Benzene dynamics

The catalyst samples have been previously characterised by and Si NMR spectroscopy. Neither the NMR study of adsorbed deuterated benzene dynamics nor the Si study of the surface silica structure indicated significant differences in the surface chemistry of the samples. Any differences in the catalytic activity of the two materials are thus ascribed to the variations in particle size and not to the catalyst preparation routes. 

Independently of the measurements of the outflow curves, the amount of benzene dynamically adsorbed (ad) behind the adsorbent bed (after equilibration of concentration) was determined by weight. These values, expressed per unit of carbon volume are presented in Table 1. The maximum of benzene adsorption observed for AG40 carbon results both from the increase in the filling the carbon particles and the removal the layers with high burn-off from external surface. 

Wyatt R E, lung C and Leforestier C 1992 Quantum dynamics of overtone relaxation in benzene. II. Sixteen-mode model for relaxation from CH(v = 3) J. Chem. Phys. 97 3477-86... 

Minehardt T A, Adcock J D and Wyatt R E 1999 Quantum dynamics of overtone relaxation in 30-mode benzene a time-dependent local mode analysis for CH(v = 2) J. Chem. Phys. 110 3326-34... 

FIG. 13-108 Initial steady state for dynamic azeotropic distillation of ethanol-water with benzene. 

The non-bonded interaction energy, the van-der-Waals and electrostatic part of the interaction Hamiltonian are best determined by parametrizing a molecular liquid that contains the same chemical groups as the polymers against the experimentally measured thermodynamical and dynamical data, e.g., enthalpy of vaporization, diffusion coefficient, or viscosity. The parameters can then be transferred to polymers, as was done in our case, for instance in polystyrene (from benzene) [19] or poly (vinyl alcohol) (from ethanol) [20,21]. 

FIQ. 3 Diffusion coefficient of benzene molecules in benzene-polystyrene mixtures normalized by the diffusion coefficient of neat benzene molecular dynamics results, NMR measurements and prediction by the Mackie-Meares model [26]. 

Additional evidence that a dynamic equilibrium exists between an enamine, N-hemiacetal, and aminal has been presented by Marchese (41). It should be noted that no acid catalysts were used in the reactions of aldehydes and amines discussed thus far. The piperidino enamine of 2-ethylhexanal (0.125 mole), morpholine (0.375 mole), and p-toluene-sulfonic acid (1.25 x 10 mole) diluted with benzene to 500 ml were refluxed for 5 hr. At the end of this time the enamine mixture was analyzed by vapor-phase chromatography, which revealed that exchange of the amino residue had occurred in a ratio of eight morpholine to one piperidine. Marchese proposed a scheme [Eqs. (4), (5) and (6)] to account for these... 

This by no means exhausts the list of structures proposed for benzene. The remainder, however, such as the structure of Thiele based upon his theory of partial valence and that of Collie based upon a dynamic model, are usually complicated and cannot be represented in any simple valence scheme. 

The purpose of this study was to compare hepatotoxic effects of monobromo-benzene, 3 dibromobenzene isomers, hexabromobenzene and tetrabromobisphenol A with special attention paid to the dynamics of changes of selected indicators of liver necrosis during acute poisoning. 

The results of our calculations based on both the static and dynamic theories show that most of the nonbenzenoid cyclic conjugated systems examined exhibit in a greater or lesser degree a marked double-bond fixation. The static theory indicates that even in benzene there exists a hidden tendency to distort into a skewed structure and that such a tendency is actually realized in [4n-f-2] annulenes larger than a certain critical size. In nonalternant hydrocarbons bond distortion is a rather common phenomenon. Fulvenes, fulvalenes and certain peri-condensed nonalternant hydrocarbons undergo a first-order bond distortion, and... 

Deuterium NMR has recently been used to study molecular motion of organic adsorbates on alumina (1.) and in framework aluminosilicates (2). The advantage of NMR is that the quadrupole interaction dominates the spectrum. This intramolecular interaction depends on the average ordering and dynamics of the individual molecules. In the present work we describe NMR measurements of deuterated benzene in (Na)X and (Cs,Na)X zeolite. 

Hendricks B, and 11 coauthors (2005) Dynamics of an oligotrophic bacterial aquifer community during contact with a groundwater plume contaminated with benzene, toluene, ethylbenzene, and xylenes an in situ mesocosm study. Appl Environ Microbiol 71 3815-3823. 

By asserting that the film thickness remains proportional to the 2/3 power of the capillary number, they establish that the dynamic pressure drop for surfactant-laden bubbles also varies with the capillary number to the 2/3 power but with an unknown constant of proportionality. New pressure-drop data for a 1 wt% commercial surfactant, sodium dodecyl benzene sulfonate (Siponate DS-10), in water, after correction for the liquid indices between the bubbles, confirmed the 2/3 power dependence on Ca and revealed significant increases over the Bretherton theory due to the soluble surfactant. 

Under good solvent conditions the dynamics of semi-dilute solutions was investigated by NSE using a PDMS/d-benzene system at T = 343 K and various concentrations 0.02 c < 0.25. The critical concentration c as defined by (112) is 0.055. 

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