Health & Environmental Research Online (HERO)


Print Feedback Export to File
3137680 
Journal Article 
C16H10 ethynyl-substituted polycyclic aromatic hydrocarbons from the pyrolysis of coal, coal volatiles, and anthracene 
Wornat, MJ; Ledesma, EB 
2000 
1 
Polycyclic Aromatic Compounds
ISSN: 1040-6638
EISSN: 1563-5333 
Taylor and Francis Ltd. 
18 
2 
129-147 
English 
WOS:000166198700002 
The acquisition of several specially synthesized reference standards of ethynyl-substituted three-ring polycyclic aromatic hydrocarbons (PAH) has enabled us to identify, for the first time, two C16H10 ethynyl-PAH among the pyrolysis products of coal and coal-derived fuels. The fuel product mixtures are analyzed by high-pressure liquid chromatography (HPLC) with diode-array ultraviolet (UV) absorbance detection, and the identifications are made by matching product components' HPLC elution times and UV absorption spectra with those of the reference standards. 2-ethynylanthracene and 2-ethynylphenanthrene are identified among the pyrolysis products of brown coal, pyrolyzed at 1000°C in a fluidized-bed reactor, and of bituminous coal volatiles, pyrolyzed at 1000°C in a tubular flow reactor. 2-ethynylanthracene is observed as a pyrolysis product, at 1300 to 1500 K, of anthracene, a three-ring model compound representative of the aromatic moieties in coal. The identification of these ethynyl-PAH provides important experimental evidence that acetylene addition to aryl radicals indeed takes place in these fuel reaction environments, as is customarily assumed in modelling of PAH growth during combustion. 2-ethynylanthracene and 2-ethynylphenanthrene are similar in that their proposed precursors, 2-vinylanthryl and 2-vinylphenanthryl, are configurationally precluded from undergoing cyclization reactions to form cyclopenta-fused PAH. Other isomers of ethynylanthracene and ethynylphenanthrene - whose precursors can undergo this cyclization - do not appear among our pyrolysis products, but the cyclization products, aceanthrylene and acephenanthrylene, do. Our experimental observations are thus consistent with theoretical calculations showing that the formation of cyclopenta-fused PAH by cyclization, when allowed, is energetically favored over the production of ethynyl-PAH. 
polycyclic aromatic hydrocarbons; ethynyl substitution; coal; anthracene; pyrolysis; HPLC with UV detection