Search results for "Hexane"
showing 10 items of 467 documents
Strukturuntersuchungen von polyamiden aus cyclischen dicarbonsäuren und piperazin durch direkten abbau im massenspektrometer
1977
Polyamide aus 1,2-Cyclobutan-, 1,2-Cyclopentan- und 1,2-Cyclohexandicarbonsaure und Piperazin wurden direkt in der Ionenquelle eines Massenspektrometers pyrolysiert. Die hohe Empfindlichkeit der massenspektrometrischen Methode erlaubt, bei Abbauraten von ca. 1%/min zu pyrolysieren und dadurch selektive thermische Abbaumechanismen neben den Fragmentierungsreaktionen nachzuweisen. Durch thermischen Abbau werden dabei Oligomere mit Piperazinendgruppen sowie gesattigte und ungesattigte Cyclobutan-, -pentan- und -hexanendgruppen gebildet. Polyamides of 1,2-cyclobutane-, 1,2-cyclopentane- and 1,2-cyclohexane-dicarboxylic acid and piperazine were pyrolyzed directly in the ion source of a mass spec…
Pore structural characteristics of mesostructured materials prepared under different conditions
2002
This paper presents an overview of the pore structural properties of different mesostructured materials prepared at room temperature, namely MCM-41, MCM-48 and MMS. The stability towards water vapour of some samples is inferred by XRD and nitrogen adsorption after and prior to water adsorption. It is shown that MMS materials are more stable than MCM-41. A new method for the stabilisation of MCM-41 using tetraethoxysilane (TEOS) in hexane as silicification agent is proposed and it is shown to be effective in stabilising the pore structure and to increase significantly the surface hydrophobicity.
Conformational mobility of thianthrene-5-oxide.
2005
[reaction: see text] Data on the apparent dipole moment of thianthrene-5-oxide (1) and (1)H NMR spectra in different solvents support the conformational mobility of 1, which flaps between two limit boat conformations with the sulfinyl group in pseudoequatorial and pseudoaxial positions, respectively. The conformational equilibrium of 1 occurs too fast for the (1)H NMR (500 MHz) time-scale even at -130 degrees C, and the equilibrium constant has not been determined. The apparent dipole moments of 1 in n-hexane and 1,4-dioxane and the (1)H NMR spectra of 1 and the model compounds cis- and trans-thianthrene-5,10-dioxides (2) and thianthrene (5) in different solvents and at various temperatures…
Solvent Effects on Vapor–Liquid Equilibria of the Binary System 1-Hexene + n-Hexane
2012
In order to study the separation of 1-hexene and n-hexane, two solvents, 2-pentanol and ethyl-butyrate, are tested as possible entrainers for an extractive distillation. In this way, isobaric vapor–liquid equilibrium (VLE) data at 100 kPa have been measured for the two ternary systems formed by the initial mixture and one of the mentioned solvents: 1-hexene + n-hexane + ethyl butyrate and 1-hexene + n-hexane + 2-pentanol. VLE data for the four constituent binary systems have also been measured. These systems are 1-hexene + ethyl butyrate, n-hexane + ethyl butyrate, 1-hexene + 2-pentanol, and finally n-hexane + 2-pentanol. All binary systems show moderate positive deviations from the ideal b…
Identification of highly effective antitrypanosomal compounds in essential oils from the Apiaceae family
2018
The Apiaceae family encompasses aromatic plants of economic importance employed in foodstuffs, beverages, perfumery, pharmaceuticals and cosmetics. Apiaceae are rich sources of essential oils because of the wealth of secretory structures (ducts and vittae) they are endowed with. The Apiaceae essential oils are available on an industrial level because of the wide cultivation and disposability of the bulky material from which they are extracted as well as their relatively cheap price. In the fight against protozoal infections, essential oils may represent new therapeutic options. In the present work, we focused on a panel of nine Apiaceae species (Siler montamon, Sison amomum, Echinophora spi…
Resorcarenes in the Boat Conformation as Building Blocks for Hydrogen-Bonded Assemblies Including Two Ammonium Cations
2001
Crystal structures are reported for various co-crystals of rccc-resorcarenes with triethylammonium chloride. Usually, two molecules of a C2v-symmetric tetraester 2 in the boat conformation are linked through four hydrogen-bonded chloride anions to give dimeric assemblies. Two of the chloride anions may be replaced by four hydrogen-bonded ethanol molecules in an otherwise similar structure. These assemblies, which consist of six or eight components, posses voluminous, negatively charged chambers in which two triethylammionium cations, 3+, are included as guests by strong electrostatic and hydrogen-bonding interactions. The host-guest N-H...Cl hydrogen bonds were clearly detected at 173 K. Th…
7-[(3-Chloro-6-methyl-6,11-dihydrodibenzo[c,f][1,2]thiazepin-11-yl)amino]heptanoic acidS,S-dioxide hydrochloride
2012
In the title compound, C(21)H(26)ClN(2)O(4)S(.)Cl, also known as tianeptine hydro-chloride, the seven-membered ring adopts a boat conformation. The dihedral angle between the mean planes of the benzene rings is 44.44 (7)°. There is an intra-molecular hydrogen bond formed via S= O⋯H-N. In the crystal, mol-ecules are connected via pairs of N-H.·O, N-H⋯Cl and O-H⋯Cl hydrogen bonds, forming inversion dimers, which are consolidated by C-H⋯O inter-actions. The dimers are linked by C-H⋯O and C-H⋯Cl inter-actions, forming a two-dimensional network lying parallel to (011).
rac-Ethyl (2Z)-3-{2-[(Z)-4-ethoxy-4-oxobut-2-en-2-ylamino]cyclohexylamino}but-2-enoate
2011
The asymmetric unit of the title compound, C18H30N2O4, contains two independent molecules. In each molecule, the cyclohexane ring adopts a chair conformation with equatorial orientation of the substituents, and the conformation is stabilized by two intramolecular N—H...O hydrogen bonds, forming rings of S(6) graph-set motif. One ethoxy group and one ethyl group are disordered over two sets of sites with refined occupancy ratios of 0.704 (2):0.296 (2) and 0.505 (3):0.495 (3), respectively. In the crystal, a weak intermolecular C—H...O hydrogen interaction is observed, involving the O atom of the major component of the disordered eth…
5′-Benzylidene-1′′-methyl-4′′-phenyltrispiro[1,3-dioxolane-2,1′-cyclohexane-3′,3′′-pyrrolidine-2′′,3′′′-indole]-4′,2′′′-dione
2017
In the title compound, C32H30N2O4, two spiro links connect the methyl-substituted pyrrolidine ring to the oxindole and cyclohexanone rings. The cyclohexanone ring is further connected to the dioxalane ring by a third spiro junction. Both the pyrrolidine and dioxalane rings adopt a twist conformation. The indole ring is nearly planar, with a maximum deviation of 0.0296 (7) Å, and the cyclohexanone ring adopts a distorted boat conformation. In the crystal, C—H...O and N—H...N hydrogen-bonding interactions connect molecules into chains running parallel to thebaxis, which are further linked into layers parallel to theabplane by C—H...O hydrogen bonds.
Headspace Volatile Composition of the Flowers of Caralluma europaea N.E.Br. (Apocynaceae)
2009
The volatile constituents of the flowers of Caralluma (Apteranthes) europaea (Guss.) N.E. Br. (Apocynaceae - Asclepiadoideae) from Lampedusa Island were analyzed by headspace method. The analyses allowed the identification and quantification of 41 compounds. The main components were, among the monoterpenoids, terpinolene (23.3%), a-terpinene (19.1%) and linalool (18.4%), whereas, among the carbonylic compounds the major constituents were heptanal (2.0%), octanoic acid (2.4%) and hexanoic acid (1.7%). It is worth to mention the presence of a nitrogen containing compound, indole (0.8%) and of a sulphur containing compound, dimethylsulphide (t). The compounds found in the flowers of C. europea…