(164c) Isolation of Thermally Polymerized Naphthalene Pitch Oligomers via Dense Gas Extraction

Semi-continuous, packed-column supercritical extraction (SCE) with toluene was used to fractionate various polycyclic aromatic hydrocarbon (PAH) pitches into their constituent oligomers. In particular, the starting model pitch samples were produced by the catalytic polymerization of pure pyrene using AlCl3, or by thermal polymerization, with both being done at temperatures from 300-500 °C.

In order to better understand the system of reactions occurring, our group chose to developed a kinetic model for the catalytic reaction of pyrene to an oligomeric pyrene pitch. Each sample was reacted for a different period of time in order to vary the oligomeric composition of the final pitch product, such that kinetic data on the pyrene polymerization process could be obtained.

Because typical concentration measurement techniques will not work on the bulk pitch, SCE was used to separate each sample into its constituent oligomers, such that an oligomeric mass balance could be performed on the reacted pitch products. Both MALDI-TOF and DEPT-135 C-NMR were used to confirm sample purities. Using the kinetic data obtained, a kinetic model was proposed and rate constants, activation energies, and pre-exponential factors were obtained for this system of reactions.

In addition to the pyrene work, this talk will discuss initial efforts to fractionate oligomers of naphthalene, anthracene, and phenanthrene into their constituent “mers” via SCE, so that those which have an inherently liquid crystalline nature can be identified.