to prove hypothesis. For this purpose, we perform experiments in the lab. 33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane33100-27-5, introducing its new discovery.

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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