Graphite, intercalated

The nuclear magnetic resonance spectroscopy is one of the techniques that are widely used for researches into intercalated graphite (Estrade-Szwarckopf 1985). Here, the major part of experimental results has been achieved for graphite intercalated with alkali metals since nuclei of isotopes Li, Ru, and Cs are known to have a magnetic moment differing from zero, which allows one to make a record of them in NMR spectra. In the case of graphite intercalated with potassium, it proved possible to record well-resolved spectra for samples with various concentrations of 

Nuclear Magnetic Resonance Studies of Interfacial Phenomena 

FIGURE 3.53 H NMR spectra of water bound to SLGO in CCVDMSO-i/g (1.5/1) medium. 

FIGURE 3.54 H NMR spectra of water in interplanar gaps of intercalated graphite at various pH values of aqueous suspensions at pH (curve 1) 0, (2) 2, (3) 5, and (4) 7. 

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Doping of alkali-metals into CNTs has been examined [11]. The X-ray powder diffraction (XRD) patterns of the K- or Rb-doped CNTs show that alkali-metals are intercalated between the CNT layers. The hexagonal unit cell is essentially the same as that of the stage-1 alkali-metal intercalated graphite ACg (A=K, Rb). For a sample doped with Rb, the observed lattice parameter of the perpendicular... 

McCarron, E. M. et al., J. Chem. Soc., Chem. Comm., 1980, 890-891 The solid product of intercalating graphite with germanium tetrafluoride-fluorine mixtures at 20°C is thought to have an oxidising and fluorinating capability close to that of elemental fluorine itself. 

The intramolecular nature of most carbocationic isomerization was proved by means of labeling experiments. [l-13C]-Propane was isomerized in the presence of aluminum bromide promoted by hydrogen bromide to form [2-13C]-propane. None of the propane product contained more than one l3C atom per molecule.64 Similarly, very little label scrambling was observed in the isomerization of labeled hexanes over SbF5-intercalated graphite.65 Thus simple consecutive 1,2-methyl shifts can account for the isomerization of l3C-labeled methylpentanes (Scheme 4.3). 

The isomerization of cycloalkanes over SbF5-intercalated graphite can be achieved at room temperature without the usual ring opening and cracking reactions, which occur at higher temperatures and lower acidities.110 In the presence of excess hydrocarbon after several hours, the thermodynamic equilibrium is reached for the isomers. Interconversion between cyclohexane (20) and methylcyclopentane (21) yields the thermodynamic equilibrium mixture [Eq. (5.46)]. 

As a model for cracking of alkanes, the reaction of 2-methylpentane (16, 2MeP) over SbF5-intercalated graphite has been studied in a flow system, with the hydrocarbon being diluted in a hydrogen stream.104,105 A careful study of the product... 

The solid product of intercalating graphite with germanium tetrafluoride—fluorine mixtures at 20°C is thought to have an oxidising and fluorinating capability close to that of elemental fluorine itself. 

The isomerization of a series of cyclic and bicyclic saturated hydrocarbons over SbF,-intercalated graphite was achieved at or below room temperature without the ring opening and cracking reactions, and the thermodynamic equilibrium was reached for the isomers in all cases (39). Interconversion between cyclohexane and methylcyclopentane also yielded the thermodynamic equilibrium mixture. 

It was shown that the SbF5-intercalated graphite efficiently promotes disproportionation of various alkylbenzenes by simple mixing at room temperature (41). The isomerization of methylpentanes was carried out over the catalyst at room temperature, -30, and - I7°C in a continuous flow system a careful study of the kinetically controlled product distribution was performed to obtain information for the reaction path (42, 43). The skeletal rearrangements of l3C- abeled 2-methyl, 3-methylpentane and... 

Lalancette et al. studied the catalytic activity of AlCl3-intercalated graphite for the alkylation of aromatics with ethyl bromide, ethylene, propylene, and isobutylene and compared it with pure A1C13 the intercalate was a milder catalyst than AICI3 and gave less polysubstituted products... 

Smith, D. S. and P. C. Eklund. 1983. Optical reflectance studies of stage 1-6 graphite-FeCl3 intercalation compounds. In M. S. Dresselhaus, G. Dresselhaus, J. E. Fischer, and M. J. Moran (eds.), Materials Research Society Symposium Proceedings, Intercalated Graphite, Vol. 20, pp. 99-104, Materials Research Society, Pittsburgh, PA. 

Ohana, I., D. Vaknin, H. Selig, Y. Yacoby, and D. Davidov. 1987. Charge transfer in stage-1 OsF6- and MoF6-intercalated graphite compounds. Phys. Rev. B 35 4522-4525. 

Holzwarth, N. A. W., S. G. Louie, and S. Rabii. 1983. Lithium-intercalated graphite Self-consistent electronic structure for stages one, two, and three. Phys. Rev. B 28 1013-1025. 

Samuelson, L. and I. P. Batra. 1980. Electronic properties of various stages of lithium intercalated graphite. J. Phys. C 13 5105-5124. 

Wang, G., P. K. Ummat, and W. R. Datars. 1988. De Haas-van Alphen effect of potassium intercalated graphite. Extended Abstracts, Graphite Intercalation Compounds, 217-219, Materials Research Society, Fall Meeting, Pittsburg, PA. 

Molodtsov, S. L., Th. Gantz, C. Laubschat, A. G. Viatkine, J. Avila, C. Cassdo, and M. C. Asensio. 1996. Electron-energy bands in single-crystalline La-intercalated graphite. Z. Phys. B 100 381-385. 

FIGURE 12.28 Effects of reaction time and heat treatment on discharge characteristics of fluorine intercalated graphite fibers. (From Touhara, H., et al., Electrochim. Acta, 32, 293, 1987.)... 

Touhara H, Fujimoto H, Kadono K, Watanabe N, Endo M. Electrochemical characteristics of fluorine intercalated graphite fiber-lithium cells. Electrochim Acta 1987 32 293-298. 

Finally, we note that our inferences on the nature of the coal/BF3 product are consistent with recent work on products of coal with ZnCl2 and AICI3 (53). Neither BF3, ZnCl2> nor AICI3 will directly intercalate graphite (2, 6), but all are considered to form sigma complexes with aromatic molecules ( 7, 54). 

Cheng H, Pez GP, Kern G, Kresse G, Hafner J (2001) Hydrogen adsorption in potassium-intercalated graphite of second stage an ab initio molecular dynamics study. J. Phys. Chem. B. 

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