Toward Validating a Framework for Modeling High-Throughput Analytical Techniques Employed for Energetic Material Screening. Part 2. Desorption/Pyrolysis-Gas-Chromatography/Mass Spectrometry (D/P-GC/MS) Results for β-Myrcene

Author(s):

Rose Pesce-Rodriguez and Michael McQuaid

Abstract:

In support of an effort to develop machine-learning methods that will accelerate the creation of detailed chemical kinetics mechanisms, gaseous products of the Pyroprobe-induced pyrolysis of β-myrcene (7-methyl-3-methylidene-1,6-octadiene) were separated via gas chromatography, and their identities and relative abundances were established via mass spectroscopy. Chromatograms generated by experiments in which samples were heated at 1000 °C/s to one of four set point temperatures (T_sp = 175, 500, 700, or 1000 °C) are presented and analyzed. Features attributable to myrcene dimers and isomers of myrcene were observed in all four cases. No products smaller than myrcene (C₁₀H₁₆) were observed in the T_sp = 175 experiment’s chromatogram. Except for a feature attributable to 3-methylene-cyclopentene, the T_sp = 500 °C experiment’s chromatogram was not significantly different from the T_sp = 175 °C experiment’s chromatogram. The main products observed in the T_sp = 700 and 1000 °C experiments were 2-methyl-1,3-butadiene, benzene, toluene, 2,4,6-trimethyl-1,3,6-heptatriene, and 5-ethylidene-1-methyl-cycloheptene. Smaller quantities of ethene, cyclopropane, 1,2-propadiene, 2-methyl-propene, 1,2-butadiene, and cis-2-pentene were also observed. In addition to these products, polycyclic aromatic compounds were produced in the T_sp = 1000 °C experiment. Normalized abundances for all products observed at each of the four T_sp values were calculated. The data poses a demanding test for a model’s capacity to represent the pyrolysis of an unsaturated hydrocarbon.