- NMR spectra of guest-host complexes of boron and silicon fluorides with crown ethers in nonaqueous solutions
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19F, 11B, and 29Si NMR spectroscopy was used to examine the behavior of the guest-host complexes (BF3·H2O) 2·18-crown-6·2H2O, (BF3·H2O)2·DCH-6B,
- Gel'mbol'dt,Selig,Ganin,Fonar',Ennan
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- Synthesis of chiral trans-anti-trans-isomers of dicyclohexano-18-crown-6 via an enzymatic reaction and the solid-state structure of one enantiomer
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Chiral trans-anti-trans-dicyclohexano-18-crown-6 isomers are synthesized via a lipase-catalyzed reaction. The solid-state structure of the (S)-enantiomer is determined and compared with those reported for 18-crown-6 and trans-syn-trans-dicyclohexano-18-crown-6.
- Yamato, Kazuhiro,Bartsch, Richard A.,Broker, Grant A.,Rogers, Robin D.,Dietz, Mark L.
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p. 5805 - 5808
(2007/10/03)
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- Conductance study of binding of some Rb+ and Cs+ ions by macrocyclic polyethers in acetonitrile solution
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A conductance study of the interaction between Rb+ and Cs+ ions and 18-crown-6 (18C6), dicyclohexyl-18-crown-6 (DC18C6), dibenzo-18-crown-6 (DB18C6), dibenzo-24-crown-8 (DB24C8), and dibenzo-30-crown-10 (DB30C10) in acetonitrile solution has been carried out at various temperatures. The formation constants of the resulting 1:1 complexes were determined from the molar conductance-mole ratio data and found to vary in the order DC18C6 > 18C6 > DB30C10 > DB18C6 ～ DB24C8 for Rb+ ion and DC18C6 > 18C6 > DB30C10 ～ DB24C8 > DB18C6 for Cs+ ion. The enthalpy and entropy of complexation were determined from the temperature dependence of the formation constants. The complexes with the 18-crowns are both enthalpy and entropy stabilized while, in the case of large crown ethers, the corresponding complexes are enthalpy stabilized but entropy destabilized.
- Shamsipur, Mojtaba,Saeidi, Mahboubeh
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p. 1187 - 1198
(2007/10/03)
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- Design and synthesis of a new class of nonmacrocyclic alkali metal host compounds
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A new class of nonmacrocyclic metal ion hosts has been examined that features a polyspirocyclic framework that offers a 1,3,5-triaxial presentation of ligating centers. These compounds are easily synthesized and exploit stereoelectronic influences to preorganize the metal ion binding site. While compounds bearing oxygen substituents (X = OH, OMe) failed to show appreciable binding of alkali metals, the aminated host (X = NHBn) exhibitied strong binding with association constants (Ka) greater than 107-108 as measured by picrate extraction analysis.
- McGarvey, Glenn J.,Stepanian, Marshall W.,Bressette, Andrew R.,Sabat, Michal
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p. 3453 - 3456
(2007/10/03)
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- SYNTHESIS OF CYCLOHEXANOCROWN ETHERS UNDER CONDITIONS OF PHASE-TRANSFER CATALYSIS
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A method was described for production of individual diastereoisomers of cyclohexanocrown ethers from the cis and trans isomers of 1,2-bis(6-chloro-1,4-dioxahexyl)cyclohexane and glycols with phase transfer catalysis.
- Kusov, S. Z.,Lubenets, E. G.,Kobrin, V. S.
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p. 1234 - 1236
(2007/10/02)
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- CATALYTIC HYDROGENATION OF DIBENZO-18-CROWN-6 AT METALS OF THE PLATINUM GROUP
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The hydrogenation of the aromatic rings in dibenzo-18-crown-6 is accompanied by hydrogenolysis of the carbon-oxygen bonds of the polyether ring.The selectivity of hydrogenation depends on composition of the solvent, the nature of the catalyst, the temperature, the hydrogen pressure, and other factors.Rhodium and ruthenium catalysts exhibit the highest activity in the reaction: in water, Ru > Rh > Pt, Pd; in 2-propanol, Rh >> Ru > Pt > Pd.The hydrogenation and hydrogenolysis are concurrent reactions, and the former is favored by high pressure.
- Gurskii, R. N.,Istratova, R. V.,Kirova, A. V.,Kotlyar, S. A.,Ivanov, O. V.,Luk'yanenko, N. G.
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p. 543 - 547
(2007/10/02)
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- AFFINITIES OF CROWN ETHERS, GLYMES, AND POLYAMINES FOR ALKALI PICRATES IN TOLUENE. APPLICATION OF POLYMER-SUPPORTED LINEAR POLYETHERS.
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This work reports the measurements of K values for polyamines, glymes, a few glycols (including that of a long-chain polyethylene glycol, carbowax 6000), and some frequently used cation-binding ligands as complexers of lithium or sodium picrate in toluene as solvent. K values for different resins obtained with the same soluble ligand provide a comparison of the effectiveness of these resins in binding ionic solutes.
- Xu,Smid
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p. 3790 - 3796
(2007/10/02)
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