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The synthesis of mono- and diallyl ethers of C4 diols (butane-, Z-2-butene- and 2-butyne-l ,4-diols) by alkylation of the diols with allyl chloride in the presence of NaOH using PTC method has been investigated. The optimal parameters for synthesis of the allyl ethers and their physico-chemical properties (1) H NMR data, boiling point, refractive index, density) are given.
Content available Historia eteru
The author, on the basis of the history of philosophy and the history of physics, presents the history of ether. Particular attention is paid to the beliefs of Albert Einstein on the issue.
Content available remote Etery allilowe : fotoreaktywne modyfikatory polimerów
Content available remote Oligonucleotides bearing pentaerythritol-derived mass tags
Five different di-O-alkylated pentaerythritol phosphoramidite building blocks (2a–e) were synthesized and introduced into oligonucleotides to obtain mass-tagged probes (6a–f) useful in RNA transcription profiling. These non-nucleosidic mass tags allow categorization of oligonucleotide probes having identical nucleoside content and, hence, identification of the probe hybridized to RNA by mass spectrometry analysis. Hybridization properties of the oligonucleotide conjugates were elucidated by melting temperature measurements.
The direct transformation of unprotected sucrose in the context of the preparation of derivatives of industrial interest is a challenging task. We show how the intrinsic properties of sucrose, i. e. its electronic conformational and structural characteristics, provide to the chemist some sources of reactivity and selectivity. We report our results in the synthesis of sucrose esters, carbonaters and ethers in aqueous medium, as well as some work on the reaction of sucrose in organic solutions to make acetals involving either the [)H-4; OH-6] or the [OH-2; OH-3] diol systems.
Badano proces konwersji alkoholu etylowego i izobutylowego. Przeprowadzono analizę termodynamiczną procesu oraz serię testów katalitycznych, w których badano aktywność i selektywność katalizatorów o charakterze kwasowym (tlenek glinu, zeolit-beta i amorficzny glinokrzemian). Stwierdzono, że w reakcji konwersji alkoholu etylowego i izobutylowego do eterów istotną rolę odgrywa temperatura i ciśnienie reakcji oraz rodzaj zastosowanego katalizatora. Wysoka temperatura sprzyja odwodnieniu alkoholi do olefin. Największą selektywność przereagowania do eteru etylowo-izobutylowego wykazywał tlenek glinu. Relatywnie najwyższą selektywność w reakcji otrzymywania eteru etylowo-fert-butylowego wykazywał zeolitbeta.
ActMty and selectMty of (a) 210-m2/g β-AI2O3, (b) amorphous aluminosilicate (Si/AI, 8.25), or (c) β-zeolite as catalyst (activated in a/r, standardized in Ar; particle s/ze, 0.2-0.3 mm; + 1 cm3 Na glass) was studied in the reaction of (1:1 by moles) EtOH with i-BuOH, 4.05 cm3/(cm3⋅h), at 1 bar over 438-573, 423-498 and 423-523 K, resp. Thermod. equil. consts. were calcd. for 6 linearly independent reactions. At higher temps. EtOH and i-BuOH dehydrated to ethylene and preferably to isobutene, resp. Br0nsted acid centers in b and c promoted the formation of olefins. The a and c were most selective toward Et i-Bu (37%, 494 K) and Et tert-Buether (6.1%, 499 K), resp. At >490 K, slight amts. of butene dimers are believed to have formed over catalyst c. Higher pressure is likely to enhance the selectMty toward ethers.
The local parameters (hydration, order, viscosity) in different aggregates (mi-celle, hexagonal and lamellar liquid crystals) in the phase diagram of poly(oxyethylene) [5]-dodecylether (C12E5) in water have been measured by EPR with two series of spin probes: x-DSA, (x == 5, 7, 10, 12 and 16) and CAT n (11. == 4, 8, 11 and 16). A rather complete map of hydration ([H20]/[Ea]) along the PEa chains has been determined. It shows that the hydration of the PEa regions is very low near the PEO/hydrocarbon interface in all phases a.nd increases towards the outer region of the PEO shell with a gradient which becomes steeper in micellar phase in comparison with the lamellar phase. Temperature increase reduces the hydration levels at all measured sites. The order of the chains decreases by dilution from the lamellar to the micellar phase, but it is preserved within the frame of the la,mellar a.t two different concentrations. The ol'der degree, 5, d.ecreases in the series .5- > 7- > 10- > 12- > 16-doxyl, irrespective of tern perature, in all t)'"pes of aggrega.tes. This trend, together with decreasing hydration values, points to the insertion of the stearic acid chain in the aggregates along the normal to the interface. In samples quenched in liquid nitrogen, however, bending of the stearic acid chain was observed in a number of cases.
W pracy omówiono ważniejsze grupy związków chloroorganicznych występujące w środowisku generalnym jako zanieczyszczenia, ich pochodzenie, losy w środowisku i organizmie oraz efekty ich toksycznego działania. Zwrócono uwagę na zmiany układowe i odległe skutki narażenia. Przedstawiono niektóre mechanizmy toksycznego działania.
Chloroorganic compounds, typified by the chlorinated aliphatic and aromatic hydrocarbons, especially biphenyls, naphthalenes, dibenzo-p-dioxins, dibenzofuranes and azo/xy/benzenes are, or were, manufactured as commercial products /the chlorinated biphenyls and naphtalenes/, and occur only as contaminants in commercial products /the chlorinated dibenzo- p-dioxins, dibenzofurans, and azo/xy/benzenes/. They have all become widespread in the environment. The chemical stability and lipophilicity of these compounds, and their resistance to degradation results in their persistence in the environment and concentration in the food chains. Their chemical structures are similar, i.e. they are approximate isostereomers. They act by the common receptor-mediated mechanism and produce similar toxic responses, although they vary greatly in potency. All classes of chloroorganic compounds have produced incidents of intoxication of industrial workers, the general population, and farm or wild animals. Chlorinated aromatic hydrocarbons elicit a numerous toxic effects which include body weight loss, thymic atrophy, immunotoxicity, hepatotoxicity and porphyria, chloracne and another dermal lesions, tissue-specific hypo- and hyperplastic responses, teratogenicity, reproductive toxicity, and carcinogenesis.
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