Identification of Isomeric Naphthyl-Anthracenes Generated from the Pyrolysis of an Anthracene/Naphthalene Mixture

Abstract

A 1:l moleratio mixture of anthracene and naphthalene was pyrolyzed in a drop-tube furnace. The product mixture was analyzed by high performance liquid chromatography with diode-array, UV-absorption spectrometric detection (HPLCDAD) and by gas chromatography/mass spectrometry (GCMS). In addition to previously characterized bianthracene and binaphthalene isomers, 6 isomeric naphthyl-anthracenes were identified. Because of the unavailability of standard reference compounds, structural elucidation was achieved by comparing UV spectral features, mass spectral fragmentation patterns, and GCMS and HPLC elution order with those for bianthracenes, binaphthalenes and other structurally similar molecules. In addition, steric hindrance to rotation at the naphthalene-anthracene bond, a factor that governs the degree of non-planarity of the isomers and thus influences HPLC elution order and MS fragmentation patterns, was estimated using a semi-empirical molecular orbital model.

Precise PPP molecular orbital calculations of excitation energies of polycyclic aromatic hydrocarbons. Part 6. Spectrochemical atomic softness parameter†

“…3 The αand the β-bands are identified as π-π* transitions described by mainly HOMOϪ1→LUMO or HOMO→LUMO+1 transitions for small PAHs. 16 However, for large PAHs they are identified as a π-π* transition described by mainly HOMOϪ2→LUMO or HOMO→LUMO+2 transitions. The characters of HOMOϪ1 (and LUMO+1) for naphthalene and anthracene resemble those of HOMOϪ2 (and LUMO+2) for naphthacene and pentacene as shown in Fig.…”

Polycyclic Aromatic Hydrocarbons with Five-Membered Rings: Distributions within Isomer Families in Experiments and Computed Equilibria

“…These similarities in PAH product distribution, observed across a broad range of experiments, may be explained if the PAH are formed via a limited set of significant reactions that occur mostly independent of fuel and reactor configuration. In fact, two canonical reactions for PAH formation and growth have been identified previously: ,− the Badger mechanism for the union of an aryl radical to an aromatic molecule, and the hydrogen-abstraction/C 2 -addition mechanism , for the addition of C 2 and subsequent ring closure. Isomerization reactions have also been suggested ,, to play a significant role in determining experimentally measured PAH product distributionsin some cases 27 bringing about the production of more mutagenically active members within an isomer family.…”