Search results for "Heptane"
showing 10 items of 103 documents
Complete Spectral Analysis of the1H NMR 16-Spin System of β-Pinene
1997
The complete analysis of the 1H NMR spectrum of β-pinene, (1S)-(-)-6,6-dimethyl-2-methylenebicyclo[3.1.1]heptane, which is of the ABCDEFGHIJX3Y3 type, is reported and earlier results are corrected. The vicinal coupling constants, 3J(H,H), are compared with the theoretical values calculated by using the Altona and co-workers’ equations for the structure derived by molecular modelling. The results were applied to the conformational analysis of β-pinene. © 1997 John Wiley & Sons, Ltd.
Synthesis of oxaspiranic compounds through [3 + 2] annulation of cyclopropenones and donor–acceptor cyclopropanes.
2014
The Sc(OTf)3-catalyzed [3 + 2]-annulation reaction between cyclopropenones and donor–acceptor cyclopropanes is described. The process leads directly to the formation of 4-oxaspiro[2.4]hept-1-ene derivatives in good to excellent reaction yields. Density functional theory calculations suggest that the [3 + 2]-annulation pathway is strongly preferred over the possible [3 + 3]-process.
Selective, homogeneous hydrogenation of cycloheptatriene to cycloheptene catalyzed by (η4-cycloocta-1,5-diene)(η6-cyclohepta-1,3,5-triene)ruthenium(0)
1980
Abstract In the presence of small amounts of [Ru(η 4 -COD)](η 6 -C 8 H 10 )] (1), cycloheptatriene is hydrogenated to cycloheptene, under one atmosphere of hydrogen at room temperature in homogeneous phase. The formation of a small amount of cyclooctene and the existence of an induction period, which do not occur when [Ru(η 4 -COD)(η 6 -C 7 H 8 )] (2) is used as the catalyst, suggest that 2 is the real catalyst. The selectivity of this hydrogenation is 100% in n-hexane as solvent, 99.5% in THF, and low in ethanol. Conversion is quantitative in THF and ethanol, but not more than 65% in n-hexane. In the presence of 1 or 2, cycloheptene is rapidly hydrogenated to cycloheptane in THF and ethano…
Determination of Kinetic and Thermochemical Parameters of a Substitution Reaction at a Square-Planar Palladium(II) Complex in Water/AOT/n-Heptane Mic…
1995
Abstract The substitution reaction [Pd(bipy)(en)] 2+ + en → [Pd(en) 2 ] 2+ + bipy (where bipy = 2,2′-bipyridine and en = ethylenediamine) has been studied in water and water/AOT/ n -heptane microemulsions at various values of the molar ratio R ( R = [water]/[AOT]) by flow microcalorimetry. From calorimetric data, molar enthalpies of reaction and rate constants were obtained. These quantities indicate that, by increasing R , the reaction becomes less exothermic and its rate constant decreases, trending to the value observed in water. These features can be reasonably rationalized in terms of the peculiar solvation state of reactants inside the AOT reversed micelles and/or the peculiar physico…
Steam catalytic cracking of naphtha over ZSM-5 zeolite for production of propene and ethene: Micro and macroscopic implications of the presence of st…
2012
One option to produce more ethene and propene can be to crack naphtha type fractions in dedicated smaller FCC units. We present here the results obtained for high temperature steam catalytic cracking (SCC) of a representative naphtha product (n-heptane) with ZSM-5. It has been found that under those conditions the presence of steam produces an irreversible dealumination of the zeolite as well as a reversible deactivation due to the interaction of water with active sites with a negative effect on protolytic cracking. A kinetic decay model that takes into account the two phenomena has been developed. The apparent activation energy is lower in the presence of steam. It appears that whilst the …
Study of AOT-stabilized microemulsions of formamide and n-methylformamide dispersed in n-heptane
1997
Abstract A wide investigation of some physicochemical properties (density, viscosity, conductance, IR spectra, permittivity) of AOT-stabilized dispersions of formamide and n -methylformamide in n -heptane has been performed. The experimental data are consistent with the hypothesis that these highly hydrophilic substances are encapsulated within AOT reversed micelles and that this structure is maintained for both systems well above the volume fraction of the dispersed phase where a percolative transition occurs. In addition, the observed properties of these microemulsions reveal the pivotal role of intermicellar attractive interactions in driving the percolative transition. A marked modifica…
Partition Behavior of Anilines in Bulk‐Phase and High‐Performance Liquid Chromatographic Systems: Influence on Correlation with Biological Constants
1992
Abstract The partition behavior of a mixed series of ring‐substituted anilines in reversed‐phase high‐performance liquid chromatographic systems is substantially different from that observed in a classical bulk‐phase partition system with n ‐heptane as the aprotic reference solvent. On the basis of the equivalence of each ring substituent in the p ‐straight‐chain methylene groups (ν value) as a function of the fraction of organic solvent (acetonitrile or methanol) in the mobile phase, the biased partition behavior for imperfect homologues and heterologues is verified relative to that of perfect homologues. This behavior was tentatively attributed, mainly, to differences in the hydrogen bond…
Calorimetric investigation of the precipitation of calcium monohydrogen phosphate in water/AOT/n-heptane microemulsions
2000
Abstract The molar enthalpies of precipitation of calcium monohydrogen phosphate (CaHPO 4 ) in water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/ n -heptane microemulsions were measured at 25°C by a calorimetric technique as a function of the molar ratio R ( R = [water]/[AOT]) at a fixed AOT concentration. Calorimetric data indicate the formation of CaHPO 4 nanoparticles encapsulated in the aqueous core of the AOT reversed micelles displaying a slow growing process with time. Their energetic state is initially different from that in bulk water approaching the value in water at longer times. The observed growing process results to be completely inhibited by the presence of small amounts o…
Water structure in water/AOT/n-heptane microemulsions by FT-IR spectroscopy
1992
Abstract FT-IR spectra in the OH stretching region of water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-heptane microemulsions as a function of the water/AOT molar ratio (R) and of the weight fraction (φ) of the micellar phase have been recorded at 25°C. After elimination of the unwanted CH contribution and correction for the water concentration, the shape of the normalized OH bands has been found to be dependent on R and practically independent of φ. The analysis of these bands in terms of “bound” and “bulk” water (representing, as a first approximation, the two water domains within the water pool) allowed the evaluation of the fraction (α) of the “bound” water as a function of R. A…
2-(Naphthalen-1-ylamino)cyclohexanol
2011
The title compound, C16H19NO, was synthesized under solvent-free conditions by reaction of 7-oxa-bicyclo[4.1.0]heptane and naphthalen-1-amine in the presence of Ca(CF3COO)2 as catalyst. The cyclohexane ring adopts a chair conformation. In the crystal, molecules are linked by intermolecular N—H...O hydrogen bonds and C—H...π interactions into chains parallel to the c axis.