- LARIAT ETHERS. VI. EVIDENCE FOR INTRAMOLECULAR CHELATION IN SODIUM AND POTASSIUM CATION BINDING BY 15-CROWN-5, CARBON-PIVOT LARIAT ETHERS
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The first compelling evidence for intramolecular sidearm involvement in sodium and potassium cation complexation by carbon-pivot lariat ethers is presented.
- Goli, Deepa, M.,Dishong, Dennis, M.,Diamond, Craig, J.,Gokel, George, W.
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- Preparation method of 15-crown ether-5
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The invention relates to a novel method for preparing 15-crown ether-5. Tetraglycol (tetraethylene-glycol) and ethylene glycol are taken as raw materials, and intramolecular dehydration condensation is performed in the presence of a catalyst and an adjuvant, so as to obtain a target product. The method has the advantages of short and fluent processes, mild reaction conditions, simple aftertreatment, high product purity and high yield, thereby being a novel green process method with great potential and market application value.
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Paragraph 0031-0032
(2017/07/12)
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- 15-crown ether -5 method for the preparation of
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The invention relates to a preparation method of 15-crown 5-ether, which comprises the following steps: uniformly stirring triglycol and dioxane in a reaction vessel; adding sodium hydroxide and stirring, heating to 40-60 DEG C; adding a mixed liquor of dichloroethyl ether and dioxane at the temperature lower than 60 DEG C, reacting for 20-24 hours at the temperature of 60-90 DEG C; cooling to room temperature, centrifuging to obtain a filtrate; pumping the filtrate into the reaction vessel and distilling to obtain a distillation substrate; moving the distillation substrate to a stainless steel still, performing vacuum rectification, removing primary fraction to obtain the product. The preparation method has the beneficial effect that comparing with the prior art, the preparation method has the advantages of safe operation, low cost, little three wastes and high yield, and the primary fraction in the reaction can be reutilized.
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Paragraph 0023-0034
(2017/03/21)
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- Facile and rapid synthesis of some crown ethers under microwave irradiation
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A series of crown ethers were synthesized from the reaction of 1,8-dichloro-3,6-dioxaoctane with the appropriate hydroxy compound under microwave irradiation in short times and high yields. Copyright Taylor & Francis Group, LLC.
- Ziafati, Ahmad,Sabzevari, Omolbanin,Heravi, Majid M.
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p. 803 - 807
(2007/10/03)
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- Thermolysis of the benzene anion radical 18-crown-6 complex
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The C-O and G-H bonds of 18-crown-6 are activated when 18-crown-6 is complexed with the potassium salt of the benzene anion radical. Evacuated glass bulbs containing the solid anion radical salt of potassium 18-crown-6 benzene anion radical were plunged into a bath at 320 C, resulting in mini-explosions and generating a series of compounds including dioxane, 2-methyl1,3-dioxolane, divinyl ether, hydrogen, methane, and 15-crown-5. Deuterium labeling studies proved that all of these compounds originated from the 18-crown-6. Further, these labeling studies were an aid in discerning the mechanism of the decomposition. Benzene, 1,4-cyclohexadiene, and cyclohexene were also generated. The last two originated from the reaction of the anion radical of benzene with hydrogen.
- Stevenson, Cheryl D.,Morgan, Grant
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p. 7694 - 7697
(2007/10/03)
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- The macrobicyclic cryptate effect in the gas phase
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The alkali cation (Li+, Na+, K+, Rb+, and Cs+) binding properties of cryptands [2.1.1], [2.2.1], and [2.2.2] were investigated under solvent-free, gas-phase conditions using Fourier transform ion cyclotron resonance mass spectrometry. The alkali cations serve as size probes for the cryptand cavities. All three cryptands readily form 1:1 alkali cation complexes. Ligand-metal (2:1) complexes of [2.1.1] with K+, Rb+, and Cs+, and of [2.2.1] with Rb+ and Cs+ were observed, but no 2:1 complexes of [2.2.2] were seen, consistent with formation of 'inclusive' rather than 'exclusive' complexes when the binding cavity of the ligand is large enough to accommodate the metal cation. Kinetics for 2:1 ligand-metal complexation, as well as molecular mechanics calculations and cation transfer equilibrium constant measurements, lead to estimates of the radii of the cation binding cavities of the cryptands under gas-phase conditions: [2.1.1], 1.25 ?; [2.2.1], 1.50 ?; [2.2.2], 1.65 ?. Cation transfer equilibrium studies comparing cryptands with crown ethers having the same number of donor atoms reveal that the cryptands have higher affinities than crowns for cations small enough to enter the cavity of the cryptand, while the crowns have the higher affinity for cations too large to enter the cryptand cavity. The results are interpreted in terms of the macrobicyclic cryptate effect: for cations small enough to fit inside the cryptand, the three-dimensional preorganization of the ligand leads to stronger binding than is possible for a floppier, pseudo-two-dimensional crown ether. The loss of binding by one ether oxygen which occurs as metal size increases for a given cryptand is worth approximately 25 kJ mol-1, and accounts for the higher cation affinities of the crowns for the larger metals. The Li+ affinity of 1,10-diaza-18-crown-6 is ~1 kJ mol-1 higher than that of 18-crown-6, while the latter has lower affinity than the former for all of the larger alkali cations (about 7 kJ mol-1 lower for Na+, and about 15 kJ mol-1 lower for K+, Rb+, and Cs+). The equilibrium measurements also allow the determination of relative free energies of cation binding for a number of crown ethers and cryptands. Molecular mechanics modeling with the AMBER force field is generally consistent with the experiments.
- Chen, Qizhu,Cannell, Kevin,Nicoll, Jeremy,Dearden, David V.
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p. 6335 - 6344
(2007/10/03)
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- The Complexation of Alkaline Cations by Crown Ethers and Cryptand in Acetone
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Stability constants and thermodynamic values for the complex formation of alkali ions by crown ethers, diaza crown ethers and cryptands have been measured by means of potentiometric and calorimetric titrations in acetone as solvent.The interactions between the ligands and solvent molecules play an important role for the complex formation.Cryptands form the most stable complexes with alkali ions if inclusion complexes are formed.Even in the case that the salts are not completely dissociated in acetone the presence of ion pairs does not influence the calculated values of the stability constants.
- Buschmann, H.-J.,Cleve, E.,Schollmeyer, E.
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p. 569 - 578
(2007/10/02)
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- Effect of an ortho-Substituent on the Decomposition of Crown Ether Complexed Arenediazonium Ions in 1,2-Dichloroethane
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The effect of an o-substituent (CH3, C2H5 and COCH3) on the complexation and the kinetics of thermal decomposition of arenediazonium tetrafluoroborates in the presence of crown ethers (15-crown-5, 18-crown-6 and 21-crown-7) and the effect of temperature on the decomposition of the complexed ions were studied by UV spectrophotometry in 1,2-dichloroethane.Solid 1:1 complexes were prepared and analyzed (by IR spectroscopy and by decomposition temperature).In the solid state, none of the arenediazonium ions is stabilized by complexation with crown ethers.In solution they form at most very weak charge-transfer complexes with 15-crown-5 but stronger insertion-type complexes with the larger 18-crown-6 and 21-crown-7 molecules (except for the o-acetyl-substituted ion, which is destabilized with increasing and ).The values of the complexation equilibrium constant K and the stabilization ability of the complexation are largest for 21-crown-7, and are much smaller than the corresponding values for the complexation of p- or m-substituted arenediazonium ions with the same complexing agents: e.i. there are clear ortho-effects due to the steric hindrance for the complexation.The values of the activation parameters ΔH and ΔS for the thermal decomposition of the complexed ions are large and positive (largest for 21-crown-7) and suggest an isokinetic relationship for each ion.The complexation in solution causes a hypsochromic shift in the UV spectrum of the arenediazonium ion which is proportional to the strength of the complexation.
- Kuokkanen, Toivo,Slotte, Thomas,Virtanen, Vesa
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p. 674 - 680
(2007/10/02)
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- TEMPLATE EFFECTS. 7. LARGE UNSUBSTITUTED CROWN ETHERS FROM POLYETHYLENE GLYCOLS: FORMATION, ANALYSIS, AND PURIFICATION
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Through the reaction of polyethylene glycols with tosyl chloride and heterogeneous KOH in dioxane not only coronands from crown-4 to crown-8 can be obtained but also larger homologues.A systematic investigation has shown that: i) crown-9 and crown-10 can be formed from nona- and deca-ethylene glycol, respectively, and isolated in pure form; ii) the whole series of polyethylene glycols from tri- to deca-ethylene glycol yields not only the corresponding crown ethers but also higher cyclooligomers that can be analyzed up to about crown-20 by glc: in particular crown-12 and crown-16 were obtained from tetraethylene glycol and purified by column chromatography on cellulose; iii) the reaction, as applied to commercial mixtures of polyethylene glycols (from PEG 200 to PEG 1000), gives fairly high yields of crown ethers also in the region of large ring sizes.The contribution of the template effect of K(+) ion and the cyclooligomerization reactions for the various ring sizes are discussed.
- Vitali, Chiara Antonini,Masci, Bernardo
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p. 2201 - 2212
(2007/10/02)
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- The Ionic Hydrogen Bond. 2. Multiple NH+...O and CH?+...O Bonds. Complexes of Ammonium Ions with Polyethers and Crown Ethers
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Complexes of ammonium ions RNH3+ (R = CH3, c-C6H11), (CH3)3NH+, and pyridineH+ with polyethers and crown ethers are observed in the gas phase in the abscence of the solvent effects.The dissociation energies, ΔH0D, of the RNH3+ polyether complexes range from 29.4 kcal mol-1 (for RNH3+*CH3OCH2CH2OCH3) to 46 kcal mol-1 (RNH3+*18-crown-6).The large ΔH0D values for complexes of polydentate ligands indicate multiple -NH+...O-hydrogen bonding.Such mutiple bonding can contribute up to 18 kcal mol-1 to the bonding in RNH3+*CH3(OCH2CH2)3OCH3 and 21 kcal mol-1 in RNH3+*18-crown-6.Multiple interactions are also evident in the (CH3)3NH+*polyether complexes where -CH?+...O-hydrogen bonding seems to occur; and consecutive -CH?+...O-bonds contribute approximately 6, 4, and 2 kcal/mol-1 respectively for up to three such bonds.Total ΔH0D values in the (CH3)3NH+*polyether complexes thus range from 26.7 kcal mol-1 in (CH3)3NH+*CH3O(CH2)2OCH3 to 41 kcal mol-1 in (CH3)3NH+*18-crown-6.Multiple interaction effects, possibly including van der Waals dispersion forces, are observed also in pyridineH+*polyether complexes.Large negative entropies in RNH3+*acyclic polyether complexes vs.RNH3+*cyclic crown ethers make the acyclic polyethers less efficient ligands.
- Meot-Ner (Mautner), Michael
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p. 4912 - 4915
(2007/10/02)
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- Crown Ethers of Low Symmetry. Spiro Crown Ethers and 16-Crown-5 Derivatives
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Spiro crown ethers 3a-c, spiro bis(crown ethers) 5a-e, and the related 16-crown-5 derivatives 6a-d were synthesized and their cation binding abilities were evaluated by study of the extraction of aqueous alkali picrates.Crown ethers carrying 13-crown-4 and 16-crown-5 skeletons showed significant changes in cation selectivity as compared with the corresponding 12-crown-4 and 15-crown-5.Spiro-13-crown-4 3a and spiro-bis 5a showed extremely low extractabilities for all cations examined, while the 16-crown-5-derivatives, including spiro-bis 5b and spiro-bis 5c, showed anomalously high Na+ selectivity.In a quantitative study of extraction equilibrium constants (Kex), 16-crown-5 was again found to have much higher selectivity for Na+ than 15-crown-5.This result is attributed to the less symmetrical spatial arrangement of donor oxygen atoms in 16-crown-5; the symmetry-extractability relationship is discussed on the basis of the size-fit concept.
- Ouchi, Mikio,Inoue, Yoshihisa,Sakamoto, Hidefumi,Yamahira, Atsushi,Yoshinaga, Masanobu,Hakushi, Tadao
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p. 3168 - 3173
(2007/10/02)
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- Preparation of Macrocyclic Polyether-Thiono Diester and -Thiono Tetraester Ligands Containing either the Pyridine Subcyclic Unit or the Oxalyl Moiety, Their Complexes, and Their Reductive Desulfurization to Crown Ethers
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The preparation of seven new macrocyclic polyether-thiono diesters and one new macrocyclic polyether-thiono tetraester is reported.The new macrocyclic compounds containing a pyridine subcyclic unit formed complexes with metal and alkylammonium salts.Complex formation by some of these ligands was shown by variable-temperature 1H NMR spectroscopy and by cation transport through a CHCl3 membrane.All of the thiono compounds were reductively desulfurized to form the corresponding crown ethers.
- Jones, Brian A.,Bradshaw, Jerald S.,Brown, Philip R.,Christensen, James J.,Izatt, Reed M.
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p. 2635 - 2639
(2007/10/02)
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- Enhancement of Cation Binding in Lariat Ethers Bearing a Methyl Group at the Quaternary, Pivot Carbon Atom
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A number of carbon-pivot lariat ethers have been prepared and compared, with their counterparts having a methyl group bonded to the side-arm-bearing or pivot carbon.All of the compounds examined are 15-crown-5 derivatives, and in this series, the methyl lariats invariably show a higher affinity for sodium than do the nonmethylated species.The results are less consistent in the case of potassium cation which is larger than the 15-crown-5 compound's cation binding hole.The enhanced stability constant observed for sodium with the methyl lariats is attributed to reduced s ide-arm mobility or conformational changes in either the side arm or macroring.
- Nakatsuji, Yohji,Nakamura, Tetsuya,Okahara, Mitsuo,Dishong, Dennis M.,Gokel, George W.
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p. 1237 - 1242
(2007/10/02)
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- The Reduction of Crown Lactones to Crown Ethers
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Crown lactones may be reduced to crown ethers using lithium aluminium hydride.
- Ager, David J.,Sutherland, O.
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p. 248 - 249
(2007/10/02)
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- USE OF ALKALI- AND ALKALINE-EARTH-METAL IONS IN THE TEMPLATE SYNTHESIS OF 12-CROWN-4, 15-CROWN-5, AND 18-CROWN-6
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The synthesis of 15-crown-5 and 18-crown-6 from bis(2-chloroethyl)ether and the appropriate polyethylene glycol has been investigated using alkali- and alkaline-earth-metal hydroxides as 'template' agents in comparison to tetra-n-butylammonium hydroxide.A classical template effect is observed for the alkali metals, giving optimum yields for Na and K in the synthesis of 15-crown-5 and 18-crown-6 respectively, but the action of the alkaline-earth metals is more complex, particularly for Mg and Ca where involvement with the counter ion prevents a good yield.The importance of base strenght in the synthesis of 15-crown-5 and 12-crown-4 is demonstrated, e.g. in the synthesis of 15-crown-5 the most effective base is found to be sodium methoxide.A novel synthesis of 12-crown-4, utilising lithium hydride as the base, gives a 24 percent yield, the highest yield so far reported.
- Bowsher, Brian R.,Rest, Antony J.
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p. 1157 - 1161
(2007/10/02)
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- POTASSIUM FLUORIDE ON ALUMINA AS BASE FOR CROWN ETHER SYNTHESIS
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Alumina coated with potassium fluoride was found to be an effective and practical reagent for the synthesis of some simple crown ethers.
- Yamawaki, Junko,Ando, Takashi
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p. 533 - 536
(2007/10/02)
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- The Synthesis of Unsubstituted Crown Ethers by the Reaction of Oligoethylene Glycols with Arenesulfonyl or Alkanesulfonyl Chlorides
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A new facile method of synthesizing crown ethers from oligoethylene glycols by treating them with arenesulfonyl or alkanesulfonyl chlorides in the presence of alkali metal hydroxide or alkoxide was described. 15-Crown-5 and 21-crown-7 were synthesized from pentaethylene glycol and heptaethylene glycol respectively in good yields, while 18-crown-6 was obtained from both hexaethylene glycol and triethylene glycol.Although the main product was 24-crown-8 in the reaction of tetraethylene glycol/TsCl/Na(K)OH in dioxane, 12-crown-4 was obtained in a moderate yield from the reaction of tetraethylene glycol/benzenesulfonyl chloride/t-BuOLi in t-BuOH.Furthermore, the analogous treatment of PEG 200 afforded a mixture of 15-, 18-, 21- and 24-crown ethers.The reaction conditions were investigated, and the scope of the reaction was discussed.
- Kuo, Ping-Lin,Kawamura, Norio,Miki, Masaki,Okahara, Mitsuo
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p. 1689 - 1693
(2007/10/02)
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- Lithium-7 Nuclear Magnetic Resonance and Calorimetric Study of Lithium Crown Complexes in Various Solvents
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Lithium-7 NMR studies have been carried out on lithium ion complexes with crown ethers 12C4, 15C5, and 18C6 in water and in several nonaqueous solvents.In all cases the exchange between the free and complexed lithium ion was fast on the NMR time scale, and a single, population average, resonance was observed.Both 1:1 and 2:1 (sandwich) complexes were observed between lithium ion and 12C4 in nitromethane solution.The stability of the complexes varied very significantly with the solvent.With the exception of pyridine, the stability varies inversely with the Gutmann donor numbers of the solvent.In general, the stability order of the complexes was found to be 15C5*Li+ > 12C4*Li+ >18C6*Li+.Calorimetric studies on thse complexes show that, in most cases, the complex are both enthalpy and entropy stabilized.
- Smetana, Alfred J.,Popov, Alexander I.
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p. 183 - 196
(2007/10/02)
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