Alkane , studies

Harris, S.J., Kerr, J.A. (1988) Relative rate measurements of some reactions of hydroxyl radicals with alkanes studied under atmospheric conditions. Int. J. Chem. Kinet. 20, 939-955. 

Siebbeles, L.D.A. Emmerichs, U. Hummel, A. Bakker, H.J. J. Chem. Phys. 1997,107, 9339. Dellonte, S. Barigelletti, F. Orlandi, G. Flamigni, L. Intramolecular Deactivation Processes and Energy Transfer Mecahanism in Liquid Alkanes Studied by N2 Laser Two Photon Excitation. Proceedings 5th Tihany Symposium on Radiation Chemistry. Dobo, J. Hedvig, P. Schiller, R., Eds. Akademiai Kiado Budapest, 1983 437 pp. 

The energetics data are presented in terms of heat of adsorption as a function of average zeolite pore diameter. Average pore diameter is applicable to those zeolites with elliptical pore openings, and the pore dimensions employed are those usually used to characterize the zeolite. The heat of adsorption as a function of pore diameter was predicted to exhibit a maximum around 5 A for all the alkanes studied, as shown on Fig. 11. The optimum heat of adsorption of straight-chain alkanes appears to be achieved by a pore with dimensions close to that of the 10-ring channel in ferrierite. 

Table I shows also the yields of individual O-heterocycles formed among the oxidation products of the different alkanes studied. Since it is known that abstraction of hydrogen by free radicals takes place more readily from a CH2 group than from a CH group (5, 6, 12), a marked tendency for the O-heterocycles not to include in the ring the terminal carbon atoms of the original hydrocarbons might be expecfed. With n-pentane and n-hexane, no such O-heterocycles are in fact found. On the other hand, n-butane on oxidation gives rise to several O-heterocycles with one or both terminal carbon atoms incorporated in the ring. This...

A Hammett correlation was also established for chlorinated alkanes studied by UV/Ti02. The least substituted compound, ethane, was used as a reference compound. Figure 9.23 demonstrates the Hammett correlation for chlo-... 

Hammett s correlation for chlorinated alkanes studied by UV/Ti02. Experimental conditions 0.1 wt% TiOj 10 ppm initial concentration 20-mL reactor volume pH 7. 

Polymerization of the bicyclo [n. 1.0] alkanes studied therefore occurs by opening of the cyclopropane ring and results in the appearance of one methyl group per structural unit. 

Figure 13.12 illustrates these three important facts about alkanes. Study the two alkanes, then complete the Practice Problems that follow. 

For the linear alkanes studied (methane, ethane and propane), the fact that only one type of acid site can be represented with the 3T and 5T clusters should not be a major problem. As shown by the MD studies, because of their sizes, steric effects are of minor importance and these molecules have equal probability of visiting aU the distinct sites of the zeolite. In another words, for these molecules, as far as steric effects are concerned, the acid sites are all alike. Thus, the interaction between any of these molecules and the zeolite will depend mainly on the sites acidic strengths, which do not differ very much from each other. Therefore, for these molecules it is a reasonable approximation to treat aU the acid sites alike. However, for isobutane steric effects are more important and the molecule should be more sensitive to the type of the acid site. It will be easier for the isobutane molecule to approach the acid sites represented by 3T and 5T clusters than the one at the channels intersection, in the real zeolite, where it preferentially adsorbs. Therefore, for isobutane and other branched alkanes (and most probably for the large n-alkanes), the chemical reactions at the 3T and 5T clusters may take place artificially easier than in the real zeolite. 

Since the work of Bailey and Norrish O-heterocycles have been found in the products of every alkane studied of carbon number > 4, as shown in Table 1 and their yields are often considerable particularly under cool-flame conditions as shown in Table 2 and Fig. 7. 

A number of papers concerned with the decomposition behaviour of organic halogen compounds in the mass spectrometer and related systems is to be found in the journal Organic Mass Spectrometry. For example, in the case of fluoro-compounds, McCarthy has discussed mass spectral correlations for fluorinated alkanes studies by other workers have included those on aromatic fluoro-com-pounds , fluorine-containing dimethyl esters , and tetrafluoroethanes . In the same journal, studies on other halogen compounds include dichlorocyclo-propanes , norbornyl chlorides and bromides , j8-phenylethyl bromides , and chloro-substituted benzynes . 

As the chains lengthen, the torsions gradually decrease in intensity and although always visible in the -alkanes studied here, are only barely observable in low molecular weight polyethylene and not detectable in the most common grades. In the shorter alkanes their overtone intensities (-490 cm ) are weak but can be extracted. The overtone to fundamental intensity ratio (5(2—o/5 (im))) for hexane was measured, 0.14 + 0.04,... 

Eichmann, R., P. Neuling, G. Ketseridis, J. Hahn, R. Jaenicke, and C. Junge (1979). n- Alkane studies in the troposphere—I. Gas and particulate concentrations in North Atlantic air. Atmos. Environ. 13, 587-599. 

While product analysis is an important source of information on the early stages of radiolysis, this approach has a serious problem For all of the alkanes studied, the yield of primary decomposition estimated from the total product yields significantly exceed the ionization yield 6 to 6.5 per 100 eV vs. 4.5 to 5 per 100 eV [1]. This suggests that some of the products were counted twice i.e., that fragmentation of the excited states is more extensive than was assumed. For example, instead of H2 elimination, the exited state may eliminate... 

Pireaux J, Svensson S, Basilier E, Malmqvist P, Gelius U, Gaudano R, Siegbahn K (1976) Core-election relaxation energies and valence-band formation of linear alkanes studied in gas-phase by means of electron-spectroscopy. Phys Rev A 14 2133-2145... 

Neat PE was also studied in the melt. The 2930 cm"l and 2850 cm"l bands behave as expected from the alkane study. A plot of the ratio of their intensities versus temperature is shown in Fig. 6. The function is also a straight line and parallel to the lines for neat n-C and diluted n-C2 5 in COCl3(Fig. 5). Therefore, the same procedure can be used to calibrate the mentioned Raman intensities for PE as was used for li this way, a quantitative measurement of the gauche bond content of a linear polymer can be obtained. 

Rate constants for hydrogen abstraction reactions of the sulfate radical have also been measured at room temperature in a solution of 95% acetonitrile-5% water [79]. For the alcohols and ethers, the rate constants measured were 20-80 times slower that those obtained in aqueous. solutions. The three alkanes studied in pure water were not also investigated in the mixed solvent, but studies on larger alkanes resulted in calculated rate constants 4.9 x lO" L mol" s" for... 

Different tqiproaches can be adopted in assigning weighting factors. In the particular case of crystalline n-alkanes studied by Snyder [27] the weighting factors to the observed intensities are inversely proportional to die respective observed values. 

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