Search results for "Non polar"

showing 7 items of 7 documents

Gas—liquid chromatographic analyses

1984

Abstract The gas chromatography (GC) of n -alkyl acetates (CH 3 COOR), chloroacetates (CH 2 ClCOOR), dichloroacetates (CHCl 2 COOR) and trichloroacetates (CCl 3 COOR), where the alcohol chain length (R) varied between 1 and 8, and certain of their monochlorinated derivatives, 176 compounds altogether, has been studied on SE-30 and OV-351 glass capillary columns under the same operating conditions. The isomeric monochlorinated esters are eluted in direct order from the 1- chloro to the ω-chloro isomer, the separation of the isomers being complete on OV- 351. On SE-30, however, the peaks of the 6- and 7-chlorooctyl esters are partly overlapped. The separation of the mixtures of odd- and e…

Capillary actionAnalytical chemistryAlcoholFormyl groupAldehydeBiochemistryAnalytical Chemistrychemistry.chemical_compoundCapillary columnStraight chainpolycyclic compoundsStructural isomerOrganic chemistryMethyleneBenzoic acidchemistry.chemical_classificationPrimary (chemistry)General MedicineCapillary gas chromatographyBoiling pointChromatographic separationSalicylaldehydeNitrobenzoatesPolarlipids (amino acids peptides and proteins)Aliphatic compoundResolution (mass spectrometry)Polarity (physics)Carboxylic acidchemistry.chemical_elementBranching (polymer chemistry)Isothermal processTurn (biochemistry)ChlorinePhenolsQuartzAlkylTetradecaneChlorophenolDegree of unsaturationChromatographyGeminalElutionOrganic ChemistryChloroacetatesComplete resolutionReverse orderChain lengthchemistryChlorobenzeneFunctional groupNitroKovats retention indexNon polarGas chromatographyVicinalGas liquid chromatographicJournal of Chromatography A
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Gas-liquid chromatographic analyses

1984

A mixture of all nine chlorinated 4-hydroxybenzaldehydes and the parent homologue was separated on a non-polar SE-30 capillary column using various isothermal and temperature-programmed operating conditions. The relative retention data for the compounds are given and the retention indices together with the retention index increments for each position of chlorine substitution are examined. The retention order 3-Cl<parent<2,5-di-Cl<2,3-di-Cl<3,5-di-Cl<2-Cl<2,3,5-tri-Cl<2,3,6-tri-Cl<2,6-di-Cl<tetra-Cl isomer obtained indicates that the effect of the position of substitution on the retention behaviour is greater than that of the number of chlorine atoms. The retention is maximal with 2-Cl and 2…

ChromatographyChemistryOrganic Chemistrychemistry.chemical_elementGeneral MedicineBiochemistryIsothermal processAnalytical ChemistryCapillary columnStationary phaseChlorineKovats retention indexNon polarGas chromatographyGas liquid chromatographicJournal of Chromatography A
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Understanding the Origin of the Regioselectivity in Non-polar [3+2] Cycloaddition Reactions through the Molecular Electron Density Theory

2020

The regioselectivity in non-polar [3+2] cycloaddition (32CA) reactions has been studied within the Molecular Electron Density Theory (MEDT) at the B3LYP/6-311G(d,p) level. To this end, the 32CA reactions of nine simplest three-atom-components (TACs) with 2-methylpropene were selected. The electronic structure of the reagents has been characterized through the Electron Localisation Function (ELF) and the Conceptual DFT. The energy profiles of the two regioisomeric reaction paths and ELF topology of the transition state structures are studied to understand the origin of the regioselectivity in these 32CA reactions. This MEDT study permits to conclude that the least electronegative X1 end atom…

Electron density010405 organic chemistryChemistrymolecular electron density theoryRegioselectivityElectronic structure010402 general chemistryelectronegativity7. Clean energy01 natural sciencesCycloaddition3. Good health0104 chemical sciencesElectronegativitynon-polar [3+2] cycloaddition reactionsComputational chemistryregioselectivityAtomSingle bondNon polarmolecular mechanismorganic_chemistryTopology (chemistry)Organics
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Collapsibility of metastable sand by non-conventional oedometer tests

2018

The stability of foundations soils could represent a clear and present threat for the conservation of even well preserved buildings, particularly for Architectural heritage conservation and land art heritage. A dramatic case is the presence of collapsible metastable sands as foundation soils, as it occurs in the sacral complex Valle dei Templi in Agrigento. This site listed by UNESCO, stands on a crest of a calcarenite cuesta, overlaying a layer of these sands. When the collapsible sand is dry, the structure is strong enough to bond the sand particles together. When the sand becomes wet, a de-structuration mechanism occurs and the soil’s strength is compromised. This paper has a twofold aim…

Poly ethylene glycol0211 other engineering and technologiesGeneral Physics and Astronomy02 engineering and technology01 natural sciencesPhysics and Astronomy (all)Architectural heritageCollapse potentialMetastability0103 physical sciencesGeneral Materials ScienceGeotechnical engineeringMechanics of Material010306 general physics021101 geological & geomatics engineeringSettore ICAR/07 - GeotecnicaSuction forceOedometer testMetastable sandPEGStabilizationCalcareniteSettore ING-IND/22 - Scienza E Tecnologia Dei MaterialiMechanics of MaterialsMechanical stabilitySoil waterNon polarMaterials Science (all)Settore GEO/05 - Geologia ApplicataGeology
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endo-Functionalized molecular tubes : selective encapsulation of neutral molecules in non-polar media

2016

Four endo-functionalized molecular tubes with urea/thiourea groups in the deep cavities have been synthesized, and their binding ability to neutral molecules studied. Very high binding affinity and selectivity have been achieved, which are rationalized by invoking the shape and electrostatic complementarity and dipole alignment.

Stereochemistrynon-polar media010402 general chemistryPhotochemistry01 natural sciencesCatalysischemistry.chemical_compoundMaterials Chemistryendo-Functionalized molecular tubesneutral moleculesMoleculeta116010405 organic chemistryMetals and AlloysGeneral Chemistry0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsDipoleBinding abilityThioureachemistryCeramics and CompositesUreaencapsulationNon polarSelectivityChemical Communications
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Gas chromatography of homologous esters

1984

Abstract The gas chromatographic retention behaviour of the propanoyl and monochloropropanoyl esters of saturated C3C5 branched-chain and unsaturated C3C6 alcohols on SE-30 and OV-351 capillary columns at several temperatures is reported. Retention index increments at 80 and 120°C show the effect of branching in the alkyl chain and also the effect of unsaturation and of its position in the chain with chlorination at the two possible positions in the acyl chain. The various incremental effects are discussed and compared with the behaviour of the corresponding n-alkyl esters.

Steric effectsCapillary actionCarboxylic acidchemistry.chemical_elementBranching (polymer chemistry)BiochemistryAnalytical ChemistryHomologous serieschemistry.chemical_compoundCapillary columnpolycyclic compoundsChlorineOrganic chemistryChlorine substituentAlkylchemistry.chemical_classificationDegree of unsaturationChromatographyOrganic ChemistryChloroacetatesGeneral MedicinechemistryAcyl chainKovats retention indexNon polarGas chromatographyAliphatic compoundJournal of Chromatography A
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Time-dependent monomerization of gramicidin A, enhanced by phosphatidylcholine in non-polar solvents

1986

Abstract The usefulness of size-exclusion high-performance liquid chromatography for the study of gramicidin A dimer—monomer conformational equilibrium in non

chemistry.chemical_compoundChromatographyChemistryPhosphatidylcholineOrganic Chemistrytechnology industry and agriculturepolycyclic compoundsGramicidin Alipids (amino acids peptides and proteins)Non polarGeneral MedicineBiochemistryAnalytical ChemistryJournal of Chromatography A
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