Search results for "Hexane"
showing 10 items of 467 documents
Lemon Oils Attenuate the Pathogenicity of Pseudomonas aeruginosa by Quorum Sensing Inhibition
2021
The chemical composition of three Citrus limon oils: lemon essential oil (LEO), lemon terpenes (LT) and lemon essence (LE), and their influence in the virulence factors production and motility (swarming and swimming) of two Pseudomonas aeruginosa strains (ATCC 27853 and a multidrug-resistant HT5) were investigated. The main compound, limonene, was also tested in biological assays. Eighty-four compounds, accounting for a relative peak area of 99.23%, 98.58% and 99.64%, were identified by GC/MS. Limonene (59–60%), γ-terpinene (10–11%) and β-pinene (7–15%) were the main compounds. All lemon oils inhibited specific biofilm production and bacterial metabolic activities into biofilm in a dose-dep…
Interdonato lemon from Nizza di Sicilia (Italy): chemical composition of hexane extract of lemon peel and histochemical investigation
2015
Considering that the determination of authenticity and of the geographical origin of food is a very challenging issue, in this study we studied by means of histological and histochemical analyses the famous Sicilian lemon known as ‘Interdonato Lemon of Messina PGI’. Since the protected geographical indication Interdonato lemon of Messina possesses high organoleptic properties, the composition of the hexane extract of lemon peel was determined by HRGC and HRGC–MS analyses and compared with that of lemon of different cultivars. The results obtained are informative of the oil’s quality and explain the variation of the lemon essential oil composition. Given the fundamental economic implications…
Über blei-haltige Heterocyclen
1990
Abstract Crystal structures of alternating six-membered rings [Ph2PbS]3-P21/c and [Ph2SnS]3-P21/n have been determined by X-ray methods. Both heterocycles exhibit a C2-symmetric twisted boat conformation with tetrahedral coordination of the metal atoms [dPbS 2.491 A (dSnS 2.401 A, dPbC 2.19 A (dSnC 2.129 A)]. No additional intermolecular contacts have been found. A ring-segment exchange reaction in solution has been observed by NMR. In the resulting equilibrium new cyclic compounds containing both tin and lead atoms with coupling constants 2J(207PbS119Sn) 226 Hz have been detected. FD-mass spectra indicate formation of dimeric molecular units.
Zinn - Chalkogen - Heterocyclen. I. 2.4.6-Hexamethyl-1.3.5-triselena-2.4.6-tristannacyclohexan, Massen- und Schwingungsspektren
2010
The mass spectrum of the title compound exhibits very similar fragmentation patterns compared with the sulfur analogon. The high stability of triply coordinated organotin cations is remarkable. There is no evidence for any stabilisation effects by pπ-dπ bonding concerning the ring bonds. The assignment of the vibration spectra leads to the conclusion that the molecule of triselenastanninane possesses a boat conformation.
N-[2-(2,2-Dimethylpropanamido)pyrimidin-4-yl]-2,2-dimethylpropanamide n-hexane 0.25-solvate hemihydrate
2013
The asymmetric unit of the title compound, C14H22N4O2·0.25C6H14·0.5H2O, contains two independent molecules of 2,4-bis(pivaloylamino)pyrimidine (M) with similar conformations, one water molecule and one-halfn-hexane solvent molecule situated on an inversion center. In one independentMmolecule, one of the twotert-butyl groups is rotationally disordered between two orientations in a 3:2 ratio. Then-hexane solvent molecule is disordered between two conformations in the same ratio. The water molecule bridges two independentMmoleculesviaO—H...O, N—H...O and O—H...N hydrogen bonds into a 2M·H2O unit, and these units are further linked by N—H...N hydrogen bonds into chains running in the [010] dire…
Vibrational spectroscopy of a tetraureidocalix[4]arene based molecular capsuleElectronic supplementary information (ESI) available: three tables cont…
2001
Structural models for self-assembled dimers composed of two urea calix[4]arenes which entrap benzene or cyclohexane are developed using Fourier transform infrared (FTIR) spectroscopy. Based on the host–guest ratio determined by 1H NMR spectroscopy in solution, and confirmed for the solid state by a thermogravimetric analysis, it is possible to prove by a comparison of the FTIR data of host, guest, complex and model compounds, that the capsule is held together by a cyclic array of weak and strong hydrogen bonds between the urea units attached at the wide rim of the calixarenes. The dimerization of the two urea units leads to a loss of symmetry, and an averaged C4 symmetrical arrangement is p…
A Modular Formal Total Synthesis of (±)-Cycloclavine
2016
Cycloclavine is a clavine-type Ergot alkaloid noteworthy for its unique pentacyclic skeleton featuring a 3-azabicyclo[3.1.0]hexane substructure. A short convergent route to the racemic alkaloid is described which comprises only eight linear steps and requires only four chromatographic purifications. The two key building blocks can be prepared in high yield from commercially available starting materials. Two consecutive coupling reactions, namely a selective alkylation of a dienolate and a Heck reaction, are the key steps of the reaction sequence.
Catalytic Oxidation of Alkanes and Alkenes by H 2 O 2 with a μ‐Oxido Diiron(III) Complex as Catalyst/Catalyst Precursor
2015
A new mu-oxo diiron(III) complex of the lithium salt of the pyridine-based unsymmetrical ligand 3-[(3-{[bis(pyridin-2-ylmethyl)amino]methyl}-2-hydroxy-5-methylbenzyl)(pyridin2-ylmethyl)amino] propanoate (LiDPCPMPP), [Fe-2(mu-O)(LiDPCPMPP)(2)](ClO4)(2), has been synthesized and characterized. The ability of the complex to catalyze oxidation of several alkanes and alkenes has been investigated by using CH3COOH/H2O2 (1:1) as an oxidative system. Moderate activity in cyclohexane oxidation (TOF = 33 h(-1)) and good activity in cyclohexene oxidation (TOF = 72 h(-1)) were detected. Partial retention of configuration (RC = 53%) in cis- and trans-1,2-dimethylcyclohexane oxidation, moderate 3 degrees…
Spectroscopic and DFT Characterization of a Highly Reactive Nonheme FeV–Oxo Intermediate
2018
The reaction of [(PyNMe3)FeII(CF3SO3)2], 1, with excess peracetic acid at −40 °C generates a highly reactive intermediate, 2b(PAA), that has the fastest rate to date for oxidizing cyclohexane by a nonheme iron species. It exhibits an intense 490 nm chromophore associated with an S = 1/2 EPR signal having g-values at 2.07, 2.01, and 1.94. This species was shown to be in a fast equilibrium with a second S = 1/2 species, 2a(PAA), assigned to a low-spin acylperoxoiron(III) center. Unfortunately, contaminants accompanying the 2(PAA) samples prevented determination of the iron oxidation state by Mossbauer spectroscopy. Use of MeO-PyNMe3 (an electron-enriched version of PyNMe3) and cyclohexyl pero…
Polarity profiles in reverse micelles of Triton X-100, as studied by spin probe and absorption probe techniques
1997
The microenvironment characteristics — polarity, viscosity and order degree - in Triton X-100 reverse micelles (RM) in cyclohexane and benzene — n-hexane 30 : 70 (v/v), were investigated with the aid of a homologous series of cationic spin probes, CAT n, of 5- and 16-doxyl stearic acids and of a new absorption probe, 4-nitropyridine-N-oxide (NP). The spectral parameters were related to local hydration values by means of a series of poly(oxyethylene) (PEO)/water calibration mixtures. All results regarding the polarities in RM and calibration mixtures have been expressed in terms of Kosower's Z values, by determining the linear dependence of the transition energies of NP, ENP, on Z, for a ser…