Model Compound Study of the Pathways for Aromatic Hydrocarbon Formation in Soot

Abstract

As a follow-up of previous work on the flame pyrolysis of biphenyl and pyrene, a more detailed analysis of the pyrolytic products has been done using additional NMR data obtained on the whole soot sample correlated with detailed high-resolution and GC mass spectrometry data on the solvent-extracted portion of the same samples. These latter data complement the earlier NMR data with details of the pre-sooting structures, referred to as “young soot”, in pyrolyzed biphenyl samples collected at 1365, 1410, and 1470 K and pyrene at 1410 and 1470 K. The data reveal the roles played by free-radical-assisted polymerization reactions as well as the hydrogen-abstraction carbon-addition (HACA) reactions for the biphenyl pyrolysis. The mass spectroscopy data of pyrene describe a much different set of reactions due to polymerization which employs free-radical reactions of the pyrene due primarily to hydrogen abstraction followed by the formation of biaryl linkages at mass numbers up to five times that of the parent pyrene. Conceptual schema of reaction mechanisms are proposed to explain the formation pathways to materials detected in the soot extracts.

Characterization of Macromolecular Structure Elements from a Green River Oil Shale, I. Extracts

“…22 One should note that biaryl linkages (zero mass bridges) are considered substituted aromatic carbons as their shift tensor and isotropic shift shows. 46 In previous work, 47 seven pyrene molecules were hooked together, having f a S = 12/112 = 0.11 and no aliphatic material. There is only a loose correlation between the amount of substituted carbons and the amount of aliphatic material when biaryl linkages are present.…”

Microwave Flash Pyrolysis

“…Gas phase pyrolysis of aromatic compounds often yields highly complex mixtures in which rings are broken, formed, rearranged, or joined together . Polycyclic aromatic ring synthesis has been widely studied because of its relationship to soot formation in combustion chemistry. , This is also a critical area of materials science where many high-temperature cycloaromatizations have been described. ,, …”

13C chemical-shift anisotropy of alkyl-substituted aromatic carbon in anthracene derivatives

“…In fact the substructure, which is shown in Fig. 7 (IUPAC name 9,10-dihydro-9,10-but [2] enoanthracene) that retains only part of the center ring above the a-carbon in a dihydroanthracene like base, reproduces dianthracene's a-position CSA to within 0.4 ppm (see Table 3). Moreover, this substructure matches d 22 to 0.5 ppm.…”

“…Information about the aromatic content of carbonaceous solids is often desired when quantifying natural materials, i.e., coal [1], coal combustion by-products [2], kerogen [3,4], humic matter [5], etc. High resolution ssNMR may be used to obtain the fraction of aromaticity and to estimate the number of fused rings in polycyclic aromatic hydrocarbon (PAH) by proper deconvolution of the high resolution carbon spectrum [6][7][8][9][10].…”