- Solution Thermodynamic Studies. 6. Enthalpy-Entropy Compensation for the Complexation Reactions of Some Crown Ethers with Alkaline Cations: A Quantitative Interpretation of the Complexing Properties of 18-Crown-6
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The interactions of 18-crown-6, 15-crown-5, and 12-crown-4 with Na+ and K+ were studied in methanol and water as solvents at 25 deg C. ΔG0 values for both 1:1 and 2:1 complexation reactions were determined by potentiometric titrations.Used in conjunction with these values, calorimetric measurements led to ΔH0 and ΔS0 values.The thermodynamic parameters obtained cannot be correlated with the cations or the crown ethers "hole" sizes in any 1:1 or 2:1 reactions.Moreover, the ΔG0 values are the results of quite different but permanently compensating combinations of the ΔH0 and ΔS0 values.These arise from several thermodynamic processes in which the role of the solvent must be considered.In the case of 18-crown-6, we present a quantitative interpretation in which this crown ether develops interactions that are stronger with Na+ than with K+.
- Michaux, Gabriel,Reisse, Jacques
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- (Z)-1, 4, 7, 10-tetraoxocyclododecane-8-alkene lithium salt complex, preparation method and application thereof
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The invention discloses a (Z)-1, 4, 7, 10-tetraoxocyclododecane-8-alkene lithium salt complex as well as a preparation method and application thereof. The chemical structure of the (Z)-1, 4, 7, 10-tetraoxocyclododecane-8-alkene lithium salt complex is shown in the specification, and X is selected from fluorine, chlorine, bromine, iodine, p-toluenesulfonyl oxygen, methylsulfonyl oxygen, boron tetrafluoride, phosphorus hexafluoride, p-nitrobenzenesulfonyl oxygen and o-nitrobenzenesulfonyl oxygen. The method has the advantages of reasonable route design, safe and easily available raw materials, high process safety, high reaction selectivity, simple purification, high product purity and high product yield, and can fully meet the requirements of industrial production of products.
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Paragraph 0075-0076; 0084-0088; 0092-0093; 0101-0107; ...
(2021/08/07)
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- 12-crown ether-4 lithium salt complex as well as preparation method and application thereof
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The invention discloses a 12-crown ether-4 lithium salt complex and a preparation method thereof, and a method for preparing 12-crown ether-4 by adopting the complex. The preparation method of the 12-crown ether-4 comprises the following steps: by taking a compound triethylene glycol monovinyl ether in a formula 1 as a raw material, adding an alkaline substance into a first reaction solvent for catalytic reaction with a compound lithium alkoxide containing a substituent group in a formula 2 under the condition of air isolation, and obtaining a compound 12-crown ether-4 lithium salt complex in a formula 3 after the reaction is completed; and then adding a compound 12-crown ether-4 lithium salt complex as shown in a formula 3 and an acidic material into a second reaction solvent, reacting at the reaction temperature of-20 to 100 DEG C, and after the reaction is completed, obtaining a compound 12-crown ether-4 as shown in a formula 4. The design route is reasonable in design, the raw materials are safe and easy to obtain, the process safety is high, the reaction selectivity is high, the product purity is high, the method is friendly to operators, the production cost is greatly reduced, and the requirements of industrial production of products can be fully met.
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Paragraph 0025; 0027-0029; 0045; 0047-0049
(2021/08/14)
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- P-OR functional phosphanido and/or Li/OR phosphinidenoid complexes?
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P-H,P-OR-substituted phosphane complexes 3a-e have been synthesized by two methods: (1) the thermal reaction of 2H-azaphosphirene complex 1 with methanol, n-butanol, or ethylene glycol monomethyl ether (3b,c,e) or (2) the reaction of P-chlorophosphane complex 2 with appropriate sodium phenolate salts (3a,d). All the complexes 3a-e were obtained in good yields and fully characterized by NMR, IR, MS, and elemental analysis. Furthermore, the structures of 3a, 3d and 3e were confirmed unambiguously by X-ray analysis. The deprotonation of complexes 3a-e by using lithium diisopropylamide in the presence of 12-crown-4 led to phosphinidenoid complexes 4a-e, which exhibit downfield 31P resonances and small tungsten-phosphorus coupling constants. Studies on the reactivity of complexes 4a-c,e revealed a phosphanido-type reactivity, and only for complex 4d, a thermally labile complex, was evidence found for a phosphinidene-type reactivity. Bifunctional phosphane complexes 3a-e have been synthesized and deprotonated with lithium diisopropylamide as base to provide Li/OR phosphinidenoid complexes 4a-e. Solutions of 4a-e display relatively high thermal stability, except for complex 4d. Whereas the NMR signatures of 4a-e correlate with a phosphinidenoid- type bonding, a phosphanido-type reactivity was revealed by reactions of 4a with electrophiles and C-C and C-O π-systems. Copyright
- Duan, Lili,Schnakenburg, Gregor,Daniels, Joerg,Streubel, Rainer
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p. 3490 - 3499
(2012/09/08)
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- The pentamethylcyclopentadienylsilicon(II) cation as a catalyst for the specific degradation of oligo(ethyleneglycol) diethers
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Catalytic open sandwiches: Oligo(ethyleneglycol) diethers RO(CH 2CH2O)nR are degraded by the unusual catalyst Cp Si+ (see scheme). The open coordination sphere at silicon allows up to four Si-O contacts; crystal structure data of the reactive compounds [Cp Si(dme)]+BR4- and [Cp Si([12]crown-4)] +BR4- (R=C6F5) show weakly bound ether molecules. Copyright
- Leszczynska, Kinga,Mix, Andreas,Berger, Raphael J. F.,Rummel, Britta,Neumann, Beate,Stammler, Hans-Georg,Jutzi, Peter
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supporting information; experimental part
p. 6843 - 6846
(2011/09/19)
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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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- Formation of heterocycles by the Mitsunobu reaction. Stereoselective ynthesis of (+)-α-skytanthine
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Cyanomethylenetributylphosphorane was shown to mediate the dehydrocyclization of diols and amino alcohols to give the corresponding 6-membered O- and N-heterocycles in 90% or better yields. Using the reaction as a key step, (+)-α-skytanthine, a unique mono terpene alkaloid, was synthesized stereoselectively.
- Tsunoda,Ozaki,Shirakata,Tamaoka,Yamamoto,Ito
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p. 2463 - 2466
(2007/10/03)
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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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- 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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- 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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