- Cleavage of different ether bonds in butyl glycidyl ether and allyl glycidyl ether by K-, K+ (15-crown-5)2
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The kind of substituent in alkyl glycidyl ethers affects the course of their reaction with K1, K+ (15-crown-5)2. The cyclic oxirane ring is exclusively cleaved in the case of butyl glycidyl ether whereas the presence of the unsaturated allyl group in the glycidyl ether molecule unexpectedly prefers the scission of the linear ether bond. In both the systems organometallic intermediates are formed. They react with crown ether causing its ring opening. Allylpotassium formed from allyl glycidyl ether reacts also with another glycidyl ether molecule; the oxirane ring is opened in this case.
- Grobelny, Zbigniew,Stolarzewicz, Andrzej,Maercker, Adalbert,Krompiec, Stanis?aw,Bieg, Tadeusz
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- Self-decomposition of K-, K+(15-crown-5)2 tetrahydrofuran solution via organometallic intermediates
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Self-decomposition of K-, K+(15-crown-5)2 tetrahydrofuran solution results in dipotassium tetraethylene glycoxide and ethylene as the main reaction products. Dipotassium triethylene glycoxide, potassium tetraethylene glyco
- Grobelny, Zbigniew,Stolarzewicz, Andrzej,Maercker, Adalbert
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Read Online
- Synthesis, characterization and spectroscopic properties of water soluble coumarins substituted with oligomeric alkoxy functions
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Novel water soluble robust fluorescent coumarins substituted with oligomeric alkoxy functions were synthesized by incorporating the Blaise reaction in the key step. Mono-methylated oligomeric polyethylene glycols were subjected to a three step protocol, namely (i) Michael addition to acrylonitrile, (ii) Blaise reaction with ethyl bromoacetate and (iii) condensation with 4-N,N-diethylamino-2-hydroxybenzaldehyde to give fluorescent water soluble coumarins. Water solubility of the coumarins increased with the number of oxygen atoms in the side chain. However, even the most water soluble coumarin in this series can be readily extracted out of water with organic solvents like dichloromethane or ethyl acetate. Both absorption and emission spectra, recorded in four solvents, namely, hexane (non-polar), ethyl acetate (moderately polar), methanol (polar protic) and water (highly polar and protic) displayed a bathochromic shift of the absorption (Δλmax ≈ 25 nm) and emission (Δλmax ≈ 57 nm) bands with increasing solvent polarity. The Δλmax of emission is more pronounced than the Δλmax of absorption, which indicates intramolecular charge-transfer (ICT) is less in the ground state compared to the excited state. Emission spectra recorded in these four solvents showed that fluorescent intensity is maximum in ethyl acetate.
- Surya Prakash Rao,Babu, Mohan,Desai, Avinash
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p. 11064 - 11072
(2014/03/21)
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- METHOD FOR THE PRODUCTION OF POLYOXYMETHYLENE DIALKYL ETHERS FROM TRIOXAN AND DIALKYLETHERS
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The invention relates to a method for production of polyoxymethylene dialkyl ethers of formula H2m+1CmO(CH2O)nCmH2m+1, where n = 2 - 10, m independently = 1 or 2, in which a dialkyl ether selected from dimethyl ether, methyl ethyl ether or diethyl ether and trioxan are fed into a reactor and reacted in the presence of an acid catalyst, whereby the amount of water introduced into the reaction mixture with the dialkyl ether, trioxan and/or the catalyst is 1 wt. %, with relation to the reaction mixture.
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Page/Page column 6
(2008/06/13)
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- METHOD FOR PRODUCING ALKYLENE GLYCOL DIETHERS
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The invention concerns a method for producing alkylene glycol diethers by reacting a linear or cyclic ether with an alkylene oxide in the presence of a Lewis acid. The invention is characterized in that the reaction is continuously carried out in a microreactor.
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Page/Page column 7-9
(2008/06/13)
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- Hydrogenolysis and One-Electron Reduction of Alkoxy Sulfones
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The readily available 1-t-butoxyalkyl sulfones were converted by hydride reduction into alkyl t-butyl ethers.Reductive coupling with sodium metal or amalgam in an aprotic solvent led to glycol bis-1,2-O-t-butyl ethers.Polyethers such as 18-crown-6 can be synthesized by this procedure.
- Julia, Marc,Uguen, Daniel,Zhang, Da
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p. 279 - 290
(2007/10/02)
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- Unconventional Ionic Hydrogen Bonds. 1. Complexes of Quaternary Ions with n- and ?-Donors
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interaction energies are obtained from the clustering of quaternary onium ions with n-donor solvent molecules.The dissociation energies (ΔHoD) of Me4N(1+) clustered with the n-donor H2O, MeOH, MeNH2, and Me3N and with the ?-donors benzene and toluene range between 8 and 10 kcal mol-1.With the weak, bulky n-donor MeCl the interaction is weaker (6.5 kcal mol-1) while the more polar ligands Me2CO and MeCONMe2 attach strongly (14.6 and 18.0 kcal mol-1, respectively) to Me4N(1+).Strong interactions, 20-23 kcal mol-1, are also observed with polyethers and CH3CO-gly-OCH3, indicating polydentate complexing.The attachment energies of ligands to Et4N(1+) are smaller by 2 kcal mol-1 than those to Me4N(1+).Ab initio calculations show that in the Me4N(1+)*H2O, MeOH, MeNH2, and MeCl complexes the ligands attach electrostatically to a cavity created by protons of three CH3 gropus rather than hydrogen bonding to one proton or to one CH3 group.Both experiment and theory indicate that a second solvent molecule (H2O or CH3OH) attaches preferentially to the first solvent molecule rather than to Me4N(1+).
- Meot-Ner (Mautner), Michael,Deakyne, Carol A.
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p. 469 - 474
(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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- 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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- Veretherungen von Diolen, Triolen und Hydroxycarbonsaeurederivaten ueber Thallium(I)-alkoholate. Eine neue Variante der Williamson-Reaktion
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The etherifications listed in tables 1 and 2 are achieved by converting hydroxy-derivatives, which contain additional oxygen functions, into thallium(I) alkoxides with thallium ethoxide, and treatment with haloalkanes.The scope and limitations of the method are discussed.
- Kalinowski, Hans-Otto,Crass, Gerhard,Seebach, Dieter
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p. 477 - 487
(2007/10/02)
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