Aromatic hydrocarbons measurement

The relationship between the log A and the van der Waals volumes of alkanes, alkylbenzenes, and polycyclic aromatic hydrocarbons measured in 70% aqueous acetonitrile on octadecyl-bonded silica gels31 is shown in Figure 6.4. 

Otson R, Davis C, Fellin P, et al. 1991. Source apportionment for PAH in indoor air (northern climates). In Cooke M, et al., eds. Polynuclear aromatic hydrocarbons Measurement, means, and metabolism. International Symposium, 11 ed. Columbus, OH Battelle Press, 667-685. 

Table 5.5 Molecular properties of polycyclic aromatic hydrocarbons measured on a model silanol phase. Reproduced by permission of Taylor and Francis, ref. 17.

Polycyclic aromatic hydrocarbons Measurement of intensity of fluorescence ultraviolet after extraction using hexane - gas-phase chromatography or measurement in ultraviolet after thin layer chromatography - Comparative measurements against a mixture of six standard substances of the same concentration ... 

Cooke M, Loening K, and Merritt K (1991) Polynuclear Aromatic Hydrocarbons Measurements, Means and Metabolism. Columbus Battelle Press. 

Goldfarb, J.L., Suuberg, E.M., 2008c. Vapor pressures and thermodynamics of oxygen-containing polycyclic aromatic hydrocarbons measured using Knudsen effusion. Environ Toxicol Chem 27,1244-1249. 

R. Atkinson, J. Arey, B. Zielinska, and A.M. Winer, in M. Cooke, K. Loening, and J. Merritt, eds.. Polycyclic aromatic hydrocarbons measurement, means and metabolism, 1991, Battelle. Columbus, pp. 69-88. 

Perera, R, Tang, D., Whyatt, R., et al, 2005a. DNA damage from polycyclic aromatic hydrocarbons measured by benzo[a]pyrene-DNA adducts in mothers and newborns from Northern Manhattan, the World Trade Center Area, Poland, and China. Cancer Epidemiol. Biomarkers Prev. 14, 709-714. 

Determination of the dissociation constants of acids and bases from the change of absorption spectra with pH. The spectrochemical method is particularly valuable for very weak bases, such as aromatic hydrocarbons and carbonyl compounds which require high concentrations of strong mineral acid in order to be converted into the conjugate acid to a measurable extent. 

The relative basicities of aromatic hydrocarbons, as represented by the equilibrium constants for their protonation in mixtures of hydrogen fluoride and boron trifluoride, have been measured. The effects of substituents upon these basicities resemble their effects upon the rates of electrophilic substitutions a linear relationship exists between the logarithms of the relative basicities and the logarithms of the relative rate constants for various substitutions, such as chlorination and... 

The solubility of hydrogen chloride in solutions of aromatic hydrocarbons in toluene and in w-heptane at —78-51 °C has been measured, and equilibrium constants for Tr-complex formation evaluated. Substituent effects follow the pattern outlined above (table 6.2). In contrast to (T-complexes, these 7r-complexes are colourless and non-conducting, and do not take part in hydrogen exchange. 

Wingen, L. M. Low, J. C. Pinlayson-Pitts, B. J. Chromatography, Absorption, and Pluorescence A New Instrumental Analysis Experiment on the Measurement of Polycyclic Aromatic Hydrocarbons in Cigarette Smoke, ... 

EPA Method 25A is the instrumental analyzer method for determination of total gaseous organic concentration using a flame ionization analyzer. The method apphes to the measurement of total gaseous organic concentration of vapors consisting primarily of alkanes, alkenes, and/or arenes (aromatic hydrocarbons). The concentration is expressed in terms of propane (or other appropriate organic calibration gas) or in terms or carrion. 

Naphthalene and other polycyclic aromatic hydrocarbons show many of the chemical properties associated with aromaticity. Thus, measurement of its heat of hydrogenation shows an aromatic stabilization energy of approximately 250 kj/mol (60 kcal/mol). Furthermore, naphthalene reacts slowly with electrophiles such as Br2 to give substitution products rather than double-bond addition products. 

If, for the purpose of comparison of substrate reactivities, we use the method of competitive reactions we are faced with the problem of whether the reactivities in a certain series of reactants (i.e. selectivities) should be characterized by the ratio of their rates measured separately [relations (12) and (13)], or whether they should be expressed by the rates measured during simultaneous transformation of two compounds which thus compete in adsorption for the free surface of the catalyst [relations (14) and (15)]. How these two definitions of reactivity may differ from one another will be shown later by the example of competitive hydrogenation of alkylphenols (Section IV.E, p. 42). This may also be demonstrated by the classical example of hydrogenation of aromatic hydrocarbons on Raney nickel (48). In this case, the constants obtained by separate measurements of reaction rates for individual compounds lead to the reactivity order which is different from the order found on the basis of factor S, determined by the method of competitive reactions (Table II). Other examples of the change of reactivity, which may even result in the selective reaction of a strongly adsorbed reactant in competitive reactions (49, 50) have already been discussed (see p. 12). 

Robertson et al.261 measured rates of bromination of some aromatic hydrocarbons in acetic acid containing sodium acetate (to eliminate protonation of the aromatic by liberated hydrogen bromide) and lithium bromide (to reduce the rate to a measurable velocity ) at 25 °C, the second-order rate coefficients for 3-nitro-N,N-dimethylaniline and anisole being 14.2 and 0.016 respectively the former compound was thus stated to be about 1012 times as reactive as benzene (though no measurement of the latter rate coefficient, inferred to be 1.33 xlO-11, could be found in the literature) and this large rate spread gives one further indication of the unreactive nature of the electrophile. Other rates relative to benzene were ... 

Spectra at p (=20) wavelengths. Because of the Lambert-Beer law, all measured spectra are linear combinations of the two pure spectra. Together they form a 15x20 data matrix. For example the UV-visible spectra of mixtures of two polycyclic aromatic hydrocarbons (PAH) given in Fig. 34.2 are linear combinations of the pure spectra shown in Fig. 34.3. These mixture spectra define a data matrix X, which can be written as the product of a 15x2 concentration matrix C with the 2x20 matrix of the pure spectra ... 

Fermi golden rule, 268 Filipescu, N., 291 Fisch, M. H., 307 Fischer, F., 379 Flash photolysis, 80-92 of aromatic hydrocarbons, 89, 90 determination of jsc, 228-230 determination of triplet lifetime, 240-242 energy of higher triplet levels, 219-220 flash kinetic spectrophotometry, 82, 83 measurement of triplet spectra, 81,82 nanosecond flash kinetic apparatus, 89 nanosecond flash spectrographic apparatus, 88... 

Geacintov, N.E. Ibanez, V. Benjamin, M.J. Hibshoosh, H. 5 Harvey, R.G. In "Polynuclear Aromatic Hydrocarbons Formation, Metabolism and Measurement" Cooke, M. 5 Dennis, A.J., Eds Battelle Press, Columbus, Ohio, 1983, 554-570. 

Bruggeman, W. A., van der Steen, J., Hutzinger, O. (1982) Reversed-phase thin-layer chromatography of polynuclear aromatic hydrocarbons and chlorinated biphenyls. Relationship with hydrophobicity as measured by aqueous solubility and octanol-water partition coefficient. J. Chromatogr. 238, 335-346. 

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