Oxidation graphite

Graphite reacts rather differently with mixtures of oxidising agents and concentrated oxoacids. A graphite oxide is formed the graphite... 

Graphite oxide may explode when heated above 200°C. Below this temperature it converts to a black powder once known as pyrographitic acid. 

The composition varies with the heat treatment and the end point according to x-ray diffraction studies it is a form of carbon that reconverts to weU-ordered graphite on heating to 1800°C. Before the use of x-rays, chemists used the Brodie reaction to differentiate between graphitic carbons and turbostratic carbons. Turbostratic carbons yield a brown solution of humic acids, whereas further oxidation of graphite oxide produces mellitic acid (benzenehexacarboxyhc acid) [517-60-2] ... 

Carbon forms 2 extremely stable oxides, CO and CO2, 3 oxides of considerably lower stability, C3O2, C5O2 and C]209, and a number of unstable or poorly characterized oxides including C2O, C2O3 and the nonstoichiometric graphite oxide (p. 289). Of these, CO and CO2 are of outstanding importance and their chemistry will be discussed in subsequent paragraphs after a few brief remarks about some of the others. 

There are two schools of thought as to the structure of graphite oxide. Ortho or meta ether linkages have been postulated to enforce a puckering of planes (Al), whereas a keto-enol tautomerism was suggested to keep the carbon layers planar (C3). 

With its oxygen functionality, graphite oxide has chemical properties more akin to those of layered disulfides or sheet silicates than to those of graphite (Gi, T1,A2). Many studies have been of an extremely applied nature the possibility of fluorination (LI, N1), redox potentials in the presence of hydrogen peroxide (V2), the apparent density (L2), the adsorption isotherms with nitrogen (L3), and the diffusion of Cs in graphite oxide (R2). 

As with graphite oxide, there are currently two views as to the structure of carbon monofluoride. Although detailed X-ray diffraction work suggested a chair arrangement of the sp -hybridized, carbon sheets (Ml), second-moment calculations of the adsorption mode of the fluorine nuclear magnetic resonance suggested that a boat arrangement is more plausible iE2). The structures are illustrated in Fig. 3. 

The concept of electrochemical intercalation/insertion of guest ions into the host material is further used in connection with redox processes in electronically conductive polymers (polyacetylene, polypyrrole, etc., see below). The product of the electrochemical insertion reaction should also be an electrical conductor. The latter condition is sometimes by-passed, in systems where the non-conducting host material (e.g. fluorographite) is finely mixed with a conductive binder. All the mentioned host materials (graphite, oxides, sulphides, polymers, fluorographite) are studied as prospective cathodic materials for Li batteries. 

Jiang J., Beck F., Krohn H. Electrochemical reversibility of graphite oxide. J. Indian Chem. Soc. 1989 66 603-9. 

Xenon tetraoxide, 4863 Xenon trioxide, 4857 See GRAPHITE OXIDE, HALOGEN OXIDES... 

Fig. 2.1 Top-down synthesis methods, (a) Micromechanical cleavage (b) ion intercalation (c) graphite oxide (d) liquid-phase exfoliation.

D. Cai, M. Song, A simple route to enhance the interface between graphite oxide nanoplatelets and a semi-crystalline polymer for stress transfer, Nanotechnology, 20 (2009) 315708. 

A. Lerf, H. He, M. Forster, J. Klinowski, Structure of graphite oxide revisited, Journal of Physical Chemistry B, 5647 (1998) 4477-4482. 

J. Hummers, William S, R.E. Offerman, Preparation of graphitic oxide, Journal of theAmerican Chemical Society, 80 (1957) 1339. 

S. Stankovich, D.A. Dikin, R.D. Piner, K. a. Kohlhaas, A. Kleinhammes, Y. Jia, et al., Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide, Carbon,... 

H.C. Schniepp, J.-L. Li, M.J. McAllister, H. Sai, M. Herrera-Alonso, D.H. Adamson, et al., Functionalized single graphene sheets derived from splitting graphite oxide, The Journal of Physical Chemistry, B. 110 (2006) 8535-8539. 

A.B. Bourlinos, D. Gournis, D. Petridis, T. Szabo, A. Szeri, I. Dekany, Graphite oxide chemical reduction to graphite and surface modification with primary aliphatic amines and amino acids, Langmuir, 19 (2003) 6050-6055. 

L.J. Cote, R. Cruz-Silva, J. Huang, Flash reduction and patterning of graphite oxide and its polymer composite, Journal of the American Chemical Society, 131 (2009) 11027-11032. 

V. Eswaraiah, S.S. Jyothirmayee Aravind, S. Ramaprabhu, Top down method for synthesis of highly conducting graphene by exfoliation of graphite oxide using focused solar radiation, Journal of Materials Chemistry, 21 (2011) 6800. 

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