- Synthesis and properties of carbosilane dendrimers of the third and sixth generations with the ethylene oxide surface layer in bulk and in monolayers at the air-water interface
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A number of carbosilane dendrimers with the ethylene oxide surface layer was synthesized. The density of the surface layer determines their capability to form a physical network due to intermolecular entanglements. The specific interactions of the ethylene oxide fragments exert a minor effect on the thermal behavior of dendritic macromolecules. The compression-expansion isotherms of Langmuir films together with Brewster angle microscopy data show that an increase in the core rigidity with increasing the generation number favors the formation of ordered molecular multilayers. The appearance of a pronounced hysteresis in the compression-expansion cycles is a common phenomenon for amphiphilic dendrimers of high generations.
- Novozhilova,Malakhova,Buzin,Buzin,Tatarinova,Vasilenko,Muzafarov
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- Thermodynamic Properties of Carbosilane Dendrimers of the Sixth Generation with Ethylene Oxide Terminal Groups
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The temperature dependences of heat capacities of carbosilane dendrimers of the sixth generation with ethyleneoxide terminal groups, denoted as G6[(OCH2CH2)1OCH3]256 and G6[(OCH2CH2)3OCH3]256, were measured in the temperature range from T = (6 to 520) K by precision adiabatic calorimetry and differential scanning calorimetry (DSC). In the above temperature range the physical transformations, such as glass transition and high-temperature relaxation transition, were detected. The standard thermodynamic characteristics of the revealed transformations were determined and analyzed. The standard thermodynamic functions, namely, heat capacity Cp°(T), enthalpy H°(T) - H°(0), entropy S°(T) - S°(0), and Gibbs energy G°(T) - H°(0) for the range from T → 0 to 520 K, and the standard entropies of formation ΔfS°of the investigated dendrimers in the devitrified state at T = 298.15 K, were calculated per corresponding moles of the notional structural units. The standard thermodynamic properties of dendrimers under study were discussed and compared with literature data for carbosilane dendrimers with different functional terminal groups.
- Sologubov, Semen S.,Markin, Alexey V.,Smirnova, Natalia N.,Novozhilova, Natalia A.,Tatarinova, Elena A.,Muzafarov, Aziz M.
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- SYMMETRICAL AND UNSYMMETRICAL ORGANOSILICON MOLECULES AND ELECTROLYTE COMPOSITIONS
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Described are organosilicon electrolyte compositions having improved thermostability and electrochemical properties and electrochemical devices that contain the organosilicon electrolyte compositions.
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Page/Page column 40
(2014/03/26)
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- Novel perfluoroalkylated oligo(oxyethylene) methyl ethers with high hemocompatibility and excellent co-emulsifying properties for potential biomedical uses
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Two series of novel perfluoroalkylated amphiphilic compounds were synthesized from monomethyl ethers of mono-, di- and tri-(oxyethylene) glycols. The first series CH3(OCH2CH2)nOCH2CH(OH)CH2-CF2(CF2CF2)nCF3 (n = 1-3) bearing the hydroxy group at the spacer between hydrophilic and hydrophobic parts was prepared by the reactions of the monomethyl ethers with 2-(perfluoroalkylmethyl)oxiranes in 76-97% yields. The second series CH3(OCH2CH2)nOCH2CH2CH2-CF2(CF2CF2)nCF3 (n = 1-3) possessing the non-hydroxylated spacer was synthesized from allyl methyl ethers of oligo(oxyethylene) glycols using radical additions of perfluoroalkyl iodides and subsequent selective reductions of the C-I bond in the adducts in overall yields of 23-69%. Some of the novel amphiphilic compounds displayed very low hemolytic activity to erythrocytes and excellent co-emulsifying properties on testing on perfluorodecalin/Pluronic F-68 microemulsions. 1-O-(2-Hydroxy-4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluorononyl)-d-xylitol was prepared by a novelized synthesis and employed as a standard compound in the testing.
- Kaplánek, Robert,Paleta, Old?ich,Ferjentsiková, Ivana,Kodí?ek, Milan
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experimental part
p. 308 - 316
(2009/12/03)
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- Thermochromism and solvatochromism of non-ionic polar polysilanes
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Polar polysilanes bearing ethereal side groups [{CH3-Si-(CH2)m-O-(CH2CH 2O)n-CH3}x, m = 3-5 and n = 0-3}] were prepared and were found to be soluble in a wide range of polar solvents. UV spectroscopic behavior is highly dependent on the nature of the solvents used but no simple relationship between λmax and specific solvent parameter is found. Small molar absorbance (ε 3)2CHOH (HFIP) in non-polar solvent (benzene, CH2Cl2) or even in (CH3)2CHOH solution, where higher HFIP concentration brings about longer wavelength absorption. This type of solvatochromism is originated by strong hydrogen bond formation between the ethereal side groups and HFIP. Because non-dissociative nature of HFIP-concerned hydrogen bonding, increased bulkiness of the side moieties brings about disentanglement. Polysilanes 1-5, though having long side chains, show thermochromism of continuous spectral shift on cooling. The same λmax value in thermochromism and solvatochromism indicates that nearly the same degree of disentanglement is caused by HFIP and thermally.
- Oka, Kunio,Fujiue, Naofumi,Nakanishi, Saburo,Takata, Toshikazu,West, Robert,Dohmaru, Takaaki
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- Approaches to new water soluble phosphines
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Approaches to water-soluble phosphines are described which involve conversion of ethylene glycol derivatives and sugar diacetonides into monoallyl ethers, and hydrophosphorylation of the latter.In the case of the sugars, water-solubility is conferred by a subsequent hydrolysis.
- Mitchell, Terence N.,Heesche-Wagner, Kerstin
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- A WATER SOLUBLE TIN HYDRIDE REAGENT
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A water soluble tin hydride has been synthesized carrying three methoxyethoxypropyl groups.It reduces various alkyl halides in water, or in organic solvents.
- Light, James,Breslow, Ronald
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p. 2957 - 2958
(2007/10/02)
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- Stable silica-based ether bonded phases for biopolymer separations
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Fast high resolution separations of biopolymers with retention of biological activity have been achieved by hydrophobic interaction chromatography using trialkoxy silyl ethers of the general formula chemically bonded to silica-based chromatographic supports. In the formula R is alkyl of from one to five carbons, m is an integer from two to five, n is an integer from one to five, p is an integer from zero of ten, and R' is methyl, phenyl, or substituted phenyl. Stable and reproducible bonded phases are prepared in a novel solventless procedure by a bonding process which uses a defined and controlled amount of water on the silica surface and a gaseous or volatile basic catalyst such as ammonia to produce a controlled amount of silane polymerization and cross-linking in addition to extensive bonding between silane and silica. High performance liquid chromatography on such weakly hydrophobic stationary phases using aqueous eluents and decreasing salt gradients under mild conditions permits high speed, high resolution separations of biopolymers such as proteins without destruction of their biological activity and without column degradation. Size exclusion chromatography can also be performed on these phases using low ionic strength eluents.
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- Deamination Reactions, 41. Reactions of Aliphatic Diazonium Ions and Carbocations with Ethers
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Aliphatic diazonium ions and carbocations were generated by deacylation of appropriate nitrosoureas (1, 5, 9) in alcohol-ether mixtures or in 2-alkoxyethanols.Ethers were generally inferior to alcohols in capturing cationic intermediates.Formation of trialkyloxonium ions led to alkyl exchange or ring opening.The observed reactivity orders were n-butyl > isobutyl for the diazonium ions, allyl > sec-butyl > tert-butyl for the carbocations, methoxy > ethoxy and oxirane > oxetane > tetrahydrofuran for the ethers, indicating the predominance of steric effects.Neighboring group participation in 4-methoxy-1-butanediazonium ions (58) and 4,5-epoxy-1-pentanediazonium ions (74) was detectable but inefficient ( 20percent of cyclic oxonium ions).
- Kirmse, Wolfgang,Jansen, Ulrich
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p. 2607 - 2625
(2007/10/02)
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- 246. Monofunctional (Dimethylamino)silane as Silylating Agent
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The reaction of triorganyl(dimethylamino)silanes with surface-hydrated silicon dioxide has been studied.These silylating agents are easy to prepare from the corresponding chloro or bromosilanes with dimethylamine.The resulting products are thermally stable and relatively volatile.Reaction with surface-hydrated silicon-dioxide preparations at a50-250 deg C for 170 h yields a dense grafted layer.However, with (dimethylamino)silanes having strongly polar substituents, a retreatment of the surface-modified silica seems to be necessary in order to attain maximum coverage.
- Szabo, Katalin,Le Ha, Ngoc,Schneider, Philippe,Zeltner, Peter,sz. Kovacs, Ervin
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p. 2128 - 2142
(2007/10/02)
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- Autoxidation of Allyl Ether Compounds. Part 1. Reactivity of Allyl Ether Alcohols.
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Cobalt catalyzed liquid phase autoxidations of some primary and secondary allyl ether alcohols were studied at 30 and 40 deg C.An optimum concentration for the catalyst was found, above which cobalt behaved like an inhibitor.Autoxidations of secondary allyl ether alcohols started immediately after adding the catalyst but the reactions of the allyl ethers of primary diols were preceded by induction periods.Induction periods depended on the carbon chain length of the diol and were not observed after methylating the hydroxyl group of the allyl ether alcohol.The phenomena are explained as resulting from inter- and intramolecular hydrogen bonding, which controls the autoxidation by decreasing the electron density on the etheral oxygen.
- Toivonen, Hannu
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