Category: 14187-32-7

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Functionalized derivatives of benzocrown ethers, I. Ionophores containing amino and pyridinium groups derived from benzo-15-crown-5, benzo-18-crown-6, and dibenzo-18-crown-6

Acylation reactions of benzocrown ethers with N-phthalimido-protected derivatives of beta-alanine and 11-aminoundecanoic acid, respectively, were investigated in acid catalysis by using the Eaton reagent. Deprotection of the obtained compounds by hydrazinolysis afforded derivatives with free amino groups the reaction of which with one or two equivalents of 2,4,6-trisubstituted pyrylium salts furnished pyridinium derivatives. All these new benzocrown ether derivatives were characterized by elemental analysis and IR and NMR spectroscopy. VCH Verlagsgesellschaft mbH, 1996.

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Children learn through play, and they learn more than adults might expect. Science experiments are a great way to spark their curiosity, get their minds active, and encourage them to do something that doesn¡¯t involve a screen. 14187-32-7, C20H24O6. A document type is Article, introducing its new discovery., Formula: C20H24O6

KINETICS AND MECHANISM OF MONOMOLECULAR HETEROLYSIS OF FRAMEWORK COMPOUNDS. II. IONIZATION OF 1-ADAMANTYL IODIDE IN ACETONITRILE

The heterolysis of 1-adamantyl iodide in acetonitrile was studied preparatively and kinetically (in the presence of triphenylverdazyl as internal indicator).Additions of LiClO4, Et4N+ClO4-, Et4N+OTs-, Et4N+I-, and Et4N+Br- do not affect the reaction rate; the normal salt effect and the salt effect of the law of mass action do not appear.Additions of water increase the reaction rate a little, while additions of LiBr, Bu4N+NO3-, LiCl, and Et4N+Cl- reduce it greatly.It is suggested that an intimate ion pair of the substrate is converted into a solvent- separated ion pair in the controlling stage of the reaction.

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Synthetic Route of 14187-32-7. Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 14187-32-7, Name is Dibenzo-18-crown-6. In a document type is Article, introducing its new discovery.

PREPARATION OF CHLOROMETHYL DERIVATIVES OF DIBENZO-18-CROWN-6 AND SYNTHESES BASED ON THEM

The reaction of chloromethylated dibenzo-18-crown-6 and some monosubstituted derivatives (4′-acetyl-, 4′-propionyl-, and 4′-tert-butyldibenzo-18-crown-6) was studied.Modification of the chloromethyl group resulted in the synthesis of various dibenzo-18-crown-6 derivatives.

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Thirteen cationic ionophores: Their acute toxicity, neurobehavioral and membrane effects

Thirteen cationic ionophores (12-Crown-4, 15-Crown-5, 18-Crown-6, Dibenzo 18-Crown-6, Dicyclohexano 18-Crown-6, 24-Crown-8, Dicyclohexano 24-Crown-8, Lasalocid, Hexacyclen trisulfate, Chiral binapthol, Valinomycin, Monensin, and A-23187) were evaluated for acute toxicologic properties, including lethality and neurobehavioral effects in multiple species (rats, rabbits, and mice) by multiple routes, skin and eye irritation and effects on membrane permeability to physiologic cations. Attention was focused on determining minimum neurobehavioral effect levels and characterizing the spectrum of these effects at different dose levels. While LD50’s followed one pattern, this was not the case with other effects. Cluster and factor analysis suggest that, though the primary mechanism of action is alteration of membrane permeability to specifi-cations (qualitative types of activity correlate with the results of membrane permeability studies), which ions are provided an increased passage varies with ring size and charge dispersion. In the intact animal absorption markedly modifies these results.

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UO2Cl4.

During the course of our structural investigations of f-element-crown ether complexes, we have had the opportunity to study several uranyl compounds. The title compound was prepared by the direct reaction of UCl//4 with dibenzo-18-crown-6 in a 1:3 ratio of CH//3CN and CH//3OH and recrystallized from pentane. The partial oxidation product left bracket UO//2Cl//4 right bracket left bracket (OH)//3) (dibenzo-18-crown-6) right bracket //2 multiplied by (times) CH//3OH, crystallizes in the orthorhombic space group Fddd. There are eight formula units in the unit cell. The uranyltetrachloride dianion is octahedral and the oxonium ion is hydrogen bonded to the crown ether. Two dibenzo-18-crown-6 moieties envelope the solvent molecule.

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Uranium(IV) terminal hydrosulfido and sulfido complexes: Insights into the nature of the uranium-sulfur bond

Herein, we report the synthesis and characterization of a series of terminal uranium(iv) hydrosulfido and sulfido complexes, supported by the hexadentate, tacn-based ligand framework (Ad,MeArO)3tacn3- (= trianion of 1,4,7-tris(3-(1-adamantyl)-5-methyl-2-hydroxybenzyl)-1,4,7-triazacyclononane). The hydrosulfido complex [((Ad,MeArO)3tacn)U-SH] (2) is obtained from the reaction of H2S with the uranium(iii) starting material [((Ad,MeArO)3tacn)U] (1) in THF. Subsequent deprotonation with potassium bis(trimethylsilyl)amide yields the mononuclear uranium(iv) sulfido species in good yields. With the aid of dibenzo-18-crown-6 and 2.2.2-cryptand, it was possible to isolate a terminal sulfido species, capped by the potassium counter ion, and a “free” terminal sulfido species with a well separated cation/anion pair. Spectroscopic and computational analyses provided insights into the nature of the uranium-sulfur bond in these complexes.

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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.14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Article£¬once mentioned of 14187-32-7, Recommanded Product: Dibenzo-18-crown-6

THE INTERACTION OF GROUP III METAL ALKYLS WITH CROWN ETHERS. THE SYNTHESIS AND STRUCTURE OF 2 AND 2

2 and 2 were prepared by the reaction of Ga(CH3)3 or Al(CH3)3 with the appropriate crown ether in toluene.After filtering and cooling, both products were obtained as colorless, air-sensitive, rectangular crystals.The structures of both compounds were determined from single crystal X-ray diffraction data collected on a CAD-4 diffractometer. 2 belongs to the monoclinic space group P21/c with unit cell parameters a 11.460(5), b 18.000(7), c 7.495(4) Angstroem, beta 105.65(4) degree, and rho(calc) 1.32 g cm-3 for Z = 2.Least-squares refinement gave a final R value of 0.061 for 1179 independent observed reflections.The molecule resides on a crystallographic center of inversion.The Ga-O distance of 2.198(8) Angstroem is among the longest yet observed.In order to accomodate the two trialkylgallium units, the crown ether is forced to adopt a chair configuration. 2 crystallizes in the space group P21/a with cell parameters a 16.423(7), b 9.812(5), c 20.935(8) Angstroem, beta 107.41(5) degree, and rho(calc) 1.07 g cm-3 for Z = 4.Least-squares refinement gave a final R value of 0.079.The greater flexibility of the crown ether in this case allows the bonded oxygen atoms to be positioned on the outside of the crown, with all six oxygen atoms in a near-planar arrangement.

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“Separated” versus “contact” ion-pair structures in solution from their crystalline states: Dynamic effects on dinitrobenzenide as a mixed-valence anion

Qualitative structural concepts about dynamic ion pairs, historically deduced in solution as labile solvent-separated and contact species, are now quantified by the low-temperature isolation of crystalline (reactive) salts suitable for direct X-ray analysis. Thus, dinitrobenzenide anion (DNB -) can be prepared in the two basic ion-paired forms by potassium-mirror reduction of p-dinitrobenzene in the presence of macrocyclic polyether ligands: LC (cryptand) and LE (crown-ethers). The crystalline “separated” ion-pair salt isolated as K(L C)+//DNB- is crystallographically differentiated from the “contact” ion-pair salt isolated as K(L E)+DNB- by their distinctive interionic separations. Spectral analysis reveals pronounced near-IR absorptions arising from intervalence transitions that characterize dinitrobenzenide to be a prototypical mixed-valence anion. Most importantly, the unique patterns of vibronic (fine-structure) progressions that also distinguish the “separated” from the “contact” ion pair in the crystalline solid state are the same as those dissolved into THF solvent and ensure that the same X-ray structures persist in solution. Moreover, these distinctive NIR patterns are assigned with the aid of Marcus-Hush (two-state) theory to the “separated” ion pair in which the unpaired electron is equally delocalized between both NO2-centers in the symmetric ground state of dinitrobenzenide, and by contrast, the asymmetric electron distribution inherent to “contact” ion pairs favors only that single NO 2-center intimately paired to the counterion. The labilities of these dynamic ion pairs in solution are thoroughly elucidated by temperature- dependent ESR spectral changes that provide intimate details of facile isomerizations, ionic separations, and counterion-mediated exchanges.

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Could LogP be a principal determinant of biological activity in 18-crown-6 ethers? Synthesis of biologically active adamantane-substituted diaza-crowns

18-crown-6 ethers are known to exert their biological activity by transporting K+ ions across cell membranes. Using non-linear Support Vector Machines regression, we searched for structural features that influence antiproliferative activity in a diverse set of 19 known oxa-, monoaza- and diaza-18-crown-6 ethers. Here, we show that the logP of the molecule is the most important molecular descriptor, among ?1300 tested descriptors, in determining biological potency (R2cv = 0.704). The optimal logP was at 5.5 (Ghose-Crippen ALOGP estimate) while both higher and lower values were detrimental to biological potency. After controlling for logP, we found that the antiproliferative activity of the molecule was generally not affected by side chain length, molecular symmetry, or presence of side chain amide links. To validate this QSAR model, we synthesized six novel, highly lipophilic diaza-18-crown-6 derivatives with adamantane moieties attached to the side arms. These compounds have near-optimal logP values and consequently exhibit strong growth inhibition in various human cancer cell lines and a bacterial system. The bioactivities of different diaza-18-crown-6 analogs in Bacillus subtilis and cancer cells were correlated, suggesting conserved molecular features may be mediating the cytotoxic response. We conclude that relying primarily on the logP is a sensible strategy in preparing future 18-crown-6 analogs with optimized biological activity.

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Bis(allyl)gallium Cation, tris(allyl)gallium, and tetrakis(allyl)gallate: Synthesis, characterization, and reactivity

A series of cationic, neutral, and anionic allylgallium complexes has been isolated and fully characterized. It includes neutral [Ga(nu1- C3H5)3(L)] (1, L = THF; 2, L = OPPh 3), cationic [Ga(nu1-C3H5) 2(THF)2]+[A]-(3, [A]-= [B(C6F5)4]-; 4, [A]-= [B(C6H3Cl2)4]-), as well as anionic [Cat]+[Ga(nu1-C3H 5)4]-(5, [Cat]+= K+; 6, [Cat]+= [K(dibenzo-18-c-6]+; 7, [Cat]+= [PPh4]+). Binding modes of the allyl ligand in solution and in the solid state have been studied comparatively. Single crystal X-ray analyses revealed a fourcoordinate neutral gallium center in 2, a five-coordinate cationic gallium center in 4 and [4¡¤THF], and a four-coordinate anionic gallium center with a bridging mu2- nu1:nu2coordination mode of the allyl ligand in 6. The reactivity of this series of allylgallium complexes toward benzophenone and N-heteroaromatics has been investigated. Counterion effects have also been studied. Reactions of 1 and 5 with isoquinoline revealed the first examples of organogallium complexes reacting under 1,2-insertion with pyridine derivatives.

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