Naphthalene, system analysis

Theoretical and experimental investigations into resonance hybridization between benzo[6-Jselenophene and naphthalene in benzoselenophene-doped naphthalene systems provided evidence for two nonequivalent centers for the impurity <85Mi 213-03). Chromatographic structural analysis by adsorption on graphitized thermal carbon black was used for the determination of conformation in 2-phenylchalcogenophenes <87MI 213-02). The adsorption of selenophene on various solid phases allowed its direct observation by EXAFS <9iMC6). 

Itagaki et al [76] have proposed that the decay kinetics observed for fluid solutions of poly(l-methoxy-4-vinylnaphthalene) (PMVN) may be explained in terms of two excimer species in addition to excited monomer. The proposal is based on variations in steady-state l,3-di(4-methoxy-1-naphthyl)propane (BMP) [77,78], presumes that the lower energy excimer comprises the normal structure with fully overlapped aromatic rings, whereas the second excimer is thought to comprise a partially overlapped structure. Steady state spectroscopy indicated a reasonable degree of evidence that three excited state species do indeed exist in the sterically hindered naphthalene systems. However the spectral and numerical deconvolution procedures adopted make the separation of intensity components used in the kinetic analysis, necessary for excited state assignment, rather optimistic. 

One of the most commonly studied systems involves the adsorption of polynuclear aromatic compounds on amorphous or certain crystalline silica-alumina catalysts. The aromatic compounds such as anthracene, perylene, and naphthalene are characterized by low ionization potentials, and upon adsorption they form paramagnetic species which are generally attributed to the appropriate cation radical (69, 70). An analysis of the well-resolved spectrum of perylene on silica-alumina shows that the proton hyperfine coupling constants are shifted by about four percent from the corresponding values obtained when the radical cation is prepared in H2SO4 (71). The linewidth and symmetry require that the motion is appreciable and that the correlation times are comparable to those found in solution. 

We employed various substrates to check for MFO in two bivalve species, a salt water mussel (Mytilus edulis) and a fresh water clam (Anodonta sp). Cytochrome P-450 was also studied. Organisms were exposed to 100 PPM Venezuelan crude in a stagnant system for up to one month. Enzyme assays were carried out with digestive gland 9000 g homogenates (17) and cytochrome P-450 analysis, with microsomes (21). The hydrocarbon substrates investigated included 1I+C-labelled benzo(a)pyrene, fluorene, anthracene, and naphthalene. The method used for separation of BP metabolites by thin layer radiochromatography has been described (7). The metabolite detection method for the other aromatic hydrocarbons was essentially the same except methylene chloride was used as metabolite extractant as well as TLC developer. Besides the hydrocarbon substrates, we also checked for other MFO reactions, N-dealkylase with C-imipramine (22) and 0-dealkylase with ethoxycoumarin (15). 

In their test system, the researchers used the ionic liquid l-butyl-3-methylimidazol-ium hexafluorophosphate (bmim)(PF6), which is stable in the presence of oxygen and water, with naphthalene as a low-volatility model solute. Spectroscopic analysis revealed quantitative recovery of the solute in the supercritical CO2 extract with no contamination from the ionic liquid. They found that CO2 is highly soluble in (bmim)(PF6) reaching a mole fraction of 0.6 at 8 MPa, yet the two phases are not completely miscible. The phase behavior of the ionic liquid-C02 system resembles that of a cross-linked polymer-solvent system (Moerkerke et al., 1998), even though... 

Yefremov et al. [34] studied systems containing tetryl by thermal analysis and found that it forms additive compounds with phenanthrene, fluorene or retene in the mole ratio 1 1 which do not melt uniformly. It also forms an additive compound in the same ratio with naphthalene, m.p. 86.8°C. 

Azulene has weak absorption in the visible region (near 7000 A) and more intense band systems in the ultraviolet. The first ultraviolet system, which commences at about 3500 A, has been examined in substitutional solid solution in naphthalene (Sidman and McClure, 1956) and in the vapour state (Hunt and Ross, 1962), and can be observed in fluorescence from the vapour (Hunt and Ross, 1956). Theory predicts that the transition is 1Al<-lAl(C2K), i.e. allowed by the electronic selection rules with polarization parallel to the twofold symmetry axis (see, e.g., Ham, 1960 Mofifitt, 1954 Pariser, 1956b). The vibrational analysis shows that the transition is allowed but does not establish the axis of polarization. The intensity distribution among the vibrational bands indicates a small increase in CC bond distance without change in symmetry. 

Typical probes for the analysis of ionic solutes include 3-hydroxy-L-tyrosine (DOPA)24 and naphthalene-2-sulfonate,26 whereas those for use with uncharged solutes include nicotinamide,27 theophylline,28 and anthracene 29 Indirect detection is nonspecific and less suitable for the analysis of complex or impure samples, because unpurified biological samples, such as urine, contain a large number of hydrophilic solutes that will give problems such as extra system peaks. However, analyses of pharmaceutical products and quantification of impurities in substances are typical of applications.23... 

The NMR method we have developed gives a direct, in situ determination of the solubility and also allows us to obtain phase data on the system. In this study we have measured the solubilities of solid naphthalene in supercritical carbon dioxide along three isotherms (50.0, 55.0, and 58.5°C) near the UCEP temperature over a pressure range of 120-500 bar. We have also determined the pressure-temperature trace of the S-L-G phase line that terminates with the UCEP for the binary mixture. Finally, we have performed an analysis of our data using a quantitative theory of solubility in supercritical fluids to help establish the location of the UCEP. 

A crystalline 2 1 complex (Cl) of antimony trichloride and naphthalene was obtained from a hot petroleum ether solution on cooling. An X-ray analysis (275) revealed an interaction between the antimony atom and the arene n system. The structure consists of layers of antimony trichloride molecules alternating with layers of naphthalene molecules. The coordination sphere around the antimony atom is portrayed in Fig. 16. Two antimony-chlorine distances are equal, while the third is significantly longer. The antimony atom is 3.2 A away from the plane of the naphthalene molecule, thus indicating a weak n interaction. 

In the intermediate domain of values for the parameters, an exact solution requires the specific inspection of each configuration of the system. It is obvious that such an exact theoretical analysis is impossible, and that it is necessary to dispose of credible procedures for numerical simulation as probes to test the validity of the various inevitable approximations. We summarize, in Section IV.B.l below, the mean-field theories currently used for random binary alloys, and we establish the formalism for them in order to discuss better approximations to the experimental observations. In Section IV.B.2, we apply these theories to the physical systems of our interest 2D excitons in layered crystals, with examples of triplet excitons in the well-known binary system of an isotopically mixed crystal of naphthalene, currently denoted as Nds-Nha. After discussing the drawbacks of treating short-range coulombic excitons in the mean-field scheme at all concentrations (in contrast with the retarded interactions discussed in Section IV.A, which are perfectly adapted to the mean-field treatment), we propose a theory for treating all concentrations, in the scheme of the molecular CPA (MCPA) method using a cell... 

Erkey and Akgerman [8] reported an adsorption equilibrium constant for naphthalene in alumina pores filled with supercritical CO2. Analysis shows that this desorption equilibrium constant is simply proportional to the solubility of naphthalene in CO2 as measured by Tsekhanskaya et al. [9]. Hence, the desorption rate constant was estimated from the following type of correlation reported for the naphthalene-ethylene system by Tsekhanskaya et al. [9] ... 

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