Chlorine-graphite compounds

In contrast to bromine, the stability of chlorine-graphite compounds is markedly worse. Because of this intercalation of chlorine into graphite occurs effectively only at low temperature. In 1952 Hennig succeeded in carrying out the process in liquid chlorine for the first time [60]. Intercalation was concluded based on the fact that electrical resistance decreased over the course of three days to 10% of the initial value. Juza et al. [164,165] came to the same conclusion noting the disappearance of the anomalous diamagnetism at —78°C. This disappearance was distinctly faster for... 

The presumed nonintercalation of a given compound may, however, be due to the fact that appropriate experimental conditions for intercalation have not yet been found. Thus, some of the rare-earth chlorides originally considered not to intercalate Cll, V5), do, in fact, do so in the presence of a complexing agent S21). In addition, the role of chlorine in compound formation has been the subject of controversy. Whereas Croft (Cl) considered the presence of an excess of chlorine to be nonessential, it has since been shown to be a sine qua non for compound formation (D3, RIO, H13, Rll, S22, B17, H25). Moreover, contrary to earlier assumptions (RIO), chlorine does not act as a catalyst, but is incorporated into the graphite to a greater or lesser extent Rll, D3). In cases where the presence of chlorine is apparently not required... 

Pyral A process for destroying toxic waste oiganochlorine compounds. The wastes are mixed with carbon and sodium carbonate and injected into a graphite-lined arc furnace. Metallic sodium, formed by reduction of the sodium carbonate by the carbon, attacks the chlorinated organic compounds, forming sodium chloride. Developed by Hydro-Quebec in the late 1980s but not yet commercialized. 

Chlorinated aliphatic compounds were dechlorinated even in water by electrochemical reduction on a Zn-modified carbon cloth cathode consisting of partly amorphous and partly graphitized carbon material with 10 wt.% Zn [9]. This electrode has good adsorption properties, conductivity, and stability in different solvents, allowing the combination of both adsorption and... 

According to Dzurus and Hennig 15) the free chlorine necessary for the occurrence of reaction between graphite and aluminum trichloride does not act catalytically, as Riidorff and Zeller first assumed, but is partly taken up in the lattice. Riidorff and Landel 61) found this to be true of the gallium trichloride-graphite compound also. For both compounds the ratio Me Cl is between 1 3.2 and 1 3.4 and the compounds therefore oxidize potassium iodide solution and cause iodine to separate. 

The history of iaclusion compounds (1,2) dates back to 1823 when Michael Faraday reported the preparation of the clathrate hydrate of chlorine. Other early observations iaclude the preparation of graphite iatercalates ia 1841, the P-hydroquiaone H2S clathrate ia 1849, the choleic acids ia 1885, the cyclodexthn iaclusion compounds ia 1891, and the Hofmann s clathrate ia 1897. Later milestones of the development of iaclusion compounds refer to the tri-(9-thymotide benzene iaclusion compound ia 1914, pheaol clathrates ia 1935, and urea adducts ia 1940. 

Synthesis by means of volatile compounds A number of halides (especially chlorides) of the transition metals display a high volatility and in the gaseous state they are easy to mix. They can be synthesized from oxides, or scrap metals, and chlorine they are highly reactive and can be utilized for the preparation of various compounds, either as powder or a coherent solid or as coatings. Mixtures, for instance, of TiCLj + CH4 + H2 have been used to prepare ultrafine TiC powder, to deposit TiC on graphite (at 1200-1300°C), etc. 

Strontium metal is not found in its elemental state in nature. Its salts and oxide compounds constitute only 0.025% of the Earths crust. Strontium is found in Mexico and Spain in the mineral ores of strontianite (SrCO ) and celestite (SrSO ). As these ores are treated with hydrochloric acid (HCl), they produce strontium chloride (SrCy that is then used, along with potassium chloride (KCl), to form a eutectic mixture to reduce the melting point of the SrCl, as a molten electrolyte in a graphite dish-shaped electrolysis apparatus. This process produces Sr cations collected at the cathode, where they acquire electrons to form strontium metal. At the same time, Cl anions give up electrons at the anode and are released as chlorine gas Cl T. 

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