Graphite, intercalation compounds halogenation

B. Halogenation in Presence of Activated Carbon and Graphite Intercalation Compounds (GIC)... 

Graphite Intercalation Compounds.— The reactions of graphitizable carbons leading to the formation of graphite intercalation compounds have been reviewed. Emphasis was placed on the insertion of alkali metals (Na), halogens (Brg), and acids (H2SO4). The effects of electronic structure and electron exchange on intercalation reactions were also considered. 

The presence of the potassium atoms causes the distance between the layers of carbon atoms to increase from the value of 235 pm in graphite to 540 pm in C8K. When rubidium and cesium atoms are placed between the layers, the distances between the carbon layers are 561 and 595 pm, respectively. As would be expected for materials that contain atoms of an alkali metal, these materials are extremely reactive in air, and they react explosively with water. A large number of other intercalation compounds have been prepared that have halogens, interhalogens, or metal halides as the included substances. 

Biintercalation, an interleaving of different inserted species, has been studied in the case of inserted halide species " . Halogen-containing solvents, with metal chlorides, can also lead to ternary phases, such as graphite-FeCl3-C2H4Cl2 . A different approach to inserted halides is the intercalation compound with trimethyltin chloride . Finally, the intercalation of halides into carbon fibers is an area of increasing interest . ... 

Yb) were synthesized and under definite conditions, compounds with iron were obtained. Graphite acts as a donor of electrons when it interacts with halogens, and intercalation compounds with Br2, ICl, IBr molecules are easily formed, while the compound with CI2 is extremely unstable. At low temperatures (15-100°C), graphite interacts with fluorine with the help of catalysts (HF, AgF). This fluorination results in the formation of graphite... 

Like the alkali metals, some halogens, particularly fluorine, form intercalated compounds with graphite crystals. Reaction usually starts at 600°C. However, graphite does not react with chlorine at temperatures below that of the electric arc. 

GICs have been first discovered from the reaction of graphite with sulfuric acid more than 150 years ago.30 In the long history of GICs research, a huge number of compounds have been yielded with a large variety of donors and acceptors, in which alkali metals, alkaline earth metals, transition metal chlorides, acids, and halogens are involved as typical intercalates. 

Covalent C—F bonds are also detectable in lamellar n charge-transfer graphite compounds such as CjSbFj C KrFj and halogen fluorides (see 16.4.2.1.1 and reviews ). These mixed covalent-rr charge-transfer compounds arise from internal fluorination by the intercalant. 

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