An experimental and theoretical study of the high temperature reactions of the four butyl radical isomers

• Published in: Physical chemistry chemical physics : PCCP 2020-09, Vol.22 (33), p.1834-18319
• Main Authors: Randazzo, John B, Sivaramakrishnan, Raghu, Jasper, Ahren W, Sikes, Travis, Lynch, Patrick T, Tranter, Robert S
• Format: Article
• Language: English
• Subjects: Activation; Adducts; Aldehydes; Chemical reactions; Cleavage; Coefficients; Densitometers; Densitometry; Disproportionation; Experiments; High temperature; High temperature gases; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Isomers; Low pressure; Mass spectra; Mass spectrometry; Nitrites; Photoionization; Pressure dependence; Rate constants; Reaction kinetics; Reaction mechanisms; Stabilization; Synchrotrons; Vapor phases
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d0cp02404j

The high temperature gas phase chemistry of the four butyl radical isomers ( n -butyl, sec -butyl, iso-butyl, and tert -butyl) was investigated in a combined experimental and theoretical study. Organic nitrites were used as convenient and clean sources of each of the butyl radical isomers. Rate coefficients for dissociation of each nitrite were obtained experimentally and are at, or close to, the high pressure limit. Low pressure experiments were performed in a diaphragmless shock tube with laser schlieren densitometry at post-shock pressures of 65, 130, and 260 Torr and post-shock temperatures of 700-1000 K. Additional experiments were conducted with iso-butyl radicals at 805 K and 8.7 bar to elucidate changes in mechanism at higher pressures. These experiments were performed in a miniature shock tube with synchrotron-based photoionization mass spectrometry. The mass spectra confirmed that scission of the O-NO bond is the primary channel by which the precursors dissociate, but they also provided evidence of a minor channel (