Carbonization of Anthracene and Phenanthrene. 2. Spectroscopy and Mechanisms

The C, H analysis and FTIR and ¹H NMR data on the carbonization products from anthracene and phenanthrene showed remarkable differences in reaction chemistry and mechanisms for these isomers. As different from phenanthrene, anthracene involves extensive hydrogenation reactions which lead to the formation of hydroaromatic compounds in the liquid phase during carbonization. Dreiding models of reaction products based on the C, H contents and spectroscopic data along with the minimization of the force field equation showed that anthracene produced planar oligomers more readily than phenanthrene. A mechanism is proposed for the two dimensional growth of discotic mesogens using Hückel molecular orbital calculations combined with structural modeling. Distinctly different chemistry and kinetics of carbonization in connection with geometrical arrangements of oligomers explain the different degrees of mesophase development obtained from anthracene and phenanthrene.