Experimental Study of a Fuel-Rich Premixed Toluene Flame at Low Pressure

Li, Yuyang; Zhang, Youmin; Tian, Zhen‐Yu; Yuan, Tao; Wang, Jing; Yang, Bin; Qi, Fei

doi:10.1021/ef800902t

Cited by 189 publications

(183 citation statements)

References 61 publications

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“…Therefore, these pathways may also account for the synthesis of indene in 'real' hydrocarbon flames. [14][15][16][17][18][19] Besides the PAH indene, we also detected three acyclic isomers -phenylallene and 3-phenyl-1-propyne (allene system) and phenylallene and 1-phenyl-1-propyne (propyne system) and proposed their formation routes. We believe that this thermal chemical reactor will be a convenient source for 'directed' synthesis of more complex PAHs via reactions with C3 and C4 hydrocarbons under controlled conditions in future experiments.…”

mentioning

confidence: 99%

A VUV Photoionization Study of the Formation of the Indene Molecule and Its Isomers

Zhang

Kaiser

Kislov

et al. 2011

J. Phys. Chem. Lett.

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The aromatic indene molecule (C 9 H 8 ) together with its acyclic isomers (phenylallene, 1-phenyl-1-propyne, and 3-phenyl-1-propyne) were formed via a 'directed synthesis' in situ utilizing a high temperature chemical reactor under combustion-like conditions (300 Torr, 1,200-1,500 K) through the reactions of the phenyl radical (C 6 H 5 ) with propyne (CH 3 CCH) and allene (H 2 CCCH 2 ). The isomer distributions were probed utilizing tunable vacuum ultraviolet (VUV) radiation from the Advanced Light Source by recording the photoionization efficiency (PIE) curves at mass-to-charge of m/z = 116 (C 9 H 8 + ) of the products in a supersonic expansion for both the phenyl-allene and phenyl-propyne systems; branching ratios were derived by fitting the recorded PIE curves with a linear combination of the PIE curves of the individual C 9 H 8 isomers. Our data suggest that under our experimental conditions, the formation of the aromatic indene molecule via the reaction of the phenyl radical with allene is facile and enhanced compared to the phenyl -propyne system by a factor of about seven. Reaction mechanisms and branching ratios are explained in terms of new electronic structure calculations.Our newly developed high temperature chemical reactor presents a versatile approach to study the formation of combustion-relevant polycyclic aromatic hydrocarbons (PAHs) under welldefined and controlled conditions.

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mentioning

confidence: 99%

A VUV Photoionization Study of the Formation of the Indene Molecule and Its Isomers

Zhang

Kaiser

Kislov

et al. 2011

J. Phys. Chem. Lett.

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“…1 product mass spectrum following corona discharge on toluene in rare gas is qualitatively similar to product mass spectra for toluene in rare gas following pyrolysis [35] or in a flames [36]. In each of these cases there is a clear pattern of formation of higher mass aromatic products; products at masses below toluene are seen as well.…”

Section: Resultsmentioning

confidence: 61%

Post Discharge Chemistry of Aromatic Molecules in Rare Gas

Sulkes

2011

Plasma Chem Plasma Process

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We have employed 800 nm 150 fs laser pulses to carry out photoionization (PI) time-of-flight mass spectrometric detection of intermediates following corona discharges on aromatic molecules (alkylbenzenes and pyridine) in He, stabilized by subsequent supersonic gas expansions. Observed product peaks appear to be at least roughly in proportion to actual number densities; PI induced fragmentation of parent ions appears not to be excessive. Consequently, 800 nm fs PI should be useful for general product analysis applications in plasma chemistry. For most alkylbenzenes subjected to corona discharges in rare gas, the overall trends in product chemistry are similar in many respects to observed flame and pyrolysis chemistry in rare gases for the same species. Following discharge, as in those other cases, H deficient carbon radical fragments initially produced react in turn to form larger aromatic species. However, compared with flame/pyrolysis, discharge produced a larger number of fragment species, which can lead to a wider and somewhat different range of higher mass aromatic products. Co-addition of even a small component of O 2 to the discharge mixes has a potent effect in inhibiting formation of higher mass aromatic products in alkylbenzenes.

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“…Single point energy calculation was performed with a combination of B3LYP/6-31? ?G(2df,p) and MP2/6-31?G(2df,p) methods, which has been verified to have higher accuracy (Li et al 2009;Wolken et al 2007). Therefore, accurate energies were calculated using the following Eq.…”

Section: Methodsmentioning

confidence: 89%

Synchrotron vacuum ultraviolet (VUV) photo-induced fragmentation of cyclic dipeptides radical cations

et al. 2011

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Cyclic dipeptides, due to their chemical properties and various bioactivities, are very attractive for medicinal chemistry. Fragmentations of three simple cyclic dipeptides including cyclo(Gly-Gly), cyclo(Ala-Ala) and cyclo(Gly-Val) in the gas-phase are determined with synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (VUV PIMS) and theoretical calculations. Cyclo(Gly-Gly) and cyclo(Ala-Ala) show the similar fragmentation pathways. The primary decomposition reactions of cyclo(Gly-Gly) and cyclo(Ala-Ala) radical cations are found to be HNCO loss and CO elimination. The appearance energies (AEs) of fragment ions [CH2NHCOCH2]+• and [CH3CHNHCOCHCH3]+• are measured to be 10.21 and 9.66±0.05 eV, respectively, which are formed from cyclo(Gly-Gly) and cyclo(Ala-Ala) radical cations with HNCO elimination. Due to the stabilization of the radical cation of cyclo(Gly-Val) with isopropyl side group, the dominant fragment ion m/z 114 assigned as [C4H6N2O2]+• is produced by γ-H migration and i cleavage to lose propylene. The ionization energies (IEs) of three cyclic dipeptides decrease in the order cyclo(Gly-Gly) (9.33±0.05 eV)>cyclo(Ala-Ala) (9.21±0.05 eV)>cyclo(Gly-Val) (9.09±0.05 eV) from measurements of photoionization efficiency spectra. It implies that IEs of cyclic dipeptides are affected by substituent groups and symmetrical characterization of molecular structures. These observations of the chemical properties of cyclic dipeptides radical ion (M+•) may be important for understanding gas-phase molecular reactivity of 2,5-diketopiperazines and guiding diketopiperazine-based drug design.

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Experimental Study of a Fuel-Rich Premixed Toluene Flame at Low Pressure

Cited by 189 publications

References 61 publications

A VUV Photoionization Study of the Formation of the Indene Molecule and Its Isomers

A VUV Photoionization Study of the Formation of the Indene Molecule and Its Isomers

Post Discharge Chemistry of Aromatic Molecules in Rare Gas

Synchrotron vacuum ultraviolet (VUV) photo-induced fragmentation of cyclic dipeptides radical cations

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