A Novel Carbonization of Naphthalene and Other Aromatic Compounds in a Molten Mixture of AlCl3–NaCl–KCl

Abstract

The use of molten salt as the solvent made it possible to carry out the carbonization process throughout in the liquid state. The process proceeded at a lower temperature than conventional ones, resulting in higher yields. The carbon was deposited from the reaction mixture as powder or flakes; it was similar to “raw coke” in its composition. Thus, 12.8 g of naphthalene was treated in a mixed melt (mp 95 °C) of AlCl3, NaCl, and KCl (60:26:14 mol%) at 300 °C for 10 h, yielding 11.3 g of carbon. Anthracene, phenanthrene, substituted naphthalene, and biphenyl also gave carbon in yields 69–99% of the theoretical yields, while N-containing heterocycles hardly reacted at all. The X-ray parameters of the carbons, the d002 spacing and the crystal thickness, Lc, varied with the kind of compound used and with other factors; after heat-treatment at 2800 °C, these values were 3.37–3.52 and 20–700 Å respectively. As the mode of reaction, an acid-catalyzed ionic mechanism was proposed, and the role of hydrogen-disproportionation was discussed.