Identification of C₂₀H₁₀Dicyclopentapyrenes in Flames:  Correlation with Corannulene and Fullerene Formation

Abstract

Ethylene combustion products obtained over a range of conditions regularly show peaks with retention times and mass spectra expected for C 20 H 10 polycyclic aromatic hydrocarbons (PAH) when analyzed by gas chromatography/mass spectrometry (GC/MS). Analysis by high-performance liquid chromatography with spectrometric diode-array detection (HPLC/DAD) yields three distinct peaks over the C 20 PAH elution interval whose UV-vis spectra differ from those of known PAH. These results, highly characteristic of ethylene flames, strongly suggested the presence of at least three C 20 H 10 PAH. Recent progress in PAH synthesis permitted the comparison of chromatographic and spectrometric data for flame samples with those of authentic dicyclopentapyrenes: dicyclopenta[cd,fg]pyrene, dicyclopenta[cd,mn]pyrene, and dicyclopenta [cd,jk]pyrene. The comparative analysis established that the three C 20 H 10 PAH long observed in ethylene flames were indeed the three dicyclopentapyrene isomers. Additional analysis of samples from a range of flames showed that the dicyclopentapyrenes are present in fullerene-deficient flames, but are absent in fullerene-producing flames. The dicyclopentapyrenes are notable for being isomers of corannulene, a possible fullerene precursor also found in a range of flames. The significance of these findings in relation to the flame production of fullerenes is discussed.

Mass spectrometric analysis of large PAH in a fuel-rich ethylene flame

“…However, the rearrangement of a PAH with an externally fused cyclopenta group toward a PAH with a centrally cyclopenta fused group is a process which has been observed under conditions pertinent to combustion as reported by Scott [26] and Lafleur et al [27]. Thus the presence of PAH with pentagon rings in the periphery detected by mass spectrometry can be considered as a signature of the presence of curved PAH with internally fused cyclopenta groups.…”

Soot Formation in Combustion Processes (Review)

“…Concentration of Propane Oxidation Products Versus the Temperature of the Second Reactor Section (p = 40 kPa, T 1 = 300 K, and t = 10 sec) T , K Partial pressure, kPa [31,90]. In [79], the maximum particle diameter measured in experiments with a low-pressure onedimensional homogeneous mixture in an acetylene flame [91,92] was correlated with the value of H/C determined under similar conditions [59].…”

“…In addition, it is found [31] that the nucleation of soot particles is accompanied by deposition of fullerenes on them.…”

Flash Vacuum Thermolysis of Acenaphtho[1,2-a]acenaphthylene, Fluoranthene, Benzo[k]- and Benzo[j]fluoranthene – Homolytic Scission of Carbon-Carbon Single Bonds of Internally Fused Cyclopenta Moieties atT ≥ 1100 °C

“…1 H NMR showed twelve distinct 1 H signals, which in combination (CP)-PAH, which have all been identified as important combustion effluents (vide infra). [16] with 1 H-homonuclear decoupling experiments strongly sugScheme 2 gested that its structure corresponds to cyclopenta[def]ben-amount of 3 corresponds to an increase of 4 as well as 6 ( Table 2). Whereas the amount of 4 increased with increaszo[hi]chrysene (6, Scheme 2 and Figure 2).…”