Action des molécules organiques sur les composés d'insertion de métaux alcalins dans le graphite II. Cas des hydrocarbures aromatiques

Abstract

Penetration of aromatic molecules (benzene, toluene) into graphite inclusion compounds (CI) of alkali metals (lithium, potassium, rubidium) has been studied by X-ray diffraction. No modification occurs with first stage CI (LiC 6, KC 8, RbC 8). Second stage CI are modified: a ternary phase, which contains two filled layers (9.4 Å) within one identity period, is observed with KC 24. The rate of benzene penetration was measured by gravimetric analysis. The penetration reaction is very slow with LiC 12, but a solution of polystyrene in benzene gives two phases, one of them corresponding to a benzene molecule parallel to the graphite layer, between this and the cation; so that the interlayer distance is 7.55 Å. We assume that the other one (13.17 Å) is due to polystyrene. Penetration into the third stage CI KC 36 can yield an inclusion of benzene. This molecule leads to an interlayer distance of 7.3 Å. In conclusion, we can say that several phases can exist under different reaction conditions (temperature, time). It seems that, initially, the aromatic molecules are parallel to the graphite layers.