Search results for "hexane"
showing 10 items of 467 documents
Enthalpy and Entropy Contributions to Solvent Quality and Inversions of Heat Effects with Polymer Concentration
2006
Vapor pressures above the solutions of polystyrene in either cyclohexane (32-60 °C) or toluene (10-70 °C) have been measured by a combination of head space sampling and gas chromatography as a function of the volume fraction φ of the polymer. The thus obtained Flory-Huggins interaction parameters Χ (φ; T) were complemented by data for three other systems (tert-butyl acetate/polystyrene, cyclohexane/poly(vinyl methyl ether), 2-propanol/poly(butyl methacrylate)) reported in the literature and analyzed in terms of their enthalpy and entropy parts Χ H and Χ s . Furthermore these experimental findings were modeled by means of an approach splitting the mixing process conceptually into two parts a…
Interfacial tension and interaction parameters
1994
In view of various contradictory theoretical equations relating the interfacial tension σ between phase-separated polymer solutions to the Flory-Huggins interaction parameter of the system, the idea that σ should depend on the extent of the ‘hump’ in the concentration dependence of the Gibbs energy of mixing was studied. This investigation is based on 12 series of σ( T ) measurements reported in the literature and on additional experiments for the system cyclohexane/polystyrene. To quantify the extent of the ‘hump’, a reduced ‘hump energy’ ɛ was introduced and its value calculated for different temperatures from the measured critical data of the systems. The analysis of the entire experimen…
The oxidation of alkanes with dimethyldioxirane; a new mechanistic insight
1997
Abstract Primary kinetic isotope effects were measured for the oxidation of cyclohexane and methylcyclohexane with DMDO in solution and in the gas phase. These experiments suggest an electrophilic oxygen insertion mechanism for the oxidation of alkanes by DMDO.
Vapor-liquid equilibria for the binary systems of methylcyclohexane with 1-propanol, 2-propanol, 1-butanol, and 2-butanol at 101.3 kPa
1997
Isobaric vapor−liquid equilibrium measurements at 101.3 kPa are reported for the binary systems methylcyclohexane + 1-propanol, + 2-propanol, + 1-butanol, and + 2-butanol. The systems show a strong positive deviation from ideality and present a minimum temperature azeotrope. The activity coefficients were found to be thermodynamically consistent by the methods of Van Ness−Byer−Gibbs and Wisniak. The date were correlated with five liquid-phase activity coefficient models (Margules, Van Laar, Wilson, NRTL, and UNIQUAC). According to the average deviations in temperature and in vapor composition the best model for the systems is NRTL.
Effect of cilomilast (Ariflo) on TNF-α, IL-8, and GM-CSF release by airway cells of patients with COPD
2003
Background: Inflammation in chronic obstructive pulmonary disease (COPD) is characterised by increased neutrophilic infiltration of the airways. Cilomilast, a novel selective phosphodiesterase 4 inhibitor in clinical development for COPD treatment, exerts anti-inflammatory effects. The ability of cilomilast to inhibit the release of neutrophil chemoattractants such as tumour necrosis factor (TNF)-α, interleukin (IL)-8, and granulocyte-macrophage colony stimulating factor (GM-CSF) by bronchial epithelial cells and sputum cells isolated from 10 patients with COPD, 14 normal controls, and 10 smokers was investigated. Methods: Bronchial epithelial cells obtained by bronchial brushing and sputum…
Organic chlorine compounds in lake sediments. III. Chlorohydrocarbons, free and chemically bound chlorophenols
1990
Abstract Chlorohydrocarbons and free and chemically bound chlorophenols, catechols and guaiacols were measured from lake sediments in Central Finland. Chlorohydrocarbons occurred at low backround levels except chlorocymenes from pulp mills and PCBs near the city of Aanekoski, where a local leakage occurrs. Free chlorophenols (hexane extractables) were found in all 18 areas studied, but the bound ones (extracted with strong alkali) only in the pulp mill reciepient lakes where they dominated. Preliminary analyses of chemically bound chlorophenols in high molecular fractions of spent bleach liquors and pulp mill effluents indicated that majority of chlorocatechols and guaiacols are bound alrea…
Crystal structure of (1S,2R,4S)-1-[(morpholin-4-yl)methyl]-4-(prop-1-en-2-yl)cyclohexane-1,2-diol
2014
Besides intramolecular O—H⋯N hydrogen bonds, the crystal structure displays intermolecular O—H⋯O and C—H⋯O hydrogen bonds linking the molecules into undulating layers parallel to the (01) plane.
Crystal structure of 5′′-(4-chlorobenzylidene)-4′-(4-chlorophenyl)-1′-methyltrispiro[acenapthylene-1,2′-pyrrolidine-3′,1′′-cyclohexane-3′′,2′′′-[1,3]…
2015
In the title compound, C36H29Cl2NO4, two spiro links connect the methyl-substituted pyrrolidine ring to the acenaphthylene and cyclohexanone rings. The cyclohexanone ring is further connected to the dioxalane ring by a third spiro junction. The five-membered ring of the acenaphthylen-1-one ring system adopts a flattened envelope conformation, with the ketonic C atom as the flap, whereas the dioxalane and pyrrolidine rings each have a twist conformation. The cyclohexenone ring assumes a boat conformation. An intramolecular C—H...O hydrogen-bond interaction is present. In the crystal, molecules are linked by non-classical C—H...O hydrogen bonds, forming chains extending parallel to theaaxis.
The endoperoxide ascaridol shows strong differential cytotoxicity in nucleotide excision repair-deficient cells
2011
Targeting synthetic lethality in DNA repair pathways has become a promising anti-cancer strategy. However little is known about such interactions with regard to the nucleotide excision repair (NER) pathway. Therefore, cell lines with a defect in the NER genes ERCC6 or XPC and their normal counterparts were screened with 53 chemically defined phytochemicals isolated from plants used in traditional Chinese medicine for differential cytotoxic effects. The screening revealed 12 drugs that killed NER-deficient cells more efficiently than proficient cells. Five drugs were further analyzed for IC50 values, effects on cell cycle distribution, and induction of DNA damage. Ascaridol was the most effe…
Electronic structure of terpene derivatives
1998
Abstract He I photoelectron spectra of terpene derivatives and their preparative intermediates have been measured. The changes of the ionization potentials are discussed in relation to the corresponding variations of the electronic structure. Especially, the effect of methyl and oxygen substitution has been studied.