Abstracted from thesis (PH. D.) - University of Michigan, 1942. / An article, by G.H. Hanson and G.G. Brown, reprinted from Industrial and engineering chemistry, v. 37, Sept. 1945. Literature cited: p. 825.

Abstracted from thesis (PH. D.)--University of Michigan, 1942. / "Presented before the Division of Petroleum Chemistry at the 104th meeting of the American Chemical Society, Buffalo, N.Y." An article, by C.F. Weinaug and D.L. Katz, reprinted from Industrial and Engineering Chemistry, v. 35, Feb. 1943. "Literature cited": p. 246.

Proefschrift--Groningen. / Summary in Dutch. Includes bibliographical references and index.

AN ABSTRACT OF THE DISSERTATION OF DINESH SINGH RAWAT, for the Doctor of Philosophy degree in APPLIED PHYSICS, presented on July 6 2009, at Southern Illinois University Carbondale. TITLE: STUDY OF GAS ADSORPTION ON AS-PRODUCED AND MODIFIED CARBON NANOTUBES MAJOR PROFESSOR: Dr. Aldo D. Migone Volumetric adsorption isotherm measurements were used to study the adsorption characteristics of Ethane (C2H6) and Butane (C4H10) on as-produced single-walled carbon nanotubes. The binding energy of the adsorbed alkane molecule was found to increase with increasing carbon chain length. Two adsorption substeps were obtained for each alkane molecule. However, the size of the high pressure substep was found to be gradually smearing with the increase in size of the adsorbed molecule. This phenomenon is interpreted as size entropy effect for linear molecules. This interpretation was also verified by determining the specific surface area of the substrate using linear molecules of different sizes. Kinetics measurements of alkane adsorption on SWNTs were also conducted and their dependence on the molecular length was determined. Similar adsorption measurements were performed for Argon (Ar) on as-produced single-walled carbon nanotubes and nanotubes that were structurally modified using acid treatment. Enhancement of the sorptive capacity and the presence of two distinct kinetics of gas adsorption verified partial opening of single walled carbon nanotubes as a result of chemical treatment. Mutiwalled carbon nanotubes were exposed to oxygen plasma treatment for varying time periods. Afterwards, adsorption measurements of Methane (CH4) were conducted on untreated and oxygen plasma treated tubes. The presence of an additional substep, after exposing multiwalled carbon nanotubes to oxygen plasma for varying time periods, suggested progressive cleaning of nanotube surface.

The work in this thesis investigates the selectivity in the direction of attack in the chlorination of a wide variety of substituted alkanes. The main chlorinating agent studied is atomic chlorine, although the selectivity of some other hydrogen abstracting radicals receives attention. Gas phase chlorination is studied, but more attention is given to the effect of solvent systems on the reaction selectivity. The chlorination of 1,1-dichloroethane is studied. The relative Arrhenius parameters for the gas phase reaction as well as for the reaction in non-complexing and complexing liquid phase systems are determined. The reaction selectivity is shown to be a balance of enthalpy and entropy effects. The selectivity in a range of solvent systems is investigated. The novel use of perfluorinated compounds as solvents is studied and selectivities are found to be nearly as high as those in the gas phase. Earlier work on the directive effects in the chlorination of 1-substituted butanes in the gas phase is extended to both non-complexing and complexing liquid phase media. The results agree with earlier proposals that in the liquid phase the inductive effect of a substituent influences the reactivity of the carbon centres much further along the alkane chain than in the gas phase. They also indicate that in complexing media the deactivating effect of the substituent is diminished and higher selectivities are obtained. The chlorination and bromination of 1-nitrobutane is studied. This is one of the few studies that have been made on the halogenation of nitroalkanes. The electron withdrawing power of the nitro group makes it the strongest deactivating group so far observed. For the first time the directive effect of two substituents, one at each end of an alkane chain, is studied. The chlorination of 1,4-disubstituted butanes are investigated. The results go some way to confirm that the polar inductive effect of a substituent is diminished in complexing media. They also confirm that in non-complexing media the effect of the substituent is felt along the whole butane chain. The gas phase results indicate that the presently held theory that in gas phase chlorination the substituent only affects the reactivity of the two carbon centres adjacent to it may not now be wholly acceptable.

The work described in this thesis focuses on the urea inclusion compounds of α, ω-dibromo-n-alkanes: Br(CH2)[sub]nBr/urea, where n=7-10. The structural and dynamic properties of the host and guest have been studied using complementary techniques. Photographic single crystal x-ray diffraction shows that, in the regions of three- dimensional guest molecular ordering, there is a well-defined offset, Δg, along the channel axis, c, between guest molecules in adjacent channels. Δg is exactly one-third of the periodic repeat distance along c of the basic guest structure: this represents a new mode of interchannel guest ordering in urea inclusion compounds. Raman spectroscopy shows that the 'bulk' conformation of the guest molecules is the linear, trans, extended form, but that there is a small, but measurable, proportion of Br end-groups in the gauche conformation. Incoherent quasielastic neutron scattering indicates that the guest molecules undergo two motions on the picosecond time-scale, at sufficiently high temperature: translations along the channel axis and reorientations about the channel axis. These motions are successfully modelled as, respectively, continuous linear diffusion between two impermeable boundaries and uniaxial rotational diffusion in a one-fold cosine potential. Deuterium nuclear magnetic resonance spectra are shown, via simulations, to be consistent with a 180° flipping motion of the urea molecules about their C=O axes, occurring on the microsecond time-scale at room temperature. This technique also provides confirmation of guest molecular motion. The structure of 1,6-dibromohexane/urea is found to differ from that of the other a,w-dibromoalkane/urea inclusion compounds studied: crystal structure determination shows that it is monoclinic, and that the host and guest structures are commensurate with one another. Raman spectroscopy confirms that the Br end-groups are exclusively in the gauche conformation. The urea inclusion compounds of various other guest molecules have also been investigated briefly. The complementary nature of the techniques used is crucial in establishing a complete picture of the structure and dynamics of all these compounds.

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